11 november 2014

11 november, the first class withprof Khatijah . we continue our lecture on genetics. We need to know the definition of these:

Genome is genetics information in cell .

 Genes is segments of DNA that code for functional product .

Genetic code is information present as genetic code that have triplet bases encoded a single amino acid called codon.

 Genotype is genetic composition of an organism.

Phenotype is actual expressed properties of an organism

DNA is double stranded helix structure. Function of DNA is acts as storage of genetic information,self-duplication and inheritance and expression of genetic message. RNA is ribonucleic acid with single stranded . There are 3 types of RNA which are mRNA , rRNA , tRNA.

The major steps in DNA replication is:
1)unwinding of strands

2)strands act as template

3)synthesis of RNA primes

4)DNA nucleotides join up yo the exposed bases by specific base pairing

5)formation of ladding and legging strands

6)formation of ne w strand is forms ‘5 to 3’

DNA replication begins at specific base sequence when helicase binds to parental DNA and begins to unwind to break hydrogen bonds. Each parent strand becomes a template used to synthesize the complementary strand. Single stranded binding SSB protein bind to single DNA strand and stabilize it. Forming replication fork. Then it prevents the double helix from re-forming until the strand are replicated . both strand require RNA primer for initiation of DNA replication. DNA polymerasecan extend existing polynucleotide chains only from 3’. Leading strand synthesize continuosly from 3’ to 5’ phosphodiester bonds formed. Legging strand synthesize discontinuously from 5’ to 3’ and producing okazaki fragments

Transcription is process by which RNA molecules are synthesize on DNA template .  translation is second step by which gene expression leads to protein synthesis. In transcription   catalyzed by DNA polymerase. Results in an DNA molecule complementary to the gene sequence of one of the two strands of double helix. In translation synthesis , anticodon are complementary to their corresponding codon