Amino acids

Question 1

How many proteins does Bacterium E. coli and a human being produce?

Answer 1

Bacterium E. coli and a human being produce about 3000 different proteins and between 50000 – 100000 different proteins , respectively.

Question 2

Where is the name “proteins” derived from?

Answer 2

Swedish chemist Berzelius suggested the name protein which is derived from the
Greek word ‘Protos” meaning ‘primary’ or ‘holding the first place’.

Question 3

Why is the name protein apt?

Answer 3

The name protein is apt since proteins are the first recognizable and distinctive expressions of genetic
information.
In a sense, they are the molecular instruments through which genetic
information is expressed.

Question 4

The various essential functions of proteins in mammalian organisms can be divided
into 2 classes:

Answer 4

i. Dynamic functions

ii. Structural functions

Question 5

I. Dynamic functions
a. Many proteins function as Enzymes
What are the requirements for a reaction to occur at a rate that is compatible with life?

Answer 5

They require a specific biochemical enzyme catalyst, which is capable of enhancing reaction rates a million
times (106).
- Thus the characteristic and functions of a cell is based on the specific enzyme that make
up of the cell.

Question 6

I. Dynamic functions - b. Some proteins bind other molecules for Transport and Storage. What does hemoglobin transport?

Answer 6

Hemoglobin transports O2 and CO2 in blood erythrocytes

Question 7

I. Dynamic functions. What is iron stored as?

Answer 7

Iron is stored as a complex with the protein ferritin in the liver

Question 8

c. Assemblies of proteins can do mechanical work such as Coordinated Motion
Actin & myosin are proteins – major components of muscle. - What is the function of actin and myosin?

Answer 8

they function in muscle contraction.

Question 9

• What do contractile assemblies[spindle fibres] consisting of proteins produce?

Answer 9

Contractile assemblies (spindle fibres) consisting of proteins produce movement/separation of chromosome during mitosis.

Question 10

d. Some proteins serve other specialised functions such as Immune Protection and Defence Proteins
- What do immunoglobins[antibodies] act against?

Answer 10

Immunoglobulins (antibodies) act against bacterial infections.

Question 11

• What does Interferon combat?

Answer 11

Interferon combats cell infected with viruses.

Question 12

e. Many proteins are responsible for Generation and Transmission of Nerve Impulses

What do receptor proteins mediate?

Answer 12

Receptor proteins mediate the response of nerve cells to specific stimuli (hormones).

Question 13

Some proteins are hormones. What do they regulate?

Answer 13

Some proteins are hormones, which regulate biochemical activity in target cells or tissues

Question 14

f. Control of Growth and Differentiation

What are proteins responsible for?

Answer 14

Proteins are responsible for the controlled sequential expression of genetic information, which is essential for the orderly growth, and differentiation of cells.

Question 15

II. Structural function

What do the structural proteins provide?

Answer 15

Structural proteins provide mechanical support and shape.

Question 16

What is the matrix for bones and ligaments formed by?

Answer 16

Collagen and elastin form the matrix for bones and ligaments – which provides structural strength of the organs and elasticity to the vascular system

Question 17

How are proteins related to the cell?

Answer 17

Proteins are the workhorses of the cell, influencing almost every facet of the cells activity
- Therefore to understand the normal functioning of an organism, it requires a clear insight into the structure and properties of proteins.

Question 18

Describe the chains comprising proteins.

Answer 18

The chains comprising proteins unlike those of carbohydrate and fats are unbranched.

Question 19

What is the monomeric unit of a polypeptide chain?

Answer 19

The monomeric unit of a polypeptide chain is an amino acid.

Question 20

Define standard amino acids.

Answer 20

Standard amino acids are those amino acids, for which a specific codon exists in the genetic code

Question 21

What do the 20 amino acids found in proteins possess?

Answer 21

All of the 20 amino acids found in proteins possess a carboxyl (-COOH), amino
group (-NH3
+), a hydrogen atom and a distinctive R group, all of which are bonded to
a central carbon atom, called the alpha () carbon atom.

Question 22

What type of molecule is an amino acid?

Answer 22

AA is a bifunctional molecule i.e. it is amphoteric because it can behave either
as an acid or a base.

Question 23

Why are standard amino acids generally referred to as an amino acid?

Answer 23

The standard amino acids are generally referred to as an amino acid because with
the exception of proline, they have a primary amino group and a carboxyl group
attached to a alpha - carbon.

Question 24

What amino group does proline have?

Answer 24

Proline has a secondary amino group and is therefore

referred to as an alpha– imino acid.

Question 25

Amino acids are classified according to their R-groups. Two types of classification:

Answer 25

i. Classification based on chemical composition of R-group

ii. Classification based on polarity of the R-group.