Bio 202 exam 3

who discovered the structure of DNA

Watson and crick

the back bone consists of

alternating sugars and phosphates

what holds both DNA strands together in the middle

hydrogen bonds (to break the bond you can boil water)

nitrogenous bases

A,G,C,T

purines

2 ring structure (adenine and guanine)

pyrimidines

1 ring structure (cytosine and thymine)

char gaffs rule

#of G = # of C units

#of A = # of T units

Nucleoside=

nitrogenous base and sugar

nucleotide

base + sugar + phosphates

Ribose sugar in RNA

has an OH

deoxyribose in DNA

just has an H

3’ carbon has an ….

5’ has a

3’- OH group

5’- phosphate group

transformation by Fredrick Griffith

• uses strains of bacteria to infect a mouse

• S strain kills b/c smooth exterior

• R strain doesn’t kill because its rough

• takes S strain and heat kill sit, the mouse lives

• then takes S strain that was heat trained and mines with R strain, and it kills the mouse

Chromosome structure

Human genome has 46 chromosomes, we pair them up into 23 pairs, homologous

chromosomes are like beads on a string

DNA is packaged with protein to form chromatin

what is the fundamental unit of chromosome packaging

nucleosome

DNA is wrapped around a disc made of

histone proteins (spool proteins), negatively charged

Nucleosomes stack. up and form…

loops to condense the chromatin

euchromatin is

not highly condensed, open and active, beads on string

heterochromatin is

highly condensed, blocks access by transcription

how is chromatin structure controlled?

positively charged amino acids (Lysine, argon, histidine)

DNA replication

genetic info is stored within DNA and needs replicated

The opening of the DNA is called the…

replication bubble

replication forks

2 form, one on left and one on right side of bubble

fragments on lagging strand are

Okazaki fragments

enzymes involved in DNA replication

1. DNA helices

2. DNA polymerase

3. primase

4. ligase

DNA helicase

unzips and opens the DNA ladder for polymerase

DNA polymerase

the enzyme that adds new nucleotides to the 3’ end, has proofreading capabilities and can remove a mispaired nucleotide

primase

starts with a short primer sequence

• can’t recognize naked DNA

ligase

joins the Okazaki fragments together

• how lagging strand fragments become one continuous strand

a problem with DNA replication

the ends of the chromosomes (telomeres) begin to “fray”

telomerase

the enzyme that synthesizes telomere sequences

what do ribosomes create

protein

mRNA from DNA is

transcription (in nucleus)

protein from mRNA

cytoplasm

DNA vs RNA

DNA

• double stranded

• deoxyribose as sugar

• uses GCAT

RNA

• single stranded

• ribose as sugar

• oxygen is present

• GCAU

The promoter

an upstream sequence of DNA that tells the polymerase where to start

eukaryotic promoters contain TATA box

binding protein binds to the TATA box

capping

caps are added to the 5’ end

polyadentylation

poly a- tails are added to the 3’ end

• the longer the poly a tail, the longer the RNA will survive

exons

coding region- will be fused together

introns

non coding region - will be removed

what is found on the end of histone tails

acetylation, methylation, phosphorylation, they regulate when the genes are turned on and off

Avery, Macleod, McCarty

DNA is the genetic material that carries hereditary info in cells

Hershey and Chase

blender experiment

radioactive labels in blender experiment

S35(protein) and P32 (DNA)

how many hydrogen bonds between A-T and C-G

3 C-G

2 A-T

what base pairs are associated with origin of replication

Adenine and Thymine

what enzyme is associated with transcription

RNA polymerase

splicing

transforms pre mRNA into mature mRNA by removing non coding regions and joining coding regions

alternative splicing

exons are joined in different combinations, allowing one gene to produce multiple distinct protein isoforms