OCR Biology A Module 2 Flashcards

prokaryotic organisms
simple single celled organisms, extremely small (2μm), free, circular dna, no nucleus, peptidoglycan cell wall, no membrane-bound organelles, helix flagellum, small ribosomes (20nm)
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eukaryotic organisms
complex multicellular organisms, larger (10-100μm), linear dna, nucleus, cell wall is either chitinous, cellulose, or non existent, many organelles, flagellum in 9+2 formation, larger ribosomes (20nm)
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parts of cells with specific functions. each comprise the cell ultrastructure.
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organelles found in a typical animal cell
cell surface membrane, rough endoplasmic reticulum, smooth endoplasmic reticulum, golgi apparatus, lysosome, ribosome, nucleus, nucleolus, nuclear envelope, cytoplasm, mitochondria
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organelles found in typical plant cell
cell surface membrane, cell wall, chloroplast, vacuole, nucleus, nucleolus, nuclear envelope, cytoplasm, smooth endoplasmic reticulum, rough endoplasmic reticulum, plasmodesmata, mitochondria, golgi apparatus, vacuole
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cell surface membrane
the membrane found on the surface of animal cells and inside the cell walls of plant and prokaryotic cells. phospholipid bilayer. regulates the movement of substances into and out of the cell. receptor molecules allow it to respond to chemicals.
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cell wall
a rigid structure that surrounds plant cells, made of the carbohydrate cellulose. supports plant cells.
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nucleus (structure)
a large organelle surrounded by a nuclear envelope (a double membrane) which is heavily porous. contains chromatin (made from dna and proteins, and a nucleolus.
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nucleus (function)
the nucleus controls the cells activities by controlling the transcription of dna. dna contains instructions to make proteins. the pores allow substances to move between the nucleus and the cytoplasm. the nucleolus makes ribosomes.
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a round organelle surrponded by a membrane, with no clear internal structure. contains digestive enzymes. these re kept separate from the cytoplasm by the surrounding membrane. can be used to digest invading cells or to break down worn organelles.
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small organelle that can be free floating or attached to the rer. made up of proteins and rna. not surrounded by a membrane. site where proteins are made.
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rough endoplasmic reticulum (rer)
system of membranes enclosing a fluid filled space. surface covered with ribosomes. folds and processes proteins that have been made at the ribosomes.
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smooth endoplasmic reticulum (ser)
a system of membranes enclosing a fluid filled space. synthesises and processes lipids.
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small fluid filled sac in the cytoplasm, surrounded by a membrane. transports substances in and out of the cell via the cell surface membrane. also transports between organelles. some are formed be golgi apparatus or er, others formed at membrane.
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golgi apparatus
grouo of fluid filled membrane bound flattened sacs. vesicles often at the edges. processes and packages new lipids and proteins, also makes lysosomes.
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double membrane, inner is folded to make cristae. inside is the matrix containing enzymes for respiration. site of aerobic repiration where atp is produced.
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small, flattened structure. double membrane, internal membrane folded into thylakoids which are stacked into grana, and linked by lamellae surrounded by stroma fluid. site of photosynthesis.
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small, hollow cylinders made of microtubules. found in animal cells and some plant cells. involved in the separation of chromosomes in cell division.
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small hair-like structures found on some plasma membranes in animal cells. outer membrane, ring of nine pairs of protein microtubules inside, single pair in the middle, allowing movement. moves substances along plasma membrane.
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on eukaryotic cells; like cilia but longer. protrusions from the cell surface and are surrounded by plasma membrane. propel cells forwards.
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difference between ribosomes
free floating ribosomes crete proteins that remain in the cytoplasm, rer ribosomes make proteins that are excreted or attached to the cell membrane.
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steps of protein production
new proteins produced at the rer are folded and processed there. transported to the golgi apparatus in vesicles, where they may undergo further processisng, e.g. sugar chains are trimmed or added. enter vesicles for exocytosis.
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network of threads in the cytoplasm. arranged as microfilaments and microtubules. support the cell's organelles, strengthen and maintain shape, respnsible for intracellular transport, its proteins can cause the cell to move.
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magnification equation
magnification = image size / object size
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conversion of mm to μm to nm
x 1000
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how much bigger the image is than the specimen
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how detailed an image is (how well a microscope distinguishes between two points which are close together.
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light microscopes
use light. have a lower resolution than electron microscopes. maximum resolution of 0.2μm. usually used to look at whole cells or tissues. maximum useful magnification is x1500.
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laser scanning confocal microscopes
use laser beams to scan a specimen usually tagged with florescent dyes. laser beam>lens>beam splitter>specimen>pinhole>detector>computer
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types of electron microscope
transmission electron microscope (tem) and scanning electron microscope (sem)
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electron microscope
uses electrons instead of light to form an image. higher resolution that light, therefore they give more detailed images. always in b&w. samples are treated with heavy metals; metal ions scatter fired electrons to contrast different structures.
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use electromagnets to focus a beam of electrons, transmitted through specimen to create 2d image. density = darkness as they absorb more electrons. specimens need to be thinly sliced. resolution 0.0002μm, magnification >1000000x
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scan a beam of electrons across the specimen, knock off electrons from the specimen which are gathered in a cathode ray tube to form an image. 3d, lower resolution than tem (o.oo2μm). magnification < 500000x
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functions of water
reactant, solvent, transport, temperature control (due to high specific heat capacity and high latentt heat of evaporation), habitat
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polarity of water
because the shared negative hydrogen electrons are pulled towards the oxygen atom, the other side of each hydrogen arom is left with a slight positive charge. the unshared electrons in the oxygen atom give it a slight negative charge.
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hydrogen bonding in water
the slightly negatively charged oxygen atoms attract the slightly positively charhed hydrogen atoms. hydrogen bonds threfore hold molecules together, giving water its useful properties.
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high specific heat capacity
energy needed to raise the temperature of 1g by 1°C. hydrogen bond between molecules can absorb a lot of energy.
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high latent heat of evaporation
it takes a lot of energy to break the hydrogen bonds between molecules therefore a lot of energy is used up when water evaporates
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very cohesive
attractions between molecules of the same type. water are cohesive because they are polar. surface tension.
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lower density when solid
water molecules are held further apart in ice than they are in water because they form a lattice with four hydrogen bonds.
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good solvent
due to its polarity, the positive end of water will be attracted to negative ions, and vice versa. ions will be totally surrounded by water molecules: they dissolve.
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complex molecules with a relatively large molecular mass, e.g. proteins
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groups of macromolecules. large, complec molecules composed of long chains of monomers joined together.
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small, basic molecular units, e.g. amino acids.
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condensation reactions
forms a chemical bond between monomers, releasing a water molecule
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hydrolysis reactions
break polymers into monomers with the supply of a water molecule.
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made of carbon, oxygen and hydrogen (1:1:2).
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monomers that make up carbohydrates, e.g. glucose and ribose
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monosaccharide with six carbon atoms (hexose). alpha and beta have their hydroxyl group switched on carbon one. chemical bonds contain energy, soluble therefore transported easily.
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monosaccharide with five carbon atoms (pentose). sugar component of rna nucleotides.
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glycosidic bonds
bonds joining monosaccharides.
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two monosaccharides joined by a glycosidic bond, e.g. maltose, (two a glucose), lactose (b glucose and galactose), and sucrose (a glucose and fructose)
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more than two monosaccharides joined by glycosidic bonds.
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main energy storage material in plants. insoluble in water so it doesnt cause water to enter cells via osmosis. mixture of two polysaccharides of a glucose: amylose and amylopectin
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long, unbranched chain of a glucose. angles of the glycosidic bonds give it a coiled structure, like a cylinder. compact.
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long, branched chain of a glucose. side branches allow the enzymes that break it down to get easier access to the glycosidic bonds. glucose can be released quicker.
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main energy storage material in animals. polysaccharide of a glucose. similar structure to amylopectin, but has more side branches. compact.
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major component of cell walls in plants. long, unbranched chains of b glucose. strong microfibril structure to due hydrogen bonds.
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macromolecules containing carbon, hydrogen and oxygen.
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one molecule of glycerol with three fatty acids attached. synthesised by the formation of an ester bond between each fatty acid and glycerol molecule.
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ester bonds
three in one triglyceride. formed by a condensation reaction
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formation of an ester bond
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fatty acids
long hydrophobic hydrocarbon tails, making lipids insoluble in water. -cooh
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saturated fatty acids
no double bonds between carbon atoms in their hydrocarbon tails. it is therefore saturated with hydrogen.
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unsaturated fatty acids
at least one double bond between carbon atoms, causing the chain to kink. double bonds can react with hydrogen to form single bonds.
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similar to triglycerides insofar as a fatty acid is replaced by a hydrophilic phosphate group head.
