genetics 3.1-3

Friedrich Miescher

disovered “nuclein” (nucleus) in WBCs that he found in the pus of pt’s

Albrecht Kossel

isolated the 5 nucleic acids or the “alphabet of life”

Phoebus Levene

discovered that nucleic acids have a sugar, base, and phosphate

nucleotides 

DNA made up from 

Frederick Griffith

discovered the transforming principle using 2 strains of rough and smooth pneumoccus bacteria to infect mice - “the Griffith experiments”

R bacteria (rough coat)

no pneumonia in rats

S bacteria (smooth coat)

pneumonia

virulence

coat type is associated with

live!

rough strain and heat killed smooth strain

dies!

smooth strain and rough strain w/ heat killed smooth strain 

Oswald Avery

discovered nucleic acids were “transforming factors” and DNA was the molecule of genetic inheritance 

Avery, Macleod, and McCarty

treated S bacteria w/ protease + DNase

DNase 

prevented trascription; there DNA is the transforming principle

10 T’s

if you have 10 A’s then you have

T

A to

C

G to

Alfred Hershey and Martha Chase

discovered that viruses can infect the E. coli bacteria by using phages in their “blender experiments” 

• proteins have a protein “head” and a DNA core 

• used radioactive S (sulfate) and P (phosphate) to label protein and DNA 

phages

used to manipulate cells and inject into genome

protein

proteins head

DNA

proteins core

proteins

S only found in

nucleic acids

P only found in

Rosalind Franklin

crystalized DNA to make an Xray diffraction pattern to reveal the double helix structure of DNA in photo 51

• died at 37 by ovarian cancer from excessive UV exposure

Maurice Wilkan

won Nobel prize w/ Watson and Crick for discovering 3D structure of DNA using X-ray diffraction

James Watson and Francis Crick

won the Nobel prize in 1962 w/ Wilkins for proposing the exact 3D structure of DNA double helix 

• sigar phospahte “backbone”

• 2 nucleotide chains in double helix

• held together w/ hydrogen bonds

• in antiparallel strands 

purines

Guanine and Adenine - double ringed structures

Pyrimidines

Cytosine and Thymine - single ringed structures

hydrogen bonds in a chain

purines and pyrimides joined by

5’ to 3’

DNA runs from a ______ direction antiparallely

chromosomes

DNA formed into ________ in the chromatin in nucleus

• 2 meters DNA each cell = tightly condensed/wound

chromatin

coiled around nucleosomes

histones

nucleosomes contain 8 proteins called

• 4 pairs of 4 proteins w/ DNA binder RNA 

• DNA is wound around these 

chromosome 

central scaffold 

5 carbons

DNA sugars have ______ numbered clockwise

6 nanometers

DNA packed into _____ per nucleus

histone tails 

histone tails add _________ to change DNA strcuture

hydrogen bonds need to be broken

to read sequence of nucleotide

semi conservative replication 

the first studies of DNA  using nitrogenic E. coli showed that is

5’ to 3’

DNA can only replicate on strand at a time and from

helicase 

unwinds parental double helix

binding protein

stabilizes separate strands

primase

adds short primer to template strands (RNA)

• RNA primer

DNA polymerase 

binds to DNA nucleotides to form new strands to the RNA primer and proofreads and repairs/replaces incorrect bases 

Ligase 

joins okazaki fragments and seals/fixes nicks in both single and double strands in sugar phosphate backbones (mutations) 

• seals sugar phosphate backbone when done w/ replication

leading or continuous strand

3’ ← 5’

lagging or discontinuous strand

5’ → 3’

discontinuous synthesis

produces Okazaki fragments on 5’ → 3’ template

exonuclease

enzymes remove RNA primers

transcription, RNA processing, Translation 

steps of protein synthesis 

transcription

production of mRNA occurring in nucleus 

RNA processing

before RNA leaves nucleus it goes through

translation 

production of protein using mRNA, tRNA, and rRNA 

hypoglosated

sugar coated

liquidated

deemed for destruction

DNA

stores RNA and protein encoding info and transfers info to daughter cells

RNA

carries protein encoding info and helps make proteins 

mRNA

carries info from DNA to ribosome; codons specify amino acid

rRNA

make up ribosome; 2 subunits join providing structural support and catalyst

• one smaller subunit and one larger 

tRNA

cloverleaf shape; anticodon forms hydrogen bonds w/ mRNA codon; transfer amino acids to ribosome 

20

how many amino acids are there

64

how many codons are there

transcription

mRNA synthesized from the template strand of DNA 

RNA

the bridge from DNA to protein

complementary strand 

the coding strand of DNA

operons

control gene expression in bacteria

• different genes in one place related to one function

transcription factors

control gene expression and link genome to environment in complex organisms 

minor groove

histones bind to

major groove

leucine zipper and zinc finger bind to

zinc finger

traps zinc molecule and binds to major groove

leucine zipper

binds to specific sequences of DNA - promoter regions

initiation - transcription

promoter (zinc finger, leucine zipper) attracts transcription factors and RNA polymerase (binding)

elongation - transcription

RNA polymerase (small) adds nucleotides to growing RNA

termination - transcription

DNA sequences prompt the RNA polymerase to fall off, ending the transcript

TATA box (thymine and adamine)

promoter region that allows transcription factor to bind to promoter region

reading strand

DNA template strand

RNA processing 

molecular events allowing the primary transcripts to become mature RNA occurring in cytoplasm 

• tightly controlled by enzymes 

RNases

carry out RNA processing by cleaving RNA

Capping step 1

removes the 5’ triphosphate → triphosphatase

capping step 2

attaches guanosine nucleotide (building block) → guanyltransferase 

capping step 3

adds methyl groups guanine and riboses in 5’ → methyltransferase 

cleavage/polyadenylation

endonuclease cleavage about 20 nucleotides down → poly A polymerase tail adds adenine to the 3’ end

• involved in stabilizing mRNA and helps understand its our DNA

splicing

cutting the pre-RNA to remove introns and joining together the extrons 

• takes place in nucleus

• introns will be degraded and snurps reused

introns

non coding sequences

extons

coding sequences

snRNPs “snurps”

small nuclear ribonucleoproteins involved in splicing by binding and processing removal 

splicesome

binding of more snurps causes looped introns or

• composed of 5 snRNPs

alternative splicing

selective inclusion or exclusion of exons

• >50% of human genes undergo it 

protein

one gene can encode more than one

transcription

DNA to mRNA

translation

mRNA to protein

codons 

triplet code of 3 RNA nucleotides to encode one amino acid 

64 codons

20 amino acids in humans allows for

titin

largest known protein → 27,000-35,000 amino acids 

AUG

methionine

CCC

proline

AAG

lysine

• non-overlapping 

• universal (common ancestor)

• degenerate (some codons encode same amino acid)

the genetic code is

initiation - translation

translation begins at start codon (AUG = met)

elongation - translation

ribosome uses tRNA anticodon to match codons to amino acids and adds to growing peptide chain

termination - translation

ends at stop codon (UAA, UAG, UGA)