Introduction to Molecular Biology & subfields.pdf

Why is molecular biology. It's subfields . What is DNA and RNA.

1. INTRODUCTION TO MOLECULAR
BIOLOGY
BASIC TERMINOLOGIES
(LECTURE # 1)
•Ms. Saba Saeed
•Lecturer
•M.Phil.(Biochemistry)

2. What is molecular biology ?
•Molecular biology is the study of the structure, function, and makeup
of the molecular building blocks of life.
•It focuses on the interactions between the various systems of a cell,
including the interrelationship of DNA, RNA and protein synthesis
and how these interactions are regulated.
•Molecular biology is closely interrelated with the fields of
biochemistry, genetics and cell biology.

3. Molecular biology is closely related to….
•Two related sciences: biochemistry and genetics. The three sciences
all concern themselves with details of how organisms work at the
molecular level.
•Biochemistry
•Often devotes more of its attention to molecules other than proteins.
It also focuses on nucleic acids and to chemical effects that happen
when larger quantities of a substance are present.
•Genetics
•Genetics is focused specifically on heritable traits and how changes in
the genetic code affect an organism.
•Each of these three fields overlap and influence the others. Genetics,
in particular, has shared much with molecular biology.

4. Sub-disciplines of molecular biology
(a)Genomics
•This is the study of genes and their functions
(b) Comparative genomics
•The study of human genetics by comparison with model organisms
such as mice and bacterium E. coli.
(c)Functional Genomics
•This is the study of genes, their resulting proteins and the role played
by the proteins in the body’s biochemical processes.

5. Cont….
(d)Gene Therapy
•This is an experimental procedure aimed at replacing, manipulating
or supplementing non-functioning or malfunctioning genes with
healthy genes.
(e)Proteomics
•This is the study of the full set of proteins encoded by a genome.
(f) DNA Forensic
•Thus is the use of DNA for identification like used to establish
paternity in child support cases, to establish the presence of a suspect
at a crime scene and to identify accident victims.

6. Basic terminologies
DNA
•Deoxyribonucleic acid is a molecule
composed of two polynucleotide
chains that coil around each other to
form a double helix carrying genetic
instructions for the development,
functioning, growth and reproduction
of all known organisms.
•Deoxyribonucleic acid, more
commonly known as DNA, is a complex
molecule that contains all of the
information necessary to build and
maintain an organism.

7. Cont….
RNA
•Ribonucleic acid, a nucleic acid
present in all living cells.
•Its principal role is to act as a
messenger carrying instructions
from DNA to control the synthesis
of proteins, although in some
viruses RNA rather than DNA carries
the genetic information.

8. Cont….
Types of RNA
•Messenger RNA (mRNA): Conveys
sequence information from the
genome to the protein synthetic
apparatus.
•Transfer RNA (tRNA): Brings
activated molecules of amino acids
to ribosomes.
•Ribosomal RNA (rRNA): Decodes
mRNAs into amino acids (fabricates
polypeptides). 2 subunits: the large
(LSU, 60S) and the small one (SSU,
40S).

9. Cont….
•Genome: A genome is the complete
set of genetic information in an
organism. It provides all of the
information the organism requires to
function. In living organisms, the
genome is stored in long molecules
of DNA called chromosomes.
•Chromosomes: A threadlike
structure of nucleic acids and
protein found in the nucleus and
carrying genetic information in the
form of genes.
•A chromosome contains hundreds to
thousands of genes. Every human cell
contains 23 pairs of chromosomes,
for a total of 46 chromosomes.

10. Chromosome is made up of DNA and proteins

12. Cont….
•Autosomal chromosomes: In humans, each cell
normally contains 23 pairs of chromosomes, for a
total of 46. 22 of these pairs, called autosomes,
look the same in both males and females.
•Sex chromosomes: The 23rd pair, the sex
chromosomes, differ between males and females.
Females have two copies of the X chromosome,
while males have one X and one Y chromosome.
The pair of sex chromosomes determines
whether a fetus becomes male or female. Males
have one X and one Y chromosome.

13. Cont….
•Karyotype: Full set of chromosomes
in a person’s cells.
•Genes: Segments of deoxyribonucleic
acid (DNA) that contain the code for a
specific protein.

14. Cont….
•Locus: Particular location of a gene
on the chromosome called its locus.
•Allele: A gene can have different
variants. The variants of the same
gene are called alleles

15. Cont….
•Histone: Highly alkaline proteins
found in eukaryotic cell nuclei that
order the DNA molecules into
structural units called nucleosome.
•Nucleosome: DNA-protein
complex.
•Chromatin: Basic repeating
structural and functional unit of
nucleosome.

17. Cont….
•Exon: Regions of mRNA that code
for a protein (coding regions).
•Introns: Regions of mRNA that do
not code for a protein (non-coding
regions).
•Trait: is any gene-determined
characteristic and is often
determined by more than one gene.

18. Cont…..
Proteins: Polypeptides (strings of
amino acid residues) and are not just
building blocks for muscles,
connective tissues, skin, and other
structures but also needed to make
enzymes.
Enzymes: Complex proteins that
control and carry out nearly all
chemical processes and reactions
within the body. The body produces
thousands of different enzymes.

19. Cont….
•Genotype (or genome): is a
person’s unique combination of
genes or genetic makeup. It results
in some of the physical
characteristics of that organism.
•Phenotype: the visible or
observable expression of the
results of genes, combined with the
environmental influence on an
organism's appearance or behavior.