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hydrocarbon ring structure attached to a hydrocarbon tail. the ring structure has a polar hydroxyl (oh) group attached to it.
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function of triglycerides
energy storage molecule. some bacteria use it to store both energy and carbon. good for storage because long tails contain lots of chemical energy. insoluble; no water enters by osmosis. bundle in droplets.
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function of phospholipids
cell membranes control what enters and leaves a cell, therefore bilayer of hydrophilic heads and hydrophobic tails acts as a barrier to water-soluble substances.
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function of cholesterol
strengthen cell mebrane by interacting with bilayer due to its small size and flattened shape. bind to hydrophobic tails making them pack closely, making the membrane less rigid.
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polymers of amino acids (polypeptide chains).
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amino acids
carboxyl group (-cooh) and amino croup (-nh2) attached to a carbon atom, with a variable group (r) determining its function. all contain arbon, hidrogen, oxygen and nitrogen.
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peptide bonds
bonds lining amino acids into polypeptides.
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primary structure
sequence of amino acids in a polypeptide chain held together by peptide bonds.
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secondary structure
hydrogen bonds form between -nh and -co groups making it coil ito an alpha helix or fold into beta pleated sheets.
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tertiary structure
chain is folded further here as more bonds form between different parts of the polypeptide chain. for proteins made from a single polypeptide chain, the tertiary structure forms their final 3d structure.
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ionic bonds
attractions between negatively and positively charged r groups on the molecule
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disulfide bonds
when two molecules of cysteine (amino acid) the sulfu atoms bond
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hydrophobic and hydrophilic interactions
affects how the protein folds in the final structure due to repelling as hydrophilic groups tend to be pushed to the outside.
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hydrogen bonds
form between slightly positively charged and slightly negatively charged hydrogen atoms in the r groups.
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quarternary structure
way multiple polypeptide chains are assembled. can include prosthetic groups, e.g. haem. determined by the bonds of the tertiary structure. final 3d structure.
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globular proteins
round and compact. hydrophilic r groups on the outside of the molecule, therefore they are soluble and easily transported. examples are insulin, haemoglobin and amylase. most enzymes are globular.
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fibrous proteins
tough and rope shaped. insoluble and strong. structuaral proteins and fairly unreactive. examples are collagen, keratin and elastin.
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inorganic ions
atom with an electric charge and doesnt contain carbon.
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ion with a positive charge
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transmission of nerve impulses and the release of insulin from the pancreas. cofactor for enzymes. important for bone formation.
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generating nerve impulses, muscle contraction, and regulating fluid balance
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same as sodium, and activates essential enzymes for photosynthesis
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effects ph balance. important for light dependent stage of photosynthesis and respiration.
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important source of nitrogen for plants
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ion with a negative charge
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important source of nitrogen for plants
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buffer to maintain the ph of blood
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involved of chloride shift which maintains the ph of the blood in gas exchange. cofactor for amylase. used in the transmission of nerve impulses.
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involved in photosynthesis and respiration reactions. synthesis of many biological molecules.
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affects ph
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biuret test
for proteins; the test solution has to be alkaline, so first sodium hydroxide solution is added, and then copper (ii) sulfate solution. if protein is present the solution will turn purple, rather than stay blue.
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iodine test
for starch; add iodine dissolved in potassium iodide solution to the test sample. if starch is present, the solution will turn blue-black rather than brown.
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emulsion test
for lipids; shake the test substance with ethanol for a minute, then pour the solution into water. if lipid is present, the solution will turn milky-white rather than transparent.
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benedicts test (reducing)
for sugars; add benedicts reagent to a sample and heat in a water bath that has been brought to boil. if positive a coloured precipitate will form. the more sugar present, the more the colour will change (from blue).
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benedicts test (non-reducing)
for sugars; non-reducing sugars may still be present, therefore they must be broken into monosaccharides. add dilute hcl to a sample and heat in a boiling water bath, add sodium hydrogencarbonate to neutralise, then carry out as normal.
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you can use the benedicts test and a colorimeter to get a quantitative result. measures absorbance.
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calibration curve
graph of controls in order to estimate the quantity of an unknown variable
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serial dilution technique
