Sarah Ball Final Exam 1113 OSU

linked genes

genes located close together are more likely to stay together

Recombant

phenotypes that do not match parents due to crossing over, more variation

Incomplete dominance

intermediate phenotypes (whitexred=pink)

Codominance

both phenotypes are expressed with no blending (roans)

ABO blood types

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pleiotropy

single gene can have multiple effects

ex. PKU, Marfan syndrom, white dogs and deafness

SRY gene

sex determining region of Y

SRY gene

enough to cause phenotype to be male. XX-males and XY-females

XX male

translocation of SRY gene

XY female

lose of SRY gene

epistasis

the phenotypic expression of one gene alters that of a different gene

ex. coat color in labs (E gene is epistatic to B gene) Bbee will be a yellow lab

polygenic ineritance

two or more genes have an additive effect on a phenotype, a spectrum

ex. skin color, eye color

environmental factors

phenotypes altered by daily life

ex. in the womb, hydrangeas and ph

pedigree

family tree

Hershey and Chase

concluded that DNA entered the bacterial cells, not protein so DNA function as genetic material

Helicase

untwists double helix and separates strands

single strand dna binding proteins

bind to separated dna strands to prevent repairing

tipoisomerase

relieves strain ahead of replication for caused by unwinding by breaking, swiveleing and rejoining dna strands

primase

an enzyme that lays down an rna primer which is complementary to the template strand

dna polymerases

an enzyme that catalyzes the synthesis of dna by adding nucleotides to an existing chain

dna polymerase iii

adds a nucleotide to the rna primer and then keeps adding complementary nucleotides to the growing strand

antiparallel

5'-->3'

leading strand

synthesized continuously towards the replication fork, requires one primer

lagging strand

synthesizes discontinuously away from the replication fork, creates okazaki fragments

okazaki fragments

Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

DNA pol I

replaces the RNA primer with DNA nucleotides

DNA ligase

joins all of the fragments into a continuous strand

replisome

The large molecular machine located at the replication fork that coordinates multiple reaction steps during DNA replication.

Telomeres

short nucleotide sequence that is repeated many times, get lost when replication occurs, reaches a critical limit

telomerase

composed of protein and rna, a template to replicate chromosomes

mismatch repair

other enzymes remove and replace incorrectly paired nucleotides, linked to cancer,

nucleotide excision repair

damaged segment is cut out by nuclease and the gap is filled in by dna polymerase and ligase using the undamaged strand as a template

archibald garrod

suggests genes determine phenotypes

beadle and tatum

created mutants by bombarding with xray to characterize defects

evolving hypothesis

one gene=enzyme/protein/polypeptide

central dogma

DNA -> RNA -> Protein

dna-->rna

transcription

rna-->protein

translation

codons

three bases at a time codes for an amino acid

silent mutations

code for the same amino acid, often third base mutation

missense mutation

code for a different amino acid

nonsense mutation

code for a stop codon, produces short protein

frameshift mutation

most severe mutation, moves frame of codon reading

mutagens

chemical or physical agent that mutates dna

current definition of a gene

a region of DNA that can be expressed to produce a final functional product that is either a polypeptide or an RNA molecule

Location of transcription

nucleus (only in eukaryotes)

Three steps of transcription

1. Initiation

2. Elongation

3. Termination

Initiation (transcription)

RNA polymerase (and sigma holoenzyme) bind to promoter

Elongation (transcription)

RNA polymerase unwinds helix, synthesizes mRNA (complementary to the DNA) in 5-3 direction

termination (transcription)

terminator sequence, RNA hairpin to release transcript

TATA box

A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex

5' cap

modified guanine end that is added to the 5'

3' polyA tail

modified enzymes of adenines to the 3' end

introns

noncoding segments

exons

coding segments that get spliced together

spiceosome (snrnps)

small nuclear ribonucleoproteins that cut out introns and put together the exons

purpose of introns

increased variation bc once spliced out, the exons can arrange in different orders

location of translation

cytoplams (ribosomes)

tRNA

translates the nucleic acids to amino acids, contains anticodons, carries specific amino acids

aminoacyl-tRNA synthetase

enzyme that attach the amino acid to the tRNA (requires energy)

rRNA

ribosomal rna, contains proteins, catalyzes the formation of peptide bonds

initiation (translation)

rRNA binds to complementary sequenceon mRNA, initiator tRNA binds to start codon, Large subunit attaches to form initiation complex

elongation (translation)

amino acids are added in chain (requires energy and elongation factors)

termination (translation)

spot codon is reached, a release factor binds to stop codon in the A site, translation assembly breaks apart

E site

location where empty tRNA exits

P site

location of tRNA with crowing polypeptide chain

A site

location where incoming active tRNA is

post translational modification

polypeptide with undergo secondary and tertiary folding

operon

group of genes operating together, consists of promoter operator and genes

promoter

where rna polymerase can bind and begin transcription

operator

segment of DNA that acts as an on off switch

lac operon

codes for enzymes necessary to transport and metabolize lactose (inducable)

inducible

the operon is usually turned off but can be switched on

inducer

binds to the repressor that is on the operator to activate (turn on)

allolactose

the inducer of lac operon

trp operon

contains genes which code for enzymes needed to synthesize tryptophan (repressible)

repressible

usually turned on but can be inhibited

respressor

binds to operator to block polymerase, turn off the operon

differential gene expression

different cell types express different subsets of genes

Eukaryotic cells can express genes through many different ways

chromatin remodeling

regulation of transcription initiation

rna processing

mrna degradation

translation regulation

protein processing and degradation

three histone tail modifications

acetylation (COCH3)

Methylation (CH3)

Phosphorylation (PO4)

Acetylation

COCH3

loosens DNA coiling which increases rate of transcripiton

HAts and HDACS

Methylation

CH3

tightens DNA coiling which shuts down gene expression

Phosphorylation

PO4

loosesns DNA coiling which increases transcription

Epigenetics

study of changes in gene expression not due to change in DNA sequence (Environmental factors of gene expression)

regulatory sequences

sections of DNA that are involved in controlling the activity of genes in eukaryotic cells.

Promoter-proximal elements, enhancers, silencers

General Transcription Factors

for all protein coding genes

interact with TATA box to form transcription initation complex

low rate of transcription

specific transcription factors

bind to regulatory sequences

strongly increase/decrease trancription rate depending on activator/repressor

recruit proteins for chromatin remodeling

gene regulation depends on

the combination of control elements

post transcriptional regulation

rna processing (alternative splicing), initiation of translation, protein processing, post-modifications (chemical adding, clevage)

thymine dimers

mutation of dna caused by uv light in which there is a confirmational change in the dna sequencing

sliding clamp

holds DNA polymerase 3 in place so it can synthesize the strands.

molecular chaperones

Can help facilitate the polypeptide's secondary and tertiary folding.

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