Biology Dr Matthews

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What bonds do non metal atoms form?
Covalent bonds
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What bonds do metal and non metal atoms form?
Ionic
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What are the elements which make up 99% of us?
Carbon, oxygen, hydrogen and nitrogen (sulfur and phosphorus)
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What is 70% of the body made up of?
Water
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What is the other 30% made up of?
Chemicals
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What is 1% of chemicals made up of?
DNA
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What are the two chemicals which make up the chemicals?
Phospholipids and polysaccharides
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What is 6% of the chemicals made up of?
RNA
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How much of the 30% is proteins?
15%
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What are calcium ions for?
Nerve impulse transmission and muscle contraction
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What are sodium ions for?
Nerve impulse contraction and kidney function
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What are potassium ions for?
Nerve impulse transmission and stomatal opening
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What are hydrogen ions for?
Catalysis of reactions and pH detrermination
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What are ammonium ions for?
Production of nitrate ions by bacteria
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What are nitrate ions for?
Nitrogen supply to plants for amino acid and protein formation
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What are chloride ions for?
Balance positive charge of sodium and potassium ions in cells
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What are phosphate ions for?
Cell membrane formation, bone nuclei acid and ATP formation
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What are hydroxide ions for?
Catalyst of reactions and pH determination
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What are hydrogen carbonate ions for?
Maintainance of blood pH
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Why is university solvent a good property of water?
Means water can dissolve many substances
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What’s its biological role?
Enables many chemical reactions to occur in cytoplasms and enables substances to be transported
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Why is a high specific heat capacity a good property of water?
It can resist temperature changes
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What’s it biological role?
Provides a stable environment within cells and for aquatic life
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What is the biological role for water being liquid at room temperature?
Provides a liquid environment for cells and aquatic organisms
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Why is a high latent heat if vapourization a good property of water?
Needs a lot of energy to be turned into gas
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What’s it biological role?
Evaporation from the surface provides a cooling effect
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Why is a high latent heat of fusion a good property of water?
Needs a lot of energy to turn it into ice
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What’s its biological role?
Water in cells and aquatic habitats are slow to freeze so provides a stable environment
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Why is density a good property of water?
Less dense then water for floating because a lattice holds them further apart
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What’s its biological role?
Ice floats enabling aquatic organisms to survive in the water under ice
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Why is wetness a good property of water?
Cohesion= when hydrogen bonds form and stick together, and also water can stick to other polar substances= adhesive
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Why is capillarity a good property of water?
Means water can move up very thin tubes because it’s cohesive and adhesive
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What’s its biological role?
Allows plants to survive so water can travel up the stem
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Why is colour a good property of water?
So light can travel through it so aquatic life and plants can survive and photosynthesise
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Why is low viscosity a good property of water?
Helps capillary flow in plants
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Why is being difficult to compress a good property of water?
Structural support in plants and animals
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What properties of water are important for blood?
Good polar solvent, capillarity, low viscosity, cohesion and adhesion and coolant
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What properties of water are important for mitochondria?
Liquid, allows reactants to occur, polar solvent, substrate for some chemical reactions
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What are the three main groups of carbohydrates?
Monosaccharides, disaccharides and polysaccharides
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How do you form disaccharides?
In a condensation reaction which produces water
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What bonds forms in a disaccharide?
A 1 4 glycosidic bond
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How do you break a glycosidic bond?
Using a hydrolysis reaction (add water)
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What does glucose+ glucose make?
Maltose
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What does glucose and galactose make?
Lactose
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What does glucose and fructose make?
Sucrose
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What type of reaction is needed when joining monosaccharides together?
Condensation reaction which also makes water
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What is the opposite reaction to condensation reaction?
Hydrolysis
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What do u do to start a hydrolysis reaction?
Add water to break the glycosidic bond
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What is a pentose monosaccharides?
Molecule which contains 5 carbon atoms
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What are two examples of pentose monosaccharides?
Ribose=RNA, deoxyribose=DNA
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What are the two types of starch?
Amylose and amylopectin
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What is amylose and amylopectin made of?
Alpha glucose
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What is the structure and bond of amylose?