make five serial dilutions within a factor of two; start with an initial glucose concentration of 40Mm. at 10cm3 to the first test tube and then 5cm3 of dilute water to the rest. add 5cm3 of the first solution to the second and mix. repeat.
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measuring absorbance of known solutions
do benedicts test on each. remove precipitate. use colorimeter to measure remaining solution by setting it on the red filter, calibrate the machine to zero with distilled water, then read and record the solutions in the cuvettes.
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device that uses a biological molecule, e.g. an enzyme, to detect a chemical. the biological molecule produces a chemical signal which is transferred to an electrical signal via a transducer.
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separation of mixtures to identify the components.
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mobile phase
stage where the molecules are moving. this is the liquid solvent.
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stationary phase
stage where the molecules arent moving. this is the piece of chromatography paper.
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four steps of chromatography
the mobile phase moves through or over the stationary phase, the components of the mixture spend different times in each phase, if spent longer in the mobile phase they travel faster and further, the times in each phase separate the mixture.
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rf value
rf value = distance travelled by spot / distance travelled by solvent
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biological molecule comprised of a pentose sugar, a phosphate group, and a nitrogenous base.
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importance of nucleotides
monomers of dna and rna (types of nucleic acid). dna stores genetic information, rna makes proteins from dna's instructions. atp and adp are also nucleotides.
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structure of dna nucleotides
sugar: deoxyribose, nitrogenous bases: adenine, thymine, cytosine, guanine, each dna nucleotide has the same phosphate group. each molecule of dna has 2 polynucleotide chain.
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structure of rna nucleotides
sugar: ribose, nitrogenous bases: adenine, uracil, cytosine and thymine, each rna molecule had the same phosphate group. one polynucleotide strand.
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two carbon-nitrogen rings joined together. adenine and guanine.
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one carbon-nitrogen ring, cytosine, thymine, uracil.
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atp and adp
phosphorylated nucleotides. adenine, ribose, and 2-3 phosphate groups.
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polynucleotide structure
phosphodiester bond between phosphate group and pentose sugar. this is the sugar-phosphate backbone.
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dna structure
two polynucleotide strands joined by hydrogen bonds into a double helix. complementary base pairing. two hydrogen bonds between adenine and thymine, three between cytosine and guanine. strands are antiparallel which forms the twist.
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purifying dna; step 1
break up the cells in your sample
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purifying dna; step 2
make a solution of detergent, salt, and distilled water
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purifying dna; step 3
combine in a beaker
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purifying dna; step 4
incubate at 60°C for 15 minutes, the detergent breaks down the cell membranes, the salt binds to the dna and causes it to clump, the temperature of the bath stops enzymes from breaking down the dna.
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purifying dna; step 5
place into an ice bath
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purifying dna; step 6
filter with filter paper and a funnel. transfer a sample to clean boiling tube.
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purifying dna; step 7
add protease enzymesto break down some proteins in the mixture, e.g., proteins stuck to the dna
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purifying dna; step 8
dribble ethanol down the side of the test tube so that it forms a layer on top
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purifying dna; step 9
a white precipitate is formed
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dna replication
performed before cell division; dna helicase breaks hydrogen bonds between strands and unzips the helix, each strand acts as a template for a new one, free floating dna nucleotides join to exposed bases, joined to strands by dna polymerase.
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semi-conservative replication
half of the strands of the new dna are from the orginal strands.
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accuracy of dna replication
it is extremely accurate to ensure genetic information is conserved each time dna is replicated. random, spontaneous mutations can occur, which change the dna base sequence, causing an abnormal protein to be produced.
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sequence of dna nucleotides that codes for a polypeptide. the sequence of amino acids in a polypeptide codes for the primary stucture of a protein.
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three bases that code for an amino acid
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single polynucleotide strand madde in the nucleus during transcription. carried the genetic code from the dna in the nucleus to the cytoplasm where its used to make a protein during translation. groups of three adjacent bases are codons.
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folded polynucleotide strand held together by hydrogen bonds. specific sequence of bases at one end called an anticodon and have an amino acid binding site at the other end. carries the amino acids needed to make proteins.
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forms the two subunits on the ribosome (along with proteins). moves along the mrna strand suring protein synthesis. helps to catalyse the formation of peptide bonds between amino acids.
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the genetic code
the sequence of base triplets in dna or rna which codes for specific amino acids. it is a non-ovelapping sequence.
