Structure of Genetic Material

Chromatin

• Genetic material in the nucleus• Made up of DNA and proteins• Thread-like and uncondensed• Appears grainy

Chromosomes

• Genetic material• Formed from condensation of chromatin• Formed during prophases of mitosis and

meiosis I• Consists of a centromere and two identical

replicated strands, called chromatids

Chromatid

• Each of the two identical chromosomes strands

• In a replicated chromosome attached by centromere

Karyotype

• A chart• Number and form of chromosomes in a cell• Determine whether chromosomes of an

individual is normal in number and structure

Homologous Chromosomes

• A pair of chromosomes that each carry genes for the same trait at the same location on the chromosome

• One is inherited from the mother, the other from the father

• Deoxyribonucleic Acid• Double helix• “Twisted Ladder”• Two sides of the ladder are made up of a

repeating sequence of sugar and phosphate groups

• The rungs of the ladder are composed of a pair of nitrogenous bases– Four bases: Adenine, Thymine, Guanine, Cytosine

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