Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-Level Biology > Biological Molecules- Substances ( Year 12 content ) > Flashcards

Biological Molecules- Substances ( Year 12 content ) Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Define monomer. Give some examples

A

A smaller unit that joins together to form a larger molecule
●monosaccharides(glucose,fructose and galactose)
●amino acids
●nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define polymer. Give some examples

A

Molecules formed when many monomers join together
●polysaccharides
●proteins
●DNA/RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens in a condensation reaction?

A

A chemical bond forms between 2 molecules and a molecule of water is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens in a hydrolysis reaction?

A

A water molecule is used to break a chemical bond between 2 molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Name the 3 hexose monosaccharides

A

●glucose
●fructose
●galactose
All have the molecular formula C6H12O6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name the type of bond formed when monosaccharides react

A

(1,4 or 1,6) glycosidic bond
2 monomers= 1 chemical bond= disaccharides
Multiple monomers= many chemical bonds= polysaccharides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name 3 disaccharides. Describe how they form

A

Condensation reaction forms glycosidic bond between 2 monosaccharides
●maltose: glucose+glucose
●sucrose: glucose+fructose
●lactose: glucose+ galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Draw the structure of alpha glucose

A

The hydroxile group(-OH) bonded to carbon 1 is below

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Draw the structure of beta glucose

A

The hydroxile group(-OH) bonded to carbon 1 is above

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the structure and function of starch

A

Storage polymer of alpha glucose in plant cells
●insoluble=no osmotic effect on cells
●large= doesn’t diffuse out of cells
Made from amylose:
●1,4 glycosidic bonds
● helix with intermolecular hydrogen bonds=compact
And amylopectin:
●1,4 and 1,6 glycosidic bonds
● branched= many terminal ends for hydrolysis into glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the structure and functions of glycogen

A

Main storage polymer of alpha glucose in animals cells
●1,4 and 1,6 glycosidic bonds
●branched= many terminal ends for hydrolysis
●Insoluble=no osmotic effect
●compact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the structure and functions of cellulose

A

Polymer of beta glucose gives rigidity to plant cells walls
●1,4 glycosidic bonds
●straight chain, unbranded molecule
● alternate glucose molecules are rotated 180°
● hydrogen crosswinds between parallel strands form microfibrils=high tensile strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the benedicts test for reducing sugars

A

1) add equal volume of benedicts reagent to a sample
2)heat the mixture in an electric water bath at 100°C for 5 mins
3) Positive result: colour change from blue to orange and brick-red precipitate forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the benedicts test for non-reducing sugars

A

1) negative result: benedicts reagent remains blue
2) heat the sample in hydrochloric acid
3) neutralise the mixture using sodium carbonate solution
4) proceed with the benedicts test as usual.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the test for starch

A

1) add iodine solution
2) positive result: colour change from orange to blue-black

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe how to test for lipids in a sample

A

1) dissolve sample in ethanol
2) add a equal volume of water and shake
3) positive result: milky white emulsion forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do triglycerides form?

A

condensation reaction between 1 molecule of glycerol and 3 fatty acids forms ester bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

contrast saturated and unsaturated fatty acids

A

Saturated
-contains only single bonds
-straight chain molecules
-Higher melting point=solid at room temperature
-found in animal fats
Unsaturated
-contains double C=C bonds
-‘kinked’ molecules
-lower melting points=liquid at room temperature
-found in plant oil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Relate the structure of triglycerides to their functions.

A

●High energy:mass ratio=high calorific value from oxidation
●Insoluble hydrocarbon chain=no effect on water potential
●less dense than water=buoyancy of aquatic animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the structure and function of phospholipids.

A

A glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic polar phosphate head.
●Forms phospholipid bilayer in water
●Tails can splay outwards=waterproofing

22
Q

Compare phospholipids and triglycerides.

A

●Both have a glycerol backbone
●Both contain the elements C,H,O
●Both formed by condensation reaction

23
Q

Why is water a polar molecule?

A

O is more electronegative than H, so it attracts the shared pair of electrons in the covalent bond more strongly.
O is delta negative
H is delta positive

24
Q

State 5 important properties of water

A

●Universal solvent
●High Specific heat capacity
●High latent heat by vaporisation
●Surface Tension
●Strong cohesion between molecules

25
Q

Explain why water is significant to living organisms?

A

●Solvent for polar molecules during metabolic reactions
●Buffer to temperature change
●Strong cohesion of water molecules allows water to move in a column in the transpiration stream

26
Q

What are inorganic ions, and where are they found in the body?

