The Structure of DND

“Deoxyribonucleic Acid”

(DNA )DNA was isolated in the late 1800s.

James Watson and Francis Crick were the first toUnravel the Structure of DNA ..

Nucleic acid : (biochemistry) any of various macromolecules composed of nucleotide chains that

are vital constituents of all living cells .Type of nucleic acid :

DNA and RNA

Types of RNA

Three main types -:

Messenger RNA (mRNA) – transfers DNA code to ribosomes for translation .

Transfer RNA (tRNA) – brings amino acids to

ribosomes for protein synthesis .Ribosomal RNA (rRNA) – Ribosomes are made

of rRNA and protein .

Structure of RNA

• Single stranded• Ribose Sugar• 5 carbon sugar• Phosphate group• Adenine, Uracil, Cytosine, Guanine

DNA : a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped

like a double helix associated with the transmission of genetic information .

Nucleotide :The basic building block of nucleic acids ,it is an organic compound made up of nitrogenous

base, a sugar and phosphate group.

Chromosomes in eukaryotes and prokaryotes are different:

PROKARYOTES EUKARYOTES

single chromosome plus plasmids many chromosomes

circular chromosome linear chromosomes

made only of DNA made of chromatin, a nucleoprotein (DNA coiled around histone proteins)

found in cytoplasm found in a nucleus

copies its chromosome and divides immediately afterwards

copies chromosomes, then the cell grows, then goes through mitosis to organise chromosomes in two equal groups

Organism Chromosome numbers

Human 46

Chimpanzee 48

House Mouse 40

Maize 20

Human chromosomes

The chromosomes of a human female

The chromosomes of a human male

Chromosomes and cell division

Chromosomes and reproduction

o Chromosomes come in pairs ;One of the pair is maternal the other is paternal .

o When parents make sex cells the number of chromosomes must be halved .One of each type of chromosome is taken .

23 unpaired chromosomes

23 unpaired chromosomes

23 unpaired chromosomes

23 unpaired chromosomes

Fertilisation

Child

Father

23 pairs of chromosomes

Sex cellsMeiosis

Mother

23 pairs of chromosomes

23 pairs of chromosomes

Meiosis and fertilisation

The inheritance of gender

Is it going to be a boy or a girl?

Video of how the embryo consists..

The Students :work

Hajar

The Supervision :Dr/ Mona