week10 : postmortem

Question 1

what is the basic unit of collagen

Answer 1

tropocollagen

Question 2

how is made type 1 collagen

Answer 2

from two alpha 1 chains and one alpha 2.

Question 3

in type III collagen there is ___ alpha ___

Answer 3

three alpha 1

Question 4

what are the most common amino acids found in collagen

Answer 4

glycine
proline
alanine
hydroxyproline
hydroxylysine.

Question 5

what is the repeating unit of amino acids in collagen

Answer 5

gly-proline-hydroxyproline or hydroxylysine

Question 6

what type of collagen is this : side by side arrays and colaent cross-linking to stabilize and strengthen the structure.

Answer 6

striated (fibrous)

Question 7

when you get older, the number of cross-linking ____ in collagen fibers

Answer 7

increase

Question 8

t or f : in collagen fibrils, the structure is old together by hydrogen cross-linking

Answer 8

false, it is covalent cross-linking

Question 9

what is the most common amino acids of elastin

Answer 9

glycine

Question 10

Elastin has ____ and ____ cross-linking

Answer 10

lysinorlysine and desmosine cross-linkage

Question 11

Lysinorlysine is from the cross-link between ___ and ____

Answer 11

allysine and lysine

Question 12

how is formed allysine

Answer 12

from the oxidation of lysine from the enzyme lysyl oxidase

Question 13

What is particular of the desmosine cross-linking ?

Answer 13

derived from four lysine chains.

Question 14

what is the cross-linkage mostly responsible for restoring the elastin shape

Answer 14

desmosine (4 lysine chains attached to phenylalanine).

Question 15

why is there rigor mortis

Answer 15

because of the lack of ATP meaning that there is no way to reduce the Ca2+ levels and so the muscles are stuck in the contraction.

Question 16

how long is the delay phase

Answer 16

12h

Question 17

how long is the resolution phase

Answer 17

from few days to 2 weeks

Question 18

what are the different phases in muscle conversion to meat

Answer 18

delay phase
rigor phase
resolution phase

Question 19

what is p94

Answer 19

it is a calpain-3, activated by submicromolar calcium concentrations

Question 20

where are concentrated the calpains in the skeletal muscles

Answer 20

in the z-disk

Question 21

what is the target of the calpains

Answer 21

z disk

Question 22

the calpains degrade ____ and __ and _____ proteins as well as other proteins ____

Answer 22

titin
troponin-T
nebulin
other proteins in the Z disk

Question 23

T or F : the cathepsins are mediated by calcium levels

Answer 23

false, only the calpains are

Question 24

the ___ is involved in th degradation of actin and myosin

Answer 24

proteosome

Question 25

The final pH (5.5) is close to the isoelectric point of ___

Answer 25

myosin

Question 26

Why is there water excuding of meat?

Answer 26

The final pH (5.5) is close to the isoelectric point of myosin so there is a aggregation of the proteins and a decrease in the water holding capacities of meat.

Question 27

what is dark meat

Answer 27

meat that has a final pH that is high because of early termination of glycolysis since there is not a lot of glycogen.

Question 28

T or F : myoglobin is one of the most heat stable muscle proteins and retain structure up to 50˚C

Answer 28

true