Brainscape's Knowledge GenomeTM

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


See full index

A Level Biology Paper 1 > Biological Molecules > Flashcards

Biological Molecules Flashcards

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

Monomer

A

Small molecules
Joins to other similar or identical monomers
To form larger complex molecules
Called polymers

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

Polymers

A

Large complex units
Consisting of repeating chains of 3 or more similar or identical monomers
Joined together by chemical bonds

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

Condensation reaction

A

Anabolic process
Making large molecules from smaller ones
New chemical bond joining molecules as a molecule of water is released

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

Hydrolysis reaction

A

Catabolic process
Breaks large molecules into small ones
Chemical bond broken as a molecule of water is added

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

What is the difference between chitin and other polysaccharides

A

Chitin is nitrogenous

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

How does amylose make starch adapted for its function

A 
Carbon 1:4 glycosidic bonds
Form long linear chains 
That coil into a helix
Compact
So good for storage
Can store a lot in a small space
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is starch

A

A carbohydrate of 2 polysaccharides of alpha glucose called amylose and amylopectin

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

How does amylopectin make starch adapted for its function

A 
Branched chain
Branches caused by carbon 1:4 and 1:6 glycosidic bonds
Large surface area
Rapid hydrolysis by enzymes
To release glucose for respiration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Starch adaptations

A

Insoluble so doesn’t affect the water potential of cell
Large molecule so doesn’t diffuse out of cell
Helical/compact so stores a lot in a small space
Branched so large surface area and rapid hydrolysis

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

How do glycogen and starch act as energy stores

A

Can be hydrolysed to glucose

Glucose using to release energy through respiration

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

Glycogen adaptations

A

Highly branched structure for large surface area for rapid hydrolysis by enzymes to release Glucose for respiration

Insoluble so doesn’t affect the water potential of cells

Large so doesn’t diffuse out of cells

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

What is cellulose

A

A beta glucose polysaccharide
Formed from condensation reactions to form long unbranched chains of beta glucose
Joined by beta 1:4 glycosidic bonds

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

Cellulose structure

A 
Long unrbanched chains
Joined by beta 1:4 glycosidic bonds
Every other molecule inverted 180°
To allow weak hydrogen bonds to form between straight chains
Making strong macrofibrills
Wound together to make cellulose fibres
Providing strength and support in plant cell walls
Resist turger pressure, osmotic pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why can’t humans digest cellulose

A

Human digestive system cannot break down the beta 1:4 glycosidic linkage in cellulose
Since it requires a specific enzyme absent in humans

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

What is a triglyceride

A

Type of lipid
Made of one molecule of glycerol joined by ester bonds to 3 fatty acids
Not a polymer since not made of similar monomers

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

Where are triglycerides found

A

Waxy cuticle of plants and insects (waterproof)

Aquatic organisms (less dense than water so organisms can stay buoyant)

Blubber in whales/seals (thermal insulator conducts heat slowly and reduces heat loss)

Stored around delicate organs (for shock absorption to protect organs from internal damage)

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

Saturated fatty acid

A

Fatty acid with no double bonds/only single bonds between carbon atoms of the hydrocarbon chain
Maximum number of hydrogen and so chain lies flat/no kink

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

Unsaturated fatty acid

A

One or more double bonds between carbon atoms in the hydrocarbon chain of a fatty acid
Causing a kink in the chain and not the maximum number of hydrogens
Can’t pack together tightly

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

Saturated vs unsaturated fatty acids

A

Both have a hydrogen chain

Saturated fatty acids only have single bonds between carbons
Unsaturated have one or more double bonds between carbons

Saturated are fully saturated with hydrogen/have maximum number of hydrogen
Unsaturated not fully saturated with hydrogen and don’t have maximum number of hydrogens

Double bond causes a kink in the chain of unsaturated fatty acids but saturated lies flat

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

What lipids are solids at r.t.p

A

Saturated lipids
Single bonds means no kinks in hydrocarbon tail
So lie flat and can pack tightly together as solids

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

What lipids are liquid at r.t.p

A

Unsaturated lipids with one or more double bonds in fatty acid tail/hydrocarbon chain
Because the kink causes the chains to be unable to pack tightly together hence liquid
E.g oil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Phospholipid

