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OCR A Biology > Unit 2 - Proteins > Flashcards

Unit 2 - Proteins Flashcards

1
Q

What are the monomeric units of proteins?

A

Amino acids

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2
Q

Where do we get amino acids from?

A

Our diet

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3
Q

Outline the journey an amino acid takes from food to protein in a cell

A
  • food is ingested
  • enzymes in the stomach/small intestine hydrolyse protein into amino acids
  • the amino acids are absorbed by the gut wall into the blood
  • the amino acids leave the blood in the tissue fluid and enter cells
  • proteins are synthesised on the ribosomes
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4
Q

How many common amino acids are there?

A

20

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5
Q

Give 4 functions of proteins

A
  • enzymes
  • hormones
  • antibodies
  • structural proteins
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6
Q

What do the interactions of differing R-groups determine?

A

The folding of the protein

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7
Q

What type of reaction occurs to form a protein from 2 amino acids?

A

Condensation

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8
Q

What type of bond is formed from the synthesis of a protein?

A

Peptide

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9
Q

What is produced in the condensation reaction between two amino acids?

A

Water and dipeptide

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10
Q

What is the general formula of an amino acid?

A
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11
Q

Between which parts of the amino acid molecules does the condensation reaction between two amino acids occur?

A

The carboxyl group of one amino acid and the amine group of another amino acid

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12
Q

What is a chain of amino acids called?

A

A polypeptide

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13
Q

What is the end of a polypeptide with an amino group called?

A

The N-terminus

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14
Q

What is the end of the polypeptide with a carboxyl group called?

A

The C-terminus

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15
Q

What is the definition of primary structure of a protein?

A

The SEQUENCE of amino acids

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16
Q

What type of bonding holds the primary structure of a protein together?

A

Peptide

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17
Q

What shape is the primary structure of a protein?

A

Linear

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18
Q

What forms the secondary structure of a protein?

A

The folding of the primary structure

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19
Q

What type of bonds hold together the secondary structure of a protein?

A

Hydrogen bonds

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20
Q

In the secondary structure, what do hydrogen bonds form between?

A

Partially positive H and partially negative O

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21
Q

What are the two possible shapes of the secondary structure?

A
  • alpha helix
  • beta pleated sheet
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22
Q

What is the tertiary structure formed by?

A

The folding of the secondary structure

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23
Q

Why do proteins fold at the tertiary level of structure?

A

Due to the interactions between the R-groups

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24
Q

What are the 4 types of bond formed at the tertiary level of structure?

A
  • ionic bonds
  • hydrogen bonds
  • disulfide bonds
  • hydrophobic and hydrophilic interactions
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25
Q

What do ionic bonds form between?

A

Positively and negatively charged ions

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26
Q

What do hydrogen bonds form between?

A

Partially positive H and partially negative O

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27
Q

What do disulfide bridges form between?

A

Sulfur atoms contained within R-groups

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28
Q

Which amino acid contains sulfur?

A

Cysteine

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29
Q

What do hydrophobic and hydrophilic interactions form between?

A

Polar and non-polar R-groups

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30
Q

What kind of shape does the tertiary structure have?

A

3D

31
Q

What forms the quaternary structure?

A

Formed by the interaction of more than one tertiary protein and/or with prosthetic groups

32
Q

What type of bonds holds together the quaternary structure?

A

-ionic -hydrogen -disulfide -hydrophobic and hydrophilic interactions

33
Q

What is a prosthetic group?

A

a non-protein component of a conjugated protein

34
Q

Define simple proteins

A

Proteins without a prosthetic group

35
Q

Give 3 characteristics of globular proteins

A

-compact -water soluble -roughly spherical

36
Q

Why are globular proteins water soluble?

A

-TERTIARY structures are folded so that the hydrophobic R-groups are kept away from the aqueous environment -hydrophilic R-groups are on the outside

37
Q

What are globular proteins used for?

A

-regulating many processes

38
Q

Give examples of the processes globular proteins regulate

A

-muscle contraction -immunity -chemical processes

39
Q

Give an example of a globular protein

A

Insulin

40
Q

Why is it beneficial for insulin to be water-soluble?

A

-insulin is a hormone -hormones are transported in the blood so must be water soluble

41
Q

What is the function of insulin?

A

Regulates blood glucose

42
Q

Are conjugated proteins a type of globular protein?

A

Yes

43
Q

What do conjugated proteins contain?

A

A non-protein prosthetic group

44
Q

Give an example of 2 conjugated proteins

A

Haemoglobin Catalase

45
Q

What is the function of haemoglobin?

A

Carries oxygen in the blood in erythrocytes

46
Q

What is haemoglobin made up of?

A

2 alpha-helices 2 beta-pleated sheets

47
Q

How many subunits make up haemoglobin?

A

4

48
Q

What does each haem group contain?

A

Iron 2+ ion

49
Q

What does each subunit of haemoglobin contain?

A

A haem group

50
Q

How do haem groups allow erythrocytes to carry out their function?

A

Iron ions in haem groups can reversibly combine with an oxygen molecule

51
Q

How many oxygen atoms can one haemoglobin molecule carry?

A

8- remember ATOMS not MOLECULES

52
Q

Define globular protein

A

spherical, water-soluble proteins

53
Q

Define fibrous protein

A

long, insoluble, structural proteins

54
Q

What is the function of catalase?

A

Break down of hydrogen peroxide which otherwise is harmful to cells

55
Q

What type of protein is catalase?

A

Conjugated

56
Q

What type of prosthetic group does catalase contain?

A

Haem

57
Q

How many haem groups does catalase contain?

A

4

58
Q

Give 3 examples of fibrous proteins

A

Collagen Elastin Keratin

59
Q

Where is Keratin found?

A

In hair, skin, and nails

60
Q

How does the primary structure of repetitive amino acid sequences affect the properties of fibrous proteins?

A

-gives them organised structures -makes strong molecules that do not fold into complex 3D shapes

61
Q

Which amino acid does keratin contain in a high proportion?

A

Cysteine

62
Q

What does Cysteine contain in its R-group?

A

Sulfur

63
Q

What type of bonding occurs a lot in keratin?

A

Disulfide bonds

64
Q

How does a high proportion of disulfide affect the properties of keratin?

A

It makes it inflexible and strong

65
Q

Where is elastin found?

A

In the walls of blood vessels and alveoli of lungs

66
Q

What does elastin allow tissues to do?

A

Expand and return to size

67
Q

Why is it beneficial for tissues to contain elastin?

A

It confers strength and elasticity

68
Q

What makes up elastin?

A

Aggregates of tropoelastin

69
Q

Where is collagen found?

A

In the skin, tendons, ligaments, and nervous system

70
Q

Why does collagen contain glycine for every 3rd amino acid?

A

Glycine is the smallest amino acid and so they can pack together more tightly

71
Q

What property does collagen have?

A

Flexibility

72
Q

Define polypeptide

A

Chains of 3 or more amino acids

73
Q

Define protein

A

one or more polypeptides arranged as a complex macromolecule

OCR A Biology (42 decks)

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