L10 Flashcards
the connective tissue or extracellular matrix refers to the complex material surrounding the cell tissue and it includes?
collagen
elastin
laminin
fibronectin
what is the most abundant protein in mammals ?
collagen , predominantly in connective tissue
what are the functions of collagen ?
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 )
collagen is not a single protein , rather is it a group. how many types are there ?
19 different types.
where can collagen type 1 and 2 be found ?
in skin and bone
describe the structure of collagen ,
triple helix
what is the basic structural unit of collagen ?
tropocollagen
what is each tropocollagen molecule made of ?
3 alpha chains , each alpha chain contains a repeated sequence of glycine-X-proline/hydroxyproline
what contributes to 1/3rd of collagens amino acid composition ?
glycine
each chain forms a ____
left handed helix , three chains join to form a right handed triple helix , which gives collagen its strength
what gives collagen its strength ?
covalent cross links formed between lysine and hydroxy lysine residues
the degree of collagen cross linking increases with ——
age, thus , in older people , the collagen containing tissues (e.g. skin, blood vessels) become less elastic and stiffer, contributing to health complications.
give some examples of inherited diseases of collagen synthesis
Ehlers-Danlos syndrome
Osteogenesis imprefecta
give an example of acquired disease of collagen synthesis .
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.
describe Ehlers-Danlos syndrome
comprises a group of inherited disorders
principal clinical features are hyper-extensibility of the skin
abnormal tissue fragility and increased joint mobility
describe Ostepgenesis imprefecta
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.
what is elastin ?
it is an important connective tissue protein that is mainly responsible for the extensibility and elasticity of tissue
where can elastin be found in large quantities ?
Elastin is found in large quantities in Lungs, arterial blood vessels, elastic ligaments etc.
how is elastin synthesized ?
as tropo-elastin
what are some abnormalities associated with elastin production ?
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
what is fibronectin ?
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
what is laminin ?
basal lamina of glomerular membrane ( of renal cells ) contain laminin
what are keratins ?
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
