Topic 7.5: Proteins Flashcards

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1
Q

Explain Primary (1°) Structure of Protein (3)

A

The order / sequence of the amino acids of which the protein is composed
Formed by covalent peptide bonds between adjacent amino acids
Controls all subsequent levels of structure because it determines the nature of the interactions between R groups of different amino acids

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2
Q

Explain Secondary (2°) Structure of Protein (4)

A

The way the chains of amino acids fold or turn upon themselves
Held together by hydrogen bonds between non-adjacent amine (N-H) and carboxylic (C-O) groups
May form an alpha helix, a beta-pleated sheet or a random coil
Secondary structure provides a level of structural stability (due to H-bond formation)

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3
Q

Explain Tertiary (3°) Structure of Protein (3)

A

The way a polypeptide folds and coils to form a complex molecular shape (e.g. 3D shape)
Caused by interactions between R groups; including H-bonds, disulphide bridges, ionic bonds and hydrophilic / hydrophobic interactions
Tertiary structure may be important for the function of the enzyme (e.g. specificity of active site in enzymes)

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4
Q

Explain Quaternary (4°) Structure of Protein (4)

A

The interaction between multiple polypeptides or prosthetic groups that results in a single, larger, biologically active protein
A prosthetic group is an inorganic compound involved in protein structure or function (e.g. the heme group in haemoglobin)
A protein containing a prosthetic group is called a conjugated protein
Quaternary structure may be held together by a variety of bonds (similar to tertiary structure)

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5
Q

What is the difference between a fibrous protein and globular protein in respect to shape?

A

Fibrous: long and narrow

Globular: round/spherical

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6
Q

What is the difference between a fibrous protein and globular protein in respect to role?

A

Fibrous: structural (strength and support)

Globular: functional (catalytic, transport, etc)

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7
Q

What is the difference between a fibrous protein and globular protein in respect to solubility?

A

Fibrous: (generally) insoluble in water

Globular: (generally) soluble in water

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8
Q

What is the difference between a fibrous protein and globular protein in respect to sequence?

A

Fibrous: repetitive amino acid sequence

Globular: irregular amino acid sequence

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9
Q

What is the difference between a fibrous protein and globular protein in respect to stability?

A

Fibrous: less sensitive to changes in heat, pH, etc

Globular: more sensitive to changes in heat, pH, etc

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10
Q

What is the difference between a fibrous protein (6) and globular protein (4) in respect to examples?

A

Fibrous: collagen, myosin, fibrin, actin, keratin, and elastin

Globular: catalase, hemoglobin, insulin, immunoglobin

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11
Q

Is collagen a fibrous or globular protein?

A

fibrous

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12
Q

Is myosin a fibrous or globular protein?

A

fibrous

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13
Q

Is fibrin a fibrous or globular protein?

A

fibrous

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14
Q

Is actin a fibrous or globular protein?

A

fibrous

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15
Q

Is keratin a fibrous or globular protein?

A

fibrous

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16
Q

Is elastin a fibrous or globular protein?

A

fibrous

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17
Q

Is catalase a fibrous or globular protein?

A

globular

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18
Q

Is hemoglobin a fibrous or globular protein?

A

globular

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19
Q

Is insulin a fibrous or globular protein?

A

globular

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20
Q

Is immunoglobin a fibrous or globular protein?

A

globular

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21
Q

Explain the significance of polar and non-polar amino acids (4)

A

Polar amino acids have hydrophilic R groups, whereas non-polar amino acids have hydrophobic R groups
For water soluble proteins, non-polar amino acids tend to be found in the centre of the protein (stabilising structure) while polar amino acids are found on the surface (capable of interacting with water molecules)
For membrane-bound proteins, non-polar amino acids tend to be localised on the surface in contact with the membrane, while polar amino acids line interior pores (to create hydrophilic channels)
For enzymes, the active site specifically depends on the location and distribution of polar and non-polar amino acids as hydrophobic and hydrophilic interactions can play a role in substrate binding to the active site

22
Q

What are the six functions of proteins?

A

structure, hormones, immunity, transport, movement, and enzymes

23
Q

What is the role of structure proteins?

A

Support for body tissue

24
Q

What is the role of hormone proteins?

A

Regulation of blood glucose

25
Q

What is the role of immunity proteins?

A

Bind antigens

26
Q

What is the role of transport proteins?

A

Oxygen transport

27
Q

What is the role of movement proteins?

A

Muscle contraction

28
Q

What is the role of enzyme proteins?

A

Speeding up metabolic reactions

29
Q

Name three examples of structure proteins

A

collagen, elastin, keratin

30
Q

Name two examples of hormone proteins

A

insulin, glucagon

31
Q

Name two examples of immunity proteins

A

antibodies / immunoglobulins

32
Q

Name two examples of transport proteins

A

haemoglobin, myoglobin

33
Q

Name four examples of movement proteins

A

actin / myosin, troponin / tropomyosin

34
Q

Name three examples of enzyme proteins

A

catalase, lipase, pepsin

35
Q

What type of protein function does collagen serve?

A

structure

36
Q

What type of protein function does elastin serve?

A

structure

37
Q

What type of protein function does keratin serve?

A

structure

38
Q

What type of protein function does insulin serve?

A

hormones

39
Q

What type of protein function does glucagon serve?

A

hormones

40
Q

What type of protein function does antibodies serve?

A

immunity

41
Q

What type of protein function does immunoglobulins serve?

A

immunity

42
Q

What type of protein function does hemaglobin serve?

A

transport

43
Q

What type of protein function does myoglobin serve?

A

transport

44
Q

What type of protein function does actin serve?

A

movement

45
Q

What type of protein function does myosin serve?

A

movement

46
Q

What type of protein function does troponin serve?

A

movement

47
Q

What type of protein function does tropomyosin serve?

A

movement

48
Q

What type of protein function does catalase serve?

A

enzymes

49
Q

What type of protein function does lipase serve?

A

enzymes

50
Q

What type of protein function does pepsin serve?

A

enzymes