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asdfghjmak 2 > P1 L1 > Flashcards

P1 L1 Flashcards

1
Q

What does forward/classical genetics seek to find?

A

The genetic basis of a phenotype or trait

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2
Q

How is phenotype defined in classical genetics?

A

It is the appearance of an individual or the manifestation of a particular genotype

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3
Q

What is the definition of genotype?

A

It is the specific composition of the genetic information

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4
Q

What is the main goal of classical genetics?

A

To isolate and analyze mutants to understand changes in DNA

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5
Q

What does reverse/molecular genetics seek to find?

A

What phenotypes arise from particular genetic sequences

Gene mutated -> Returned to Organism -> Observe Phenotype

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6
Q

What are the advantages of working with bacteria?

A
  1. easy to grow and manipulate
  2. haploid
  3. asexual reproduction
  4. clones can be isolated on agar plates
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7
Q

Define haploid and explain the advantage

A

one copy or allele of each gene - easier to identify mutations

only have one chromosome, also called a nucleoid.

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8
Q

Screening vs selection

A

Screening: shows different phenotypes
Selection: allows only one specific phenotype to grow.

Screening identifies resistant bacteria, while selection isolates rare mutants

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9
Q

What are bacteriophages?

A

Viruses that infect bacteria
This makes it possible to move DNA between bacteria

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10
Q

Gregor Mendel has:

A

a) showed that hereditary traits do not occur in random proportions in the offspring
b) carried out crossing experiments on pea plants

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11
Q

Johannes Friedrich Miescher

A

The chemistry of the nucleus.
He isolated phosphate-rich structures (nuclein) that are known today as nucleic acids.

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12
Q

Phoebus Levene

A

-> The chemical composition of nucleic acid.
“DNA is too simple to code genes”
He assumed that the proteins carry the genetic information

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13
Q

What are the 3 components of DNA?

A

Base + sugar + phosphate
(genetic information + structure and backbone)

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14
Q

DNA vs RNA

A

clockwise double helix

Sugar:
Desoxyribose vs Ribose

Bases:
[Adenine, Guanine, (purine)] [Thymin, Cystosin (pyramine)] vs
[Adenine, Guanine,] [Uracil, Cytosin]

Nucleoside:
dAdenosine, dGuanosine, dThymidine, dCytodine vs
aenosine, guanosine, uridine, cytadine

Nucleotide: (sugar + base)
dAMP, dGMP, dTMP, dCMP vs
AMP, GMP, UMP, TMP

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15
Q

DNA/RNA Pairing

A

A-T/U
C-G

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16
Q

What is the difference between DNA and RNA?

A

DNA contains thymine, while RNA contains uracil; DNA has deoxyribose, RNA has ribose

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17
Q

What is the significance of the 5’ and 3’ ends of a nucleotide chain?

A

They indicate the polarity of the strand, with 5’ being the phosphate end and 3’ being the hydroxyl end

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18
Q

Frederick Griffith’s research?


A

He studied/demonstrated bacterial transformation and the epidemiology of bacterial pneumonia with mice

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19
Q

What characteristic does the S-strain and R-strain of Streptococcus pneumoniae have?

A

S-strain: It has a polysaccharide capsule and is virulent
R-strain: strain has no capsule and is non-virulent

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20
Q

What did Griffith conclude about the transformation factor?

A

It was passed from the heat-inactivated S-strain to the living R-strain - mouse died

r - lives
s - dies
s inactivated - lives
s inactivated + r - dies ^^

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21
Q

Oswald Avery Findings

A

If the DNA is destroyed, the S-strain cannot be reactivated and the mouse remains alive. He discovered this through selection and tested this with other destroyed parts of the cell (e.g. proteins, RNA, lipids, etc.).

DNA = genetic information

22
Q

Erwin Chargaff contributions to the understanding of DNA?

A

He discovered the base pairing rules in DNA

23
Q

What is the structure of DNA as proposed by Watson and Crick?

