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Genetics > Chapter 2: DNA - The Genetic Material > Flashcards

Chapter 2: DNA - The Genetic Material Flashcards

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Biology 101 flashcards
1
Q 
Griffith's Experiment 
L> S: virulent strain 
L> R: avirulent strain 
L> varieties I and II  
how can the mutations occur?
A

L> smooth, shiny colonies
L> rough colonies

  • IIS –> R—> IIS
    IIIS—> R—> IIIS
    L> cannot go between varieties ( i.e. IIS–> IIIS)
    AKA they are type specific mutations
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2
Q

Griffith’s Experiment
What is the S strain infectious?
L> R strain difference?

A
  • the presence of a polysaccharide coat (capsule) surrounding each cell. Gives them their shiny appearance.
    L> lacks the capsule…via mutation stopping it from getting it
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3
Q

Griffith’s Experiment Give a run through ! NO PEAKING G.

  • Mice + IIR ( R derived from IIS ) = ?
  • Mice + living IIIS = ?
  • Mice + IIIS (killed via heat) = ?
A
  • Mice + IIR ( R derived from IIS ) = mice lived
  • Mice + living IIIS = death ( IIIS could be extracted from blood)
  • Mice + IIIS (killed via heat) = mice lived
  • Results : bacteria had to be alive and have the coating to be virulent.
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4
Q

Griffith’s Experiment Give a run through ! NO PEAKING G. (Part 2)
- mice + (living IIR + heat killed IIIS) = ??
L> issue?
L> conclusion?

A
  • dead mice, living IIIS was found in blood….
    L> living IIIS could not be from IIR ( IIR–> IIS)
    L>conclusion: IIR had somehow TRANSFORMED into IIIS via interaction with dead IIIS.
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5
Q

Griffith’s Experiment Give a run through ! NO PEAKING G.

  • Genetic material from the dead IIIS had been added to the ___ in the ___.
  • What did Griffith think the unknown agent was? ( transforming principle)
A
  • genetic material, living IIR
  • thought a protein was the cause…thought wrong
    ALSO agents are important in recombinant dan exp
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6
Q

When you think of Griffith one would think of the discovery of _____?

A
  • genetic material
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7
Q

Avery’s experiment:

- what was his study about?

A
  • the transformation of S- type to R-type bacteria to learn what the agent was.
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8
Q

Avery knew the transforming agent had to be one of what four things?

A
  • polysaccharides, proteins, RNA or DNA
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9
Q

Avery’s experiment:

  • DNA +RNA from IIIS + RNase = ___ + IIR bacteria=???
  • DNA + RNA from IIIS bacteria + DNase=___+ RNA IR bacteria = ???
A 
- only DNA remains...
L> added to IIR bacteria 
L> = plate growth on medium-> IIIS trasnformants produced 
- only RNA remains 
L> added to IIR bacteria 
L> no IIIS transformants
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10
Q

Avery’s experiment:

- results of this showed what?

A
  • DNA not RNA was the transforming nucleic acid agent.
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11
Q

When one thinks of Avery think also of what?

A

confirmation of genetic material

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12
Q

Hershey and Chase:

L> there was lingering controversy over what?

A

DNA and protein being the genetic material

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13
Q

Hershey and Chase:

L> they used what to test the controversy in this experiment?

A
  • T2 bacteriophages consisting of only DNA and a protein coat.
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14
Q

Hershey and Chase:
PREPARATION
> T2 phage + E.coli and grow in the medium with P32…=?
> T2 Phage + E.coli and grow in the medium with S35=??

A
  • T2 progeny with DNA labeled via P32

- T2 progeny with protein labeled via S35

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15
Q 
Hershey and Chase: 
EXPERIMENT 
> T2 P32 DNA + E.coli --(blend)--> =??
> T2 S35 Protein phage + E.coli---(blend)--> =???
- conclusion?
A
  • phage ghosts outside of cell. (protein)
    -radioactivity recovered in host and passed on to phage progeny!
    – radioactivity recovered in phage ghosts and not passed on to the progeny.
    L> Protein does not get into the cell and therefore cannot pass on information to other gens therefore DNA is the heredity material…
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16
Q

What is a retrovirus?ex?

A
  • starts off with RNA and uses Reverse transcriptase—-> DNA—-> RNA
    (rna dependent dna poly)
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17
Q

DNA Double Helix:

- consists of two what?

A
  • polynucleotide chains
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18
Q

DNA Double Helix:

- the two strands are antiparallel or parallel?

A
  • antiparallel
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19
Q

DNA Double Helix:

- backbone is made of?

A
  • sugar-phosphate backbone
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20
Q

DNA Double Helix:
- What kind of bonds are between the bases?
L> how many between A and T ?
L> “…..” C and G?