Compact helical structure with a 1-4 glycosidic bond
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What is the structure and bond of amylopectin?
Branched structure with a 1-4 glycosidic by bond
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Where are both amylose and amylopectin (starch) both found?
In plastids (organelles) in chloroplasts or amyloplasts
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What are the key feature of amylose?
Good as storage, insoluble, compact because of helical structure
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What are the key feature of amylopectin?
Good as storage, insoluble and easily hydrolised to release glucose monomers
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What is the structure of glycogen?
Branched alpha glucose with a 1-6 glycosidic bond
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Where is glycogen found?
Liver and muscle cells and fungi
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What are key features of glycogen?
Less dense and is more soluble than starch for quick energy sources, used for storage as well
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What is the structure and bonds of cellulose?
Beta glucose with a 1-4 glycosidic bond with every other beta rotating 180 degrees
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What are microfibriles to do with glucose chains?
Glucose chains are joined together by hydrogen bonds
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Where is cellulose found?
Makes cell walls and in human faeces
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What is the key feature of cellulose?
Most common organic polymer on earth which is very strong, is a polysaccharide and insoluble
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Name reducing sugars
Glucose, fructose, lactose, maltose and galactose
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Name non reducing sugar
Sucrose
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What can reducing sugar do?
Donate electrons or reduce another molecule or chemical
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How does benedicts solution change colour?
Copper (II) sulfate gains and electron from a reducing sugar turning it from blue to red
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What are the six functions of lipids?
Energy storage, energy source, membrane formation, insulation (electrical and thermal), protection of plant (waxy cuticle), some hormones
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What type of bond does a saturated fat have?
Single carbon bond
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What type of bond does an unsaturated fat have?
Double and single carbon bond
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What does the shape of the fat depend on ?
Wether it’s healthy or unhealthy
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What is a triglyceride made of?
Three fatty acid chains and one glycerol
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What elements are triglycerides made of?
Oxygen, hydrogen and carbon
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What diseases can be caused by high triglycerides levels?
Diabetes, obesity, chd
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What are the properties of lipids?
Insulation, energy, insoluble in water, fats oils waxes, supply th emits energy per unit fat
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What are the properties of carbohydrates?
Immediately used in respiration, glucose monomers, soluble apart from in stores
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What are the two subcategories of unsaturated fatty acids?
Trans or cis
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What is the difference between cis and trans fats?
Just the way the atoms/ groups are arranged around a double bond
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How are cis fats arranged?
The two ch2 groups at the top with the two h groups at the bottom
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How are trans fats arranged?
One ch2 group and h at the top and another ch2 and h at the bottom
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How does a cis fats arrangement affect its properties?
The arrangement creates the greatest kink so chains can’t pack closely together which results in weak attractive forces between chains leading to a liquid lipid rather than a solid
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Why are saturated fat molecules straight?
Because they contain only single carbon carbon bonds
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What is the basic structure of every amino acid?
One r group, one carboxyl group and one amine group
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What is different in each amino acid?
The r group and the range of chemicals it contains
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What are five of the 20 amino acids for?
Non essential roles so the body can make them
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What are six of the 20 amino acids needed for?
Conditional essential ness by children and infants
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What’s are nine of the 20 amino acids needed for?
Essential things as they can only be obtained by food
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What is a peptide?
A polymer made of amino acid molecules
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How to amino acids join?
By the amine and carboxyllic group connecting via the central atom
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What reacts when the bonds are formed between amino acids?
The hydroxyl in the carboxyllic group and the hydrogen in the amine group of another amino acid
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What is the result of a dipeptide forming?
A water molecule being released from the condensation reaction
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How do you break a peptide bond?
By adding water to start a hydrolysis reaction
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What is a polypeptide?
Many peptides joined together
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What is the catalyst called when forming a polypeptide?
Preptidyl transferase (in ribosomes)
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What makes polypeptides fold differently?
The different types of bond which form from different r groups in different amino acids
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Why’s the shape of a polypeptide so important?
Because different shapes means different functions
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What is the primary structure of a protein?
A sequence of amino acids joined directed by DNA instructions
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What are the bonds in the primary structure of a protein?