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more possible combinations of triplets than there are amino acids, therefore multiple codons cose for the same amino acid.
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rna polymerase attaches to the dna breaking hydrogen bonds, preparing a strand as a template. complementary rna is formed by lining up free nucleotides (urasil). continuous process, gradually recoils. mrna leaves through nuclear pores (stop codon).
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translation (1)
mrna attaches to a ribosome where trna molecules carry amino acids. thye anticodon on the trna attaches to the rna by base pairing. this is repeated across the strand. rrna catalyses th formation of a peptide bond between the amino acids brought fort
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translation (2)
rrna catalyses th formation of a peptide bond between the amino acids brought forth by the trna, joining them. the trna molecules move away, leaving their amino acids behind. this process continues until a stop codon is reached.
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speed up chemical reactions by acting as biological catalysts. they don't get used up in the reaction and catalyse metabolic reactions. can affect structure or function, can be intra or extracellular.
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enzyme structure
globular proteins with an active site determined by the tertiary structure. the substrate must fit into the active site for the reaction to be catalysed.
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enzyme-substrate complex
when a substrate binds to an enzyme's active site
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activation energy
the amount of energy that needs to be supplied to the chemicals before the chemical reaction will start. often provided as heat.
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enzymes and rate of reaction
enzymes reduce the amount of activation energy needed by forming an enzyme-substrate complex as they can a) hold molecules together reducing repulsion in synthesis reactions, or b) in a breakdown reaction it puts strain on the bonds in the substrate.
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lock and key model
enzymes only work with substrates that are complimentary to their active site.
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induced fit model
the enzyme-substrate complex changes shape to complete the fit, locking the substrate tightly to the enzyme. explains their specificity.
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enzyme-product complex
a substrate has been converted to its products, but it hasnt yet been released from the active site
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factors affecting enzyme activity
temperature, ph, enzyme concentration, substrate concentration
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enzymes and temperature
more hear = more kinetic energy, molecules move faster therefore substrate molecules are more likely to collide with active sites. energy of these collisions increases. reaction stops after the optimum temperature as it breaks some of the bonds.
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the enzyme no longer functions as a catalyst.
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the q10 value / temperature coefficient
shows how much the rate of reaction changes when the temperature is raised by 10°C. q1o value of 2 means the rate doubles.
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enzymes and ph
above and below the optimum ph, the h+ and oh- ions can break the ionic and hydrogen bonds that hold together the tertiary structure
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enzyme concentration
the more enzymes there are, the more likely they are to collide with a substrate, therefore the rate of reaction is increased. if substrate concentration becomes the limiting factor, increasing enzymes will have no further effect.
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substrate concentration
higher the substrate concentration, faster reaction as collision is more likely, more active sites will be occupied. after a saturation point enzymes become limiting factor. decreases with time so rate does too (initial rate is highest)
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measuring how fast the product appears under different conditions
catalase and hydrogen peroxide; measure how fast oxygen is produced when temperature is increased. upside down measuring cylinder. buffer solution.
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measuring how fast substrate breaks down under different conditions
amylase and starch; concentration of amylase over time in a spotting tile identified by iodine.
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non-protein substances bound to enzymes to make them work
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inorganic cofactors
inorganic ions such as cl- ions in amylase, which help form the enzyme-substrate complex. dont directly participate so arent used up.
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organic molecules that are used up in the reaction, often act as carriers for chemical groups between enzymes and are therefore continually recycled. often vitamins.
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prosthetic groups
a cofactor tightly bound to an enzyme, such as zinc ions in carbonic anhydrase.
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competitive inhibitors
similar shape to the substrate so bind to the active site, but no reaction takes place. semi-permanent.
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non-competitive inhibitors
bind to the allosteric site causing the active site to change shape so the substrate can no longer bind. permanent.
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reversible inhibition
hydrogen or ionic bonds between enzyme and inhibitor
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irreversible inhibition
covalent bonds between enzyme and inhibitor
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drugs and inhibition
antiviral drugs work by inhibiting enzymes which catalyse the replication of viral dna, and some antibiotics weken bacterial cell walls by inhibiting enzymes that make its proteins.
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examples of enzyme inhibiting drugs
antiviral: reverse transcriptase inhibitor, antibiotics: penicillin inhibits transpeptidase
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metabolic poisons
