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biology > topic 1A: biological molecules > Flashcards

topic 1A: biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

monomers

A

smaller molecular units which can create larger molecules (e.g. monosaccharides, amino acids and nucleotides)

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2
Q

polymers

A

large, complex molecules composed of long chains of monomers joined together (e.g. polysaccharide, polypeptide and polynucleotide)

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3
Q

2 key chemical reactions

A

condensation reaction and hydrolysis reaction

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4
Q

condensation reaction

A

joins two molecules together, with the formation of a chemical bond and involves the elimination of a molecule of water.

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5
Q

hydrolysis reaction

A

separates two molecules by breaking a chemical bond and involves the addition of a water molecule.

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6
Q

monsachharides + examples

A

the monomers which form larger carbohydrates e.g. glucose, fructose and galactose

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7
Q

carbohydrates contain the elements…

A

-C (carbon)
-H (hydrogen)
-O (oxygen)

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8
Q

hexose sugar

A

a monosaccharide with six carbon atoms in each molecule e.g glucose

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9
Q

2 types of glucose

A

alpha and beta

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10
Q

insomers

A

same molecular formula but different structure with atoms arranged in a different ways

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11
Q

draw alpha glucose molecule

A

H
OH

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12
Q

draw beta glucose molecule

A

OH
H

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13
Q

disaccharides

A

a disaccharide is formed when two monosaccharides join together by a condensation reaction, forming a glycosidic bond (e.g. maltose, lactose and sucrose)

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14
Q

disaccharides formulas

A

-(2 alpha) glucose + glucose ->maltose + water (glycosidic bond)
-glucose + galactose -> lactose + water
-glucose + fructose -> sucrose + water

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15
Q

glycosidic bond

A

forms between two monosaccharides by a condensation reaction and releases a molecule of water

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16
Q

polysaccharides + examples

A

polysaccharides are formed when more than 2 monosaccharides join together by a condensation reaction, releasing a water molecule for each glycosidic bond
e.g. starch, glycogen and cellulose

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17
Q

starch function

A

-a main energy storage molecule in plants for excess glucose as starch (when a plant needs more glucose for energy, it breaks down starch to release the glucose)

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18
Q

starch structure + formation

A

-made up of two polysaccharides of alpha glucose by a condensation reaction
-amylose and amylopectin

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19
Q

amylose

A

-a long, unbranched chain of alpha glucose, the angles of the glycosidic bonds creates a coiled and compact structure

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20
Q

amylopectin

A

-a long, branched chain of alpha glucose, its side branches allows starch to hydrolyse and release glucose rapidly

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21
Q

starch structure related to function

A

-coiled structure - because the angle of the glycosidic bond, therefore this makes it compact to store more glucose in a small space
-branched chains: can be hydrolysed (broke down) quickly so that glucose can be released quickly
-insoluble in water: no osmotic effect so this doesnt affect the water potential (good for storage as water cant enter the cell by osmosis)

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22
Q

glycogen function

A

-main energy storage molecule in animals for excess glucose as glycogen
-mainly stored in muscle and liver cells

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23
Q

glycogen structure

A

-made up of two polysaccharides of alpha glucose by a condensation reaction
-loads more side branches coming of it
-very compact molecule

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24
Q

glycogen structure related to function

A

-branched: rapid hydrolysis (break down) so that stored glucose can be released quickly which is important for energy release in animals
-compact: good for storage, so it can store more glycogen in a smaller space
-insoluble: no osmotic effect so it doesnt affect water potential

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25
Q

cellulose function

A

-provides structural strength in cell walls of plants due to the microfibrils (strong fibres) formed by the hydrogen bonds

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26
Q

cellulose structure

A

-polysaccharide of beta glucose monosaccharides bonded by a condensation reaction, they form straight cellulose chains
-the long, unbranched cellulose chains are linked together by many hydrogen bonds to form microfibrils (strong fibres) which provide structural support and strength for plant cells

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27
Q

cellulose structure related to function

A

-hydrogen bonds form between chains: forms microfibrils (strong fibres) which create collective strength to the cell wall making it rigid
-straight and unbranched

28
Q

2 types of lipids

A

triglycerides and phospholipids

29
Q

what elements are contain in lipids?

A

carbon, hydrogen and oxygen

30
Q

structure of triglycecides

A

-contains one molecule of glycerol with three fatty acids attached to it

31
Q

explain how glycerol is bonded with the three fatty acids

A
  • the glycerol bonds with the three fatty acids by three separate CONDENSATION reactions, which forms three water molecules and three ester bonds
    1. molecule of glycerol and a fatty acid bond by a condensation reaction which releases a water molecule and removed (this reaction repeats 3 times)
    2. therefore three ester bonds and three molecules of water are released and removed
32
Q

draw the basic structure of a fatty acid

A

-RCOOH - this is formed by a condensation reaction between a glycerol and fatty acid

-variable R-group - hydrocarbon chain (this may be saturated or unsaturated
-COOH = carboxyl group

33
Q

what can fatty acids be + draw?

A

two type of fatty acids: the R group may be saturated and unsaturated - difference is in their hydrocarbon tails (R group)

SATURATED: no double bonds in hydrobarbon chains - all carbons are fully saturated with hydrogen
UNSATURATED: one or more c=c double bond in hydrobarbon chains, this causes the chain to kink/ bend

34
Q

structure of phospholipids

A

-similair to a triglyceride structure
-except one of the fatty acid molecules are replaced by a phosphate group, the two fatty acids are joined to the glycerol molecule by a condensation reaction

35
Q

properties of triglycerides related to function

A

function: energy storage

-ENERGY SOURCE: a high ratio of C-H bonds to carbon atoms, so this contains lots of chemical energy - a load of energy is release when they are broken down
INSOLUBLE: the fatty acids are hydrophobic and non polar, so they are insoluble in water (clump together as droplets, tails inwards - shielding themselves from water), so there is no effect on water potential of cell

36
Q

properties of phospholipids related to function

A

FUNCTION: forma bilayer in cell membrane, allowing diffusion of lipid-soluble (non polar) or very small substances and restricting movement of water soluble (polar) or larger substances

-phosphate heads are hydrophillic, so they are attracted to the water so point to water (aqueous environment) either side of membrane
-fatty acid tails are hydrophobic repelled by water so point away from water / to interior of membrane

37
Q

test for lipids

A

EMULSION TEST
1. add ethanol, shake (to dissolve lipids), then add water
2. positive result = milky white emulsion

38
Q

protein

A

a protein is a polymer made up of the monomer, amino acids

39
Q

4 groups from the structure of an amino acid

A

-carboxyl group (COOH)
-amine group (NH2)
-R (variable group- 20 different amino acids)
-hydrogen atom

40
Q

describe how amino acids join together

A

the amino acids join together between the carboxyl group of one and the amine group of another by a condensation reaction removing a water molecule, this forms a peptide bond.

41
Q

peptide bond

A

formed by a condensation reaction between two amino acids

42
Q

dipeptide

A

formed by the condensation of two amino acids

43
Q

polypeptide

A

formed by the condensation of many amino acids
-1 or more polypeptide chains is a protein

44
Q

peptide bond formation

A

a condensation reaction between the OH on carboxyl group and the H on amine group, which releases a water molecule and forms a peptide bond

45
Q

proteins structural levels

A
  1. primary structure
  2. secondary structure
  3. tertiary structure
  4. quaternary structure
46
Q

primary structure

A

a specific sequence of amino acids in a polypeptide chain, this determines the shape and function of the protein

47
Q

secondary structure

A

-hydrogen bonds form between the amino acids in the chain this causes the polypeptide chain to be coiled (alpha helix) or folded (beta sheet)

48
Q

tertiary structure and additional bonds

A

-the tertiary structure is the secondary structure which is coiled and folded further, to form a unique 3D shape, which leads to additional bonds forming between different parts of the polypeptide chain

-hydrogen bonds, ionic bonds and disulphide bridges

-hydrogen bonds: between R groups
-disulphide bridges: only occur between cysteine amino acids (if there is a sulfur in R group)
-ionic bonds: between charged R groups

-tertiary structure creates the final 3D structure for proteins of only one polypeptide chain

49
Q

Quaternary structure

A

-a Quaternary structure is a protein made up of more than one polypeptide chain (which are bounded together)
-the Quaternary structure is the proteins final 3D structure
-examples: haemoglobin, insulin collagen

50
Q

relationship between protein structures and function

A

-the sequence of amino acids is determined by the genetic code, this effects the primary structure
-the primary structure determines how the polypeptide is coiled or folded in the secondary structure
-the secondary structure determines where bonds form, this affects the whole shape of the protein
-the shape of a protein determines its function
-altering the primary structure affects the tertiary structure shape, which affects its function

51
Q

protein types

A

-globular- soluble, R group folded creates 3D shape (e.g. enzymes)
-fibrous- insoluble, structural, 3D shape (e.g. collagen + keratin - structural protein)

52
Q

enzymes

A

enzymes are biological catalysts which speeds up the rate of a chemical reaction without getting used up (a tertiary structure with a specific 3D shape)

53
Q

how do enzymes speed up a reaction?

