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biology year 1 > biological molecules A > Flashcards

biological molecules A Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

monomer…

A

small,single molecule,many of which can be joined together to form a polymer

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2
Q

polymer…

A

large molecule made up of many similar/identical monomers joined together

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3
Q

condensation reaction…

A

-joins 2 molecules together
-eliminates a water molecule
-forms a chemical bond

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4
Q

hydrolysis reactions…

A

-separates 2 molecules
-requires addition of a water molecule
-breaks a chemical bond

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5
Q

polymers —> monomers

A

hydrolysis reaction

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6
Q

monomers—>polymers

A

condensation reaction

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7
Q

4 examples of monomers…

A

~ Monosaccharides( Glucose, galactose)
~ Nucleotides
~ amino acid
~ fatty acid or glycerol

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8
Q

what elements do carbohydrates contain?

A

C,H and O

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9
Q

monosaccharides…

A

the monomers from which larger carbohydrates are made

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10
Q

disaccharides…

A

formed by the condensation of 2 monosaccharides

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11
Q

glucose is a ……. sugar

A

hexose

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12
Q

what are the two types of glucose?

A

alpha glucose and beta glucose

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13
Q

what type of bond is formed between two monosaccharides as a molecule of water is released ?

A

glycosidic bond

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14
Q

What is a Sucrose made up of?

A

Fructose & Glucose

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15
Q

What is Maltose made up of?

A

Glucose & Glucose

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16
Q

What is Lactose made up of?

A

Glucose & Galactose

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17
Q

what is the test for reducing sugars?

A

1.add benedict’s reagent (blue) to sample
2.heat in a boiling water bath
3.positve= green/yellow/orange/red precipitate

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18
Q

what is the test for non reducing sugars?

A

-heat sample with benedict’s reagent and if it stays blue then there’s no reducing sugar present
-Heat sample in a boiling bath with dilute HCl
-Add sodium hydrogen carbonate
-Heat sample with benedict’s reagent
-Positive result will form a brick red precipitate

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19
Q

which disaccharide is a non-reducing sugar?

A

-sucrose

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20
Q

which disaccharides are reducing sugars?

A

-maltose and lactose

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21
Q

are all monosaccharides reducing sugars?

A

yes

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22
Q

polysaccharides…

A

When three or more monosaccharides are joined together by a condensation reaction with a glycosidic bond connecting each monosaccharide.

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23
Q

What 2 polysaccharides make up starch?

A

Amylose and Amylopectin

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24
Q

why is starch a good storage molecule?

A

-insoluble in water and doesn’t affect water potential
-large molecule so it cannot leave the cell
-helical therefore compact for storage in cell

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25
Q

what happens when a plant needs more glucose for energy?

A

it breaks down starch to release the glucose

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26
Q

compare amylose and amylopectin

A

amylose:
-unbranched alpha glucose
-1,4 glycosidic bonds
-helical so compact
amylopectin:
-branched alpha glucose
-1,4 and 1,6 glycosidic bonds
-branched means enzymes can easily access more glycosidic bonds

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27
Q

describe how the structure of glycogen is related to its functions

A

-branched; can rapidly be hydrolysed to release glucose for respiration to provide energy
-large polysaccharide molecule; cant leave cell
-insoluble in water; water potential of cell not affected

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28
Q

describe the structure of glycogen

A

-polysaccharide of alpha glucose
-joined by glycosidic bonds
-branched structure

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29
Q

suggest how glycogen acts as a source of energy

A

-hydrolysed to glucose
-glucose used in respiration

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30
Q

what is the function of cellulose in plants? Explain how its structure accomplishes its function.

A

-long unbranched chains of beta glucose
-when beta glucose molecules bond they form straight cellulose chains
-cellulose chains are linked by hydrogen bonds to form strong fibres meaning cellulose provides structural support for cells

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31
Q

describe the structure of cellulose and explain how it is adapted for its function in cells

A

-every other beta glucose molecule is inverted in a long, straight, unbranched chain
-many hydrogen bonds link parallel strands (cross links) to form micro fibrils (strong fibres)
-h bonds are strong in high numbers
-provides strength and structural support to plant cell walls

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32
Q

give similarities between starch and cellulose

A

-both polysaccharides
-contain glucose
-contain glycosidic bonds
-have 1-4 links
-hydrogen bonding within structure

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33
Q

test for starch

A

-add iodine dissolved in potassium iodide solution to test sample
-positive result: browny orange to blue black colour

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34
Q

what are lipids made from?

