topic 1 Flashcards
1
Q
What is a monomer?
A
a smaller / repeating) unit / molecule from which larger molecules / polymers are made;
2
Q
What is a polymer?
A
made up of many identical / similar molecules / monomers / subunits
3
Q
Condensation reaction
A
joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water
4
Q
Hydrolysis reaction
A
breaks a chemical bond between two molecules and involves the use of a water molecule
5
Q
Bonds in:
Lipids
Proteins
Carbohydrates
DNA
A
Ester = lipids
Peptide = proteins
Glycosidic = carbohydrates
Phosphodiester = DNA
6
Q
Monosaccharides in
disaccharides:
Lactose
Sucrose
Maltose
A
Glucose and galactose = lactose
Glucose and fructose = sucrose
2 glucose = maltose
7
Q
Alpha and beta
glucose structure
A
Structure: C6H12O6
Alpha: OH group below
Beta: OH group above
8
Q
Comparing cellulose
and glycogen
A
- Cellulose is made up of β-glucose (monomers) and glycogen is
made up of α-glucose (monomers); - Cellulose molecule has straight chain and glycogen is branched;
- Cellulose molecule has straight chain and glycogen is coiled;
- glycogen has 1,4- and 1,6- glycosidic bonds and cellulose has only 1,4- glycosidic bonds;
9
Q
Starch structure and
function
A
- Insoluble (in water), so doesn’t affect water potential;
- Branched / coiled / (α-)helix, so makes molecule compact;
OR
Branched / coiled / (α-)helix so can fit many (molecules) in small area; - Polymer of (α-)glucose so provides glucose for respiration;
- Branched / more ends for fast breakdown / enzyme action;
- Large (molecule), so can’t cross the cell membrane
10
Q
Cellulose structure
and function
A
- Long and straight chains;
- Become linked together by many hydrogen bonds to form fibrils;
- Provide strength (to cell wall).
11
Q
Describe how an
ester bond is formed in a phospholipid
molecule.
A
- Condensation (reaction) OR Loss of water;
- Between of glycerol and fatty acid;
12
Q
Unsaturated fatty
acids
A
Double bonds (present) / some / two carbons with only one hydrogen / (double bonds) between carbon atoms / not saturated with hydrogen;
13
Q
Triglycerides
compared to
phospholipids
A
- Both contain ester bonds (between glycerol and fatty acid);
- Both contain glycerol;
- Fatty acids on both may be saturated or unsaturated;
- Both are insoluble in water;
- Both contain C, H and O but phospholipids also contain P;
- Triglyceride has three fatty acids and phospholipid has two fatty
acids plus phosphate group; - Triglycerides are hydrophobic/non-polar and phospholipids have
hydrophilic and hydrophobic region;
Accept ‘non-polar’ for hydrophobic and ‘polar’ for hydrophilic. - Phospholipids form monolayer (on surface)/micelle/bilayer (in
water) but triglycerides don’t;
14
Q
Amino acid structure
A
H, NH2, COOH bonded to a central carbon and then a variable R group
15
Q
Protein structure
A
- Structure is determined by (relative) position of amino acid/R
group/interactions; - Primary structure is sequence/order of amino acids;
- Secondary structure formed by hydrogen bonding (between amino
acids); - Tertiary structure formed by interactions (between R groups);
- Creates active site in enzymes OR Creates complementary/specific
shapes in antibodies/carrier proteins/receptor (molecules); - Quaternary structure contains >1 polypeptide chain OR Quaternary
structure formed by interactions/bonds between polypeptides
16
Q
Enzyme action
A
- Reduces activation energy;
Accept ‘reduces E a ‘. - Due to bending bonds
OR
Without enzyme, very few substrates have sufficient energy for reaction
17
Q
Enzymes and
temperature
A
- At low temperatures, molecules have less kinetic energy
- So less successful collision/less enzyme-substrate complexes form
- At higher temperatures (above optimum) denaturation is due to more
(kinetic) energy; - Breaks hydrogen / ionic bonds (between amino acids / R groups);
- Change in shape of the active site / active site no longer
complementary so fewer enzyme-substrate complexes formed / substrate does not fit;
18
Q
Induced fit model
A
- Substrate is not complimentary to the enzyme active site.
