Biological Molecules
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- Created by: keirah47
- Created on: 31-10-22 18:39
what are monomers and polymers?
- monomers = small units which are the components of larger molecules
- polymers = molecules made from many monomers joined together
- polymers = molecules made from many monomers joined together
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give examples of monomers and the polymers they make
- monosaccharides (eg glucose) --> di/polysaccharides (eg starch)
- amino acids --> proteins
- nucleotides --> DNA
- amino acids --> proteins
- nucleotides --> DNA
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what is a condensation reaction?
- monomers are joined together by a chemical bond
- water molecule is released
- water molecule is released
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what is a hydrolysis reaction?
- a chemical bond is broken between two molecules
- water is used
- water is used
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what are carbohydrates?
- molecules consisting of only carbon, hydrogen and oxygen
- long chains of sugar units called saccharides
- monosaccharide (single monomer), disaccharide (two monomers), polysaccharide (many monosaccharides)
- monomers joined by a glycosidic bond formed
- long chains of sugar units called saccharides
- monosaccharide (single monomer), disaccharide (two monomers), polysaccharide (many monosaccharides)
- monomers joined by a glycosidic bond formed
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give examples of mono/di/polysaccharides
- monosaccharides = alpha glucose, beta glucose
- disaccharides = sucrose (glucose and fructose), maltose (2 glucose), lactose (glucose and galactose)
- polysaccharides = glycogen and starch (alpha glucose), cellulose (beta glucose)
- disaccharides = sucrose (glucose and fructose), maltose (2 glucose), lactose (glucose and galactose)
- polysaccharides = glycogen and starch (alpha glucose), cellulose (beta glucose)
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what is the structure of glycogen and what are its properties?
- main storage energy storage molecule in animals
- alpha glucose monomers joined by 1,4 and 1,6 glycosidic bonds
- heavily branched so energy released quickly as enzymes act simultaneously on branches
- large but compact, maximising energy stored
- insol
- alpha glucose monomers joined by 1,4 and 1,6 glycosidic bonds
- heavily branched so energy released quickly as enzymes act simultaneously on branches
- large but compact, maximising energy stored
- insol
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what is the structure of starch and what are its properties?
- stores energy in plants
- mixture of two polysaccharides (amylose and amylopectin)
- amylose = unbranded chain joined by 1,4 glycosidic bonds, coiled so compact to store a lot of energy
- amylopectin = branched, made up of 1,4 and 1,6 glycosidic bonds,
- mixture of two polysaccharides (amylose and amylopectin)
- amylose = unbranded chain joined by 1,4 glycosidic bonds, coiled so compact to store a lot of energy
- amylopectin = branched, made up of 1,4 and 1,6 glycosidic bonds,
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what is the structure of cellulose and what are its properties?
- component of cell walls in plants
- long, unbranched chains of beta glucose, joined by 1,4 glycosidic bonds
- microfibrils are strong threads, made of long cellulose chains running parallel to one another, joined by hydrogen bonds forming strong cross l
- long, unbranched chains of beta glucose, joined by 1,4 glycosidic bonds
- microfibrils are strong threads, made of long cellulose chains running parallel to one another, joined by hydrogen bonds forming strong cross l
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what does Benedict's reagent test for and why?
- reducing sugars
- all monosaccharides and some disaccharides
- sugars that donate electrons to the reagent
- all monosaccharides and some disaccharides
- sugars that donate electrons to the reagent
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how do you test for a reducing sugar and what are the results?
1. add 2cm^3 of liquid food sample to a test tube
2. add 2cm^3 of Benedict's reagent
3. heat gently in a water bath for 5 minutes
- clear blue --> brick red = reducing sugar present
2. add 2cm^3 of Benedict's reagent
3. heat gently in a water bath for 5 minutes
- clear blue --> brick red = reducing sugar present
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how do you test for a non-reducing sugar and what are the results?
1. conduct a test for a reducing sugar
2. a negative result (solution remains blue)
3. in another test tube combine 2cm^3 of liquid food sample and 2cm^3 of dilute HCl to hydrolyse into monosaccharides
4. heat gently in a water bath for 5 minutes
5. add
2. a negative result (solution remains blue)
3. in another test tube combine 2cm^3 of liquid food sample and 2cm^3 of dilute HCl to hydrolyse into monosaccharides
4. heat gently in a water bath for 5 minutes
5. add
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what is the test for starch?
- adding iodine
- orange --> blue/black = starch present
- orange --> blue/black = starch present
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what is a triglyceride?
- lipids made of one molecule of glycerol and three fatty acids
- joined by ester bonds formed in a condensation reaction
- joined by ester bonds formed in a condensation reaction
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what is the difference between a saturated and unsaturated fatty acid?
- saturated = no carbon-carbon double bonds, found in animal fats
- unsaturated = contain carbon-carbon double bonds, found in plants, liquid at room temperature (able to bend, cannot pack tightly)
- unsaturated = contain carbon-carbon double bonds, found in plants, liquid at room temperature (able to bend, cannot pack tightly)
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what are the properties of triglycerides?