Peptide bonds only
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What is the secondary structure of a protein?
When the oxygen, hydrogen and nitrogen atoms of amino acids in terrace
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Which bonds are used in the secondary structure?
Hydrogen bonds which pull the protein into a alpha helix or beta sheet of amino acids
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What is the tertiary structure of a protein?
Folding of the protein into final structure which brings different r groups together so they can interact and fold further
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What are the different bonds and interactions between the tertiary structure of the protein?
Hydrophobic and hydrophilic interactions between polar and non polar r groups (weak), hydrogen bonds (weakest), ionic bonds between opposite r groups, disulfide bonds (bridges) covalent and strongest
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What do all the bonds and interactions do in the teritairy structure?
Produce a very complex shape with specialised characteristics and functions
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What is the quaternary structure of a protein?
From association of two or more individual proteins called subunits
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What are the bonds between quaternary structure?
They are the same as the ones in the tertiary structure between two proteins instead of one
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What types of subunits are enzymes made of ?
Two identical ones
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What types of subunits is insulin made from?
Two different ones
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What types of subunits is haemoglobin made from?
Four subunits with two identical pairs
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What depends on the way the protein folds?
The different r groups in the amino acids and if they are hydrophobic or hydrophilic
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Where do hydrophobic groups arrange themselves in a protein?
Inside the protein (shielded from water)
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Where do hydrophilic groups arrange themselves in a protein?
Outside of the protein
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How are peptides broken down?
By adding water to break the peptide bond which is catalysed by the enzyme protease which separates the amine and carboxyllic groups
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What is thin layer chromatography used for?
To separate individual components of a mixture eg, separate and identify mixture of amino acid in solution
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What are the two phases of thin layer chromatography ?
Mobile and stationary
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What does the mobile phase do ?
Pick up the amino acids and move then through the stationary phase
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What is applied to the stationary phase?
On top of a rigid substance (metal/ glass) a thin layer of silicone gel is applied
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How is thin layer chromatography carried out?
Like normal chromatography, then adding indicator to the results to observe the spots
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What is the equation for rF value?
Distance moved by substance divided by distance moved by solvent
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What are the two types of nucleaic acid?
DNA , RNA
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What elements do nucleotides and nucleic acid contain ?
Carbon, hydrogen, oxygen, nitrogen and phosphorus
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What does lots of nucleic acid make?
Nucleotides
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What is an individual nucleotide made of?
Pentose monosaccharide (5 C atoms), phosphate group (inorganic molecule), nitrogenous base ( complex organic molecule)
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What reaction is used to join nucleotides?
Condensation reactions
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What do the nucleotides bond to?
Pentose sugar covalently bonds with hydroxyl group
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What bond is between two nucleotides ?
A phosphodiester bond
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What give the DNA it’s strong sugar phosphate back bone?
The phosphodiester bonds
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How are phosphodiester bonds broken?
By hyrdrolysis
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What are the four different base pairs?
Thymine + adenine, cytosine + guanine
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Define pyramidines
Smaller bases with single carbon ring structures
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Define purines
Larger bases with double carbon ring structures
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What is the double helix structure of DNA?
Two stands of polynucleotides coiled into a helix
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How are the two DNA strands held together?
By hydrogen bonds between the bases
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Define anti parallel
Two strands of DNA arranged which run in the opposite direction
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What does the pairing of bases allow to happen?
DNA to be copied and transcribed
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How many hydrogen bonds are between thymine and adenine?
2
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How many hydrogen bonds are between cytosine and guanine?
3
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How do the bases link together?
By a small pyramindine base fitting into a large purine base
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What does a constant distance between the DNA backbone mean ?
That a parallel polynucleotide chain is maintained
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What does the sequence of bases mean?
Genetic coding and info
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What is role of RNA?
To transfer genetic info from DNA to proteins to make enzymes and tissues for body
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Why is the DNA copied into mRNA?
So it can fit through the nuclear pore
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What is RNA made of ?
A phosphate group and ribose and base
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What is different in RNA with thymine?
It’s replaced with a different base called uracil
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What is pentose sugar replaced with RNA?
