Proteins Flashcards

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1
Q

Why are proteins needed in our body?

A

For cell growth/repair, Structural role, help metabolic processes

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2
Q

What roles do proteins have in metabolic processes?

A

Proteins can form antibodies, enzymes and hormones

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3
Q

Where do proteins have a structural role?

A

In cytoplasm and muscle, collagen and elastin in the skin, collagen in bone, keratin in hair

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4
Q

What are proteins (and amino acids) made of?

A

Carbon, hydrogen, oxygen and nitrogen

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5
Q

What is the building block of a protein?

A

An a amino acid, small monomers (amino acids) join together to form a protein

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6
Q

What is important about the sequence of amino acids in a protein?

A

It determines the type and function of the protein formed

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7
Q

What 2 groups do all amino acids have?

A

An amino group, a carboxyl group

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8
Q

What are the two groups in an amino acids attached by?

A

Centrally, a carbon atom, carrying a hydrogen one side and an R group the other

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9
Q

What is the formula for an amino group?

A

NH2

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10
Q

What is the formula for a carboxyl group?

A

COOH (the carbon is double bonded to one of the oxygen)

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11
Q

What is an R group?

A

A side chain, acts as a functional group and helps determine internal bonds/function/shape (Residual group)

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12
Q

What is a dipeptide?

A

2 amino acids joined together

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13
Q

What is a polypeptide?

A

Multiple amino acids joined together (a polymer of amino acids)

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14
Q

How do two amino acids join to form a dipeptide?

A

Joined by a condensation reaction (1 H2O molecules is lost)

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15
Q

What bond forms between 2 amino acids?

A

A peptide bond

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16
Q

How can a peptide bond be broken/ 2 amino acids un-attatch?

A

Hydrolisis (using 1 H2O molecule)

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17
Q

What atoms are involved in forming the peptide bond between two amino acids?

A

The OH of one of the amino acids COOH group, and one of the H’s of the other amino acids amino group (providing the H2O molecule which is lost)

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18
Q

What is the primary structure of a protein?

A

The sequence, type and number of amino acids in the amino acid chain

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19
Q

What is the secondary structure of a protein?

A

After primary structure, the chain takes a particular shape and either folds or coils

20
Q

What determines weather the protein folds or coils (in its secondary structure) ?

A

The order of amino acids determines the bonds that form and where they form between certain amino acids in the chain

21
Q

What are the 2 forms of secondary folding?

A

An Alpha helix and a beta pleated sheet

22
Q

How is the alpha helix held in place?

A

Hydrogen bonds between amino acids in one part of the chain and those a little further along the chain

23
Q

How is the beta pleated sheet held in place?

A

It folds in a fan style way (diagonal up, diagonal down) Hydrogen bonds connect adjacent pleated sheets above and below one another

24
Q

What is the tertiary structure of a protein?

A

The three-dimensional shape of the protein, further coiling and twisting after the secondary structure

25
Q

What are the two types of tertiary structure?

A

Globular and fibrous

26
Q

What is a globular protein?

A

A tertiary structure - folds and coils into a complex 3D shape

27
Q

What is a fibrous protein?

A

A tertiary structure - twists the secondary structure to form a long rope-like shape

28
Q

What is a hydrogen bond in proteins?

A

Attraction between the slight neg charge of one amino acid (e.g. CO) and the slight pos charge of another amino acid (e.g NH)

29
Q

Ionic bond?

A

Attraction between a pos charged R group of one amino acid and a neg charged R of another amino acid

30
Q

Disulfide bond?

A

Covalent bond between sulfur atoms of the R groups of two cysteine amino acids

31
Q

What is quaternary structure?

A

A protein made up of more than one polypeptide chain, that type of protein will not function without all of it’s sub units

32
Q

What is a prosthetic group?

A

Non-protein part of a protein, containing inorganic molecules/inorganic ions (e.g. haem in haemoglobin contains inorganic ions and is the p group)

33
Q

Conjugated protein?

A

A globular protein with a prosthetic group

34
Q

Structure of haemoglobin?

A

Its a conjugated protein(globular), 4 polypeptide chains (2 alpha, 2 beta) and each chain is associated with a haem group

35
Q

Structure of collagen?

A

A fibrous protein, 3 polypeptides twisted around one another like a plait (each chain is made of 3 repeating amino acids)

36
Q

What can chains of collagen form?

A

The chains in turn form collagen fibril, which links with others to form collagen fibre

37
Q

Why is collagen important?

A

Provides support in heart/arteries/bone/cartilage and elasticity in skin

38
Q

What is the helical structure of haemoglobin?

A

Folded into a right-handed alpha-helical

39
Q

What is the helical structure of collagen?

A

Wound into a left-hand helical structure

40
Q

Is haemoglobin soluble in water?

A

Yes (dissolves)

41
Q

Is collagen soluble in water?

A

No

42
Q

Are there many types of amino acid in haemoglobin?

A

Yes most of all 20

43
Q

Are there many types of amino acid in collagen?

A

Made of very few (normally 3), glycine mainly

44
Q

Is there a prosthetic group in collagen?

A

No

45
Q

Role of haemoglobin?

A

Transport oxygen

46
Q

What test to use for proteins?

A

Biuret test, use a control tube for comparison. add equal volumes of protein suspension and sodium hydroxide, shake well, then add copper sulfate drop by drop

47
Q

What colour should the protein suspension turn after buret test?

A

Mauve/purple if present, copper sulfate blue if not