- high ratio of energy storing carbon-hydrogen bonds : carbon atoms = energy store
- low ratio of mass : energy = good storage molecule, beneficial for animals as less mass to move around
- large and non-polar = insoluble in water, do not affect water pot
- low ratio of mass : energy = good storage molecule, beneficial for animals as less mass to move around
- large and non-polar = insoluble in water, do not affect water pot
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what is a phospholipid?
- one of the fatty acids of a triglyceride is substituted by a phosphate group
- phosphate heads are hydrophilic and the tails are hydrophobic so form micelles when in contact with water
- polar molecule
- phosphate heads are hydrophilic and the tails are hydrophobic so form micelles when in contact with water
- polar molecule
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what are the properties of phospholipids?
- bilayer can be formed in aqueous environments (because polar molecule)
- form glycolipids with carbohydrates which are important on cell surface membrane for cell recognition
- form glycolipids with carbohydrates which are important on cell surface membrane for cell recognition
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how do you conduct an emulsion test?
1. add 2cm^3 of liquid sample with 5cm^3 of ethanol to a test tube
2. shake to dissolve all the lipid
3. add 5cm^3 of water and leave to stand for 5 minutes
4. white/milky emulsified layer forms = lipid present
2. shake to dissolve all the lipid
3. add 5cm^3 of water and leave to stand for 5 minutes
4. white/milky emulsified layer forms = lipid present
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what is an amino acid made from?
- central carbon (C)
amine group (NH2)
- carboxylic acid (COOH)
- hydrogen atom (H)
- variable group (R)
amine group (NH2)
- carboxylic acid (COOH)
- hydrogen atom (H)
- variable group (R)
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how many amino acids are there and how are they different?
- 20
- different R groups
- different R groups
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how do amino acids bond?
- form peptide bonds in condensation reactions
- molecule of water formed
- dipeptide = 2 amino acids
- polypeptide = 3 or more amino acids
- molecule of water formed
- dipeptide = 2 amino acids
- polypeptide = 3 or more amino acids
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what is protein structure?
- primary = order and number of amino acids
- secondary = initial folding, hydrogen bonds, alpha helix/beta pleated sheets
- tertiary = further folding, 3D shape, strong disulfide bridges (if R group contains sulfur - cysteine), ionic bonds, weak hydrogen
- secondary = initial folding, hydrogen bonds, alpha helix/beta pleated sheets
- tertiary = further folding, 3D shape, strong disulfide bridges (if R group contains sulfur - cysteine), ionic bonds, weak hydrogen
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how do you test for a protein?
1. add 5cm^3 of liquid sample and 5cm^3 of sodium hydroxide to a test tube
2. add 1cm^3 of Biuret solution
3. blue --> mauve = protein present
- Biuret tests for peptide bonds
2. add 1cm^3 of Biuret solution
3. blue --> mauve = protein present
- Biuret tests for peptide bonds
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what are enzymes?
3D tertiary structured globular proteins, increase rate of reaction by lowering activation energy, biological catalyst
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what is the induced fit model?
- enzyme's active site is complementary to the substrate
- not exactly identical
- when substrate is detected, tertiary structure undergoes a conformational change to accommodate substrate
- forms an enzyme-substrate complex to catalyse reaction
- not exactly identical
- when substrate is detected, tertiary structure undergoes a conformational change to accommodate substrate
- forms an enzyme-substrate complex to catalyse reaction
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how does temperature affect the rate of enzyme-controlled reactions?
- rate increases up to optimum temperature as kinetic energy increases so more successful collisions
- beyond optimum temperature, movement puts too much stress on weak hydrogen bonds in the tertiary structure so the active site changes and the enzyme den
- beyond optimum temperature, movement puts too much stress on weak hydrogen bonds in the tertiary structure so the active site changes and the enzyme den
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how does pH affect the rate of enzyme-controlled reactions?
- below and above the optimum pH, too acidic/alkaline solutions can interfere with the charges on the amino acids, cause hydrogen bonds to break so active site changes and the enzyme denatures so cannot form an enzyme-substrate complex to catalyse reactio
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how does enzyme concentration affect the rate of enzyme-controlled reactions?
- rate increases as concentration increases as more active sites available to bind to
- beyond a certain point there are more active sites than substrates so rate plateaus and the substrate concentration becomes the limiting factor
- beyond a certain point there are more active sites than substrates so rate plateaus and the substrate concentration becomes the limiting factor
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how does substrate concentration affect the rate of enzyme-controlled reactions?
- rate increases when concentration increases as more enzyme-substrate complexes form
- beyond a certain point rate no longer increases as all active sites are occupied and the enzymes are saturated so enzyme concentration becomes the limiting factor
- beyond a certain point rate no longer increases as all active sites are occupied and the enzymes are saturated so enzyme concentration becomes the limiting factor
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how do competitive inhibitors affect the rate of enzyme-controlled reactions?
