Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BI1051: Genetics and Evolution > Prokaryote and Extra-chromosomal Genetics > Flashcards

Prokaryote and Extra-chromosomal Genetics Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

How is a prokaryotic chromosome stored within the cell?

A

As a nucleoid (non-compartmentalised).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How many chromosomes do prokaryotes typically have?

A

One.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do prokaryotic chromosomes compare in terms of size?

A

Much smaller.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the shape of prokaryotic chromosomes.

A

Circular.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How are aggregates of cells produced?

A

Via binary fission.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define the term prokaryotic genetics.

A

Constant segregation and assortment of genetic information via cellular level gene transfer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define the term plasmid.

A

An extra-chromosomal circle of DNA containing non-essential genes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What genetic information is stored on plasmids?

A

Genes allowing replication/segregation of the plasmid.

Genes that confer auxiliary metabolic pathways.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How many origins of replication do prokaryotic chromosomes have?

A

Usually one.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define the term conjugate plasmid.

A

A plasmid containing genes that allow the plasmid to transfer a copy of itself to another cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the name given to genes that allow conjugation?

A

Transfer genes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are plasmid - strains?

A

Cells lacking a specific conjugative plasmid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are plasmid + strains?

A

Cells possessing a specific conjugative plasmid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do tra genes encode?

A

Proteins called pilins that extrude from the cell to form pili.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where are tra genes found?

A

On plasmids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do pili function?

A

They recognise and adhere to the plasmid to form a channel between cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are transposable elements?

A

Mobile DNA sequences that are able to jump from one location to another within a cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are inverted repeats?

A

Flanking identical short DNA sequences.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do transposase enzymes recognise?

A

Inverted repeats.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What do transposase enzymes do?

A

Catalyse transposition.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the simplest transposable elements?

A

Insertion sequences.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What genes do insertion sequences contain?

A

tnp genes which encode for transposases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Define the process of replicative transposition.

A

Creating a new copy of the transposable element.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Define the process of non-replicative transposition.

A

A transposable element jumping from one position to another.

25
Q

How are transposable elements “selfish gene” parasites?

A

They proliferate throughout the genome by jumping between/within chromosomal and plasmid locations.

26
Q

How is a transposon formed?

A

Two insertion sequences flank a gene which disrupts the normal function of transposases.

27
Q

Define the term transposon.

A

A transposable element carrying extra genes.

28
Q

How do transposons get transferred between chromosomes and plasmids?

A

Transposases have no specific DNA target.

29
Q

How can genes on a chromosome be transferred between cells?

A

The genes could become part of a transposon and then become incorporated into the plasmid. This plasmid can then be transferred to other cells via conjugation.

30
Q

What happens when there is no selection for a plasmid?

A

A mixed population will be formed: some cells will have the plasmid, some won’t.

31
Q

What happens when selection for a plasmid occurs?

A

Those with the advantageous plasmid survive and spread the plasmid within the population.

32
Q

What is meant when a pilus is described as promiscuous?

A

It means that it has the potential for conjugation between species.

33
Q

What is a reciprocal strand exchange?

A

Homologous recombination between a chromosome and plasmid as a result of the two aligning because of identical genes.

34
Q

What is sometimes formed from reciprocal strand exchange?

A

A co-integrated molecule (the chromosome and plasmid combine).

35
Q

What is meant by plasmid excision?

A

The plasmid separating from the co-integrated molecule. Opposite of reciprocal strand exchange.

36
Q

Define the term episomal plasmid.

A

A plasmid with sequences homologous to a host cell

chromosome, capable of reversible integration and excision.

37
Q

Define the process of transduction.

A

The transfer of genes via viral transfer as a result of incorporating sections of the host genome.

38
Q

Define the process of transformation.

A

The deliberate uptake of DNA from the external environment and its incorporation into the host cell chromosome.

39
Q

What is the term given to the ability to take up DNA?

A

Competence.

40
Q

Eukaryotic gene transmission is vertical. How do prokaryotes compare?

A

Gene transmission in prokaryotes can be both vertical and horizontal.

41
Q

Define vertical gene transmission (VGT).

A

Transfer of genetic information down a lineage (generation to generation)

42
Q

Define horizontal gene transmission (HGT).

A

Transfer of genetic information between lineages (between living cells).

43
Q

What processes allow horizontal gene transmission (HGT) in prokaryotes?

A

Conjugation, transduction and transformation.

44
Q

Define the mobilome.

A

The genetic material that can actively move within a genome and between individuals.

45
Q

What could be classed as part of the mobilome?

A

Plasmids, transposons, DNA transduced by viruses and DNA in the environment.

46
Q

How is horizontal gene transfer restricted (HGT)?

A

Conjugation is generally limited to one species.
Cells have mechanisms to select DNA.
Prokaryotes have immune systems to destroy foreign DNA.

47
Q

What is quorum sensing?

A

A form of HGT prevention. The cell only becomes competent when it senses other similar cells growing nearby.

48
Q

Why do prokaryotes often contain restriction endonucleases?

A

They cleave foreign DNA in order to prevent the cell being harmed.

49
Q

How is host cell DNA protected from restriction endonucleases?

A

Host DNA is modified by DNA methylase so isn’t recognised.

50
Q

Where do the organelles and cytoplasm originate from in a eukaryotic cell?

A

From the maternal gamete.

51
Q

What shape are mitochondrial chromosomes?

A

Circular.

52
Q

What shape are chloroplast chromosomes?

A

Circular.

53
Q

What are the evolutionary origins of mitochondria and chloroplasts?

A

They were originally bacteria that entered into

a symbiotic relationship with archaeal-like cells.

54
Q

Why do maternally-inherited organelle traits show phenotypic variability?

A

Variability in the number of mitochondrial chromosomes in each mitochondrion.

55
Q

What is one technique that can be used to avoid maternally inherited diseases?

A

“3 parent” IVF combined with transplant of healthy mitochondria.

56
Q

What is Wolbachia?

A

An alpha-proteobacteria that is an endosymbiont in

arthropod and nematode cells.

57
Q

How are Wolbachia cells transmitted?

A

Maternally via egg cell cytoplasm.

58
Q

How does Wolbachia proliferate?

A

It increases the proportion of females as it is passed on maternally.

BI1051: Genetics and Evolution (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions