DNA &Role In Hereditary Flashcards

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1
Q

Genetic of nonviolent pneumococci?

A

Method: take livings strain s and inject in mouse
Living r strain → mouse healthy no bacterial cell found in heart
H eat s strain → turns diff
Inject in mouse = No bacterial cell found in heart

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2
Q

C chemical nature

A
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3
Q

Bacteriophage T2: reproduction cycle

A
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4
Q

Nucleotide

A

Base + ribose I deoxyribose = nucleoside + base
+Phosphate → nucleotide

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5
Q

What types of bases are there?

A

Pyridines → cytosine & thymine
Purines → adenine & guanine( 2RINGS)

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6
Q

What is chargraffs rule?

A

Amount of a= amount of T
Amount of c= amount of G
Purines = pyramidines

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7
Q

X-ray crystallography how ?

A

The a-ray source is

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8
Q

How is base pairing in DNA complimentary?

A

DNA consists of 2 antiparrallel like a ladder
A-t pairs and g-c pairs forming the rungs
Phosphate sugar chains form the backbone s
↓ 5’ end ↑ 3’ end
Individual nucleotide subunits consist of base,etc

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9
Q

What ave the three possible models for DNA replication?

A

Original DNA → after round of replication → semi-conservative replication →2 double helix 50/50 - both
2nd- original DNA strand → 2 double helix each1-originale
3rds original DNA strand → dispersive

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10
Q

The meselston-stahl experiment

A

Ecoligrown in 15N medium transferred to normal 14N
E. Cool replicates every 20 min →New DNA will incorporate 14N
14N/14N DNA →sample at 0 mins parent -

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11
Q

Results of meselson- stahl experiment?

A

This pattern could only have been observed if each DNA molecule contains a template strand from parental DNA this DNA replication is semi - conservative

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12
Q

How does a new DNA strand grow?

A

By adding to its 3’ end
A new nucleoside triphosphate attaches to the 3 ‘ end sugar phosphate end
Energy from cleaving the pyrophosphote used to bind the nucleotide → replication complex catalyses the reaction

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13
Q

What is the key enzyme for the replication process?

A

DNA polymerase binds to the template strand ensures the correct base that fits into the new strand
The template strand and KMA plume go through DNA polymerase to create a new strand

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14
Q

The new DNA strand requires what?

A

The primer is made of RNA a molecule similar to DNA and is synthesised by primate
The DNA polymerase than begins adding nucléoïdes to the 3’ end of the primer
The protein → sliding DNA clamp ↑ the efficiency of DNA polymerisation

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15
Q

What other proteins collaborate in the replication process?

A

DNA helices
Single-strand binding proteins
Okazaki fragments

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16
Q

What does DNA helices do?

A

Uses energy from ATP to unwind the DNA

17
Q

What do single strand binding proteins do?

A

Keep the strands from getting back together

18
Q

What is the Leading strand?

A

Only leading strand is pointing in the right direction

19
Q

What is Okazaki fragments?

A

Synthesis of logging strand occurs in smallp discontinues stretches *

20
Q

How do the 2 new strands form in different way?

A

Leading strand → 3’ } nucleotides continuosly added to the Lagging strand → 5’ . end of new leading stead
* The lagging strand waits until a stretch has been unwound then a primer canbe added & nucléoïdes are added to the primer 3’ end to fill stretch

21
Q

DNA replication

A

Leading and lagging strand synthesis video

22
Q

What do telomeres do?

A

When undergoing replication → chromosomes con lose 50-200 base pairs with each replication
To stop loss of important genes → chromosomes have “ telomeres “→ repealing sequence of genes

23
Q

What is telomerase?

A

Telomerase= catalyses the addition of extra telomere sequence to lengthen lagging strand again after replication to prevent telomeres lost

24
Q

How does telomerase work?

A

Telomeres bind s an RNA template
DNA p olymerose then fills in complementary bases
Telomerase is the removed and DNA polymerase then fills in the gap with extra Okazaki fragments.

25
Q

What function does DNA polymerase?

A

DNA polymerase has a proofreading function
If bases are paired incorrectly the nucleotides are removed
DNA proofreading

26
Q

What is a mismatch repair?

A

Mismatch repair enzymes con tell newly synthesised stands strand, from old one, when they detect mismatches
They replace mismatched bases on the New strand

27
Q

What is long-after copying?

A

Newly synthesised stead becomes indistinguishable from old strand but random mutations might occur
Excision repair enzymes scan DNA for mismatches due to mutations but replacement occurs on a random strand (not always correct)