bio chem questions-plz help me wid ans n reason

[crazydentist]

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Amino acid that contributes to tertiary structure of protein by causing a bend in the primary sequence?
Leucine
Alanine
Proline
Tyrosine
Aspartic acid

An enzyme that is activated by epinephrine?
hexokinase
glucokinase
phoshofructokinase

Absorption of calcium in smalll intestine is increased by?
Lowering pH
ingestion of fat
high phosphate intake
administration of parathyroid hormone
administration of vit E
adenyl cyclase

 

[nist7]

Amino acid that contributes to tertiary structure of protein by causing a bend in the primary sequence?
Leucine
Alanine
Proline
Tyrosine
Aspartic acid

Proline

If I remember right, its quirky structure allows the polypeptide to make a U-turn sort of deal.

 

[crazydentist]

ok..but why not leucine...its a branched chain amino acid...

 

[skabbaraju]

An enzyme that is activated by epinephrine?
hexokinase
glucokinase
phoshofructokinase
adenyl cyclase

It activates adenylate cyclase pathway which will increase glycogenolysis.

 

[simkarl]

Proline is the Amino acid that contributes to tertiary structure of protein by causing a bend in the primary sequence?---> Proline. (proline which is synthesized from glutamate )contributes to the tertiary structure of most proteins,
Especially in proline the side chain forms a cyclic structure with the amino group
And the tertiary structure is stabilized by non covalent interaction between amino acid side chains.
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glucagon epinephrine and PTH activate cAMP and increas glycolysis and glyconeogenesis.
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Absorption of calcium in smalll intestine is increased by?
Lowering pH (ans) but don't have explanation ,, thanks for any input regarding this question.

 

[crazydentist]

hey thanx for the info...but hw does lower ph in intestine increase absorption of Calcium?...ne body....?