The ribose
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What happens to RNA after it’s been used?
It dissolves in cytoplasm
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How does the RNA dissolve in the cytoplasm?
By the bonds being hydrolysed which releases the nucleotides which are reused
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How is DNA replicated?
Helix unwinds, hydrogen bonds are broken, nucleotides now open, free nucleotides join to open nucleotides, sugar phosphate backbone formed of new strand, DNA reforms
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What does DNA polymerase do?
Catalysts formation of phosphodiester bonds between nucleotides
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What does the DNA ligase enzyme do?
Joins DNA strands and forms phosphodiester bond
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What does the enzyme DNA helicase do ?
Unwinds and separates DNA strand
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What is the purpose of DNA?
Contains genetic info and codes for proteins
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What is a gene?
A hereditary unit which is a section of DNA
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What are the three types of protein?
Globular protein, conjugated protein and fibrous protein
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How do globular proteins form?
Fold into tertiary structure and the hydrophobic r group is kept away from the aqueous environmental and hydrophilic is on the outside of the protein
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What doe the structure of the globular protein enable it to do?
Make it soluble in water as they’re compact and a spherical shape as well
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What is an example of a globular protein ?
Insulin which is a hormone used for blood glucose regulation and so needs to be dissolved into blood stream and have a specific shape so they can fit into specific receptors in cell surface membrane s
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What are globular proteins sensitive to?
pH and temperature change
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What are conjugated proteins?
Proteins which contain a non protein component (prosthetic group)
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What is a protein without a prosthetic group called?
Simple protein
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Examples of prosthetic groups
Glycoproteins, lipoprotein and metal ions
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What is an example of a conjugated protein ?
Haemoglobin which is a quaternary protein which has two alpha and two beta subunits which each contain a prosthetic haem group
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How can haemoglobin deliver oxygen?
By the iron ions present in the haem group being able to reversibly combine with oxygen molecules
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Why are fibrous proteins long and insoluble?
Because they have a high proportion of amino acids with hydrophobic r groups in their primary structure e
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What are the properties and shape of a fibrous protein?
A strong long molecule which isn’t folded into a complex 3D shape which is insoluble
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What is an example of a fibrous protein ?
Elastin found in elastic fibres which give structures flexibility to expand and return to normal size
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What is a quaternary fibrous protein example?
Tropoelastin which can stretch and recoil like a spring and the structure is stabilised by cross linking covalent bonds involving amino acid lysine
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What are two examples of phosphorylated nucleotides?
ADP and ATP
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How do you phosphorylate a nucleotide ?
Add one or more phosphate groups to the nucleotide
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What is the composition of ADP?
D= diphospate, base adenine, ribose and two phosphate groups
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What is the composition of ATP?
Base adenine, ribose and three phosphate groups
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What is the function of ATP?
Provides energy for chemical reactions in the cell
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How is ATP synthesised?
From ADP and an inorganic phosphate group using the energy generated from an energy releasing reaction
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How is energy released by ATP?
ATP is broken back down into ADP with energy being released from the phosphate bond
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What bond holds two nucleotides together?
Phosphodiester between two phosphate groups
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Define gene
A sequence of DNA which codes for a polypeptide
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Recall the process of translation
mRNA formed in nucleus, travels out of nuclear pore, attaches to ribosome
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What is mRNA ?
Messsenger RNA made in the nucleus which carries genetic code from the DNA to the cytoplasm
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What is tRNA ?
Found in the cytoplasm which has an amino acid binding site with anti codons which carries the amino acid to the ribosome during translation
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What is rRNA ?
Ribosomal rna, forms the two subunits of a ribosome helping to catalyse the formation of peptide bonds between the amino acids
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How is the genetic code non overlapping>
Each base is read in a triplet separate from the triplet before and after it so bases are not shared
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What does it mean when the genetic code is generate?
Some amino acids are coded for by more than one base triplet
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What is the first stage of protein synthesis?
Transcription
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Describe the transcription stages
RNA polymerase breaks dna strand, strand is used as a template and free nucelotides line up, hydrogen bonds form forming mRNA, stops after reaching stop codon, and goes through nuclear pore
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What is the second stage of protein synthesis?