A

A type of lipid
Consisting of a molecule of glycerol
Bonded to a phosphate group
And go two molecules of glycerol by ester bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Phospholipid function

A

Main component of cell membranes

Forming the phospholipid bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Explain the structure and interaction of phospholipids

A

Phosphoglycerol head is hydrophilic because it is polar (-ve) and so attracts water
The fatty acids are hydrophobic and so repel water

In water they form small droplet called micelles
The hydrophobic tails orientate into the middle and the hydrophilic heads outwards towards the water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Test for reducing sugars

A

Benedicts test

Add 2cm³ benedicts solution to sample
Heat to 95°C

Colour change from blue to green/yellow/orange/red/brick red precipitate indicates presence of reducing sugar
Stronger colour change means more reducing sugar present
No colour change means no reducing sugar but may be a non reducing sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Test for non reducing sugars

A

Modified benedicts test

Add 2cm³ benedicts solution to sample
Heat to 95°C

Colour change from blue to green/yellow/orange/red/brick red precipitate indicates presence of reducing sugar
Stronger colour change means more reducing sugar present
No colour change means no reducing sugar but may be a non reducing sugar

Boil a fresh sample with dilute hydrochloric acid for a few minutes to hydrolyse glycosidic bonds
Neutralise by adding small solid pieces of sodium hydrogen carbonate
Repeat benedicts test
Colour change (like a reducing sugar) means non reducing sugar is present

Since the sucrose has been hydrolysed, it can react with the benedicts solution to give a positive result

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Reducing sugars

A 
Glucose
Fructose
Lactose
Maltose
Galactose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Non reducing sugars

A

Sucrose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Monosaccarides

A

Glucose
Lactose
Fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Disaccharides

A

Maltose (Glucose+Glucose)
Sucrose (Glucose+Fructose)
Galactose (Glucose+Galactose)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What elements do amino acids contain

A

Nitrogen
Carbon
Hydrogen
Oxygen

Some contain Sulphur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

List the parts of an amino acid

A 
Amino/amine group (NH2)
Carboxylic acid group (COOH)
Variable side chain (R)
Hydrogen (H)
All attached to centre carbon (alpha)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Explain the ends of an amino acid

A

N terminal ~ Amine group at the end

C terminal ~ Carboxyl group at the opposite end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How do amino acids bond

A

Via condensation reactions
A molecule of water is released as a peptide bond produced
Between the amine and carboxyl group
The water is from the hydroxyl group of one amino acid and hydrogen from the amine of the other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What makes amino acids different

A

The different R groups (variable side chains)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Primary structure

A 
Type
Number
Order
Of amino acids in polypeptide chain
Held together by peptide bonds (C-N) from condensation reactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Secondary sturcture

A

The way the polypeptide chain folds into a beta pleated sheet
Or coils into an alpha helix (H bond every 4th AA)
Held together by weak hydrogen bonds

38
Q

Tertiary structure

A

Further folding of peptide chain into a specific complex 3D structure
R groups determine how it folds
Held together by ionic bonds between ionised oppositely charged R grouos
Hydrogen bonds between R groups
Disulphide bridges between cysteine amino acids
Final 3D structure for proteins made of one polypeptide

39
Q

Quaternary structure

A

The way multiple polypeptide chains assemble themselves
Held together by ionic, hydrogen and disulphide bonds
Some van der waals
Bonds between different polypeptide polypeptides
Final 3D structure for proteins made of more than 1 polypeptides

40
Q

Where do hydrogen bonds occur in proteins

A

Secondary structure
Tertiary structure between H and O atom of different hydroxyl groups
Quaternary between H and O atom of different polypeptides

41
Q

Where do ionic bonds form in proteins

A

Tertiary
Between opoisitely charged R groups of different amino acids
Quaternary
Between oppositely charged R groups of different polypeptide chains

42
Q

Where do disulphide bridges form in proteins

A

Tertiary
Between sulphur and hydrogen of adjacent variable R groups
Usually cysteine amino acid
Quaternary
Between sulphur and hydrogen of suffering polypeptides amino acids R groups

