BS120: Proteins

Question 1

What are…

The 4 Main Bio-molecules in the Human Body

Answer 1

1. Proteins (17.0%)
2. Lipids (13.8%)
3. Carbohydrates (1.5%)
4. Nucleic Acids

Question 2

Define

Proteins

Answer 2

1. the most abundant and functionally diverse molecule in living systems
2. a macromolecule consisting of alpha-amino acids connected by peptide bonds
3. organic nitrogenous compound that are high in molecular weight
4. polymers of amino acids

Question 3

Percents

What are the 5 major elements of protein?

Answer 3

1. Carbon (50-55%)
2. Oxygen (19-24%)
3. Nitrogen (13-19%)
4. Hydrogen (6-7.3%)
5. Sulfur (0-4%)

Question 4

8 Functions and their Type of Protein are:

Answer 4

1. Catalytic Function [enzymes]
2. Regulatory Function [hormones]
3. Gene Regulatory Function [genetic proteins]
4. Protection Function [defensive proteins]
5. Transportation Function [transporters]
6. Storage Function (storage proteins)
7. Contractile Function (contractile proteins)
8. Structural Function (structural proteins)

Question 5

Amino Acid Formula:

Answer 5

R-CH(NH2)-COOH

Question 6

The major building block of protein is

Answer 6

alpha amino acids

Question 7

Amino acids in living organisms can be found as both

state

Answer 7

• free form
• in the form of peptides and protein

Question 8

What are chaperones?

Answer 8

They are a specialized group of proteins required for proper folding of proteins.

Question 9

Where do peptide bonds happen in 2ry and 3ry structures?

and between what

Answer 9

The folding of 2ry and 3ry structures have a peptide bond between -CO and -NH.

Question 10

Disulfide bridge in insulin:

Answer 10

3:
- 1 intrachain in the A chain
- 2 interchain between the A and B chains

Question 11

Are there disulfide bonds in the primary structure of a protein?

Answer 11

NO, they are in the tertiary structure. (3D)

Question 12

What does it mean that a peptide bond has coplanarity?

Answer 12

It means that there is partial sharing of two pairs of electrons between the amide nitrogen and carboxyl oxygen

Question 13

Where is free rotation prevented?

Answer 13

Between the carbonyl carbon and the nitrogen of the peptide bond

Question 14

What purposes does the disulfide bridge serve in insulin?

5

Answer 14

1. Preserves structure
2. Stabilizes 3ry and 4ry structures
3. Functional conformation needed for insulin’s biological activity
4. Enables insulin to interact correctly with insulin receptors
5. Role in regulating blood glucose levels

Question 15

How does the primary structure get sequenced?

genes

Answer 15

• unique a.a sequence determined by genes
• mutation can lead to a change in these a.a sequences and cause disease.

Question 16

What is the healthy sequencing of hemoglobin A (HbA)?

Answer 16

Glutamic acid in position 6

Question 17

In abnormal hemoglobin S (Hb S), what is in position 6?

Answer 17

Valine

remember “surveilance”

Question 18

In abnormal haemoglobin C (Hb C) what is in position 6?

Answer 18

Lysine

Question 19

What is Hb S and what can happen due to it?

Answer 19

Sickle cell disease, where Hb S is a variant of the protein that causes sickle cell anemia.
- at low oxygen levels: altered hemoglobin molecules bond together and distort the shape of RBCs, creating abnormal sickle-shaped cells.

Question 20

Ketogenic a.as are:

Answer 20

• Leucine
• Lysine

LK

Question 21

Glucogenic a.as:

Answer 21

ALL a.as except (ile, tyr, trp, phe, leu, lys)

Question 22

mixed ketogenic and glucogenic a.as:

Answer 22

• isoleucine i
• tyrosine y
• tryptophan w
• phenylalanine f

IFWY (i f w you) mixed

Question 23

semi-essentials

which a.as are needed for growing children but not adults?

Answer 23

His h & Arg r

Question 24

semi-essential

which a.as are needed post-trauma/surgery?

Answer 24

His h & Gln Q

Question 25

Essential a.as: | 8

Answer 25

FHIKLMTVW

Question 26

semi-essential a.as:

Answer 26

HRQ

Question 27

non-essential a.as:

Answer 27

ACDEGNPSQY | akdynepsiky

Question 29

If pH is greater than pl...

Answer 29

the amino acid is negatively charged.

Question 30

if the pH is less than pl...

Answer 30

then it is positively charged

Question 31

which amino acids have a taste?

Answer 31

- glycine & alanine (sweet) - arginine (bitter)

Question 32

T/F: a.as have very high melting points

Answer 32

True! (200-300 celsius) - because of hydrogen and ionic bonds

Question 33

at melting point, they...

Answer 33

are in their **crystalline/ zwitterionic structure**

Question 34

Colour of a.as:

Answer 34

Colourless, they are **crystalline**

Question 35

T/F: solubility in water increases as a.as is considered polar/ charged.

Answer 35

True. Polar a.as can form hydrogen bonds so they are more soluble in water.

Question 36

Where do non-polar a.as exhibit high solubility?

Answer 36

non-polar solvents examples: 1. benzene 2. chloroform 3. ether

Question 37

Are a.as soluble at pl?

Answer 37

NO, AAs are insoluble at isoelectric point because of the net neutral charge.

Question 38

What can increase solubility of AAs?

Answer 38

higher temp example: tyrosine is soluble in hot water