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Genetics > Lecture 8 > Flashcards

Lecture 8 Flashcards

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Biology 101 flashcards
1
Q

what is genetic material?

A

Information contained in genes that gets passed onto new generation; Source of variability among organisms

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2
Q

what are the 4 characteristics needed for a molecule to be genetic material?

A

replication, store information, express information, and allow variation by mutation

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3
Q

what is the central dogma of genetics?

A

DNA > RNA > protein

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4
Q

What are the characteristics of retroviruses?

A

-They convert their RNA to DNA before taking over the host cell
=Replicate unusually
RNA serves as a template for DNA synthesis
-Complementary synthesis of DNA by RNA-dependent DNA polymerase reverse transcriptase

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5
Q

what was the Hershey-Chase experiment?

A
  • foundation experiment responsible for finding DNA was the source of genetic material
  • P32 found DNA and S35 found proteins
  • There is then radioactivity in the dna but the others inject their genome but leave their radioactive “ghost” on the outside
  • The ghosts are labeled and cells are not and the opposite was true for the dna infected phages
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6
Q

what do nucleotides consist of?

A
  • a nitrogenous base
  • a pentose sugar
  • a phosphate group
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7
Q

what are the two kinds of nitrogenous bases?

A
  • purines

- pyrimidines

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8
Q

Purines

A
  • nine membered ring
  • adenine
  • guanine
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9
Q

pyrimidines

A
  • six membered rings
  • cytosine
  • thymine
  • uracil (RNA)
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10
Q

What nitrogenous bases do DNA have?

A

A, T, G, and C

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11
Q

what nitrogenous bases do RNA have?

A

A, C, U, and G

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12
Q

what is the difference between deoxyribose and ribose sugar?

A

deoxy means without oxygen, the difference is that there is not an oxygen on the 2’ hydrogen

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13
Q

what is the 5’ group attached to?

A

a phosphate group

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14
Q

what is the 3’ group attached to?

A

a nucleotide

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15
Q

what is a nucleoside?

A

a nitrogenous base with a pentose sugar

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16
Q

what is a nucleotide?

A

the same thing as a nucleoside, but it has a phosphate group attached to it

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17
Q

what are the three types of nucleosides?

A

nucleoside monophosphate, nucleoside diphosphate, and nucleoside triphosphate

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18
Q

how are nucleotides linked?

A

through phosphodiester bonds, they are connected from the 5’ group to the 3’ group

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19
Q

what is adenine complementary to?

A

thymine and uracil

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20
Q

what is guanine complementary to?

A

cytosine

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21
Q

what are the three classes of RNA?

A

messenger RNA, ribosomal RNA, and transfer RNA

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22
Q

ribosomal RNA (rRNA)

A
  • structural components of ribosomes for protein synthesis

- catalytic ribosomes that start the process of making proteins

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23
Q

messenger RNA (mRNA)

A
  • template for protein synthesis
  • carry genetic information from the gene to the ribosome
  • piece of RNA that encodes proteins and the process of making proteins
  • leaves the nucleus and goes into the cytoplasm
24
Q

transfer RNA (tRNA)

A
  • carries amino acids for protein synthesis

- is an adapter molecule that can read the mRNA and bring the right amino acid to make a protein

25
Q

are there other forms of RNA?

A
  • Telomerase RNA and RNA primers: used to replicate DNA at the ends of chromosomes
  • SnRNA: small nuclear RNA that processes mRNA
  • RNA, micro RNA, and siRNA: gene regulation
26
Q

what does semiconservative mean?

A

each replicated DNA molecule consists of an old strand and a new strand

27
Q

how does the semiconservative model work?

A
  • the two strands of the parent DNA is then split apart, then one new strand of DNA is made
  • it consists of one old strand and one new strand
28
Q

what direction does DNA polymerase go into?

A

5’ to 3’ direction

29
Q

what are the 7 issues that need to be resolved in DNA replication?

A
  1. Unwinding of helix
  2. Reduce increased coiling generated during unwinding
  3. Synthesis of primer for initiation
  4. Discontinuous synthesis of second strand
  5. Removal of the R N A primers
  6. Joining of gap-filling D N A to adjacent strand
  7. Proofreading
30
Q

how do you know the difference between genes and proteins?

A

genes are lower case and have italics while proteins are upper case and have no italics

31
Q

dnaA

A
  • unwinding of the helix
  • initiator protein encoded by dnaA gene
  • binds to ORI causing conformation change
  • exposes ssDNA for DNA helicase to bind
32
Q

DNA helicase

A
  • made of dnaB polypeptides
  • recruits holoenzyme to bind to replication fork and initiate replication
  • unwinds DNA
33
Q

reducing the supercoiling

A
  • DNA gyrase
  • snips to allow tension to unravel
  • relieves coiled tension from sunwinding helix
34
Q

Where does DNA replication begin?

A

at the origin of replication (ORI)

35
Q

what does the ORI do?

A
  • where new synthesis of DNA begins

- unwinding occurs

36
Q

replication fork

A
  • is at the site of replication

- where the helix is unwound

37
Q

what is the termination sequence for DNA synthesis?

A

TER

38
Q

what way is replication?

A

bidirectional

-there are two replication forks

39
Q

replicon

A

length of DNA being replicated

40
Q

how many ORIs do bacteria have?

A

1

41
Q

DNA polymerase 1

A
  • directs DNA synthesis
  • requires a DNA template
  • chain elongation
42
Q

chain elongation

A
  • occurs in the 5’ to 3’ direction, adding one nucleotide at a time to the 3’ end
  • once a nucleotide is added, two terminal phosphates cleaved off, providing a newly exposed 3’ OH
43
Q

DNA Polymerase 1,2,3

A

-can elongate existing DNA strand by adding a monomer to the 3’ end, but cannot initiate DNA synthesis

44
Q

DNA Polymerase 1, 2, 4, 5

A
  • involved in DNA repair

- repair DNA damaged by external forces like UV light

45
Q

DNA Polymerase 3

A

acts as a holoenzyme (has multiple functioning parts as a single structure)

46
Q

alpha

A
  • polymerase 3 subunit

- 5’ - 3’ polymerization

47
Q

epsilon

A
  • polymerase 3 subunit

- 3’ - 5’ exonuclease

48
Q

theta

A
  • polymerase 3 subunit

- core assembly

49
Q

tau

A
  • polymerase 3 subunit

- connects core to rest of the holoenzyme

50
Q

synthesis of primer for initiation

A
  • made from RNA
  • recruited to replicate from helicase
  • provides the 3’ OH required by DNA pol 3 for elongation
  • DNA pol 1 removes primer to replace with DNA
51
Q

discontinuous synthesis of second strand

A

-there are two strands of a double helix that run antiparallel to each other

52
Q

continuous strand

A
  • continuous DNA synthesis

- leading strand that only have one RNA primer

53
Q

discontinuous strand

A
  • discontinous DNA synthesis

- lagging strand with many RNA primers

54
Q

removal of RNA primers

A
  • Okazaki fragments
  • lagging strand synthesized as Okazaki fragments
  • DNA pol 1 removes primers
  • DNA is then filled in the gaps
55
Q

joining of gap filling DNA

A
  • DNA ligase
  • catalyzes phosphodiester bonds
  • seals nicks and joins fragments
56
Q

proofreading

A
  • DNA polymerase is not perfect

- relies on exonuclease activity 3’ - 5’ to remove nucleotide mistakes and fic them

Genetics (11 decks)

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