BIOL 230 -> Unit 2 (WIP)

Fundamentals of Cell and Molecular Biology... Chapters 6, 7, 8...

DNA Polymerase

Synthesizes new DNA by adding nucleotides to a growing chain in the 5’ → 3’ direction

DNA Ligase

enzyme that joins DNA together and seals cracks in Okazaki fragments. Creates covalent bonds (phosphodiester bonds in this case) to join nucleotides and uses ATP as energy.

Nucleotide

Nitrogenous base (ATCG), Pentose Sugar (5 carbon sugar), and and a phosphate group

DNA Nitrogenous Bases

Adenine and Guanine (Purines: double-ringed structures) Thymine and Cytosine (Pyrimidines: single-ringed structures)

DNA Primase

Enzyme that synthesizes short RNA sequences called primers to give DNA polymerase a starting point to build a new strand

Primer

a short strand of RNA that provides a necessary starting point for DNA polymerase to begin building a new DNA strand

Helicase

A motor protein that uses energy from ATP Hydrolysis to separate DNA double helix

Topoisomerase

enzymes that regulate the twisting and coiling of DNA. Relieves backbone of tension from untwisting

Binding Proteins

specialized molecules that attach to DNA to help open, stabilize, and copy genetic code. Allows strands to serve as templates for primase and polymerase.

Torsional Stress

As helicase moves forward, the DNA ahead gets wound more tightly. It’s difficult to unwind and stalls replication (topoisomerase relieves tension)

Depurination

Spontaneous loss of purine base (A or G)

Deamination

Spontaneous loss of a DNA amino group

Somatic Cell

Any cell in a multicellular organism, excluding reproductive cells

Xeroderma Pigmentosum

Sensitivity to UV and an inability to repair DNA damaged by the sun

Germ-line mutation

When an organism fails to repair DNA and the entire organism carries the mutation (half of gametes carry mutation)

Somatic Mutation

An organism fails to repair DNA and a patch of cells are affected, causing a gradual accumulation of random mutations in somatic cells

Thymine Dimers

UV induced covalent bonding of thymine (occurring constantly when you’re exposed to sunlight)