interfere with metabolic reactions causing damage, illness or death. often enzyme inhibitors.
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examples of metabolic poisons
cyanide, non competitive inhibitor of cytochrome c oxidase which catalyses respiration. malonate is competitive w/ succinate dehydrogenase. arsenic is non-competitive with pyruvate dehydrogenase.
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metabolic pathways
series of connected metabolic reactions regulated by end-product inhibition. each reaction is catalysed by a different enzyme, inhibition contols how much end product is made. reversible.
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inactive precursors
enzymes synthesised in metabolic pathways to prevent damage to cells part of the molecule inhibits action as an enzyme, once this is removed the enzyme becomes active. some proteases are synthesised this way to prevent damage to cell walls.
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cell surface / plasma membranes
barrier between cell and environment, control which substances enter and leave the cell. partially permeable. substances can pass by diffusion, osmosis, or active transport. allow cell communication and recognition.
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membrane-bound organelles
divide cells into compartments, act as a barrier between the organelle and the cytoplasm, making functions more efficient. parially permeable, can form vesicles, some have a double membrane which are folded and sites for reactions.
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fluid mosaic model, 1972
fluid phospholipid bilayer as theyre constantly moving, protein molecules scattered throughout. glycoproteins, glycolipids, cholesterol.
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phospholipid bilayer
form a barrier to dissolved substances. hydrophilic head and hydrophobic tails. as the centre is hydrophobic the membrane doesnt allow water soluble substances through, but fat soluble substances can diffuse through
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cholesterol in a membrane
gives the membrane stability by fitting between phospholipid tails, causing them to pack closer together. creates a further barrier through hydrophobic regions.
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proteins in a membrane
control what enters and leaves the cell. channels allow small charged particles through, carriers allow larger charged molecules through by facillitated diffusion and active transport. receptors for molecules in cell signalling.
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glycolipids and glycoproteins
stabilise membrane by forming hydrogen bonds with surrounding water molecules. receptors for messenger molecules in cell signalling, sites where drugs, antibodies and hormones bind. antigens.
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cell surface molecules involved in self-recognition and immune response.
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solvents and membrane permeability
permeability depends on solvent surrounding membranes as some solvents (ethanol) dissolve lipids in the cell membrane, making it lose structure. increasing concentration/changing solvent increases permeability.
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temperatures below 0°C and membrane permeability
phospholipids don't have much energy therefore theyre packed close and rigid. channel and carrier proteins denature, increasing permeability, ice crystals can pierce the membrane.
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temperatures between 0 and 45°C and membrane permeability
phospholipids can move and arent tightly packed, membrane is partially permeable. as temperature increases so does lipid movement, making the membrane more permeable.
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temperatures above 45°C and permeability
phospholipid bilayer starts to break down, making the membrane more permeable. water expansion inside the cell, putting pressure on the membrane. proteins denature so they can't control what enters and leaves, increasing permeability.
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investigating temperature on membrane permeability
betroot cells and colorimetry; put cubes into test tubes of water and place into water baths of different temperatures. measure absorbance of coloured solution left with a blue filter
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passive net movement of particles along a concentration gradient until even distribution.
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factors effecting rate of diffusion
concentration gradient, surface area, membrane thickness, temperature
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investigating diffusion
diffusion of hydrochloric acid into agar jelly with phenolphthaelin and sodium hydroxide
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diffusion of water molecules across a partially permeable membrane down a water potential gradient.
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water potential
likelihood of water molecules to diffuse into or out of a solution
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isotonic solutions
if the two solutions have the same water potential. no net movement.
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hypotonic solutions
cell is placed in a solution of higher water potential. cells swell.
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hypertonic solutions
cell is placed in a solution of lower water potential. cells become plasmolysed.
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investigating water potential on plant cells
potato cylinders or eggs with their shells dissolved.
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facillitated diffusion
speeds up diffusion of large or polar molecules down a concentration gradient passively. carrier or channel proteins.
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carrier proteins and facillitated diffusion
large molecules attach, the protein changes shape, releasing the molecule on the opposite ide.
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channel proteins and facillitated diffusion
pores in the membrane for smaller ions and polar molecules
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active transport
active process using carrier proteins moving molecules against a concentration gradient
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active process. movement of large molecules or objects into a cell as vesicles are pinched off.
