Notes/Add. Pointers for Lab

Question 1

Functions of amino acids:

Answer 1

• to serve as building blocks for proteins
• constituents of proteins
• act as the monomer unit in protein synthesis

Question 2

T/F - Your body needs 20 different amino acids to function correctly.

Answer 2

T

Question 3

Functions of Proteins:

Answer 3

Structural – for support (ex. collagen, elastin)

Catalytic – for hastening biochemical reactions (ex. amylase)

Storage – for storage of amino acids (ex. casein, ovalbumin)

Transport – for transport of other substances (ex. hemoglobin)

Regulation – for regulation of bodily activities (ex. insulin, glucagon)

Receptor – for response of cell to external stimuli (ex. neuron receptors)

Contractile – for movement (ex. myosin, actin)

Defensive – for protection against disease (ex.antibodies)

Question 4

T/F - Millon’s test is an analytical test used for the detection of the amino acid tyrosine, which is the only amino acid containing the phenol group.

Answer 4

T

Question 5

Test that detects tripeptides

Answer 5

Biuret test (at least two peptide bonds)

Question 6

T/F - Xanthoproteic test is used to detect amino acids containing an aromatic nucleus (tyrosine, tryptophan and phenylalanine) in a protein solution which gives yellow color nitro derivatives on heating with conc. HNO3.

Answer 6

T

Question 7

factors that denature proteins

Answer 7

Heat, acid, high salt concentrations, alcohol, and mechanical agitation

Question 8

the biuret reagent is made up of (salts)

Answer 8

hydrated copper sulfate
sodium hydroxide
Rochelle salt (sodium-potassium tartrate)

Question 9

how do heavy metals denature proteins?

Answer 9

Heavy metal salts, Ag+, Hg+ and Pb+ denature proteins by reacting with the sulfhydryl groups to form stable, metal-sulfur bonds. This prevents formation of needed disulfide bonds.

Question 10

what test uses HNO3?

Answer 10

Xanthoproteic test (involves heating of protein with conc. HNO3 which produces yellow colour)

Question 11

Function of proenzymes

Answer 11

group of proteins that display no catalytic activity but can be transformed into active enzymes within an organism.

Question 12

Products of urea cycle:

Answer 12

1 molecule of urea
2 molecules of ADP
1 molecule each of AMP
fumaric acid

Question 13

Overview of Urea Cycle

Answer 13

The urea cycle or ornithine cycle converts excess ammonia into urea in the mitochondria of liver cells. The urea forms, then enters the blood stream, is filtered by the kidneys and is ultimately excreted in the urine.

Question 14

the urea cycle consumes _______ by combining it with the basic ammonia, helping to maintain a neutral pH.

Answer 14

acidic waste carbon dioxide

Question 15

One of the nitrogen atoms in the urea cycle is obtained from the ___

Answer 15

transamination of oxaloacetate to aspartate
(The fumarate that is produced in step three is also an intermediate in the citric acid cycle and is returned to that cycle)

Question 16

urea cycle takes place in what organ?

Answer 16

The liver (only site where urea is synthesized and ultimately excreted by the kidneys)

Question 17

not present in the urea cycle

Answer 17

Asparagine

Question 18

fate of amino group in citrulline-aspartate condensation

Answer 18

A condensation reaction occurs between the amino group of aspartate and the carbonyl group of citrulline to form argininosuccinate.

Question 19

The eleven non-essential amino acids are:

Answer 19

alanine
arginine
asparagine
aspartic acid
cysteine
glutamic acid
glutamine
glycine
proline
serine
tyrosine

Question 20

nine essential amino acids:

Answer 20

histidine
isoleucine
leucin
lysine
methionine
phenylalanine
threonine
tryptophan
valine

Question 21

a biologically important process by which living cells reversibly transfer the amino group from an amine or α-amino acid to an α-keto carboxylic acid

Answer 21

Transamination

Question 22

Role of chymotrypsin

Answer 22

a digestive enzyme synthesized in the pancreas that plays an essential role in proteolysis, or the breakdown of proteins and polypeptides

Question 23

aids in the digestion of proteins in the duodenum by preferentially cleaving peptide amide bonds.

Answer 23

chymotrypsin

Question 24

a serine protease produced by the pancreas that catalyzes cleavage of carboxyl groups present on small hydrophobic amino acids, such as glycine, alanine, and valine.

Answer 24

Elastase

Question 25

the breakdown of elastin, a protein that imparts elasticity to connective tissue.

Answer 25

elastase

Question 26

breaks down proteins as a component of the digestive process.

Answer 26

trypsin

Question 27

acts on proteoses and peptones and converts them into polypeptides.

Answer 27

trypsin

Question 28

secreted by the pancreas as trypsinogen, is activated by enterokinase in the duodenum, and hydrolyzes protein molecules to peptides and amino acids.

Answer 28

trypsin

Question 29

involved in the degradation of proteins in the digestive tract

Answer 29

Digestive carboxypeptidases A and B

Question 30

a zinc-containing metalloprotease that removes the amino acid residue from the C-terminal of a peptide chain

Answer 30

Carboxypeptidase A

Question 31

acts upon basic amino acids, such as arginine and lysine (releases C-terminal lysine and arginine from substrates)

Answer 31

Carboxypeptidase B

Question 32

a method to purify DNA by using physical and/or chemical methods from a sample separating DNA from cell membranes, proteins, and other cellular components.

Answer 32

DNA extraction

Question 33

causes local pH changes and denatures proteins

Answer 33

HCl

Question 34

Lab technicians can add ethanol or isopropyl alcohol (rubbing alcohol) so that the DNA clumps and form a visible white precipitate. t’s important to use cold alcohol because?

Answer 34

it allows a larger amount of DNA to be extracted. If the alcohol is too warm, it may cause the DNA to denature [bold], or break down.

Question 35

What is the complementary base pairing rule for DNA?

Answer 35

in a double strand of DNA, adenine will always pair with its complement thymine and cytosine will always pair with its complement guanine.