A

●ions that don’t contain a carbon atom
●Found in cytoplasm

27
Q

Explain the role of hydrogen ions in the body.

A

●High concentration of H+= low(acidic) pH
●H+ ions interact with H-bonds and ionic bonds in the tertiary structure of proteins, which cause them to denature

28
Q

Explain the role of iron ions in the body?

A

Fe2+ bonds to porphyrin ring to form haem group in haemoglobin
Haem group has binding sites to transport 1 molecule of O2

29
Q

Explain the role of sodium ions in the body?

A

Involved in co-transport for absorption of glucose and amino acids in small intestine

30
Q

Explain the role of phosphate ions in the body?

A

Component of:
●DNA
●ATP

31
Q

Whats the general structure of an amino acid?

A

-COOH carboxyl group
-R variable “R” group
-NH2 amine group

32
Q

Describe how to test for proteins in a sample

A

Biuret test
1) Add equal volumes of sodium hydroxide to a sample at room temperature
2) Add drops of dilute(II) sulfate solution. Swirl to mix
3) positive result: colour changes from blue to purple
Negative result: The solution remains blue

33
Q

How many different amino acids are there, and how do they differ from each other?

A

20
Differ only by the “R” group

34
Q

How do dipeptides and polypeptides from?

A

●condensation reaction forms peptide bond
●Dipepetides: 2 amino acids
●Polypeptides: 3 or more amino acids

35
Q

How many levels of protein structure are there?

A

4

36
Q

Whats the ‘primary structure’ of a protein

A

Sequence of amino acids in the polypeptide

37
Q

What’s the ‘secondary structure’ of a protein?

A

Folding of the polypeptide chain into a Alpha helix or Beta pleated sheet which is determined by hydrogen bonds

38
Q

Whats the ‘tertiary structure’ of a protein

A

Further folding of the polypeptide chain into its unique 3D shape this is determined by disulfide bridges, ionic bonds, hydrogen bonds

39
Q

What’s the ‘quaternary structure’ of a protein?

A

●Functional proteins may consist of more than one polypeptide
●May involve the addition of prosthetic groups

40
Q

Describe the structure and function of globular proteins

A

●Spherical and compact
●Hydrophilic R groups face outwards and hydrophobic R groups face inwards= usually water-soluble

41
Q

Describe the structure and functions of fibrous proteins

A

●can form long chains or fibres
●Insoluble in water
● useful for structure and support e.g. collagen in skin

42
Q

What are enzymes?

A

Biological catalysts speed up the rate of a reaction by providing an alternative pathway for reactants with a lower activation energy

43
Q

Explain the Induced fit model of enzyme action

A

●shape of active site is not directly complementary to substrate and is flexible
● this causes temporary hydrogen bonds to form, forming a ES complex
●this puts strain on substrate bonds, lowering activation energy

44
Q

How have models of enzymes action changed?

A

●initially lock and key model:rigid shape of active site complementary to only 1 substrate
●currently induced fit model: also explains why binding at allosteric sites can change shape of active site

45
Q

Name 5 factors that affect the rate of enzyme-controlled reactions.

A

●enzyme concentration
●substrate concentration
●concentration of inhibitors
●pH
●temperature

46
Q

How does substrate concentration affect the rate of reaction?

A

Rate of reaction increases proportionally to substrate concentration. However, it levels off when a maximum number of ES complexes form at a give time.

47
Q

How does enzyme concentration affect the rate of reaction?

A

Given that substrate is in excess, rate increases proportionally to enzyme concentration, rate levels off when maximum number of ES complexes form at a given time.

48
Q

How does temperature affect rate of reaction?

A

Rate increases as kinetic energy increases and peaks at optimum temperature.
Above optimum, ionic and H-bonds in tertiary structure=active site no longer complementary to substrate(denaturation)

49
Q

How does pH affect the rate of reaction?

A

Enzymes have a narrow optimum pH range
Outside range, H+/OH- ions interact with hydrogen bond and ionic bonds in tertiary structure.

50
Q

Contrast competitive and non-competitive inhibitors

A

COMPETITIVE INHIBITORS
●similar shape to substrate=binds to active site
●do not stop reaction;ES complexes can still form when inhibitor is released
●increasing substrate concentration decreases their effect
NON-COMPETITIVE INHIBITORS
●bind at allosteric site
●disrupts the tertiary structure, causing enzyme to denature
●increasing substrate concentration has no impact on their effect l

51
Q

How do you calculate the rate of reaction?

A

Change in concentration of product or reactant/time

52
Q

State the formula for pH

A

pH=-log10[H+]

A-Level Biology (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions