BASIC GENETICS

by A.A. OSUNTOKI, Ph.D
CHROMOSOME
** A nucleoprotein complex
**Carries genetic information
**Contains DNA and basic proteins
**The protein kind and types may vary in different cell types

THE GENE
The molecule of heredity
Contained on the chromosome
Every cell of an organism contains the full genetic complement (except mature rbc)
Part of the blue-print for the particular organism
Made up of DNA(deoxyribonucleic acid) in all organisms except some viruses
Sequence of DNA capable of independent expression(replicon) .

DNA
Deoxyribonucleic acid
Polymer of deoxyribonucleotides
Linked by 31-51 phosphodiester bonds
Double stranded helix
Two anti-parallel strands
Stabilized by hydrogen bonds between base pairs -AT, GC.
The bases carry genetic information

RNA
Ribonucleic acid
A close chemical relative of DNA
Present in several forms in living cells
Copied from DNA by a process called transcription
Involved in protein synthesis

THE GENETIC CODEThe information in the genome is organized into genes or cistrons
The message of genes is encoded in a triplet of nucleotides called codons
There are 64 codons
61 specify amino acids
3 specify chain termination
The genetic code is degenerate

GENE EXPRESSION
A gene is to be expressed when the gene product is being made
The gene product can be RNA or protein
Gene expression involves the central dogma

DNA RNA PROTEIN


Replication: The formation of daughter DNA strands .
Transcription: The transfer of genetic information to RNA
Translation : The conversion of the genetic information into a protein(s)

Genes act by determining protein structure.
MUTATION
Any change in the nucleotide sequence
Two broad classifications
Point mutation
Frameshift mutation
Genetic diseases result from mutations.