A

lower the activation energy by:

-providing an alternative pathway for the reaction with lower energy

-binding reactants at active site and positioning them correctly

-bringing reactants together so less kinetic energy is used by moving round and trying to collide

54
Q

two types of enzyme action models

A

-lock and key theory
-induced fit model

55
Q

lock and key theory

A

-old and outdated model

-every enzyme has an active site which has a fixed shape and has a specific and unique shape due to the specific folding and bonding in the tertiary structure of proteins

-the substrate is complementary to the enzymes active site, so the substrate binds to it - this forms an enzyme-substrate complex

  • the enzyme catalyses a reaction to release products - enzyme is unchanged and can be reused
56
Q

induced fit model

A

-the substrate binds to a not complementary active site of an enzyme, this causes the active site to change shape slightly and to mould itself around the substrate in order to complete the fit
-the enzyme is flexible causing bonds in the substrate distort the hydrogen bonds holding the enzyme
-this forms an enzyme-substrate complex, the enzyme catalyses a reaction and releases products
- the enzyme’s active site returns to its original shape

57
Q

enzymes properties relate to their tertiary structure - enzyme specificity

A

-enzymes are very specific - they only catalyse on reaction as only one substrate is complementary to the active site

-the shape of the active site is determined by the tertiary structure which is determined by the primary structure (sequence of amino acids in a polypeptide chain)

-if there is a mutation which affects the gene, the primary structure is affected, this changes the way the polypeptide is bonded and folded, and therefore affects the shape of the protein in its tertiary structure which alters the shape of the active site, this means that the substrate will not fit and the reaction wont be catalysed

58
Q

factors affecting enzyme activity

A

-pH
-temperature
-enzyme concentration
-substrate concentration
-competitive inhibitor
-non competitive inhibitor

59
Q

temperature affecting enzyme activity

A

-as the temperature increases, the rate of an enzyme controlled reaction increases
-as temperature increases there is more kinetic energy so the molecules vibrate more and move faster
-this makes the enzyme more likely to collide with the substrate molecule - the energy of collisions also increase
-the rate of reaction increases up to the optimum temperature

-if the temperature goes above the optimum temperature, the vibration cause some of the hydrogen bonds to break, which are holding the enzymes tertiary structure shape
-the enzyme is denatured, as the active site changes shape - no longer functions as a catalyst

60
Q

pH affecting enzyme activity

A

-all enzymes have an optimum pH (usually pH 7 (neutral), but pH 2 for pepsin since it’s found in the acidic stomach)

-if the pH is above and below the optimum pH, the enzyme denatures (active site changes shape) due to the H+ and OH- ions altering the ionic and hydrogen bonds that are holding the enzymes in its tertiary structure

61
Q

substrate concentration affecting enzyme activity

A

-increasing the substrate concentration, increase rate of reaction
-more substrate molecules means a collision between substrate and enzyme is more likely - enzyme-substrate complexes are more likely
-increases up to a ‘SATURATION’ POINT where all the enzymes active sites are in use
-increasing substrate concentration after this point has NO FURTHER EFFECT
-over the reaction time, substrate concentration reduces as the product is formed, meaning rate of reaction decreases over time - this makes the initial rate of reaction, the highest rate of reaction

62
Q

enzyme concentration affecting the rate of reaction

A

-increasing enzyme concentration, increases the rate of reaction
-the more enzyme molecules there are in a solution, the more likely collisions with substrate molecules and form enzyme-substrate complexes
-if substrate concentration is limiting, increasing concentration of enzyme has no further effect

63
Q

enzyme inhibitors

A

molecules that bind to the enzyme that they inhibit - prevents enzyme activity

64
Q

competitive inhibitors affecting enzyme activity

A

-competitive inhibitors molecules have a similar shape to the substrate molecule, which means it competes with the substrate molecules to bind to the active site, but no reaction takes place, instead they block the active site so no substrate molecules can fit in it

-this reduces the amount of enzyme-substrate complexes that can form

-increasing competitive inhibitors, reduces the rate of reaction, as they take up nearly all the active sites (and hardly any of the substrate will get to the enzyme)

-increasing substrate concentration, increases the chances of the substrate getting to an active site before the inhibitor, so this increases the rate of reaction

65
Q

non competitive inhibitors affecting rate of reaction

A

-non competitive inhibitor molecules dont compete for the active site as they have a different shape, the inhibitors binds away from the enzyme’s active site and instead binds to an allosteric (alternative) site, this alter the tertiary structure of the enzyme causing a permanent conformational(shape) change in the active site and becomes a different shape so the substrate is no longer complementary to the enzyme and can no longer bind to it

-therefore substrates cannot bind and form enzyme-substrate complexes

-increasing the substrate concentration, has no effect to the rate of reaction, as the non competitive inhibitors doesn’t compete and alters the shape of the active sites - enzyme activity will still be inhibited

biology (9 decks)

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