A

from a variety of different components but they all contain hydrocarbons

35
Q

why are unsaturated lipids liquid at room temperature?

A

-presence of the double bond means that the molecule is able to bend
-therefore unsaturated fats cannot pack together tightly, hence its liquid at room temperature

36
Q

describe how to test for lipids in a sample

A

1-dissolve solid samples in ethanol
2-add an equal volume of water and shake
3- positive result = milky white emulsion forms

37
Q

what are micelles?

A

-tiny droplets consisting of fatty acids and monoglycerides surrounded by bile salts

38
Q

name the two types of lipids

A

triglycerides and phospholipids

39
Q

what are the components of triglycerides?

A

-glycerol
-three fatty acids which have long tails made of hydrocarbon

40
Q

why do the hydrocarbon tails make lipids insoluble in water?

A

they are hydrophobic so they repel water molecules

41
Q

how are triglycerides formed?

A

-condensation reaction of glycerol and three molecules of fatty acids
-removal of three molecules of water
-ester bonds formed

42
Q

name two types of fatty acids

A

saturated and unsaturated

43
Q

how can you tell whether the fatty acid is unsaturated or saturated?

A

unsaturated fatty acids have double bonds between carbon atoms and saturated fatty acids do not

44
Q

how is an ester bond formed

A

by a condensation reaction between glycerol and a fatty acid

45
Q

what are the components of phospholipids?

A

-phosphate group
-glycerol
-two fatty acids

46
Q

is the phosphate group hydrophobic or hydrophilic?

A

hydrophilic as it attracts water

47
Q

are the fatty tails hydrophobic or hydrophilic?

A

hydrophobic as they repel water

48
Q

why are triglycerides used as an energy storage molecule?

A

-long hydrocarbon tails of fatty acids contain lots of energy and triglycerides have 3 fatty acids so are able to store lots of energy
-insoluble due to hydrophobic tails which means it doesn’t affect water potential

49
Q

why do the tails face inwards?

A

to shield themselves from water with their glycerol heads

50
Q

why do storage molecules have to be insoluble?

A

otherwise they would dissolve and release whatever they are storing whenever they come into contact with water

51
Q

what do phospholipids do ?

A

make up the bilayer of cell membranes which control what enters and leaves the cell

52
Q

which properties of phospholipids make it suitable to form up the bilayer of cell membranes?

A

-hydrophobic tail and hydrophilic head so they form double bilayer with their heads facing out
-allows them to form a membrane that acts as a barrier to water soluble substances

53
Q

what test is for lipids?

A

emulsion test

54
Q

describe an emulsion test

A

-shake test substance with ethanol then pour the solution into water
-any lipid will show up as a milky emulsion
- the more lipid there is, the more noticeable the milky colour will be

55
Q

what are proteins made from?

A

made up of one or more polypeptides of the monomer amino acid

56
Q

describe the structure of proteins as enzymes

A

-spherical shape since the polypeptide chains are tightly folded
-soluble to be used in metabolic processes
-used in digestive enzymes and in biological molecule synthesis

57
Q

how many amino acids are common in all organisms but differ only in their side group?

A

20

58
Q

what bond does the condensation reaction between two amino acid form?

A

peptide bond

59
Q

how do dipeptides and poly peptides form?

A

-condensation reaction forms a peptide bond and eliminates a molecule of water
-dipeptide: 2 amino acids
-polypeptide:3 or more amino acids

60
Q

how many levels of protein structure are there?

