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MBG*2040 > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

What are parasexual processes?

A

The transfer of genetic material without meiosis.

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2
Q

What are the three parasexual processes that occur in bacterial gene transfer?

A

Conjugation

Transformation

Transduction

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3
Q

How has bacteria and viruses made important contributions in the science of genetics?

A
  • Understand the characteristics and definitions of a gene.
  • Understand the basic principles of inheritance
    _ Understood the first evidence of gene interactions.
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4
Q

Why are bacteria valuable research objects?

A

1.) Small
2.) Rapid Reproduction
3.) Genetic Variability
4.) Simple structures and physiology
5.) Selective media (antibiotic resistance)

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5
Q

How are bacteria simple structures?

A

Bacteria are simple structures as they have one allele

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6
Q

What are bacterial viruses called?

A

Bacteriophages

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7
Q

How do bacteriophages replicate?

A

They replicate by infecting a bacterial cell and relying on the host to replicate genome.

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8
Q

What are the two cycles that a bacteriophage can enter?

A

Lytic or Lysogenic

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9
Q

What are some examples of a lysogenic virus?

A

HIV (AIDS), Herpes which can remain dormant in your body for your whole life (hence, why HIV is not curable)

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10
Q

How can bacteria grow in a liquid or solid medium?

A

You are always starting off with a sterile liquid media, then inoculating bacteria into the medium and then watch the bacteria grow and divide.

Put the bacteria onto a Petri dish with gelatin agar on it and spread evenly. Burn off any aerosols with Bunsen burner. After a few days, you will see the bacteria multiplying and forming into visible colonies.

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11
Q

How do you know if your bacteria has been accurately made?

A

If it is opaque.

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12
Q

What do bacteriphages produce on a Petri dish?

A

They produce clearances (plaques) on plates with dense bacterial cultures within hours of infection

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13
Q

What are some characteristics of a T4 Bacteriophage

A
  • Protein Head
  • 168,00 base pairs and 150 characterised genes
  • Fairly large and complex genome
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14
Q

What phase does the T4 bacteriophage only enter?

A

The lytic phase where it lyses the cell to infect other cells

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15
Q

What are some Characteristics of the Lambda Bacteriophage?

A

50 genes and 48,000 base pairs

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16
Q

What phases does the Lambda bacteriophage enter?

A

It can enter the lytic phase (lyses the cell like T4) or it can enter into the lysogenic phase (where it inserts its DNA into the host and goes into latency)

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17
Q

What is a Retrovirus?

A

A virus that uses RNA as its genetic material

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18
Q

What do RNA genomes require in regards to mutations?

A

Requires a higher number of mutations and can adapt more quickly to host.

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19
Q

What is Reverse Transcriptase?

A

An enzyme; the viruses has to have its own way of reversing transcription of original host to make complementary DNA and viral RNA degrades.

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20
Q

What is cDNA?

A

Complementary DNA (cDNA) is DNA that was reverse transcribed (via reverse transcriptase) from an RNA

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21
Q

What does bacteria’s DNA look like?

A

Most bacteria have a haploid genome, a single chromosome consisting of a circular, double stranded DNA molecule.

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22
Q

What is the Lambda phage called in its integrated state (during replication?)

A

During replication, the lambda phage is in its most integrated state and the phage turns into a prophage, where its lytic genes are kept off.

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23
Q

What way does Gene Transfer in always go?

A

It is unidirectional, which means it goes from donor to host cell.

24
Q

Where does additional genetic material arise in for bacteria?

A

The plasmids: small circular DNA

25
Q

What are episomes?

A

Episomes are large circular DNA that can integrate into the bacterial chromosome for replication.

26
Q

What does bacteria not do?

A

They do not undergo meiosis, therefore can not have a chiasmata.

27
Q

What does an Ecoli colony look like?

A

Very small and scattered (tiny blue and white dots)

28
Q

What does Serratia Marcencens look like?

A

Red, large dots.

29
Q

What does a bacterial colony that grows only the supplemented medium have?

A

A mutation in the gene that encodes the synthesis of an essential nutrient.

30
Q

What is Conjugation?

A

Direct transfer of DNA from one cell to the other via the establishment of a cytoplasmic bridge.

31
Q

What is Transformation?

A

The transfer of free DNA (out of the cell) from one bacterium to another.

32
Q

What is Transduction?

A

Transfer of genes from one cell to another via bacteriophage.

33
Q

Which Parasexual Process is cell-cell contact required?

A

In conjugation only

34
Q

Which parasexual process is sensitive to DNAase?

A

Transformation as it is the only process where the DNA sees the external environment

35
Q

What is DNAase?

A

An enzyme that chops up bacteria.

36
Q

What did the U-Tube Experiment identify?

A

The 3 Ways of Parasexual Gene Transfer and that Genetic Exchange requires the direct contact between cells.

37
Q

What does Competent bacteria do?

A

Bind exogenous DNA and transport it into the cell.

38
Q

What is the percentage of the entire bacterial population that undergoes transformation?

A

About 0.2 - 0.5%

39
Q

What is transformation measured as?

A

Measured as a change in phenotype (i.e, going a+ to a-, b+ to b-) or vice versa and this occurs with a certain frequency

40
Q

What would be a transformed cell?

A

One in which a phenotypical change took place (example wild type to recessive our vice versa)

41
Q

What was the conclusion about cotransformations?

A

The rate of cotransformations is inversely proportional to the distance between genes.

42
Q

Why in the example of transformation did we never get C+ A+ B- or C+ B+ A- within the same transformed cell?

A

Because A and c and B and C are extremely far apart on the chromosome

43
Q

What type of reproduction would Conjugation be seen as?

A

“Sexual” reproduction, in which there is dirt contact

44
Q

What is Conjugation mediated by?

A

F - the “fertility factor” - an episome

45
Q

What can the F factor exist as?

A

An extra chromosomal DNA or it can insert into the bacterial chromosome and replicate as part of it.

46
Q

What is F-

A

Always the recipient cell in conjugation, that does not have the fertility factor.

47
Q

What is the HFr cell?

A

The F factor integrated into the F- factor.

A high frequency of recombination cell.

48
Q

What pulls the cells together to make conjugation bridge?

A

Pilus

49
Q

What is the F+ Cell Always?

A

The donor cell

50
Q

What is the F- cell Always?

A

The recipient cell

51
Q

What does replication of F factor always occur in?

A

Both the donor and the recipient cell during transfer

52
Q

Conjugation between an F+ cell and an F- cell usually result between which of the following?

A

Two F+ Cells

53
Q

What is a plasma considered?

A

A extra-chromosomal circular piece of DNA that can replicate independly of the chromosome and is not needed for the survival of the host cell.

54
Q

What is a R plasmid?

A

A resistance plasmid

55
Q

Is an episome essential for the host?

A

No. It an be replicated autosomal or be integrated into the bacterial chromosome.

56
Q

What is the conclusion about the ability to be cotransduced?

A

Genes locate close to one another are more likely to be cotransduced; so the rate of cotransduction is inversely proportional to the distance between genes

57
Q
A

MBG*2040 (26 decks)

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