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DNA Flashcards

1
Q

what are the 4 bases in dna

A

adenine, guanine, cytosine, thymine

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2
Q

that is a nucleotide

A

phosphate group, nitrogen containing base, and a pentose sugar

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3
Q

what is the sugar in DNA

A

deoxyribose

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4
Q

what is a pentose sugar

A

a sugar with 5 carbons

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5
Q

what is the difference between deoxyribose and ribose

A

deoxyribose has a H group not an OH group

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6
Q

what is the nitrogenous bases

A

a ring of compounds that are on the inside of the dna helix

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7
Q

what is the difference between purines and pyrimidines

A

purines have an amide groupe while pyrimidines have an amino group and double bonds

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8
Q

name the purines

A

adenine and guanine

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9
Q

name the pyrimidines

A

thymine, cytosine, and uracil

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10
Q

what is adenine complimentary with

A

thymine

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11
Q

what is thymine complimentary with

A

adenine

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12
Q

what is cytosine complimentary with

A

guanine

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13
Q

what is guanine complimentary with

A

cytosine

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14
Q

how many hydrogen bonds are between A and T

A

2

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15
Q

how many hydrogen bonds are between G and C

A

3

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16
Q

what is the phosphate backbone

A
  • protects the bases
  • chain created with phosphodiester bonds
  • provide energy by breaking P group off
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17
Q

how is the double helix arranged

A

5 prime to 3 prime and antiparallel

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18
Q

how discovered DNA

A
  • Miescher 1869
  • Kossel- 1878
  • Flemming 1882
  • Koltsov- 1927
    -Griffin - 1928
  • Avery, MacLeod & McCarty- 1944
    Hershey- Chase experiment- 1952
    -Franklin – Gosling- 1952
    -Watson – Crick- 1953
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19
Q

what did Miescher do

A
  • 1869
    discovered nuclein
    believed protein was hereditary molecule
20
Q

what did Kossel do

A
  • 1878
  • Isolated non protein component of nuclein
  • discovered the bases
21
Q

what did Flemming do

A

-1882

observed chromosomes in cell division

22
Q

what did Koltsov do

A
  • 1927

- inherited traits are from huge hereditary molecule, double helix, and replicated semi-conservatively

23
Q

what did griffin do

A
  • 1928

- injected mice with different strains of pneumonia and discovered a transformation factor

24
Q

what did Avery, MacLeod, MCarty do

A
  • 1944

- bacteria collected from mice and isolated and purified it. Tested it and DNA was hereditary molecule

25
What did Hershey and Chase do
- 1952 | - Radioactively labelled protein and DNA to prove DNA is hereditary molecule. Radioactive DNA was passed on
26
what did Franklin and Gosling do
- 1952 | - photo 51, xray confirmed double helix that was anti-parallel
27
what did watson and crick do
modeled the structure of DNA
28
give details of the griffin experiment
- three strains of pneumonia - virulent S, nonvirulent R and heat killed virulent strain - R and heat killed= mouse lives - S and R+heat killed = mouth died - R strain had taken up a transforming principle so it became S strain
29
give details of Avery, MacLeod, MCarty experiment
- isolated the bacteria from dead mice - tested for protein with protein degrading enzyme + other tests and still transformed - DNA was produce in this transformation - DNA acting stopped the process
30
give details of the Hershey - Chase experiment
- bacteriophage= virus that infects bacteria to make more viruses - virus = protein and DNA - Protein was labelled with 35S and DNA was labelled with 32P - bacteria was infeced with it and then separated and centrifged - pellet from bacteria that was 32P radioactive at bottom while 32S was supernatant- viruses
31
what is Chargaff's rule
DNA has an equal number of A to T and equal number of G to C
32
compare structure of DNA to it's function
- stable for hereditary - hyrogen bonds allow for easy separation for replication - large molecule = large amount of info - base pairs allow helical cylinder that protects bases from corruption - complimentary base pairs allow easy replication
33
give an overview of H bonding
- weaker bond that is easy to break - only between H + H,O,N,F - atoms must be in a linear line - donor = alcohol, carboxyl, amide, amine - acceptor = lone pairs
34
what is nuclear division
the nucleus divides via either mitosis or meiosis
35
what is mitosis
cell division that produces identical daughter cells and has the same type of chromosomes as the parent cell
36
what is cytokineses
follows nuclear divisions and is the process the while cell divides by
37
what is meiosis
a cell division that results in 4 daughter cells, each with half the number of chromosomes as the parent cell and is the production of gametes
38
what is semi-conservative replication
the two strands in DNA separate and free nucleotides pair with pair with the exposed bases on the single chains to form two new DNA molecules, each containing one original and one newly synthesized strand of DNA.
39
what is conservative replication
Conservative replication would leave intact the original DNA that acts as a template that generates a completely new DNA molecule
40
what is dispersive replication
the original DNA chain breaks and recombines in a random fashion before the double helix structure unwinds and separates to act as a template
41
what are the prerequistes for semi-conservative replication
- the four types of free nucleotides - both strands need to act as a template - the enzymes DNA polymerase, DNA primase, DNA helicase, NA ligase and topoisomerase - a source of chemmical energy from the P backbone
42
give a brief mechanism of DNA replication
- DNA gyrase prevents supercoiling - DNA helicase breaks the H bonds and single strand binding proteins stop the replication fork coming back together - replication fork = leading strand and lagging strand - primase creates RNA primers that DNA polymerase can attach to at the 3 prime of template - DNA polymerase adds complimentary nucleotides from the 5 to the 3 prime of new DNA. Continousley for leading, pieces in lagging - RNase H removes RNA primers - DNA polymerase 1 replaces it with nucleotides - DNA liagse bonds nucleotides together
43
what are okazaki fragments
the DNA that is synthesised in sections on the lagging strand because the helix closes. RNase H, DNA polymerase 1 and DNA ligase need to act on this one more.
44
how was semi conservative replication proven
Meselson-Stahl experiment
45
what was the procedure of the Meselson-Stahl experiment
- control group of bacteria grown on 14N - sample bacteria grown on heavy 15N - bacteria sample transferred to 14N and left for 1,2,3 divisions - bacteria was purified and DNA isolated - DNA was centrifuged to see the density of each generation
46
what are the results of Meselso-Stahl experiment
- control= 100% 14N - gen 0= DNA bottom, 100% 15N - gen 1= DNA middle, 50% 14N and 15N - gen 2= 1 band middle, one top, 75% 14N and 25%N - proves semi con model

Biochemistry (10 decks)

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