L 22 Protein Structure And Modfications

Question 1

What are orders of protein structure

Answer 1

Primary,secondary,tertiary and quaternary

Question 2

How is primary structure defined

Answer 2

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

Question 3

How is secondary structure defined

Answer 3

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

Question 4

How is specific structure of secondary proteins kept

Answer 4

By hydrogen bonds

Question 5

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

Answer 5

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

Question 6

What is tertiary structure

Answer 6

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

Question 7

How is tertiary structure stabilized

Answer 7

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

Question 8

What are domains

Answer 8

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

Question 9

What is quaternary structure

Answer 9

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

Question 10

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

Answer 10

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

Question 11

What are chaperons

Answer 11

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

Question 12

What is denaturation

Answer 12

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

Question 13

What are causes of denaturation

Answer 13

Physical: high temp
Chemical: acidic or basic ph

Question 14

Effects of denaturation

Answer 14

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

Question 15

How can perms relax hair

Answer 15

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

Question 16

How are proteins classified

Answer 16

Chemical composition
Shape
Biological value

Question 17

How are they classified based on chemical composition

Answer 17

Simple proteins which are only made of amino acids

Conjugated proteins which contain a non protein portion

Question 18

Give examples for simple proteins

Answer 18

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

Question 19

Give examples of conjugated proteins

Answer 19

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

Question 20

How are proteins classified based on shape

Answer 20

Either fibrous or globular

Question 21

What are fibrous proteins and give examples

Answer 21

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

Question 22

What are globular proteins and give examples

Answer 22

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

Question 23

How can proteins be classified by biological imp

Answer 23

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