L 22 Protein Structure And Modfications Flashcards

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1
Q

What are orders of protein structure

A

Primary,secondary,tertiary and quaternary

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2
Q

How is primary structure defined

A

Linear sequence of amino acid residues linked to each other by peptide bonds

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3
Q

How is secondary structure defined

A

Regular recurring arrangements of adjacent amino acid residues in a polypeptide chain

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4
Q

How is specific structure of secondary proteins kept

A

By hydrogen bonds

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5
Q

What are the 2 main types of secondary structure and describe them

A

Alpha helix:rigid spiral structure consisting of tightly packed coiled polypeptide backbone core with side chain of amino acids extending outward from central axis

Beta pleated sheet: 2 or more segments of polypeptide chain line up next to each other forming sheet like structure

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6
Q

What is tertiary structure

A

3D folded and biologically active confirmation of a protein referred to as tertiary structure

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7
Q

How is tertiary structure stabilized

A

By interactions between side chains,ionic interactions,disulfide bonds and hydrogen bonds

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8
Q

What are domains

A

3D Structural part of protein that can fold function and exist independently of rest of protein chain
Some proteins have a single domain while others may have many

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9
Q

What is quaternary structure

A

Arrangement of polypeptide subunits held together by non covalent interactions (as H bonds)

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10
Q

Clinical implication: how can improper folding of proteins affect a person

A

They are tagged and degraded however they can accumulate especially in old age and can cause Parkinson’s and Alzheimer’s

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11
Q

What are chaperons

A

Family of proteins that guide proteins along proper pathways for folding shielding them from anything that might bind and hinder the process
They can be termed heat shock as they are made in large amounts when cell is exposed to heat

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12
Q

What is denaturation

A

Involves destruction of higher level structural organization of protein(secondary,tertiary)due to rupture of covalent bonds

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13
Q

What are causes of denaturation

A

Physical: high temp
Chemical: acidic or basic ph

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14
Q

Effects of denaturation

A

Loss of biological activity of protein and hormone
Changes of antigenic property of proteins
Denatured proteins are easily digested due to unfolding of peptide chains

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15
Q

How can perms relax hair

A

Denaturation of disulfide bonds in hair that are responsible for curly appearance

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16
Q

How are proteins classified

A

Chemical composition
Shape
Biological value

17
Q

How are they classified based on chemical composition

A

Simple proteins which are only made of amino acids

Conjugated proteins which contain a non protein portion

18
Q

Give examples for simple proteins

A

Plasma albumin which is an imp in transport protein in blood

Collagen which is a major component of connective tissue that make up tendons ligaments skin and muscles

19
Q

Give examples of conjugated proteins

A

Glycoproteins:carbohydrate added to polypeptide backbone which plays an imp role in cell signaling,cell attachment and regulating immune system
Lipoproteins: lipids added and plasma lipoproteins play a key role in absorption and transport of lipids

20
Q

How are proteins classified based on shape

A

Either fibrous or globular

21
Q

What are fibrous proteins and give examples

A

Elongated strand like structures and are usually present in form of rods or wires and have only primary and secondary structure
Have mechanical and structural function
Keratin

22
Q

What are globular proteins and give examples

A

Have compact and more or less spherical structure
Soluble in water
All structures
Myoglobin: O2 carrier in ms cells providing O2 to working muscle
Hb: responsible for transferring O2 from lungs to tissues

23
Q

How can proteins be classified by biological imp

A

HIGH value or LOW
HIGH= meat, poultry,fish and dairy
Low= legumes and vegetables