Genetics

Epigensis

the form of an animal gradually emerges fro a formless egg

who studied epigenesis with eggs

aristotle

preformationism

preformed structure in gametes

homunculus

name for preformed organisms

who studied preformationism and epigenesis will cells

roux and driesch

what did driesch study with

sea urchins

lamarkism

an organism’s experiences can be passed on to the next generation

pangenesis

heredity information passes from soma to germline to germline to soma

who study pangenesis

galton with bunnies and their blood, found gemmules aren’t real

Who tested pangensis with mice and their tails

weismann

how do you develop traits?

genetic determinism

epigentics

no change in DNA sequence, but change structures on the chromosomes

Fredrick Griffith’s transformation experiment (1928)

grew smooth and rough colonies of virus

type r didn’t kill mice

type s did kill mice

type s heat killed didn’t kill mice

type s heat killed + type r did kill mice

type r gets transformed into type s

McLeod, McCarty, and Avery transformation (1944)

try to figure out what is the material of heredity

DNase

Rnase

Protease

type s treated with p and r got transformation

type s treated with d got no transformation

shows DNA is the material for heredity

Hershey-Chase (1952)

bacteriophage only have DNA and protein

trying to figure out if DNA or protein was released into bacteria

phages treated with 32p radioactive, which tagged DNA, then put into cold media, then blended and centrifuge, found radioactivity in pellet

phages treated with 35s radioactive, which tagged protein, then put into cold media, then blended and centrifuge, found radioactivity in supernant

max absorption for DNA

260 nm

max absorption for protein

280 nm

What else can serve as genetic material

RNA can, TMV evidence

purines

adenine and guanine

pyrimidines

thymine, uracil, cytosine

Base Analogs

can substitute for normal base pair

5-methylcytosine

natural CpG site with methyl group on 5’ which decreases gene expression

Cytodine

Chemotherapy that removes methyl to increase tumor suppresion expression

Retrovir and remdesivir

man made, blocks addition of nucleotides

Base pairing proposed by..

Chargaff 1948

Paper Chromatography

separates chemicals and pigments

[A]=

[T]

[G]=

[C]

[A+ ]=

G = [T+C]

X-ray crystallography

very short wavelengths that allow you to look at different refraction patterns

Rosalin Franklin

got two refraction patterns for DNA

Linus Pawling

proposed structure or alpha-helix

5’ end has

phosphate

3’ end has

hydroxyl

how many hydrogen bonds does a+t have

2

how many hydrogen bonds does g+c have

3

major and minor grooves come from

base pairs not pairing straight across

B-DNA

hydrated

10 bp

right-handed

A-DNA

dehydrated

11 bp

right-handed

Z-DNA

left-handed helix

Bacteria

circle genome

topoisomerases

prevent wind up of DNA (DNA gyrase)

scaffolding protein

DNA loop structures

Eukaryotes

linear chromosomes with chromatin

chromatin

DNA and protein (11nm)

histone subunits

octamer, H2A H2B H3 H4

2 wraps of DNA around histone is how many base pairs

146 bp

nucleosome

histones and DNA

what brings nucleosomes together

H1

Heterochromatin

highly condensed with no gene expression

euchromatin

low condensation with active gene expression

FISH

color chromosomes differently

human genome stats

3.2 Gbp

22,000 protein coding genes

46 (2n) chromosomes

hyperchromic shift

the place where DNA starts to denature according to gc content

density gradient ultraccentrifugation

E. coli chromosome fragments in 6M CsCl then centrifuged which leads to separation by density

found the average gc concentration with repetitive DNA sequence

percent of coding genes in humans

1.5%

Unique genes

actin, tublin, sonic hedgehog

highly repetitive DNA

satellite peaks, telomere, centromere

Middle repetitive DNA

tandom and interspaced

tandom

multicopy (rDNA), microsatellite (dinucleotide), minisatellite (VNTRS)

Interspaced

LINEs and SINEs

LINEs

L1

SINEs

Alu

Potential models for DNA

semiconservative, conservative, and dispersive

Meselson and Stahl

14N and 15N

e. coli grew in 15N overnight, centrifuged, and separated by density

15N e. coli put in 14N for 30 minutes to see where DNA ends up

fits semiconservative and dispersal

John Cairns

e. coli in H3 overnight then put in cold media

found theta structure for DNA replication

Arthur Kornberg’s “reconstruction experiment”

found the four essentials for DNA replication

took out all e. coli proteins, chromatography to separate into different fractions

found one fraction with replication, tried to separate it further, but no replication occurred

four essentials for DNA replication

single strand template

dNTPS ( deoxynucleotide-triphosphates)

DNA polymerase

RNA primer

template strand is read in…

3’-5’

what provides energy for phosphodiester bonds

triphosphates

Synthesis happens in what direction

5’-3’

Origin of replication

at rich where replication begins

DNAa

initiate denaturing causing ss DNA

DNAb

code for helicase

helicase

separates DNA strands “unzips”

Single Stranded DNA binding protein

prevents DNA from coming back together

DNA polymerases require what to bind

3’ OH

what lays down RNA primer

DNA primase

DNA pol III

3’-5’ exonuclease activity (proof reads)

DNA pol I

hops on DNA strand after DNA pol III falls off and removes RNA primer and finishes DNA synthesis

what connects okazaki fragments

DNA ligase

Eukaryotic replication

multiple origins of replication

TERT

telomerase reverse transcriptase, elizabeth blackburn

telomeres

extra sequences on ends of chromosomes

what makes up TERT

reverse transcriptase and RNA molecule

what is reverse transcriptase

RNA dependent DNA polymerase

what does reverse transcriptase do

convert RNA to DNA

What is the RNA molecule

complimentary strand to DNA

What cells use TERT

stem and cancer cells

Hayflick limit

age influences amount of cell division, people age from reduced telomerase activity

Central dogma

replication to transcription to translation

DNA to RNA to protein

RNA polymerase

make RNA copies of sequence

where are mRNA

ribosome

what does DNA polymerase do

replicate DNA

Reverse transciptase function

RNA back to DNA

similarities between DNA and RNA

4 nucleic acid bases

phosphodiester bonds

polarity

synthesis 3’-5’

how does RNA polymerase know where to start

mRNA is template

tRNA

middle repetitive

80-90 nucleotides

64 different codons

what does anticodon loop do

read mRNA

rRNA

transcribed as one

broken down into 3 units

what most RNA in cells are