A

A double helix with antiparallel complimentary strands

24
Q

What are the dimensions of a DNA in nm and per 10 base pairs?

A

Diameter: 2 nm
One turn: 3.4 nm (10 base pairs)
minor groove: 1.2 nm
major groove: 2.2 nm

1A = 0.1nm

25
Q

Why are the major and minor grooves in DNA important?

A

They provide access for proteins to interact with specific DNA sequences

26
Q

How must the bases be on the inside and the phosphate group on the outside?

A

Because of the repulsion / hydrophobic interactions between bases

27
Q

What is the significance of the complementary nature of DNA strands?

A

The sequence of one strand provides information about the other strand

28
Q

What is the importance of the antiparallel nature of DNA strands in replication and transcription?

A

It allows for the proper base pairing and directionality during replication and transcription

29
Q

What are the predictions made by Watson and Crick regarding DNA?

A

-Duplication of DNA (Replication)
-Coding of genetic information by meaningful sequences (genetic code)
-Formation of mutations due to incorrect base pairing (tautomeric forms)

30
Q

Why is it important that the hydrogen bonds of the base pairing are so weak?

A

So that the double strand can be split more easily into the 2 single strands for both reading and replication of DNA

31
Q

What is a chromosome?

A

A chromosome is a long continuous strand of DNA that is wound as a double helix and contains all essential genetic information

32
Q

What are the 2 functions of the genome?

A
  1. replication -> It serves as a template
  2. expression -> It serves as storage
33
Q

What is the average length of a bacterial gene?

A

About 1000 bp long

34
Q

What are the mechanisms to compact DNA?

A

-(Negative) supercoils
-Histone proteins
-SMC proteins (Structural Maintenance of Chromosomes)

The DNA is either wrapped around itself or around the proteins. -> Supercoils

35
Q

What is the relaxed state of double-stranded DNA?

A

Two strands are wrapped around each other once every 10.5 bp

36
Q

How are supercoils created?

A

Through over- and under winding the DNA

37
Q

Positive supercoiled

A

> 1 turn per 10.5 bp
< 10 base pairs per turn
- through the activation of the replication fork

38
Q

Negative supercoiled

A

< 1 turn per 10.5 bp
> 10 base pairs per turn
- through Gyrase

39
Q

What happens to DNA during replication in terms of supercoiling?

A

Positive supercoiling occurs in non-replicated regions
negative supercoiling occurs in region that was just replicated

40
Q

What is the function of topoisomerases?

A

To regulate the overwinding or underwinding of DNA

41
Q

DNA>Process

A

Becomes overwound / positively supercoiled

42
Q

DNA<Process

A

underwound / negatively supercoiled

43
Q

What type of DNA break does Topoisomerase I create?

A

Single-strand breaks - removes negative supercoils

44
Q

What type of DNA break does Topoisomerase II create?

A

Double-strand breaks, energy dependant - ATP introduces superhelical structures

removes the positive supercoil

45
Q

How does negative supercoiling by gyrase work (5 steps)

A

A) Gyrase consists of the two subunits A and B
B. The DNA binds to the gyrase.
The DNA is now in subunit B and binds 2 ATP molecules
C. The G segment of the DNA is cut off and the T segment is transported through the gap. An ATP molecule is hydrolysed in the process.
D. The broken G segment is ligated and the 2nd ATP molecule is hydrolysed. The system returns to the initial situation.

46
Q

What needs to be considered for supercoiling by gyrase?

A

The process consumes ATP. It is a type 2 toposiomerase. It removes positive supercoils and introduces negative supercoiling

47
Q

How do quinolones affect gyrase activity?

A

Quinolones block the binding reaction of the gyrase. This leads to a lot of cells with double-strand breaks. These cells then die due to DNA damage.

48
Q

What is the primary, secondary and tertiary structure of DNA?

A

a) Primary: The sequence of bases
b) Secondary: The double helix
c) The condensed loop structure

49
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50
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51
Q
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52
Q
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asdfghjmak 2 (8 decks)

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