Dna Stuffs Flashcards by porter hacking

Griffith

DNA v. Proteins
Bacteria that killed rats
R-strain in not deadly
S strain deadly
Heat killed s - mouse lives
Heat killed s+ live r= mouse dead

Only heat up to 60-65 protiens deconstruct and cell wall falls apart

R cells picks up dna from dead s strain and immediately divided so the new deadly bacs are made

DNA was the one responsible because the proteins were denatured

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Hershey and chase

1- P which labeled DNA
2- S which labeled protien

The phosphorus was with dead cells

The protien stayed in the solution at the top

Stop phase at manufacturing phase where you can clip off virus husk and see what molecule moved

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Nucleotide make up

Phosphorus (groups)
Pentosugar
Nitrogen base

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Pyramidines

C T U single ring

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Purines

AG double rings

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Label carbons

1 is far right
2 if has h instead of oh makes it deoxyribose
3 oh
4 branch
5 phosphorous group

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Bases with two hydrogen bonding

AT and U potentially

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Bases with three bonding sites

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Chargrafs rule

15% Adanine 15% thiamine
35% G is 35% C

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Location of DNA

Eukaryotes - in nucleus (much more compacted)
Prokaryotes - in plasma in núcleo if

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Level 1 DNA compaction

DNA in double helix is wrapped around the histone

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Level 2 structure compaction

The Histones with dna wrap around to form nucleosomes which are coiled into chromatin fibers

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Level 3 dna structure compaction

Chromatin fibers wrap around more protien fibers

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Level 4 dna structure condensation

Chromatin are condensed and duplicated into a chromosome

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S phase

Where DNA is replicated into sister chromosomes

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Conservative replication

Parent strands stay together
And daughter strands pair up

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Semi conservative

One parent strand stays with daughter strand completely intact

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Dispersive

All 4 new strands are made with random parts of both the daughter and parent strand

Meselson and stahl

Allow bacteria to grow in two types of nitrogen N15 and N14

Amount changes in set pattern
1st gen 100% in the center - which rules out conservative

2nd gen - had 50% in the middle and 50% on top which proved the semi conservative replication

Where does replication start and dif of pro v eu

Origin of replication
Eukaryotes - have multiple organs
Prokaryotes - have 1

Eu have telomerase
Pro no

Rules of dna replication

Read template 3- 5
Synthesis goes 5-3

Leading strand - one continuous fragment

Lagging strand- has multiple segments (Okazaki fragments)

3 prime end

Oh group

5 prime end

Phosphate group

Helicase

Unwinds the dna

Single strand binding protiens

Bound to unwound strand to keep them apart Because of the hydrophobic nature of the inside of dna

Topoisomerase

Goes in front of the helicase and relaxes the wind of the dna Controles the stress

Primase

Lays down 3-5 RNA nucleotides at the orgin 5-3

DNA polymerase 3

Needs open 3prime end Begins synthesis of new strand of dna starting from the primer lays 5-3

DNA polymerase 1

Gets rid of primer RNA and replaces it with DNA but leaves a gap Cannot creat phosphodiester bonds sugar backbone

Ligase

Closes or minds the gap

Telomere

Tip Or Aglet With repeated DNA pattern because of shrinking

Telomerase

Occurs in cells that actively divide a lot ie dermal cells Because of the gap that happens at the end of dna replication Telomerase comes in and adds a whole chunk of the DNA telomere pattern to 3prime end to make it even longer So that primase and polymerase and liGase can come in and add more to the short strand and extend side

Proof reading

DNA polymerase 3 stops and goes back and fixes pair as it goes about synthesis

Mis match repair

Past the point of proof reading Nucleas comes in and clips out incorrect base and then poly 3 comes back to fix it Proof reading + mix math = 99%

Thymine dymers

UV causes horizontal intermolecular or covalent bonds instead of hydrogen bonds across or verticle

Nucleotide excision repairs

Nucleare comes in and cuts out the thymine dymers but it has to cut a decently large chunk And then poly 3 can come back and put in correct sequence

Xeroderma pigmentosa

Person doesn’t have nuclease involved with Excision repairs so they are unable to rapair UV effected DNA which leads to high amounts of cancer and other skin damage

Mutation

1% error From repair processes

Silent mutation

Change Doesn’t effect the amino acid that is coded 1 base is changed

Missense mutation

Change of one base causes a change in the amino acid which does and doesn’t effect the protien ie cikle cell anemia

Nonsense mutation

An accidental stop When base change causes a stop amino acid to early in the sequence Can cause protien to be too short which can effect folding and ultimately cause cell death

Read through mutation

Stop codon does not appear and the amino acid chain just keeps reading which generally not bad but gives protiens tails Most effective when deleted 1 to 2 but not 3 nucleotides

Phase shift mutation

If a base is added or deleted then the three by threes will shift causing all the amino acids to be wrong after the mutation which causes a completely wrong protein to be made which would be catastrophic

Codon

3 bases read at the same time that turns into one amino acid