DNA Structure and Replication Flashcards by Emily Cottenden

what was believed to be genetic material in the 1940s

protein

How well did you know this?

Not at all

Perfectly

what is the transforming agent in bacterial transformation?

DNA

How well did you know this?

Not at all

Perfectly

explain Griffith’s in vivo transformation experiments

he injected a mouse with four different bacterium
Control: inject with virulent IIIS, mouse dies
-Inject with non virulent IIR, mouse lives
Heat killed: inject with killed IIIS, mouse lives
Critical experiment: inject with living IIR and killed IIIS, mouse dies, tissue analysis shows live IIIS

How well did you know this?

Not at all

Perfectly

explain Avery-MacLeod-McCarty in vivo transformation experiments

treated IIIS filtrate with different neutralizing agents for protein, RNA, lipids, carbs, and DNA to see which was the transforming agent

How well did you know this?

Not at all

Perfectly

IIR v IIIS
-which is virulent/impact on injected mice

IIIS is virulent and killed mice

How well did you know this?

Not at all

Perfectly

what was the discovery of transforming non-virulent IIR cells into virulent IIIS cells

discovery of transformation

How well did you know this?

Not at all

Perfectly

what is transformation used by to transfer DNA

bacteria

How well did you know this?

Not at all

Perfectly

in Avery, MC^2 destroying which material led to transformation not occurring? why is this important?

when DNA was destroyed transformation did not occur.
proved that DNA was the transforming agent

How well did you know this?

Not at all

Perfectly

explain Hershey-Chase bacteriophage experiment

labeled protein phages and DNA phages separately then traced each radioactive label in the course of infection

How well did you know this?

Not at all

Perfectly

DNA contains large amounts of [what], whereas protein contains large amounts of [what]?

DNA: phosphorus
Protein: sulfur

How well did you know this?

Not at all

Perfectly

what were phage proteins labeled with in hershey-chase?
DNA phages?

Proteins: 35S
DNA: 32P

How well did you know this?

Not at all

Perfectly

what was infected bacteria labeled with in hershey-chase? what did it prove was the genetic material in T2 phages?

infected bacteria were labeled with 32P which proved genetic material in T2 is DNA not protein

How well did you know this?

Not at all

Perfectly

dNMPs and dNTPs

dNMPs: monophosphates-part of the nucleotide chain
dNTPs: triphosphates-not part of the nucleotide chain

How well did you know this?

Not at all

Perfectly

T/F dNTPs and dNMPs are both part of the polynucleotide chain

FALSE. only dNMPs are

How well did you know this?

Not at all

Perfectly

chemical structural difference between DNA and RNA

DNA has an H on the 2’ carbon whereas RNA has an OH on the 2’ carbon

How well did you know this?

Not at all

Perfectly

structural difference between nucleosides and nucleotides

Nucleoside: Nitrogenous base + Pentose sugar

Nucleotide: Nucleoside + Phosphate group

How well did you know this?

Not at all

Perfectly

nomenclature difference between nucleosides and nucleotides

Nucleoside: ends with ‘SINE’

Nucleotide: ends with ‘ACID’

How well did you know this?

Not at all

Perfectly

most significant nucleoside phosphate

NTP(precursor for ATP)

How well did you know this?

Not at all

Perfectly

assembly of polynucleotide chains(3 componants)

-individual nucleotides assemble through DNA polymerase
-phosphodiester bond forms between 3’ hydroxyl group and paired 5’ phosphate group
-each chain has a sugar phosphate backbone alternating sugar and phosphate groups

How well did you know this?

Not at all

Perfectly

3 required properties of genetic code

must replicate
must encode information
must be able to change/mutate

How well did you know this?

Not at all

Perfectly

complementary vs antiparallel sequences?

Complementary: bases of one strand pair with corresponding base of the other strand(EX: A-T, C-G)

Antiparallel: the 2 strands are antiparallel to each other with respect to 5’ and 3’ ends

How well did you know this?

Not at all

Perfectly

Chargaff’s rules

-A=T AND G=C
-(A+G) = (C+T)
-(G+C) ≠ (A+T)

How well did you know this?

Not at all

Perfectly

how do chargaff’s rules correlate to the base composition studies critical conclusions?

it showed a specific chemical affinity between nitrogenous bases

How well did you know this?