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active process. movement of molecules out of a cell as vesicles fuse with the membrane.
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cell cycle
process that all body cells in multicellular organisms use to grow and divide
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stage of cell growth and dna replication. cells dna is unravelled and replicated to double its genetic content, organelles are replicated so the cell has spare ones. atp content is increased.
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m phase
mitosis and cytokinesis
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stages of interphase
g1, s, g2
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importance of checkpoints
occur at key points to make sure it is ok for the process to continue
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gap phase 1
cell grows and new organelles and proteins are made. includes a checkpoint where the cell checks that chemicals needed for replication are presentand for any damage to the dna
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synthesis phase
cell replicates its dna
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gap phase 2
cell keeps growing and proteins needed for division are made. includes a checkpoint where the cell checks that all dna has been replicated without any damage.
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function of mitosis
repair samaged tissue, reproduce asexually, growth
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joining between chromatids
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separate strands
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sister chromatids
two strands on the same chromosome
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chromosomes condense, centrioles move to opposite ends forming the spindle fibres, nuclear envelope breaks down
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chromosomes line up down the centre at the spindle equator and become attached to the spindle by their centromere. checkpoint: ensures all centromeres are attached to the spindle.
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centromeres divideand spindles contract
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chromatids reach opposite poles, uncoil and nuclear envelope forms
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begins at anaphase. cleavage furrow. division.
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homologous chromosomes
pairs of matching chromosomes with different alleles.
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happens in reproductive organs to produces gametes. cells formed by meiosis are all genetically different
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meiosis 1
reduction division halves the chromosome number
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prophase 1
chromosomes condense, homologous chromosomes pair up, crossing over occurs. centrioles move to opposite ends forming the spindle fibres, nuclear envelope breaks down.
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metaphase 1
homologous chromosomes line up at spindle equator by their centromeres
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anaphase 1
spindles contract, one chromosome goes to each end of the cell
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telophase 1
nuclear envelope forms; two haploid daughter cells are produced
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meiosis 2
same occurs without the crossing over at prophase and half the number of chromosomes. four haploid daughter cells are poduced
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how genetic variation occurs in gametes
crossing over of chromatids and independent assortment of chromosomes
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the process by which a cell becomes specialised for its job
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when a cell is adapted for its function
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specialised erythrocytes
biconcave discs, large surface area, no nucleus
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specialised neutrophils
flexible, many lysosomes, lobed nucleus
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specialised epithelial cells
cells joined by interlonking cell membranes and a base membrane, cilia or microvilli. can be squamous.
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specialised sperm cells
flagellum, mitochondria, acrosome containing digestive enzymes, streamlined.
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specialised palisade mesophyll
many chloroplasts, thin walls.
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specialised root hair cells
large surface area, thin permeable cell walls, mitochondira
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specialised guard cells
in pairs, vacuoles take up more water in light, thin outer walls thicker inner wallsto force them to bend outwards
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group of cells thata re specialised to work together to carry out a particular function. can contain more than one cell type.
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tissue example: cartillage
type of connective tissue formed in the joints. formed when chondroblasts secrete an extracellular matrix which they become trapped inside.
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group of different tissues that work together to perform a particular function.
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organ system
organs work together to perform a function
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Other cards in this set

Card 2


complex multicellular organisms, larger (10-100μm), linear dna, nucleus, cell wall is either chitinous, cellulose, or non existent, many organelles, flagellum in 9+2 formation, larger ribosomes (20nm)


eukaryotic organisms

Card 3


parts of cells with specific functions. each comprise the cell ultrastructure.


Preview of the back of card 3

Card 4


cell surface membrane, rough endoplasmic reticulum, smooth endoplasmic reticulum, golgi apparatus, lysosome, ribosome, nucleus, nucleolus, nuclear envelope, cytoplasm, mitochondria


Preview of the back of card 4

Card 5


cell surface membrane, cell wall, chloroplast, vacuole, nucleus, nucleolus, nuclear envelope, cytoplasm, smooth endoplasmic reticulum, rough endoplasmic reticulum, plasmodesmata, mitochondria, golgi apparatus, vacuole


Preview of the back of card 5
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