Lecture # 06

Question 1

When was the theory on Central Dogma proposed and by whom?

Answer 1

the theory on Central Dogma was proposed by Francis Crick in 1958.

Question 2

What is Central Dogma?

Answer 2

The process by which DNA instructions are converted is called Central Dogma.

Question 3

How many processes are included in Central Dogma?

Answer 3

Central Dogma includes 3 main processes:

1) Replication
2) Transcription
3) Translation

Question 4

By which steps does protein synthesis occur?

Answer 4

protein synthesis is mainly a 2-step process:

i) firstly, the DNA is transcribed by RNA
ii) secondly, RNA is translated into proteins.

Question 5

Where in the cell does Transcription occur?

Answer 5

Transcription occurs in nucleus of a cell.

Question 6

What is used as a template to make RNA ?

Answer 6

Genetic information in DNA is used as a template to make RNA.

Question 7

what are the three types of RNA?

Answer 7

the three types of RNA are:

a) Messenger RNA
b) Ribosomal RNA
c) Transfer RNA

Question 8

which three steps are involved in Transcription Process?

Answer 8

Transcription Process involves 3 steps which are:

1. Initiation
2. Elongation
3. Termination

Question 9

Where in the cell does translation occur?

Answer 9

Translation occurs in the cytoplasm of the cell.

Question 10

which component of a cell serves as a blueprint for synthesis of proteins?

Answer 10

The mRNA (Messenger RNA) serves as a blueprint for synthesis of proteins.

Question 11

which component of a cell is responsible for synthesis of proteins? And what does it use to do so?

Answer 11

Ribosomes are responsible for synthesis of proteins, by using the genetic information from mRNA.

Question 12

What are the three steps involved in the Translation Process ?

Answer 12

Translation Process involves 3 steps :

1. Initiation
2. Elongation
3. Termination

Question 13

Give four(4) salient features of plasma membrane.

Answer 13

The salient features of Plasma Membrane are as follows:

1. it is flexible membrane surrounding cell
2. it is Best described by fluid mosaic model
3. Some proteins float freely in the membrane
4. Other proteins are anchored at specific locations.

Question 14

Briefly describe the structure of plasma membrane.

Answer 14

The plasma membrane consists of Lipid Bilayer, that is Amphipathic in nature. It contains:

1. phospholipids,
2. cholesterol and
3. glycolipids

Question 15

what is the chemical nature of phospholipids?

Answer 15

Phospholipids Amphipathic in nature. so they have two main parts:
A) Polar part (Hydrophilic) that is the Phosphate containing ‘head’
B) and Non-polar part (Hydrophobic) Two fatty acid ‘tails’

Question 16

In the plasma membrane, what is the chemical nature of Cholesterol?

Answer 16

Chemically, Cholesterol is:
Weakly amphipathic
• Polar part – Hydroxyl group
• Non-polar part – steroid rings and hydrocarbon tail

Question 17

In the plasma membrane, what is the chemical nature of Glycolipids?

Answer 17

Chemically, Glycolipids have:

i) Polar part – Carbohydrate groups
ii) Non-polar part –fatty acid tails

Question 18

What are Glycolipids located in the plasma membrane?

Answer 18

In the plasma membrane, Glycolipids are only present in layer facing ECF (Extra Cellular Fluid)

Question 19

What are the of Functions of Lipid Bilayer?

Answer 19

Functions of Lipid Bilayer
1. Forms the basic structure of the membrane.
2. Barrier to passage of substances between
ICF and ECF.
3. Responsible for fluidity of the membrane.

Question 20

which types of membrane proteins are present in the plasma membrane?

Answer 20

the types of membrane proteins are present in the plasma membrane are classified as
A) Integral proteins, which are amphipathic in nature and are embedded in the membrane.
B) Peripheral proteins, that are not firmly embedded in the membrane.

Question 21

What are the (6) functions of plasma membrane proteins?

Answer 21

Membrane Proteins function as:

1) ion channels
2) Carriers
3) Receptors
4) Enzymes
5) Linkers
6) Identity markers

Question 22

Which two main things does membrane fluidity depend on?

Answer 22

Membrane Fluidity Depends on:
I) No. of double bonds in Fatty acid tails
II) Cholesterol

Question 23

What are the (3) major functions of Membrane Fluidity?

Answer 23

the (3) major functions of Membrane Fluidity?

a) Allows interactions to occur
b) Enables movement of membrane component
c) Allows self sealing

Question 24

What are the types of channels present inside cells?

Answer 24

Based on the stimulus to which they respond, ion channels are divided into three super-families:

i) voltage-gated channels,
ii) ligand-gated channels and
iii) mechano-sensitive ion channels.