A
  • hydrogen
    L> two bonds
    L> triple bonds
21
Q

DNA Double Helix:

- Why is it ideal for denaturation of DNA to occur in areas rich in A and T?

A
  • because the bonds between A and T are much weaker in comparison to the strong triple hydrogen bonds of C and G
22
Q

DNA Double Helix:

- Bases per turn?

A

10

23
Q

DNA Double Helix:

  • Major Groove?
  • Minor Groove?
A
  • proteins/factors can come in and interact with the DNA to control it’s expression or synthesis… but it does not interrupt binding of bases. ( easier on major groove bc the backbone isn’t in the way)
24
Q

Three types of DNA?

A
  1. A-DNA
  2. B-DNA
  3. Z-DNA
25
Q

A-DNA???Characteristics!

A
  • it’s right handed
  • 10.9 bases per turn
  • 2.2nm
  • short and wide
  • dehydrated (extracted DNA)
26
Q

B-DNA characteristics!

A
  • right handed
  • 10 bases per turn
  • 2 nm
  • long and thin
  • in solution ( within cell?)
27
Q

Z-DNA characteristics!

A
  • left handed
  • 12 bases per turn
  • 1.8 nm
  • long and thin
  • unknown location
28
Q

B-DNA is a ____ that aids in certain cell processes, such as recombination!

A
  • conformation
29
Q

Z-DNA ___ have been found in cells.

A
  • binging proteins
30
Q

Prokaryote Chromosomes:

- structures DNA can take?

A
  • double stranded, single, circular or supercoiled
31
Q

Prokaryote Chromosomes:

L> They tend to have a main area of genetic material and then about _ or more smaller chromosomes.

A
  • 1

L> they can replicate autonomously of the main one…..may be or not be essential to the cells life

32
Q

Prokaryote Chromosomes:

L> Plasmid?

A
  • autonomously replicating small chromosomes to essential to the life of the cell
33
Q

Prokaryote Chromosomes:

- Nucleoid?

A
  • chromosomes arranged in a dense clump in a region of the cell ( bacteria and archaea)
    L> no membrane separating it from the rest of the cell
34
Q

Prokaryote Chromosomes:
- Supercoiled??
L> knick?

A
  • genetic material is twisted in space about its own axis
    L> when a break occurs in a strand of the backbone….of a supercoiled circular DNA molecule…via tension from supercoiling… DNA spontaneously untwists and produces a relaxed DNA circular.
35
Q

Can supercoiling occur in linear chromosomes?

A
  • yes

- occurs at localized regions and the ends behave as if they are fixed.

36
Q

Types of supercoiling:

  • positive
  • negative
A
  • one more turn to make

- one less turn to make

37
Q

Prokaryote Chromosomes:

- Topoisomerase?

A
  • enzyme that controls the amount and type of DNA supercoiling found in all organisms!…..it can make one or two cuts in dan to take out tangling …
38
Q

Prokaryote Chromosomes:

- Topoisomerase (DNA gyrase?)…eases what?

A
  • eases tension in the genome if this is absent the organism dies.
39
Q

Eukaryotic Chromosomes :

- Chromatin?

A
  • combination of DNA and protein..packages DNA into smaller volumes.
40
Q

Eukaryotic Chromosomes :

Histones?

A
  • proteins that package and order DNA
  • most abundant protein in chromatin
  • 5 types
41
Q

Eukaryotic Chromosomes :

DNA loop?

A
  • access for replication…attach to nuclear lamina keeping it in place while other things occur.
42
Q

C-value?

A
  • haploid DNA content in our cells
43
Q

C-value paradox?

A
  • if an organism has a high c value it does not mean it is more complex..
44
Q

Chargaff’s Rules?(list em)

4

A
  1. Purine bases = 50% if all DNA nucleotides in an organism
  2. Pyrimidines bases = 50% of all DNA nucleotides in an organism
  3. Adenine nucleotides= thymine nucleotides
  4. Guanine nucleotides = cytosine nucleotides
45
Q

Details of Chromatin?

Two main kinds?

A
  1. Euchromatin

2. Heterochromatin

46
Q

Details of Chromatin?

1. Euchromatin ?

A
  1. parts of genome in its active cycle…
    L> genes that are actively transcribed
    - house keeping genes
    L> not packed as densely, generally lacking repetitive sequences
47
Q

Details of Chromatin?
2. Heterochromatin?
L> types? (2)

A
  • generally transcriptionally inactive…
    L> Constitutive
    L> Facultative
48
Q

Details of Chromatin?
2. Heterochromatin
L> Constitutive

A
  • same position on homologous chromosomes

L>centromeres and telomeres condensed , highly repetitive and inactive transcription

49
Q

Details of Chromatin?
2. Heterochromatin
L> Facultative?

A

L> more variable depending on cell type or its stage….specialized proteins
L> not always transcribed ex seminal vesicles

Genetics (14 decks)

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