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Microbiology PMY 3 > Week 2-genetic Differences Between Prokaryotes And Eukaryotes > Flashcards

Week 2-genetic Differences Between Prokaryotes And Eukaryotes Flashcards

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1
Q

Differentiate gene arrangement between eukaryotes and prokaryotes

A

Eukaryotes- genes are scattered or exist as multi gene families

Prokaryotes- genes usually arranged as operons

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2
Q

Differentiate initiator tRNA between eukaryotes and prokaryotes

A

Eukaryotes- methionine

Archea- methionine

Bacteria- formyl methionine

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3
Q

Differentiate between eukaryotes and prokaryotes, the presence of introns

A

Introns exist in. Eukaryotes and Archea but nit bacteria

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4
Q

Differentiate between eukaryotes and prokaryotes the presence of histones

A

Histones exist in muffler chromosomes in eukaryotes, some species of Archea but not in bacteria

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5
Q

Differentiate between eukaryotes and prokaryotes, polyploidy

A

Eukaryotes and Archea are polyploidy but not bacteria

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6
Q

Differentiate between eukaryotes and prokaryotes ribosomal subunits

A

80s(60s and 40s) in eukaryotes but 70s(30s and 50s)

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7
Q

Differentiate between eukaryotes and prokaryotes, survival above 80 degrees Celsius

A

Eukaryotes cannot survive, but Archea will(some over 100 degrees Celsius) and bacteria also

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8
Q

Differentiate between prokaryotes and eukaryotes genome size, MB

A

Eukaryotes- large(10-100000 um)

Archea - small(0.5-5um)

B@cteria- small(0.6-10um)

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9
Q

Differentiate cell wall/peptidoglycan between eukaryotes and prokaryotes

A
  • Eukaryotes have no cell wall( cellulose/chitin)
  • Archea- no(psuedo-peptidoglycan)
  • Bacteria has a peptidoglycan cell wall
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10
Q

Differentiate between prokaryotes and eukaryotic in terms of genes per MB

A

Eukaryotes-human,11 genes/MB

Prokaryotes- Approximately 900 genes /Mb

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11
Q

Differentiate between prokaryotes and eukaryotes the chromosomes

A

Eukaryotes- linear- many copies

Archea and bacteria- mostly single circular copies

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12
Q

Describe prokaryotic cell cycles

A

Fast cell cycles permit new mutations to be quickly generated and stabilized in the progeny

This improves the overall genetic pool
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13
Q

Discuss the prokaryotic genome

A

Prokaryotes are haploid, have no recessive or dominant genes

Bacterial genome use the universal genetic triplet codons but may have various amino acids as a result of different preferences

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14
Q

Given there are no recessive/dominant genres in prokaryotes, describe One method of genetic diversity

A

Horizontal gene transfer in one of the mechanisms to introduce diversity and boosts survival in hostile environments

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15
Q

Differentiate the Nucleic acid in prokaryotes and eukaryotes

A

Nucleic acid- eukaryotes- linear dsDNA in nucleus and chloroplasts, circular dsDNA in mitochondria and plasmids

Archea- circular dsDNA

Bacteria - circular or linear dsDNA

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16
Q

Differentiate between prokaryotes and eukaryotes the presence of plasmids

A

Eukaryotes- in some algae, fungi and Protozoa

Archea- in some cells

Bacteria- yes, in some cells frequently more than one cell

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17
Q

How much bacteria have ONE Circular chromosome?

A

90% of bacteria

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18
Q

How much bacteria have 2 circular chromosomes ?

A

A few bacteria have 2 circular chromosomes

Brucella sp.

Burkholderia mallei

Burkholderia pseudomallei

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19
Q

How much bacteria have linear chromosomes?

A

Some bacteria: Borrelia sp.

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20
Q

What are replicons?

A
  • Genetic piece that contains all the necessary elements to replicate on its own
  • All prokaryotic replicons have single replication start site known as origin(ori)
    • exception: some Archea May have 2 or 3 ori sites
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21
Q

What are plasmids ?

A

-Replicons that comes for genes that are non-essential for basic cell growth but can can provide survival advantage

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22
Q

What are episomes?

A

-Plasmids with ability to integrate in the chromosome and replicate as part of it

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23
Q

How do similar plasmids interact within the same cell?