Translations
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Describe the process of translation
mRNA attaches to ribosome, tRNA carries amino acid to ribosome with anticodon, ribosomal RNA catalyses formation of peptide bond between amino acids
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What can enzymes affect?
Structure and function
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What are the two types of enzymes?
Extra cellular and intra cellular
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What is an example of an intracellular enzyme?
Catalase- breaks down hydrogen peroxide so its not harmful
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What is an example of extra cellular enzyme?
Amylase and trypsin- in the human digestive system
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What type of protein are enzymes?
Globular proteins
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What is the active site of the enzyme related determined by?
Tertiary structure
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How does an enzyme lower the activation energy?
Making reactions happen at lower temperature when the enzyme substrate complex is formed
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How does the enzyme substrate complex forming lower the activation energy?
Close joining reduces any repulsion between molecules, for breakdown of a substance fitting into the active site puts strain on the substrate so breaks up easier
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What is the lock and key model ?
Substrate fits completementary to the active site
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What is the induced fit model ?
As the substrate binds to the active site, the active site changes shape slightly to fit the substrate slightly more closely
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What are the four factors which effect enzyme activity?
Temperature, pH, enzyme concentration, substrate concentration
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How does temperature effect enzyme activity?
More kinetic energy= Faster movement meaning a substrate is more likely to collide with enzyme. Too high temp= active site denatured
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*** does pH effect enzyme activity?
H+ ions and OH- ions can mess up ionic and hydrogen bonds that hold enzymes tertiary structure in place so enzyme is denatured
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How does enzyme concentration affect rate of reaction?
More enzyme molecules= more likely collision so more likely to be enzyme substrate complexes. If substrate is limited then sometimes adding more enzyme has no effect
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How does substrate concentration affect rate of reaction ?
Higher conc means more likely collision so more likely to be broken down, only up to saturation point where all activie sites are full so no difference is made
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Why does the rate of reaction decrease over time?
?Because the substrate is being used up so fewer collions with occur
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What is a cofactor?
A non protein substance bound to the enzyme
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What do cofactors do?
Help the substrate and enzyme bind together
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What is the difference between a cofactor and co enzyme?
Cofactors= Inorganic, coenzyme= organic molecules
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Why are co enzymes also called carriers?
Because they move chemical groups between enzymes, they are also recycled
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What is the name for if a co factor is permanently bound to an enzyme?
A prosthetic group
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How can enzyme activity be stopped?
By using an enzyme inhibitor
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What are competitive inhibitors?
Molecules which have the same shape as the substrate so they block the active site
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What are non competitive inhibitors?
Molecules which bind away from the active site changing its shape so the substrate can’t bind
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What bonds make an inhibitors irreversible?
Covalent bonds
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What bonds make inhibitors reversible?
Weak hydrogen or ionic bonds
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What are examples of drugs which are enzyme inhibitors?
Antiviral drugs and antibiotics, cyanide, malonate, arsenic (types of poisons)
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What is a metabolic pathway?
A series of connected metabolic reactions where the product of the first reaction is used in the second
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What is end product inhibition?
When the final product of a metabolic pathway inhabits an enzyme which acts earlier on in the pathway
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What is the benefit of end product inhibition?
It’s a good way of regulating the pathway and controlling the amount of end product that gets made
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How can enzyme inhibition help to protect cells?
By acting as inactive precursors in metabolic pathways to prevent them causing damage to cells
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What are the functions of cell surface membranes?
Act as a barrier between the cell and the environment, recognition of other cells and cell signalling
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What are the functions of membranes inside the cell?
Compartmentalisation, transportation in vesicles, which substances enter and leave the cell, site of chemical reactions
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What is known as the fluid mosaic structure?
A phospholipid bilayer containing cholesterol and protein molecules which is constantly moving
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What do the phospholipids do in the bilayer?
Forms a barrier to dissolved substances, due to arrangement of hydrophobic tails and hydrophilic heads
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What is cholesterols role in membranes?
Gives it stability, binding to the hydrophobic tails causing them to pack more closely together.
