Chapter 8

Chapter 8 PATricK Fitzsimmons

WATSON AND CRICK

James Watson and Francis Crick are the two individuals who discovered that DNA was in the shape of a double-helix. Deoxyribnucleaic-acid (DNA) was originally discovered in 1869 by Friedrich Miescher. Watson and Crick discovered its shape using experimental data.

Francis Crick James Watson

DNA

CHARGAFF'S RULE

Chargaff's Rule states that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine.

Irwin Chargaff .

BASE PAIRS

Base pairs bond when three hydrogen bonds form between guanine and cytosine. Two hydrogen bonds form between adenine and thymine or adenine and uracil. Complementary pairs always involve one purine and one pyrimidine base

CHROMOSOMES

Chromosoms are threadlike structures of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. Humans normally have 23 chromosomes.

KARYOTYPES

Karyotypes are the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

DNA REPLICATION

DNA replication occurs in two steps. First, an initiator protein unwinds a short stretch of the DNA double helix. Then, a protein known as helicase attaches to and breaks apart the hydrogen bonds between the bases on the DNA strands, pulling apart the two strands.

THE DAMAGING OF DNA

THE END

Created By

Patrick Fitzsimmons

Appreciate

Credits:

Created with images by kyz - "Fairy DNA" • Can H. - "Karyotype"

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