- Active site alters shape to fit around substrate/forms an enzyme-
substrate complex - Bonds are stressed/bent
19
Q
Competitive inhibitor
action
A
- Similar shape to the substrate/complimentary to the enzyme active
site - Binds to active site
- So less enzyme-substrate complexes can form
20
Q
Non-competitive
inhibitor action
A
- Attaches to the enzyme at a site other than the active site;
Accept ‘attaches to allosteric/inhibitor site’ - Changes (shape of) the active site
OR
Changes tertiary structure (of enzyme); - (So active site and substrate) no longer complementary so less/no
substrate can fit/bind
21
Q
DNA nucleotide
A
Deoxyribose Sugar, Bases GCAT, and Phosphate Group
22
Q
DNA replication
A
- Strands separate / H-bonds break;
- DNA helicase (involved);
- Both strands / each strand act(s) as (a) template(s);
- (Free) nucleotides attach;
- Complementary / specific base pairing / AT and GC;
- H-bonds reform;
- DNA polymerase joins nucleotides (on new strand);
- Reject: if wrong function of DNA polymerase
- Forming phosphodiester bonds
- Semi-conservative replication / new DNA molecules contain one old strand and one new strand;
- Reject: if wrong context e.g. new DNA molecules contain half of each original strand
23
Q
DNA polymerase
function
A
- Joins (adjacent DNA) nucleotides;
- (Catalyses) condensation (reactions);
- (Catalyses formation of) phosphodiester bonds (between adjacent nucleotides)
24
Q
DNA structure to
function
A
- Weak / easily broken hydrogen bonds between bases allow two strands to separate / unzip;
- Two strands, so both can act as templates;
- Complementary base pairing allows accurate replication
25
Eukaryote DNA
compared to
prokaryote/mitochon
drial/chloroplast
1. DNA shorter;
2. Fewer genes;
3. DNA circular not linear;
4. Not associated with protein/histones, unlike nuclear DNA;
5. Introns absent but present in nuclear DNA;
Ignore references to double and single stranded DNA
26
Starch test
1. Add iodine / stain specific for starch to the slide / cells / tissue / add
iodine / stain specific for starch and examine under microscope;
2. Blue-black / blue / black / purple;
27
Protein test
1. Add biuret (reagent);
2. (Positive result) purple/lilac/violet /mauve;
28
Non reducing sugars
test
1. Heat with acid and neutralise;
2. Heat with Benedict's (solution);
3. Red precipitate/colour;
29
Reducing sugars
test
1. Heat with Benedict (solution);
2. Red precipitate/colour;
30
Emulsion test
1. Dissolve in alcohol (ethanol) , then add water;
2. White emulsion shows presence of lipid.
31
ATP synthase reaction
ADP + P i ⟶ ATP + H 2 O
32
ATP compared to DNA
nucleotide
1. ATP has ribose and DNA nucleotide has deoxyribose;
2. ATP has 3 phosphate (groups) and DNA nucleotide has 1 phosphate (group);
3. ATP - base always adenine and in DNA nucleotide base can be different / varies;
33
Properties of water
and why they are
important
1. A metabolite in condensation/hydrolysis/
photosynthesis/respiration;
2. A solvent so (metabolic) reactions can occur
OR
A solvent so allowing transport of substances;
3. High heat capacity so buffers changes in temperature;
4. Large latent heat of vaporisation so provides a cooling effect
(through evaporation);
5. Cohesion (between water molecules) so supports columns of water (in plants);
6. Cohesion (between water molecules) so produces surface tension supporting (small) organisms