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What is the function of proteins in the membrane?
Control what enters and leaves the cell, some form channels some form carriers and some act as receptors
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What is the function of glycolipids and glycoproteins in the membrane?
Stabilise the membrane forming hydrogen bonds with water molecules, site where drugs and antibodies bind, receptors for cell signalling, also antigens
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How do cells communicate with each other?
Using messenger molecules where one cell releases a hormone, this travels to another cell and that binds to a receptor on its cell membrane
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How do the cell signals go to the right cells?
Receptor proteins on the surface have complementary shapes
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What is a cell which responds to a particular messenger molecule called?
A target cell
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How do drugs work>
Bind to receptor either triggering a response or blocking the receptor to prevent it from working
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How does increasing the temperature affect membrane permeability?
0-45 degrees causes phospholipids to move around increasing its permeability. 45 degrees+ causes bilayer to melt down becoming more permeable
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How does changing the solvent affect membrane permeability?
Surrounding cells in solvent (ethanol) increases permeability because solvents dissolve the lipids in the membrane losing its structure
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Define diffusion
Net movement of particles from an area of high conc to an area of low conc
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How do small, non polar molecules move across the membrane?
They can diffuse through spaces between phospholipids
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What does the rate of diffusion depend on ?
Concentration gradient, thickness of exchange surfaces, surface area, temperature
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What two molecules does facilitated diffusion use>
Carrier proteins and channel proteins
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Why does the membrane have to use facilitated diffusion?
Some molecules are too large or are charged
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What do carrier proteins do and how do they work>
Move large molecules into or out of the cell with the molecules attaching to the carrier protein, the protein then changes shape and releases the molecule on the other side of the membrane
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What do channel proteins do and how do they work?
Form pores in membrane for changed particles to diffuse through
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Define active transport
Uses energy to move particles from a low concentration to a high concentration
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How do carrier proteins perform active transport>
The molecule attaches to the protein, changes shape and moves across membrane with energy from ATP being used to move solute against the conc gradient
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What is endocytosis and when is it used?
When molecules are too large to be taken into a cell and so the plasma membrane forms a vehicle around it this also uses ATP
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What is exocytosis and when is it used?
When a vesicle containing substances which need to be excreted from the cell and so fuse with the plasma membrane releasing the substances using ATP
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Define osmosis
The movement of water molecules across a partially permeable membrane from an area of high water potential to an area of low water potential
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What substance has the highest water potential?
Pure water
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What happens to an animal cell when its put into a hypotonic solution?
Net water movement into the cell so the cell bursts as the water potential is higher outside the cell
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What happens to an animal cell when it put into an isotonic solution?
Stays the same as the movement of water molecules is the same in and out
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What happens to an animal cell when its put into a hypertonic solution?
The cell shrinks as the water molecules move out of the cell from a higher water potential to a lower one
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What is cell growth and dna replication called in the cell cycle?
Interphase
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What is the period of cell division called?
M phase
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What two processes does the m phase contain?
Mitosis (nuclear division) and cytokinesis (cytoplasmic division)
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What three phases is interphase divided into?
G1, S and G2
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Describe the whole cell cycle
The cell replicated DNA, cell keeps growing an proteins needed for cell division are made, G2 checkpoint where the DNA is checked to see its not damaged, Mphase, metaphase checkpoint, cell grows and new organelles made, G1 checkpoint where checked for che
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What are the 4 stages of mitosis?
Prophase, metaphase, anaphase, telophase
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What is the prophase>
Chromosome condense with centrioles moving to opposite ends of the cell forming a network of protein fibres called a spindle, nuclear envelope breaks down and chromosomes are free in the nucleus
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What happens in the metaphase?
Chromosomes line up along middle of cell and become attached to the spindle by their centromere. Metaphase checkpoint then checks that all chromosomes are attached
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What happens in the anaphase?
Centromeres divide separating the pair of chromatids with the spindles contracting pulling the chromatids to opposite ends of the cell
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What happens in telophase?
Chromatids reach oppposite poles on the spindle, they uncoil and become chromosomes again with a nuclear envelope forming found them creating two nuclei
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What happens in cytokinesis?
