History of DNA Structure & Replication

Genetic Material

the hereditary information of all living cells in contained in the nucleic acid called DNA

DNA

controls the reproduction, development, and functionality of all living things

Gene

segment of DNA that function as the unit of inheritance

Genome

the complete collection of an organisms genes

Nucleic Acids

are one of the four macro molecules of life. It contains genetic in all living things.

nucleotides

contain a nitrogen base, sugar, and phosphate group

Nitrogen bases

adenine, cytosine, thymine & guanine

Watson - Crick ( Franklin) Model

2 strands = ladder like structure

Held together by hydrogen bonds between the nitrogen bases.

Complementary base pairs

due to the size of each base, certain base pairs always go together (adenine- thymine) using hydrogen bonds

Rosalind Franklin (1920-1958)

Was a chemist & x ray crystallographer. Her work led to the discovery of the double helix structure.

Humans have __ amount of chromosomes and how many pairs ?

46 & 23

Homologous chromosomes

pairs of chromosomes that contain a paternal and maternal copy.

They have the same genes in the same location, or locus.

Karyotype

photographing (imagining) chromosomes during mitosis and examining them

Out of the 23 pairs __ are called what?

autosomes

What is the name of the remaining pair?

sex chromosomes (x, y)

DNA replication

DNA base pairs are considered the blueprint for proteins.

The sequence of nitrogen bases (ATGC) can be laid out in a varying manner, and this sequence codes for different proteins needed to do the work of the body.

DNA Replication Stages

1) DNA double helix splits down the middle.

2) New DNA strands are synthesized by using the parent strand as a template and pairing with new complementary base pairs.

-Happens in “bubbles”

DNA Replication Enzymes

Replication is aided by numerous enzymes.

Helicases

unwind the double helix, making bases available for pairing

DNA polymerases

move along the parent strands in the replication bubble and join new molecules. Also edit the DNA for mismatched pairs.

Mutations

As you know, sometimes there are mistakes in a DNA molecule. Our cells have repair mechanisms mostly enzymes that can repair and correct these mistakes.

-Environmental stressors (UV radiation) can help penetrate living cells and alter DNA.