Bio - evolution chap. 14

Griffith

used mice and strep bacteria to discover transformation

Avery, McCarty, and MacLeod

used different enzymes to denature DNA, RNA, or proteins to determine that DNA was the transforming factor

Hershey and Chase

labeled the virus that effects bacteria with radioactive isotopes to confirm that DNA, not protein, carried genetic information.

Chargaff

determined that there were equal amounts of adenine and thymine and equal amounts of guanine and cytosine - gave us these rules

Franklin and Wilkins

known for using x-ray crystallography/diffraction to take pictures of DNA and determine its diameter

Watson and Crick

used information from other scientists to determine the chemical structure of DNA and construct the first double helix model of DNA

Meselson and Stahl

Proved semiconservative replication was correct

helicase

splits open the DNA double helix (breaks hydrogen bonds between bases) to start replication

topoisomerase

prevents over-winding to relieve stress upstream of the replication fork

DNA polymerase I

replaces RNA primers with DNA

DNA polymerase III

builds the new DNA strand with complementary base pairing

primase

creates RNA primer to begin replication

ligase

seals backbones of all fragments/pieces together to create two whole strands

purines

double ring; A and G

pyrimidines

single ring; C, U, T

Heterochromatin

compacted, during mitosis / meiosis, and are genes that are turned off

Euchromatin

Unwound, during replication, and genes that are turned on

Sanger sequencing

determine the order of the bases in a strand of DNA and therefore sped up our ability to "read" DNA

Gel electrophoresis

allows us to separate DNA based on size and charge

leading strand

continuously built in the 5’ to 3’, new DNA is made

lagging strand

grows in 5’ → 3’ direction but is coming out of the replication fork

Okazaki fragments

short fragments of DNA on lagging strand
only

Proofreading & repair part 1

DNA polymerases proofread as bases added/during replication

Proofreading & repair part 2

Mismatch repair - special enzymes fix incorrect pairings

Proofreading & repair part 3

nucleotide excision repair - nucleases cut damaged DNA then DNA polymerase and ligase fill and seal the gap

steps of replication 

1. Helicase unwinds the DNA double helix

2. New bases are added to build the new strands

3. DNA ligase seals all fragments together

4. Each old strand is paired with a full new strand

Telomerase

enzyme that builds telomeres on chromosomes

Telomeres

repeated bases of DNA = buffers (junk)

Silent mutation

mutation that is not expressed

point mutation

mutation that affects a single base

prokaryote DNA

circular, cytoplasm, 1 chromosome, no histones, supercoiled DNA, double stranded

Eukaryote DNA 

Linear, Nucleus, 1+ chromosomes, has histones, forms chromatin, double stranded

Frameshift mutation

caused by the insertion or deletion of nucleotides in a DNA sequence, where the number of inserted or deleted bases is not a multiple of three