Molecular biology is the study of molecular underpinnings of the process of replication, transcription and translation of the genetic
material.
•This field overlaps with other areas of biology and chemistry,
particularly genetics and biochemistry. Molecular biology chiefly concerns
itself with understanding the interactions between the various systems of a
cell, including the interactions between DNA, RNA and protein biosynthesis as
well as learning how these interactions are regulated.
•Much of the work in molecular biology is
quantitative, and recently much work has been done at the interface of
molecular biology and computer science in bioinformatics and computational
biology.
•Since the late 1950s and early 1960s, molecular biologists have
learned to characterize, isolate, and manipulate the molecular components of
cells and organisms includes DNA, the repository of genetic information; RNA, a close relative of
DNA; and proteins, the major structural and enzymatic type of molecule in cells.
components involved in molecular biology are
- DNA
- RNA
- PROTEIN
Gene :
Unit of heredity
•The DNA segments that carries genetic
information are called genes.
• It is normally a stretch of DNA that codes for a type of protein or for an RNA
chain that has a function in the organism.
•Genes hold the information to build and
maintain an organism's cells and
pass genetic traits to offspring.
Deoxyribonucleic acid (DNA)
•DNA is a nucleic acid that contains the genetic instructions used in the development and
functioning of all known living organisms
and some viruses.
•DNA is a set of blueprints
needed to construct other components of cells,
such as proteins and RNA
molecules.
•Two
long strands makes the shape of a double helix.
•Two strands run in
opposite directions to each other and are therefore anti-parallel.
•Chemically,
DNA consists of two long polymers
of simple units called nucleotides,
with backbones made of base, sugars and phosphate
groups.
•The DNA chain is 22 to 26 Ångströms wide (2.2 to 2.6 nanometres), and one nucleotide unit is 3.3 Å
(0.33 nm) long.
Phosphate+ sugar + Base = nucleotide
Bases
•Types:- adenine and guanine (fused five- and six-membered
heterocyclic compounds) – Purines
•cytosine & thymine (six-membered
rings)-Pyrimidines.
• A fifth pyrimidine base, called uracil (U),
usually takes the place of thymine in RNA and differs from thymine by lacking a
methyl
group on its ring.
•PAIRING :
A =T and A=U
G≡C•Types:- adenine and guanine (fused five- and six-membered
heterocyclic compounds) – Purines
•cytosine & thymine (six-membered
rings)-Pyrimidines.
• A fifth pyrimidine base, called uracil (U),
usually takes the place of thymine in RNA and differs from thymine by lacking a
methyl
group on its ring.
•PAIRING :
A =T and A=U
G≡C
•The DNA double helix is stabilized by hydrogen bonds between the bases attached to the two
strands.
•One major difference between DNA and RNA is
the sugar, with the 2-deoxyribose in DNA being replaced by the alternative
pentose sugar ribose in RNA.
Double-stranded
RNA
•Double-stranded RNA (dsRNA) is
RNA with two complementary strands, similar to the DNA found in all cells.
• dsRNA forms the genetic material of some viruses (double-stranded RNA viruses).
Types of RNA
|
Type
|
Abbr
|
Function
|
Distribution
|
Messenger RNA
|
mRNA
|
Codes for protein
|
All organisms
|
|
Ribosomal RNA
|
rRNA
|
Translation
|
All organisms
|
|
Transfer RNA
|
tRNA
|
Translation
|
All organisms
|
in post-transcriptional
modification
|
Small nuclear RNA
|
snRNA
|
Splicing and other functions
|
|
|
Y RNA
|
|
RNA
processing, DNA replication
|
Animals
|
|
Telomerase RNA
|
|
Telomere synthesis
|
Most
eukaryotes
|
Regulatory
RNAs
|
Antisense RNA
|
aRNA
|
Transcriptional attenuation / mRNA degradation / mRNA stabilisation / Translation block
|
All organisms
|
Basic differences between eukaryotes and prokaryotes
|
Attribute
|
Eukaryotes
|
Prokaryotes
|
|
Organisms
|
Plants, animals and fungi
|
bacteria and cyanobacteria
|
|
Cell wall
|
No (animals); Yes (plants)
|
yes
|
|
Chromosome segregation
|
Mitotic spindle
|
Cell
membrane
|
|
meiosis
|
+
|
_
|
|
Ribosome size
|
80 s
|
70 s
|
|
Cell organelle
|
|
|
|
Nuclear membrane
|
+
|
Absent
|
|
Endoplasmic reticulum
|
+
|
-
|
|
Golgi apparatus
|
+
|
-
|
|
Mitochondria
|
+
|
-
|
|
Chloroplast
|
+
|
No comments:
Post a Comment