Cytoplasm divides using starting in anaphase and ending in telophase
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How can you observe the cell cycle?
By staining the chromosomes
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Why is meiosis a form of reduction division ?
Because the cells that divide have a full number of chromosomes but the cells form only have half
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What are cells called that have half the number of normal chromosomes?
Haploid cells
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Why are cells formed by meiosis genetically different?
Because they end up with different combination of chromosomes
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Describe the stages of meiosis 1
Phrophase 1, metaphase1, anaphase1, telophase1
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What happens in propahse1?
Chromosomes condense, arrange into homologous pairs and crossing over occurs, centrioles then move to opposite ends of the cell forming spindle fibres with the nuclear envelope breaking down
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What happens in metaphase 1?
Homologous pairs line up across the centre and attach to spindle fibres by their centrometeres
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What happens in anaphase1?
Spindles contract separating homologous pairs with one chromosome going to each end of the cell
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What happens in telophase 1?
Nuclear envelope forms round each group of chromosomes
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What happens in meiosis II?
The exact same as meiosis 1 but in each new sister cell inherits one chromatid from each chromosome forming four haploid cells
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What happens to chromatids during prophase 1?
The homologus pairs come together and pair up, the chromatids twist around each other and bits of chromatid swap over
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Why do the chromatids swap over?
Because they contain the same genes but now have different combinations of alleles
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What are the two main events which leads to meiosis producing cells which are genetically different?
Crossing over of chromatids and independent assortment of chromosomes
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How does the crossing over of chromatids in meiosis 1 create genetic variation?
That each four daughter cells contain chromatids with different alleles
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How does independent assortment of chromosomes create genetic variance?
The random arrangement of the homologous chromosomes means each combination of the genetics is different in each daughter cell
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What are stem cells?
Undifferentiated type of cells
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What process do the stem cells use to become more specialised?
Differentiation
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What do the stem cells in the bone marrow differentiate to become?
Erythrocytes and neutrophils
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What do stem cells in the meristems of plant differentiate into?
Xylem vessels and phloem sieve tubes
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How are neutrophils specialised?
They’re flexible to be able to engulf pathogens and have many lysosomes to be able to breakdown engulfed particles
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How are erythrocytes specialised?
Biconcave shape for large surface area, no nucleus and contain haemoglobin so they can carry more oxygen
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How are epithelial cells specialised?
Have interlinking cell membranes with ciliates epithelia so they can mov particles away and are thin to provide efficient diffusion of gases
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How are sperm cells specialised?
Have flagellum to swim to egg, have lots of mitochondria for energy for swimming, acrosome contains digestive enzymes to enable sperm to penetrate egg
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How are palisade meosphyll cells specialised ?
Contain many chloroplasts to absorb sunlight and thin walls so carbon dioxide can easily diffuse in
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How are root hair cells specialised?
Large surface area for absorption, thin permeable wall, extra mitochondria for energy for active transport
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How are guard cells specialised?
Found in pairs, with thickened inner walls and thinner outer walls to force them to bend outwards, light sensitive to allow substance to diffuse in and out
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Define tissue
A group of cells and any extra cellular material that are specialised to work together to carry out a particular function
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What is squamous epithelium?
A single layer of flat cells lining a surface found in many places eg, the alveoli in the lungs
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What is ciliates epithelium?
A layer of cells covered in cilia foun don the surface where things need to be moved eg, lining of trachea
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What is muscle tissue ?
Made up of bundles of muscle fibres, smooth, cardiac and skeletal muscle
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What is cartilage made of?
Connective tissue found in the joints which shapes and supports the ears nose and windpipe
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What is the function of xylem tissue?
Transports water and minerals from the roots to other places in the plant in one direction and supports the plants
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What two cells make up the xylem?
Parenchyma cells and xylem vessel cells
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What is the function of phloem tissue?
Transports sugars around plant arrranged in tubes
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What cells is the phloem tube made of?
Sieve cells, companion cells and some ordinary plant cells
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Define organ
Group of different tissues that work together to perform a particular function
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Define organ system
A group of organs working together to form an organ system to perform a particular function
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