43
Q

What are van der waals and where are they found

A

Hydrophobic interactions

Between R groups that are both water hating

44
Q

List 3 types of globular proteins

A

Transport proteins
Enzymes
Hormones

45
Q

Examples of the globular transport proteins

A

Haemoglobin
Carrier proteins
Channel proteins

46
Q

Examples of the globular protein enzymes

A

Lipase
DNA polymerase
ATP synthase

47
Q

Examples of the globular protein hormones

A

Insulin
Oestrogen
Thyroxine

48
Q

What is a globular protein

A

A type of protein that is spherical in shape

And soluble in water

49
Q

3 types of structural protein

A

Collagen
Keratin
Silk

50
Q

Explain the 3 types of structural protein

A

Collagen: Connective tissue e.g tendons/cartilage
Keratin: Hair and nails
Silk: In spiders webs

51
Q

Structural protein

A

Type of protein that is strong, tough and insoluble in water
Made of elongated or fibrous polypeptide chains
3 polypeptides

52
Q

Why are enzymes only specific to one substrate

A

Enzymes have a specific 3D tertiary structure
Which determines the shape of active site so it is only complementary to one substrate
Therefore it can only form an Enzyme Substrate Complex with the one substrate complementary to its active site
So can only catalyse one type of reaction

53
Q

Test for proteins

A

Biuret test for proteins
Detects peptide bonds

Add equal volumes of sample and biuret solution to a test tube
Colour change of blue to purple/violet = protein present
No colour change, stays blue = no protein present

54
Q

What are enzymes

A

Globular proteins
That are biological catalysts
Increase the rate of reaction by lowering the activation energy
By stretching/distorting/weakening substrate bonds
Not used up in the reaction and remain unchanged

55
Q

Explain the lock an key model

A

Active site is rigid and does not change shape
Substrate enters and binds to enzymes active site
Substrate fits exactly into it - complementary
Products are formed and no longer fit into active site
So released
Enzyme free to take part in another reaction

56
Q

Explain the induced fit model

A

Substrate enters enzymes active site and binds to it to form enzyme substrate complex
Binding induces a change in shape of active site
Slight change in shape of 3D specific tertiary structure of active site causes stress/distorts substrates bonds
Lowering the activation energy of reaction
When substrate leaves, active site returns to original shape

57
Q

Compare and contrast globular and fibrous proteins

A

Both have peptide, hydrogen and ionic bonds
Same bank of 20 amino acids makes them up

Globular round and spherical/Fibrous elongated
Globular compact and folded/Fibrous strong and tough
Globular soluble in water/Fibrous insoluble in water
Globular involved in metabolic reactions/Fibrous involved in forming structures

58
Q

How does temperature affect enzyme activity

A

T^ to optimum, so does rate
Increases kinetic energy of substrates molecules
More likely to successfully collide and react
More ESC/second

Beyond optimum
Atoms within amino acids vibrate faster because more kinetic energy
Causes weak hydrogen bonds and ionic bonds between neighbouring amino acids to break
3D tertiary structure changes and coukd alter active site
No longer complementary to substrate
No ESC
Denatured and no longer catalyses any chemical reactions

59
Q

How does denaturation occur

A

Beyond optimum
Atoms within amino acids vibrate faster because more kinetic energy
Causes weak hydrogen bonds and ionic bonds between neighbouring amino acids to break
3D tertiary structure changes and coukd alter active site
No longer complementary to substrate
No ESC
Denatured and no longer catalyses any chemical reactions

60
Q

How does pH affect enzyme activity

A

pH is a measure of hydrogen ion concentration
If pH is changed from optimum (more acidic or more basic)
The charge on the R groups of amino acids are altered
Ionic bonds and weak hydrogen bonds are broken in tertiary structure
Active site changes shape
Substrate no longer complementary
Less/no ESC formed
Rate decreases
Enzyme denatured

61
Q

What is pH

A

Measure of hydrogen ion concentration

62
Q

2 types of inhibitors

A

Competitive

Non competitive

63
Q

What are inhibitors

A

Substances that decrease the rate of reaction by binding to enzyme at active site or allosteric site

