DNA and Chromosomes

identify structure, function, + chemical components of DNA

structure: double helix

function: contains instructions needed for organism to survive

chemical components: sugar group, phosphate group, nitrogen base (adenine, guanine, cytosine, thymine)

DNA replication steps

1. DNA helicase : DNA unzips and unwinds

2-3. DNA Polymerase: attatches free nucleotides and proofreads new strands of DNA to make sure theres no base pairing errors. Forming two DNA molecules each with one original DNA strand and one newly synthesized DNA strand

Erwin Chargaff

determined relationship between nitrogen bases (guanine, cytosine, adenine, and thymine) found that A=T and C=G

Rosaline Franklin

took X-ray photo of DNA and the pattern helped Watson and Crick build a model that explained the scientific structure of DNA

Watson and Crick

took Rosalines X-Ray photo of DNA and the pattern helped Watson and Crick to build a model that explained the scientific structure of DNA. called the double helix

Genome

full set of genetic info that an organism carries in its DNA

• consists of 44 autosomes and 2 sex chromosomes

karyotype

shows the complete diploid set of chromosomes grouped together in pairs (diploid means two because each parent gave us one set of chromosomes, so we have a pair of each set)

autosomes

chromosomes that are not sex chromosomes, there are 44

• dont determine individuals sex

• determine most traits

sex chromosomes

determine the individuals sex, there are 2 (the X and Y)

which chromosomes are responsible for determining an organisms biological sex

• females have 2 copies of X chromosomes while males have 1 X and 1 Y

• all egg cells carry an X chromosome while half of sperm cells carry an X and half carry Y (50% probability that a zygote will be boy or girl)