A

4

61
Q

define the primary structure of a protein

A

-sequence of amino acids in the polypeptide chain
-determined by sequence of codons on mRNA

62
Q

define the secondary structure of a protein

A

-hydrogen bonds form between the amino acids in the chain
-makes it automatically coil into alpha helix
or
-fold into a beta pleated sheet

63
Q

define the tertiary structure of a protein and name the bonds present

A

3D structure formed by further folding of polypeptide
-disulfide bridges
-ionic bonds
-hydrogen bonds

64
Q

describe each type of bond in the tertiary structure of proteins

A

-disulfide bridges: strong covalent S-S bonds between molecules of amino acid cysteine
-ionic bonds: relatively strong bonds between charged R groups (pH changes cause these bonds to break)
-hydrogen bonds: numerous and easily broken

65
Q

define quaternary structure of a protein

A

-functional proteins may consist of more than one polypeptide
-precise 3D structure held together by the same types of bond as tertiary structure
-may involve addition of prosthetic groups e.g metal ions or phosphate groups

66
Q

describe the biuret test for protein

A

-test solution needs to be alkaline, so first you add a few drops of sodium hydroxide solution
-then add some copper(ll) sulfate solution
-if the protein is present, solution turns purple, and if not it stays blue

67
Q

list 4 types of protein molecules found in organisms

A

-enzymes
-antibodies
-transport proteins
-structural proteins

68
Q

what are enzymes?

A

-biological catalyst for intra and extracellular reactions
-specific tertiary structure determines shape of active site, complementary to a specific substrate
-formation of enzyme-substrate complexes lowers activation energy for metabolic reactions

69
Q

what does it mean to call enzymes “biological catalysts”?

A

-they catalyse metabolic reactions at cellular level (respiration) and in the organism as a whole (digestion)

70
Q

explain why maltase can only catalyse the hydrolysis of maltose?

A

-active site of enzyme has specific shape
-only maltose can bind
-to form E-S complex

71
Q

what is activation energy?

A

the energy required to start a chemical reaction

72
Q

explain the induced fit model of enzyme action

A

-shape of active site is not directly complementary to substrate
-conformational change enables ES complexes to form
-this puts strain on substrate bonds, lowering activation energy

73
Q

explain the lock and key model

A

-substrate fits into the enzyme like a key fits a lock
-this was before the induced fit model that came based upon new evidence

74
Q

how do enzymes lower activation energy?

A

-enzymes attach to substrates and can hold the two substrates close together, reducing repulsion and allowing bonding to occur more easily
-enzymes break up the substrate more easy as it applies strain on the bonds

75
Q

name 5 factors that affect the rate of enzyme-controlled reactions

A

-enzyme concentration
-substrate concentration
-concentration of inhibitors
-pH
-temperature

76
Q

how does temperature affect rate of reaction?

A

-more heat means more kinetic energy so molecules move faster
-this makes the substrate molecules more likely to collide with the enzymes active sites
-if temperature goes above a certain level, the enzyme vibrates more and this breaks some of the bonds that hold it in shape
-active site changes shape and the substrate can no longer fit
-the enzyme is denatured

77
Q

what are the 3 aspects to consider when choosing a temperature for an experiment

A

-sufficient kinetic energy
-does not denature proteins
-optimum

78
Q

how does pH affect rate of reaction?

A

-all enzymes have an optimum pH value and most human enzymes work best at pH 7
-above and below the optimum pH, H+ and OH- ions can disrupt the ionic bonds and hydrogen bonds that holds the enzymes tertiary structure in place
-enzyme becomes denatured and active site changes shape

79
Q

how does substrate concentration affect rate of reaction?

A

-more substrate molecules means a collision between substrate and enzyme is more likely and so more active sites will be occupied
-then all active sites become full so increase in substrate concentration has no further effect and its beyond saturation

80
Q

how does enzyme concentration affect rate of reaction?

A
  • more enzyme molecules means more likely a substrate molecule is to collide with one and form a enzyme substrate complex
    -if amount of substrate is limited, there’s more than enough enzyme molecules so adding more enzyme has no further effect
81
Q

How can you measure the rate of an enzyme controlled reaction?

A

-how fast the product of the reaction appears
-disappearance of the substrate

82
Q

what do non competitive inhibitors do?

A

-inhibitor molecule fits onto enzyme away from active site
-inhibitor causes changes that alter active site
-substrate can no longer fit into active site

83
Q

what do competitive inhibitors do?

A

-inhibitor fits into active site because it is a similar shape to the substrate molecule

84
Q

contrast competitive and non-competitive inhibitors

A

*competitive=
-similar shape to substrate
-do not stop reactions
-increasing substrate concentration decreases their effect
*non-competitive=
- not similar to substrate
-may not stop reaction
-increasing substrate concentration has no impact on their effect

biology year 1 (10 decks)

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