64
Q

What is a competitive inhibitor

A

Similar structure to substrate
Binds to active site
Prevents substrate from binding
Fewer ESC/second
Reduced rate
Some product still formed if not all enzymes occupied
Takes longer for all substrate to form products as opposed to no inhibition

65
Q

What is a non competitive inhibitor

A

Binds to enzyme away from active site at allosteric site
Causes a change in shape to enzyme and active site
Substrate no longer complementary to active site
Fewer ESC/second
Fewer products

66
Q

How does substrate concentration affect the rate of reaction

A

When substrate concentration is low so is the rate of reaction because there are few collisions
So few ESC/second
Substrate is the limiting factor
As concentration increases, more active sites filled and more ESC/second (substrate still a limiting factor)
Plateaus when all enzymes active sites are saturated and enzyme is new limiting factor
Rate falls to 0 when all substrate converted into product

67
Q

What 4 things can R groups be

A

Hydrophobic (repels water)
Hydrophilic (attracts water)
Negatively charged
Positively charged

68
Q

What is the optimum temperature

A

Temperature at which enzymes perform best at (fastest rate)

Maximum kinetic energy that can be applied to molecules before the hydrogen and ionic bonds start to break

69
Q

Why can a protein be a substrate for 2 different enzymes

A

Different parts of protein have different amino acid sequence and different shapes
Each enzymes active site has a specific shape
And 2 different enzymes can be completely to different parts of the same protein

70
Q

2 types of amino acids

A

Essential

Non essential

71
Q

What are essential amino acids

A

Obtained from food and diet

72
Q

What are non essential amino acids

A

Can be synthesised by the body

73
Q

Example of essential amino acids

A

Valine
Leucine
Tryptophan

74
Q

Examples of non essential amino acids

A

Glycine
Tyrosine
Serine

75
Q

Where does the condensation reaction between 2 monosaccharides occur

A

Between the OH hydroxyl groups on C4 of one monosaccharide

And the OH hydroxyl groups on the C1 of another

76
Q

Isomer

A

Same chemical formula

Different atom arrangement

77
Q

Sources of glucose

A

Fruit and veg
Honey
Dairy

78
Q

Sources of galactose

A

Fruit and veg

Dairy

79
Q

Sources of fructose

A

Fruit and veg

Honey

80
Q

Sources of maltose

A

Fermentation

Found in germinating seeds

81
Q

Lactose sources

A

Found in milk of lactating female mammals

82
Q

Sources of sucrose

A

Transported in the phloem of plants

83
Q

Why are hydrogen bonds important in cellulose

A

Holds chain/molecules together to form cross links between chains called microfibrills
Providing strength and rigidity to cellulose cell wall
Weak hydrogen bonds provide strength in large numbers

84
Q

Hydrolysis of disaccharide equation

A

C12H22O11 + H2O&raquo_space;> C6H12O6 + C6H12O6

85
Q

Condensation reaction for a disaccharide

A

C6H12O6 + C6H12O6&raquo_space;> C12H22O11 + H2O

86
Q

Features of sugars and features of polysaccharides

A

Sugars: sweet, soluble, white crystalline

Polysaccharides: Not sweet, insoluble

87
Q

What is a precipitate

A

A solid suspended in a lipid

88
Q

2 different reducing sugars of same concentration both produce red precipitates
After 10 minutes one had twice as much precipitate
Why

A

One solution was a disaccharide that was at the same concentration as the monosaccharide
The enzyme hydrolysed the glycosidic bond in the disaccharide
Releasing two monosaccharides
The two monosaccharides are both reducing sugars
So there is double the amount of reducing sugars
Meaning double the precipitate in benedicts test

89
Q

How would you determine the concentration or an unknown solution

A

Make up different known concentrations of ‘x’
Carry out the correct test on each sample
Take readings of absorbance/transmission
Using a colorimeter
Plot readings to produce a graph called a calibration curve
With concentration on x and absorbance on y
Draw a line of best fit
Read unknown sample absorbance/transmission from the calibration curve
Read off corresponding concentration of solution

90
Q

How can an acidic pH make proteib active

A

Change in ionic and hydrogen bonds/breaks them

So changes the tertiary structure

A Level Biology Paper 1 (16 decks)

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