L10

Question 1

the connective tissue or extracellular matrix refers to the complex material surrounding the cell tissue and it includes?

Answer 1

collagen

elastin

laminin

fibronectin

Question 2

what is the most abundant protein in mammals ?

Answer 2

collagen , predominantly in connective tissue

Question 3

what are the functions of collagen ?

Answer 3

gives strength and support to the tissue

contributes to proper allignment of cells . which in turn helps in cell proliferation and differentiating into different tissues

collagen in blood vessels also contributes to blood clotting ( thrombus formation )

Question 4

collagen is not a single protein , rather is it a group. how many types are there ?

Answer 4

19 different types.

Question 5

where can collagen type 1 and 2 be found ?

Answer 5

in skin and bone

Question 6

describe the structure of collagen ,

Answer 6

triple helix

Question 7

what is the basic structural unit of collagen ?

Answer 7

tropocollagen

Question 8

what is each tropocollagen molecule made of ?

Answer 8

3 alpha chains , each alpha chain contains a repeated sequence of glycine-X-proline/hydroxyproline

Question 9

what contributes to 1/3rd of collagens amino acid composition ?

Answer 9

glycine

Question 10

each chain forms a ____

Answer 10

left handed helix , three chains join to form a right handed triple helix , which gives collagen its strength

Question 11

what gives collagen its strength ?

Answer 11

covalent cross links formed between lysine and hydroxy lysine residues

Question 12

the degree of collagen cross linking increases with ——

Answer 12

age, thus , in older people , the collagen containing tissues (e.g. skin, blood vessels) become less elastic and stiffer, contributing to health complications.

Question 13

give some examples of inherited diseases of collagen synthesis

Answer 13

Ehlers-Danlos syndrome

Osteogenesis imprefecta

Question 14

give an example of acquired disease of collagen synthesis .

Answer 14

This is a disease due to the deficiency of vitamin C (ascorbic acid).
Vitamin C is needed to hydroxylate lysine and proline to form the cross links in collagen.
Vitamin C deficiency results in unstable and weak collagen.
Scurvy is characterized by bleeding of gums, poor wound healing and subcutaneous hemorrhages.

Question 15

describe Ehlers-Danlos syndrome

Answer 15

comprises a group of inherited disorders
principal clinical features are hyper-extensibility of the skin
abnormal tissue fragility and increased joint mobility

Question 16

describe Ostepgenesis imprefecta

Answer 16

Extremely fragile bones
Caused by a defect in the gene that produces type 1 collagen, an important building block of bone.
The severity depends on the specific gene defect.

Question 17

what is elastin ?

Answer 17

it is an important connective tissue protein that is mainly responsible for the extensibility and elasticity of tissue

Question 18

where can elastin be found in large quantities ?

Answer 18

Elastin is found in large quantities in Lungs, arterial blood vessels, elastic ligaments etc.

Question 19

how is elastin synthesized ?

Answer 19

as tropo-elastin

Question 20

what are some abnormalities associated with elastin production ?

Answer 20

Williams syndrome is a genetic disease due to impairment in elastin synthesis.
Decreased synthesis of elastin is found in aging of skin and pulmonary emphysema

Question 21

what is fibronectin ?

Answer 21

cell surface protein that is closley involved in the interaction of cells with extra cellular matrix

it actively participates in cell adhesion and cell migration

Question 22

what is laminin ?

Answer 22

basal lamina of glomerular membrane ( of renal cells ) contain laminin

Question 23

what are keratins ?

Answer 23

structural fibrous proteins found in hair , skin , nails , horns , etc

polypeptide of keratinn form alpha helical structure and are held together by disulfide bond . the toughness and strength of keratin is directly related to disulfide bonds