- similar shape to substrate
- bind to the active site instead of the substrate to prevent enzyme-substrate complexes forming so rate decreases
-rate can be increased again if substrate concentration is increased
- bind to the active site instead of the substrate to prevent enzyme-substrate complexes forming so rate decreases
-rate can be increased again if substrate concentration is increased
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how do non-competitive inhibitors affect the rate of enzyme-controlled reactions?
- bind away from the active site and cause the shape of the active site to change
- no longer complementary to the substrate so enzyme-substrate complexes cannot form, rate decreases
- increasing substrate concentration has no effect as the active site is
- no longer complementary to the substrate so enzyme-substrate complexes cannot form, rate decreases
- increasing substrate concentration has no effect as the active site is
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what is the structure of DNA?
- nucleotides = deoxyribose (pentose) sugar, phosphate group, nitrogen-containing organic base (adenine/cytosine/guanine/thymine)
- double helix = 2 polynucleotides joined by hydrogen bonds between complementary base pairs (A-T/C-G)
- double helix = 2 polynucleotides joined by hydrogen bonds between complementary base pairs (A-T/C-G)
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what is the structure of RNA?
- nucleotides = ribose (pentose) sugar, phosphate group, nitrogen-containing organic base (adenine/cytosine/guanine/uracil)
- relatively short polynucleotide chain
- relatively short polynucleotide chain
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how do nucleotides bond in DNA/RNA?
- phosphodiester bonds form in a condensation reaction
- dinucleotide --> polynucleotide
- bond forms between sugar of one nucleotide and phosphate group of another
- water produced
- dinucleotide --> polynucleotide
- bond forms between sugar of one nucleotide and phosphate group of another
- water produced
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why is DNA a stable molecule?
- phosphodiester backbone = protects the more chemically reactive nitrogen-containing organic bases inside the double helix
- high numbers of hydrogen bonds = 2 between A-T and 3 between C-G
- helix shape = compact
- high numbers of hydrogen bonds = 2 between A-T and 3 between C-G
- helix shape = compact
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what is semi-conservative replication?
- ensures genetic continuity between generations of cells
- genetic information is passed from one generation to the next
(result of using template strand)
- genetic information is passed from one generation to the next
(result of using template strand)
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how does DNA replicate?
1. DNA helicase causes 2 strands of DNA to separate by breaking the hydrogen bonds between complementary bases
2. one strand acts as a template
3. complementary base pairing occurs between the template strand and free nucleotides
- DNA polymerase bonds t
2. one strand acts as a template
3. complementary base pairing occurs between the template strand and free nucleotides
- DNA polymerase bonds t
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what is ATP?
- nucleotide derivative = ribose, adenine, 3 phosphate groups
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what are the uses of ATP?
- energy source = ATP is hydrolysed by ATP hydrolase to form ADP and a phosphate molecule (energy released when high energy, unstable bond between phosphates are broken)
- inorganic phosphate can be used to phosphorylate other compounds = make more reacti
- inorganic phosphate can be used to phosphorylate other compounds = make more reacti
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what are the properties of ATP?
- immediate energy source = preferred to glucose, broken down in one step to release energy fast
- not stored in large quantities = can be reformed from ADP in seconds
- many uses = metabolic processes, movement, active transport, secretion and activation
- not stored in large quantities = can be reformed from ADP in seconds
- many uses = metabolic processes, movement, active transport, secretion and activation
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why is water important?
- polar molecule = positive and negative charges, forms hydrogen bonds so water molecules can stick together
- metabolite = used in metabolic reactions such as condensation and hydrolysis (forming and breaking of chemical bonds)
- solvent = allows gases t
- metabolite = used in metabolic reactions such as condensation and hydrolysis (forming and breaking of chemical bonds)
- solvent = allows gases t
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where are inorganic ions found in the body?
- cytoplasm and body fluid of organisms
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- what are examples of essential ions and their uses?
- hydrogen = determine pH (e.g. of blood)
- iron = component of haemoglobin, helps oxygen bind so can be carried in red blood cells
- sodium - co-transport of glucose and amino acids
- phosphate = DNA and ATP
- iron = component of haemoglobin, helps oxygen bind so can be carried in red blood cells
- sodium - co-transport of glucose and amino acids
- phosphate = DNA and ATP
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Other cards in this set
Card 2
Front
give examples of monomers and the polymers they make
Back
- monosaccharides (eg glucose) --> di/polysaccharides (eg starch)
- amino acids --> proteins
- nucleotides --> DNA
- amino acids --> proteins
- nucleotides --> DNA
Card 3
Front
what is a condensation reaction?
Back
Card 4
Front
what is a hydrolysis reaction?
Back
Card 5
Front
what are carbohydrates?
Back
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