Not at all

Perfectly

base stacking definition

creates gaps among sugar-phosphate backbone that partially exposes nucleotides

How well did you know this?

Not at all

Perfectly

major vs minor grooves

Major is wider and deeper than minor grooves

B-DNA properties

-most common -right handed twist -low salt conditions

A-DNA properties

-mainly in bacteriophage and in vitro -high salt/dehydration -base tilted in relation to axis -grooves modified

Z-DNA properties

-found near transcription start sites -zigzag conformation -left handed helix -no major groove

what are the 3 forms of DNA

A-DNA B-DNA Z-DNA

3 attributes of DNA replication shared by all organisms

-each strand of parental DNA remains intact -each parental strand serves as template for complimentary daughter strand -completion results in formation of tw identical daughter duplexes composed of one parental and one daughter strand

basics of DNA replication

semiconservative bi-directional main synthesis- polymerase III direction 5' - 3' start at point(s) of origin

3 theoretical models of DNA replication

Semiconservative Conservative Dispersive

what is the origin of replication in prokaryotes

location where DNA replication begins

what is the replication fork in prokaryotes

located at the end of the replication bubble where replication is complete

what is the replication bubble in prokaryotes

expands around the origin of replication as DNA replication proceeds bi-directionally from it

main differences in DNA replication between prokaryotes and eukaryotes

Eukaryotic DNA replication is more complex -more DNA -linear chromosomes -DNA complexed with proteins

what is a consensus sequence

comparing a region of DNA between related species and determining the most common nucleotide found at a specific position of DNA

why do prokaryotes have only one origin of replication

because bacterial DNA is a circle so origin of replication meets up with the terminus of replication

steps of DNA replication in bacteria(7 steps)

-helicase breaks H bonds, topoisomerase calms supercoiling -single-stranded binding prevents reannealing -primase synthesizes RNA primers -polymerase III synthesizes daughter strand -polymerase III elongates leading strand and lagging strand -polymerase I removes and replaces RNA primer -DNA ligase joins okazaki fragments

what is RNA priming

universal initiation of DNA replication

what are Okazaki fragments

discontinuous strands of replicated DNA

how are okazaki fragments combined after being synthesized

combined by DNA ligase

Function of DNA polymerase I

remove primer and fill gaps

Function of DNA polymerase II

repairs DNA damage from external forces and damage at replication fork

Function of DNA polymerase III

proofreading and DNA polymerization

Function of DNA polymerase IV and V

repair DNA damages caused by external forces

what is the function of the sliding clamp

clamp onto double-stranded DNA during replication to anchor polymerase III

why does proofreading need to occur

detect mismatches cut out wrong nucleotides

what activity allows DNA polymerase to work

presence of sliding clamp

what causes supercoiling? what controls it?

it is torsional stress caused by the unwinding of chromosomes during replication. controlled by topoisomerases

how many telomeres are important in chromosomes

4 (one cap on each chromosome end)

main characteristics of telomeric sequences

contain special repeat: TTAGGG

T/F prokaryotes have telomeres

FALSE

what causes the gap in telomeres? what enzyme fixes it?

gap is caused by telomerase adding extra telomeric sequence to the lagging strand. polymerase fills the gap

telomerase activity steps (4 steps)

-telomeric repeat added to lagging strand -repeats fold back and form G-G bond -polymerase fills the gap formed -hairpin turn is cleaved and removed -telomerase synthesizes new telomeric sequence on the end

difference between PCR amplification and dye terminator sequencing(sanger sequence)

PCR does not contain ddNTPS which are present in sanger sequence

What is the most commonly used DNA polymerase? What is it isolated from? Where does it naturally occur?

Taq isolated from Thermus Aquaticus found naturally in hot springs

fill in the blank: cancer cells maintain _____ activity and are ______

telomerase, imortalized

what do groves in DNA allow for

DNA binding proteins can make direct contact with nucleotides

semiconservative DNA replication

each daughter duplex has one daughter and one parental strand

conservative DNA replication

one daughter duplex has both daughters, the other has both parents

dispersive DNA replication

each daughter duplex contains interspersed daughter ant parental segments

main enzyme groups that control DNA replication and their basic functions

Helicases-unwind and stabilize Gyrases-cut and stabilize RNA polymerase-synthesize RNA primers DNA polymerase-synthesize DNA Ligase-stitch fragments