genetics midterm

categories: DNA structure and basics, DNA replication, griffith experiment, transcription, RNA processing, translation, proteins, and techniques.

4 key properties of DNA

DNA structure/basics -

replicates faithfully

stores information

mutates/recombines

evolves

components of a DNA nucleotide:

DNA structure/basics -

sugar (deoxyribose)

phosphate

nitrogenous base

what is the difference between purines and pyrimidines?

DNA structure/basics -

purines (A,G) = 2 rings

pyrimidines (C,T) = 1 ring

what are the base pairing rules

DNA structure/basics -

A—T = 2 H bonds

C—G = 3 H bonds

what does antiparallel mean?

DNA structure/basics -

strands run in opposite directions (5’—>3’ and 3’—>5’)

what is the leading strand

DNA replication -

synthesized continuously toward replication fork

what is the lagging strand

DNA replication -

synthesized discontinuously away from fork

what are okazaki fragments

DNA replication - short DNA fragments on lagging strand

why are okazaki fragments needed?

DNA replication - DNA polymerase only works 5’—>3’

what does DNA ligase do?

DNA replication - joins DNA fragments

what does topoisomerase do?

DNA replication - relieves supercoiling tension

what is semi-discontinuous replication?

DNA replication - one strand continuous, one strand discontinuous

what are S and R strands?

Griffith experiment -

S = virulent

R = non-virulent

what is transformation

Griffith experiment - uptake of foreign DNA

what proved DNA is the transforming factor?

Griffith experiment - DNase destroys transformation

what enzyme performs transcription?

Transcription - RNA polymerase

what direction is RNA synthesized

Transcription - 5’—>3’

what is a promoter

Transcription - DNA sequence where transcription begins

what is the +1 site

Transcription - first nucleotide transcribed

what is the sigma factor

transcription - helps RNA polymerase bind promoter

steps of transcription

initiation, elongation, termination

difference between template and coding strand

transcription - template = used for RNA synthesis, coding = matches RNA sequence

what are introns

RNA processing - noncoding regions removed

what are exons

RNA processing - coding regions kept

what is alternative splicing

RNA processing - one gene —> multiple proteins

what is a codon

translation - a 3-nucleotide sequence coding for amino acid

what is the start codon

translation - AUG

what is degeneracy

translation - multiple codons —> same amino acid

what is the ribosomes function

translation - makes proteins

what are the ribosome sites and purpose

translation -

A site = The entry point for a new aminoacyl-tRNA, which carries a specific amino acid to be added to the growing polypeptide chain based on the mRNA codon.

P site = Holds the tRNA attached to the growing polypeptide chain

E site = holds the deacylated (empty) tRNA after its amino acid has been added to the chain

what does tRNA do

translation - matches anticodon to codon

what is wobble

translation - flexibility in the 3rd base pairing

what forms peptide bonds

translation - ribosome

what determines protein structure

proteins -

amino acid sequence

levels of protein structure

proteins - primary, secondary, tertiary, quaternary

what is a peptide bond

proteins - bond between amino acids

what is PCR

techniques - polymerase chain reaction, amplifies DNA exponentially, used to detect pathogens

steps of PCR

techniques - denature, anneal, extend

what do restriction enzymes do

techniques - cut DNA at specific sequences

how is DNA extracted

techniques - detergent + protease + alcohol

what direction does DNA polymerase work

DNA replication -

5’—>3’ only

/ what does mRNA do

Carries genetic information from DNA to the ribosome for translation

/ what does tRNA do

Brings the correct amino acid to the ribosome and matches anticodon to mRNA codon

/ what does rRNA do

Structural and catalytic component of ribosomes; helps form peptide bonds

/ what does snRNA do

Involved in splicing; helps remove introns from pre-mRNA

/ what do miRNA/siRNA do

Regulate gene expression by blocking translation or degrading mRNA

/ DNA polymerase III function

Main enzyme that synthesizes new DNA strand

/ DNA polymerase I function

Removes RNA primers and replaces them with DNA - exonuclease activity

/ DNA polymerase II function

DNA repair