APBIO FINAL QUIZ

1928, Griffith

He had 2 strains of bacterium, 1 pathogenic, 1 harmless.
Mixed heat killed remains of the pathogenic with living cell of the harmless, result: some living cell became pathogenic (transformation)

1944, Avery, McCarty, & MacLeod

The transforming substance was DNA, only DNA worked in transforming harmless bacteria into pathogenic bacteria.

Bacteriophages/phases

Used in molecular genetic research, they attach themselves to e coli outer membrane then punch through and inject DNA into e coli eventually destroying it.

Hershey & Chase (1952) 

Designed an experiment, concluded that injected DNA of the phage provides the genetic information

1950, Chargaff

DNA composition varies from one species to the next, the diversity made DNA more credible candidate

Chargaff’s rules

Equal number of A and T bases and same for G and C

Wilkins & Franklin

Used X-ray crystallography to find DNA’s molecular structure

Rosalind Franklin

Her image of DNA told Watson that DNA was double Helical. She concluded there was 2 antiparallel sugar phosphate backbones and nitrogenous bases connect in the molecules interior

Watson and Crick

Built the first double helix model

Anti-parallel

1 strand is 3 prime to 5 other is 5 prime to 3

Why A with T and C with G

A and C are purine and C and G is pyrimidine. Purine + Pyrimidine the width between them were consistent with x ray data

How DNA replicate itself

Each strand act as a template for building a new strand, they unwind and new strand place upon it using the base pairing rule (ATCG)

Semiconservative Model

Each daughter molecule will have one old strand and one newly made strand.

Meselson and Stahl

Their nitrogen experiment supported semi conservative model, labeled old strand with heavy isotope of nitrogen and new one with light isotope.

Helicase

Unwind parental double helix

Single strand binding protein

Bind to and stabilizes single stranded DNA til it can be used as template

DNA polymerase

Add new nucleotide, can only add new nucleotide on the 3 prime end. Cant initiate synthesis

DNA Primase

Add RNA primer

RNA primer

one bit of RNA

DNA pol 1

Removes RNA Nucleotides of primer from 5 prime end and replaces with DNA nucleotide

DNA ligase

Add 3 prime end of DNA which replaces primer to rest of leading stand and join okazaki fragments of lagging strand

Replication fork

A Y-shaped region where new DNA strands are starting

Topoisomerase

Correct over winding ahead of replication forks by breaking, swiveling, and rejoining DNA strands

Telomeres

Located at the end of chromosome, postpone erosion of genes

Telomerase

Speed up the lengthening of telomeres in germ cell

Chromatin

Complex of DNA and protein can be found in the nucleus of eukaryotic

Histones

Protein responsible for the 1st level of DNA packing in chromatin

RNA

Between genes and the protein which they code

Transcription

Make mRNA using DNA as a template

RNA polymerase

Separate DNA strands apart and combine the RNA nucleotide

Promoters

Signal the initiation of RNA synthesis

Transcription factors

Allow for the binding of RNA polymerase and initiation of transcription

Elongation

RNA polymerase move along DNA untwist double helix 10-20 bases at a time

Termination

Bacteria: Polymerase stop at the end of terminator sequence
Eukaryotes: Polymerase eventually falls off the DNA

Modification before cytoplasm…

• 5’ end get a 5’ cap

• 3’ end get poly a tail

• intron spliced out, Extron binded together

tRNA

Translate mRNA to protein

Mutation

Change genetic material of cell or virus

Point Mutation

Chemical changes in just one base pair of a gene

Silent Mutation

No effect on amino acid

Missense Mutation

Code for an amino acid but not necessarily the right amino acid

Nonsense Mutation

Change an amino acid codon to a stop codon, almost always lead to a nonfunctional protein