Chapter 2: DNA - The Genetic Material Flashcards
(49 cards)
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
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
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.
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.
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
6
Q
When you think of Griffith one would think of the discovery of _____?
A
- genetic material
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.
8
Q
Avery knew the transforming agent had to be one of what four things?
A
- polysaccharides, proteins, RNA or DNA
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
10
Q
Avery’s experiment:
- results of this showed what?
A
- DNA not RNA was the transforming nucleic acid agent.
11
Q
When one thinks of Avery think also of what?
A
confirmation of genetic material
12
Q
Hershey and Chase:
L> there was lingering controversy over what?
A
DNA and protein being the genetic material
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.
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
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…
16
Q
What is a retrovirus?ex?
A
- starts off with RNA and uses Reverse transcriptase—-> DNA—-> RNA
(rna dependent dna poly)
17
Q
DNA Double Helix:
- consists of two what?
A
- polynucleotide chains
18
Q
DNA Double Helix:
- the two strands are antiparallel or parallel?
A
- antiparallel
19
Q
DNA Double Helix:
- backbone is made of?
A
- sugar-phosphate backbone
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
- A-DNA
- B-DNA
- Z-DNA
25
A-DNA???Characteristics!
- it's right handed
- 10.9 bases per turn
- 2.2nm
- short and wide
- dehydrated (extracted DNA)
26
B-DNA characteristics!
- right handed
- 10 bases per turn
- 2 nm
- long and thin
- in solution ( within cell?)
27
Z-DNA characteristics!
- left handed
- 12 bases per turn
- 1.8 nm
- long and thin
- unknown location
28
B-DNA is a ____ that aids in certain cell processes, such as recombination!
- conformation
29
Z-DNA ___ have been found in cells.
- binging proteins
30
Prokaryote Chromosomes:
| - structures DNA can take?
- double stranded, single, circular or supercoiled
31
Prokaryote Chromosomes:
| L> They tend to have a main area of genetic material and then about _ or more smaller chromosomes.
- 1
| L> they can replicate autonomously of the main one.....may be or not be essential to the cells life
32
Prokaryote Chromosomes:
| L> Plasmid?
- autonomously replicating small chromosomes to essential to the life of the cell
33
Prokaryote Chromosomes:
| - Nucleoid?
- 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
Prokaryote Chromosomes:
- Supercoiled??
L> knick?
- 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
Can supercoiling occur in linear chromosomes?
- yes
| - occurs at localized regions and the ends behave as if they are fixed.
36
Types of supercoiling:
- positive
- negative
- one more turn to make
| - one less turn to make
37
Prokaryote Chromosomes:
| - Topoisomerase?
- 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
Prokaryote Chromosomes:
| - Topoisomerase (DNA gyrase?)...eases what?
- eases tension in the genome if this is absent the organism dies.
39
Eukaryotic Chromosomes :
| - Chromatin?
- combination of DNA and protein..packages DNA into smaller volumes.
40
Eukaryotic Chromosomes :
| Histones?
- proteins that package and order DNA
- most abundant protein in chromatin
- 5 types
41
Eukaryotic Chromosomes :
| DNA loop?
- access for replication...attach to nuclear lamina keeping it in place while other things occur.
42
C-value?
- haploid DNA content in our cells
43
C-value paradox?
- if an organism has a high c value it does not mean it is more complex..
44
Chargaff's Rules?(list em)
| 4
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
Details of Chromatin?
| Two main kinds?
1. Euchromatin
| 2. Heterochromatin
46
Details of Chromatin?
| 1. Euchromatin ?
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
Details of Chromatin?
2. Heterochromatin?
L> types? (2)
- generally transcriptionally inactive...
L> Constitutive
L> Facultative
48
Details of Chromatin?
2. Heterochromatin
L> Constitutive
- same position on homologous chromosomes
| L>centromeres and telomeres condensed , highly repetitive and inactive transcription
49
Details of Chromatin?
2. Heterochromatin
L> Facultative?
L> more variable depending on cell type or its stage....specialized proteins
L> not always transcribed ex seminal vesicles
