Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

A Level Biology - 2.1.2 Biological molecules > Proteins > Flashcards

Proteins Flashcards

(65 cards)

Start Studying
1
Q

How do proteins exist?

A

Not as long straight chains because the R group causes the polypeptide to fold

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

Why do R groups interact with each other?

A

Their different properties and this causes the poly tide to fold to form final protein

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

What is primary structure?

A

The sequence of amino acids in a polypeptide

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

How are amino acids held together?

A

By peptide bonds

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

What does the sequence of amino acids determine?

A

Where certain R groups occur which determines which bonds can occur and where, deciding the shape of the final protein e.g. enzymes and their active site

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

What is secondary structure?

A

The folding and coiling caused by hydrogen bonding between hydrogen and oxygen of nearby amino acids

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

What is an alpha helix?

A

It is when hydrogen bonds pull the peptide chain into coils

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

What are beta pleated sheets?

A

Polypeptide chains lying parallel in sheets held together by hydrogen bonds where the pattern forms pleats

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

What is tertiary structure?

A

Brought about by further folding of secondary structure caused by bonds and interactions between R groups

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

What are the 4 types of bonds within tertiary structure?

A

Hydrogen bonds, hydrophobic interactions, ionic bonds and disulfide bonds

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

What are hydrogen bonds?

A

Weak attraction caused by H being shared between 2 atoms

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

What are hydrophobic interactions?

A

Weak association between R groups that do not dissolve in water

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

What are ionic bonds?

A

Weak attraction between groups of opposite charge

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

What are disulfide bonds?

A

Strong covalent bonds between cysteine amino acids

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

What happened when all bonds break in tertiary structure?

A

Te protein experiences denaturalisation and the whole protein unravels

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

What is the order the bonds within tertiary structure break?

A
  1. Hydrophobic interactions
  2. Hydrogen bonds
  3. Ionic bonds
  4. Disulfide bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where do hydrogen bonds form?

A

Also between hydrogen and nitrogen?

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

What do disulfide bonds form?

A

Between R groups containing -SH groups

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

What is quaternary structure?

A

The level of structure where two or more polypeptide subunits are bonded together, and the subunits can be identical or different.

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

What are 4 examples of quaternary structure?

A

Insulin - two different subunits, haemoglobin - two sets of identical subunits, antibodies - light and heavy chains and catalase with 4 different subunits.

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

What are the two shapes of proteins?

A

Globular or fibrous

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

What are characteristics of globular proteins?

A

Usually soluble in water and have metabolic roles

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

What are examples of globular proteins?

A

Haemoglobin, enzymes and antibodies

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

What are characteristics of fibrous proteins?

A

Usually insoluble and have structural roles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are examples of fibrous proteins?
Silk, collagen and keratin
26
What type of protein is haemoglobin?
A conjugated protein
27
What is the structure of haemoglobin?
It has a quaternary structure with 2 alpha polypeptides, 2 beta polypeptides and 4 haem prosthetic groups
28
How is haemoglobin shaped?
It is ball shaped with a hydrophilic group towards the exterior and hydrophobic towards the interior so is soluble.
29
Where is haemoglobin located?
Within red blood cells
30
What is the role of haemoglobin?
Transports oxygen from the lungs to be released in the tissue
31
How many oxygen molecules can bind to haemoglobin?
One oxygen molecule to each iron in the 4 haem groups
32
How is the shape important?
It is important to how well it can bind and release oxygen
33
Where is the haem located?
In the centre of each subunit, so it’s protected from being oxidised and destroyed by the oxygen it transports
34
What is insulin?
A hormone involved in blood glucose regulation
35
Where is insulin transported?
In the blood so it needs to be soluble
36
What do hormones do?
They fit into the specially shaped receptor proteins on cell surface membranes
37
What does tertiary structure do for hormones?
It gives the hormone a precise shape to fit the receptor
38
What is catalase?
An enzyme specific to a particular reaction
39
What is catalase’s substrate?
Hydrogen peroxide
40
Where does hydrogen peroxide come from?
ApIt is a common by-product of metabolism but it damages cells and organelles
41
What is the structure of catalase?
It is a quaternary protein with 4 haem prosthetic groups
42
How does catalase work?
Iron (II) ions are present which allows catalase to interact with hydrogen peroxide and speed up its breakdown which produces oxygen and water
43
Where is catalase found?
In all cells
44
What is the equation for the breakdown of hydrogen peroxide?
2H₂O₂ -> 2H₂O + O₂
45
What are features of fibrous proteins?
They are insoluble molecules with high proportions of hydrophobic R groups and are not folded into complex 3D shapes, their amino acids usually have a limited range of small amino acids which leads to a very organised structure.
46
What are examples of fibrous proteins?
Keratin, elastin and collagen
47
Where is keratin found?
In hair, skin and nails
48
Where is elastin found?
Walls of blood vessels and alveoli
49
Where is collagen found?
Skin, tendons, ligaments and nervous tissue
50
What does keratin contain?
A large proportion of sulfur containing amino acids with many strong bonds
51
What is keratin like as a protein?
It is strong, inflexible and insoluble
52
What determines the flexibility of keratin?
The number of bonds
53
Where is elastin present?
Elastic fibres
54
What is the structure of elastin?
It has a quaternary structure made of many stretchy molecules called tropoelastin
55
Why is elastin flexible?
It is essential for lining arteries which need to expand and return to its original shape
56
What is the structure of collagen?
It has a quaternary structure with each polypeptide chain a coil made of 1000 amino acids which 3 of the r wish together in a triple helix to form a molecule
57
What are the amino acids in collagen?
Every 3rd amino acid is glycine and there are as many prolines and hydroxyproline amino acids and the R groups are small
58
What do collagen molecules form?
Hydrogen bonds and covalent bonds called cross links with two other collagen molecules to form fibrils
59
What do crosslinks do?
They are staggered along the molecules to give strentgh and flexibility
60
What do fibrils for,?
They are joined by together to form a collagen fibre of quaternary structure
61
What is collagen a component of?
Bone, cartilage, tendons and wall of arteries providing mechanical strength such as tendons, ligaments and skin
62
What are tendons and ligaments?
They are mostly collagen with many fibres in large bundles and they connect skeletal muscle to bone, forming strong connections to pull bones for movement
63
What is collagen’s purpose in skin?
The fibres form a mesh that is resistant to tearing
64
How are bones formed?
From collagen plus calcium phosphate to make them hard
65
How is collagen used cosmetically?
It is injected for example into lips to make them look fuller

A Level Biology - 2.1.2 Biological molecules (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions