Genetics Exam 2

4 criteria for genetic material

information, replicatiojn, transmission, variation

Nucleotide

Building blocks of DNA RNA

Deoxyribose

Sugar of DNA

Ribose

sugar of RNA

phosphodiester linkage

joins building blocks

how are phosphodiester bonds added

5’ to 3’

H bonds

joins base pairs

How many h- bond are between A and T

2

How many h bonds are between C and G

3

Purines

Adenine and Guanine

Pyrmidines

Cytosine and Thymine

Where do bases project form

backbone

B DNA

common form, right handed, 10 bp/turn parallel strands, helical

Z DNA

forms under certain conditiojns, left handed, 12 bp/ turns, bases tilted, zigzag

DNA

DNA double stranded, deoxyribose, A-T, C-G double helix, nucleotide, stable

RNA

single stranded, ribose, A-U C-G, hairpin, loops, buldges

Bacterial chromosome

single and circular chromosomes in nucleoid

How many bp long are bacterial chromosomes

million

How many genes are in bacteria chromosomes

few thousand

How many orgins of replicaiton do bacteria have

1

Orgin of replication

Initiation of DNA replication

Negative supercoiling

Creates tension used to separate DNA strands

Control of supercoiling

DNA gyrase and DNA tooisomerase I

Introns

intervening regions, non coding, but within coding sequence

DNA replication

process of copying genetic material

3 models of DNA replication

conservative, semiconservative, dispersal

Conservative model

parental stay together after replication

semiconservative model

after replication DNA has 1 parental and daughter strand

dispersive model

parental and daughter DNA segments interspersed in both strands

Where does bacterial DNA replication begin

orgin of replication

Direction of bacterial DNA replication

bidirectional

3 regions of origins of chromosomes replication

AT rich region

DnaA boxes

GATC methylation sites

What regulates replication

DNA methylation

What does DNA helices do

Unwinds DNA

What does RNA primase do

lays down short 10-12bp RNA primer

How many primers are in leading strand

1

How many primers are in lagging strand

multiple

What synthesizes DNA

DNA polymerase III

What removes the primer and replaces it with DNA

DNA polymerase I

What joins okazaki fragments

DNA ligase

What repairs DNA

DNA polymerases

What does trans lesion synthesis

DNA polymerase V

Does DNA polymerase I proofread

yes

Does DNA polymerase II proofread

yes

does DNA polyermase III proofread

yes

Does DNA polymerase IV proofread

No

Does DNA polymerase V proofread

no

What can DNA polymerase III not do

Carry out de novo synthesis

DNA Polymerase III holoenzyme

10 subunits that resembles right hand with thumb between fingers

Subunit α

\n Synthesizes DNA

Subunit ε

3' to 5' proofreading (removes mismatches nucleotides)

\
Subunit θ

Accessory protein that stimulates the proofreading function

\
Subunit β

Clamp protein which allows DNA polymerase to slide along DNA without falling off

Subunits τ, γ,δ, δ', ψ, and χ

Clamp loader complex, involved with helping the camp protein bind to the DNA

Which direction does DNA polymerase III move in leading strand?

Towards replication fork

\
Which direction does DNA polymerase III move in lagging strand?

Away from replication fork

Is leading strand discontinuous synthesis or continuous synthesis?

Continuous

Is lagging strand discontinuous synthesis or continuous synthesis?

Discontinuous

\
Does the leading or lagging strand contain Okazaki fragments?

Lagging strand

Primosome

DNA helices + primase (coordination of activities)

\
Replisome

Both holoenzymes moves towards fork with the lagging strand looped. Lagging strand is released when Okazaki fragments are complete. Then the enzyme clamps on to next primer.

\
How many termination of replication sequences per oriC?

One for each fork

What does termination utilization substance do?

bind ter sequences which stops replication

What does DNA ligage do in Ter

links daugher strand

Catenanes

2 chromosomes linked together

Decantenates

DNA gyros

DNA polymerase makes

phosphodiester bonds

What does polymerase processivity allow

Synthesis of very long strands

true of false- errors in replication are rare

true

Are mismatches more stabler or less stable

less stable

what deos mismatches casue

distortion of helix and poor fit in active site

how does DNA polymerase proofread

removes mismatched base w 3’ to 5’ exonucleus activity and inserts correct base

mutation

heritable change in an organisms genetic material

Pros of mutation

genetic variation, increased fitness, adaptations to a changing enviroment

cons of mutation

may cause death, disease, expression

types of mutation

changes in chromosomes number

change in chromsomes

structure, change in individual gene sequence

types of mutations

substitution, insertion, deletion

Point mutation

change in individual gene sequence

substitution mutation

one base replaced by another

insertion mutation

addition of one or many bases causes framshifts

deletion mutation

loss of one or many bases, causes framshift

silent mutation

change in sequence doesn’t affect protein sequence

missense mutation

Change in sequence changes protein sequence

Nonsense mutation

change in sequence codes for stop codon

frameshift mutation

1 bp deletion or insertion changes protein sequence and codes for stop codon

Promoter sequences mutation

may increase or decrease the rare of transcription

Gene

segment of DNA that is made into protein or a functional RNA molecule

DNA to RNA

trascription

RNA to protein

Translation

RNA polymerase

copies DNA sequence to RNA sequence

DNA to mRNA

proceeds to translation to become proteins

DNA to rRNA

associates with proteins to form ribosomes

DNA to tRNA

adaptors used in translation

DNA to regulatory RNA

influences transcription and translation

Regulatory sequences

regulatory sequence bind here, influence the rate of transcription

promoter

where RNA polymerase binds to initiate transcription

Termintator

Site that triggers end of transcription

Shine Delgarno

ribosomes binding site

Ribosomes binding site

ribosomes binds to this region of mRNA to initiate translation

Start codon

code for the first amino acid of a polypeptide