Introduction to Molecular Biology First Week Gihan E-H Gawish, MSc, PhD Ass. Professor Molecular Genetics and Clinical Biochemistry KSU
Dec 13, 2015
Introduction to Molecular BiologyFirst Week
Gihan E-H Gawish, MSc, PhDAss. Professor
Molecular Genetics and Clinical Biochemistry
KSU
Molecular BiologyWhat is the molecular biology science? And
Why it is important to study?!
Molecular biology; the study of gene structure
and functions at the molecular level to
understand the molecular basis of hereditary,
genetic variation and the expression patterns of
genes
Molecular Biology
DNA the molecule of life
The totality of genetic information and is encoded in the DNA (or, for some viruses, RNA)
The Genome
Deoxyribonucleic Acid (DNA)
The genetic material of all cellular
organisms and most viruses, the
gigantic molecule which is used to
encode genetic information for all
life on Earth.
The Chromosomehttp://www.johnkyrk.com/chromosomestructure.html
The storage place for all genetic information, the number of chromosomes varies from one species to another.
In normal human cell
DNA contained in the
nucleus, arranged in 23
pairs of chromosomes.
22 pairs of chromosomes
(autosomes); the 23
chromosome pair
determines the sex of
individual and is composed
of either two (x)
chromosomes (female) or
an (x) and (y) chromosome
(male).
Genes located on
chromosome on it's place
or locus.
Base composition of DNA varies from one species to another.
All living things are
grouped into three
domain:
Eukaryotes
Prokaryotes
and Archaea.
In all cells, DNA does not exist free in solution but rather as a protein-coated complex called chromatin
:// . . / / / / .http www sumanasinc com webcontent animations content organelles html
Eukaryotic Cell Eukaryotes are generally more advanced than
prokaryotes.
Eukaryotic cells are found in animals; plants; fungi and protists cell.
Cell with a true nucleus, where the genetic material is surrounded by a membrane
Eukaryotic genome is more complex than that of prokaryotes and distributed among multiple chromosomes.
Eukaryotic DNA is linear.
Eukaryotic DNA is complexed with proteins called histones.
Numerous membrane-bound organelles.
Complex internal structure.
Cell division by mitosis.
Prokaryotic Cell Prokaryotic Cell Unicellular organisms, found in all
environments. These include bacteria and archaea.
Without a nucleus.
no nuclear membrane (genetic material dispersed throughout cytoplasm
No membrane-bound organelles
Cell contains only one circular DNA molecule contained in the cytoplasm
DNA is naked (no histone)
Simple internal structure.
Cell division by simple binary fission.
Archaea are prokaryotes; organisms without nucleus but some aspect of their molecular biology are more similar to those of eukaryotes.
Timeline Events of Molecular Biology:
• 1860 Mendel – Mendel’s law of inheritance, gene& chromosome
• 1868 Miescher – nuclein, contained an acidic material
• 1890 Weismann - substance in the cell nuclei controls development.
• 1900 Chromosomes shown to contain hereditary information, later shown to be composed of protein & nucleic acids.
• 1928 Griffith’s Transformation Experiment
• 1944 Avery’s Transformation Experiment
• 1953 Hershey-Chase Bacteriophage Experiment
• 1953 Watson & Crick propose double-helix model of DNA
• 1956 Gierer & Schramm/Fraenkel-Conrat & SingerDemonstrate RNA is viral genetic material.
The law of independent assortment
The law of independent segregation
The law of dominance
1 -Mendel’s Three Law of Inheritance:// . . / / /http www sumanasinc com webcontent animations c
/ / .ontent mendel mendel html
Comment: Genes are located on chromosomes
Called in nuclein since it was from the nucleus
Had large amounts of phosphorous and no sulfur so was very different than protein
2 -Friedrick Miescher, a Swiss chemist
(Discovery of Deoxyribonucleic acid)
Comment: the two constituents of chromosomes; Proteins & DNA
Analytical Tests forC, H,P,O and N
“Nuclein”