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Alex's Genetics > Lecture 16a > Flashcards

Lecture 16a Flashcards

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Biology 101 flashcards
1
Q

What is the germ line?

A

Cell lineage that produces the gametes (ex: sperm or egg in mammals).

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2
Q

What types of engineering or mutations will be passed on to offspring?

A

Only GENOME engineering or other mutations that affect the GERM LINE will be passed on to offspring.

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3
Q

What do somatic cell lineages do? What can they not do?

A

Somatic cell lineages contribute to the body of the organism. These are the rest of the cells in the body besides germ cells.

However, these cells do NOT produce gametes.

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4
Q

What has iPS technology allowed for with male somatic cells?

A

We can take male somatic cells and turn them into iPS cells, get rid of the Y chromosome, and then obtain oocytes.

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5
Q

Where is the bacterial chromosome found?

A

In the nucleoid of the cell

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6
Q

T/F: The nucleoid is bound by a membrane.

A

False! The nucleoid is NOT bounded by membrane.

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7
Q

What is the DNA in a bacterial chromosome in direct contact with?

A

The cytoplasm. This is because the nucleoid is not bound by a membrane.

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8
Q

Bacterial chromosomal DNA is compacted about __________-fold.

A

Bacterial chromosomal DNA is compacted about 1000-fold.

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9
Q

What are two ways that help to compact bacterial chromosomal DNA?

A

1) The formation of loop domains
2) DNA supercoiling

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10
Q

What is DNA supercoiling performed by?

A

DNA gyrase a.k.a. DNA topoisomerase

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11
Q

How does DNA gyrase produce negative supercoils?

A

DNA gyrase uses ATP to introduce negative supercoils.

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12
Q

What are topoisomers described as?

A

The same rubber band in every way but differing in the number of supercoils.

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13
Q

T/F: Positive and negative supercoiling are in the SAME directions.

A

False! Positive and negative supercoiling are in opposite directions.

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14
Q

T/F: Chromosome function is NOT influenced by DNA supercoiling.

A

False! Chromosome function is influenced by DNA supercoiling.

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15
Q

Is the chromosomal DNA in bacteria positively or negatively supercoiled?

A

Negatively supercoiled.

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16
Q

In ___________, there is _______ _____________ supercoil per ____ turns of the double helix.

A

In E. coli, there is one negative supercoil per 40 turns of the double helix.

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17
Q

What are the two major effects of negative supercoiling?

A

1) Helps in the compaction of the chromosome, which is important for cell division.
2) Creates tension that may be released by DNA strand separation.

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18
Q

In ___________, people discovered Simple Transposons.

A

bacteria

19
Q

What are simple transposons?

A

These are DNA sequences that can excise themselves from a chromosome and insert themselves elsewhere.

20
Q

What catalyzes the excision and insertion in simple transposons?

A

An enzyme called Tranposase.

21
Q

In simple transposons, they are in the ___________ direction and are ___________ at both ends of the element.

A

direction, repeated

22
Q

What is a composite transposon?

A

When two simple transposons combine.

23
Q

T/F: Antiobiotic-resistance genes are not advantageous for bacteria.

A

False! Antiobiotic resistance genes confer a selective advantage for bacteria.

24
Q

How are composite transposons created?

A

Created by 2 transposons flanking an additional sequence and behaving as one transposon. One transposon gene/sequence may then be lost turning them into obligate composite transposons.

25
Q

What is the best understood bacterial plasmid?

A

The E. coli F factor

26
Q

What are replicative transposons?

A

These keep the original copy while generating a new one.

27
Q

What is the process of creating replicative transposons called?

A

Replicative transposition

28
Q

What is a cointegrant?

A

This is a large circular chromosome with 2 single-stranded transposable elements.

29
Q

T/F: Replicative transposons cannot give rise to any other transposon.

A

False! Replicative transposons can also give rise to composite transposons.

30
Q

Composite transposons contain ____________ genes that are _____ _________________ for transposition per se.

A

additional, not necessary

31
Q

What is retrotransposition? What are the transposons called?

A

Replicative transposition via an RNA intermediate.

The transposons are called retrotransposons or retroelements.

32
Q

T/F: Retrotransposition is only found in prokaryotes.

A

False! Retrotransposition is very common but it is only found in eukaryotes.

33
Q

Retroelements use an ____ ___________ in their transposition mechanism.

A

RNA intermediate

34
Q

What two enzymes are critical for moving retroelements?

A

Reverse transcriptase and integrase.

35
Q

T/F: Bacterial chromosomes take up a LOT of space in the cell.

A

False! Bacterial chromosomes occupy a limited amount of space in the cell.

36
Q

What is binary fission?

A

This is the process by which bacterial replication occurs.

37
Q

How is bacterial chromosomes’ structure similar to eukaryotic? What is different?

A

They are similar in that they both are organized into loop domains.

Bacterial chromosomes are not chromatin though.

38
Q

How are Topoismers named base on?

A

Based on the number of supercoils present.

39
Q

How does DNA supercoiling help with DNA strand separation?

A

DNA supercoiling helps proteins to separate DNA strand separation due to tension. RNA polymerase can then separate DNA by itself due to this supercoiling.

40
Q

In a composite transposon, what inverted repeats are involved in the transposition event?

A

Only the two inverted repeats at the end of the transposon are involved in the transposition event.

41
Q

Describe what can happen with transposons and plasmids. Why can this be bad?

A

One bacteria can carry a plasmid with a transposable element and transfer this element/plasmid to another bacterial cell. This can be bad for humans if there are antibiotic resistance genes present.

42
Q

Describe the process of replicative transposition.

A

1) There are two plasmids/chromosomes. One has a transposable element and the other does not, so it has a target DNA.
2) Transposase cuts single-strandedly at the end of the transposable element and on the target DNA.
3) Strands between plasmids/chromosomes are exchanged and ligated together.
4) Gaps are filled in by DNA polymerase and sealed by DNA ligase to produce a cointegrant.
5) Resolve catalyzes recombination between the 2 and makes them 2 separate structures, each with a transposable element.

43
Q

If the transposon encodes a protein for site-specific recombination, what is this protein called?

A

Resolvase

44
Q

What are two types of recombination transposons use to make 2 separate structures?

A

Site-specific recombination and homologous recombination.

Alex's Genetics (38 decks)

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