A

Similar plasmids are incompatible with each other and cannot be maintained in same cell

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24
Q

Some bacterial genomes contain about _______% of the DNA in the form of plasmids

A

20

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25
Q

How much plasmids are there in every cell?

A

Number of plasmids in every cell varies from 1-3 to hundreds of copies

 -depends on the ori type and the plasmid size
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26
Q

How do plasmids confer survival advantage?

A
  • F factor
  • R factor
  • Virulence factor
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27
Q

What are the types of plasmids?

A
  • R plasmids
  • Col plasmids
  • F-plasmids(fertility factors)
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28
Q

What are the functions of R plasmids ?

A

Code for antibiotic resistance genes

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29
Q

What are the functions of Col plasmids?

A

Code for toxins which kill other bacteria known as Colicins

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30
Q

What are the functions of F-plasmids(fertility factors)?

A

Facilitates transfer of genetic material from cell to cell via conjugation

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31
Q

Explain the R plasmid

A

Resistance transfer factors (RTFs)

Contains genes for conjugation and replication

Has multiple r determinants
Tc, tetracycline
Kan, kanamycin
Hg, Mercury

32
Q

What are tra genes?

A

A set of genes that control the transfer of plasmids between different organisms

33
Q

What are virulence factors?

A

Responsible for bacterial pathogenicity and enable a bacteria to replicate and disseminate within a host in part by subverting or eluding host defenses

34
Q

What carries virulence factors?

A

They are carried by chromosomes, plasmids, bacteriophages or other genetic elements such as transposons

35
Q

When and who discovered transposons?

A

Discovered by Barbara McClintock in 1940

36
Q

All transposons have a specific __________ _________

A

Recombinase: transposase

37
Q

Distinguish between transposons and replicons

A

They are not replicons, they are missing the genes for replication and ori element

38
Q

What is a requirement for transposons to replicate?

A

They MUST be integrated into a replicon in order to replicate

 -chromosome or plasmid
39
Q

What is the purpose of transposase?

A

Transposase catalysts the movement by either a cut and paste mechanism or by a replicative transposition mechanism

-They “ hop” from one site to another by replication and recombination
  • Insertions can be in the same or different replicon
    - Chromosome or plasmid
40
Q

Describe transposons structure

A
  • variable in size- usually in the range of several kilobases
  • insertion sequence elements-( IS elements) have insertion sequences at both ends
  • Different genes that give advantage to the bacteria in certain conditions
  • transposase are responsible are responsible for transposition
41
Q

What are insertion sequences?

A

Segments of bacterial DNA that can move from one position on a chromosome to a different position on the same chromosome or on a different chromosome

42
Q

Both the _____________ ___________ And __________ are essential for transposition

A

Inverted repeats

Transposase

43
Q

What are the 2 type of transposition?

A
  • conservative

- Replication

44
Q

Describe DNA replication in prokaryotes and eukaryotes and differentiate their points of origin

A

DNA replication is bidirectional- where replication is moving along both directions of the starting point

Prokaryotes- have ONE origin of replication

Eukaryotes- have MULTIPLE origins of replication

45
Q

What is the most abundant RNA?

A

rRNA

46
Q

What are the functions of rRNA?

A
  • rRNA are used as a structural component of the cell

- rRNA associates with ribosomal proteins to form complete structural proteins

47
Q

Note the structure of rRNA

A

rRNA are arranged into two distinct ribosomal pieces of different size, known generally as the large and small subunit of the ribosome

48
Q

Describe the prokaryotic ribosomal RNA

A

Prokaryotic ribosomal units

  • 30s and 50s (Svedberg units) ribisomal subunits
  • join during protein synthesis to form 70s ribosome
49
Q

Highlight the use of 16s rRNA from small 30s prokaryotic ribosomal subunit

A

The 16s rRNA from the small 30s prokaryotic ribosomal subunit recognizes the Shine—Dalgarno sequence of the mRNA

-use of 16s rRNA gene sequences to study bacterial phylogeny and taxonomy is the most common housekeeping genetic marker used for various reasons

50
Q

Why is rRNA gene sequences to study bacterial phylogeny and taxonomy the most common housekeeping genetic marker used?

A
  1. The presence in almost all bacteria, often existing as a multi gene family, or operons
  2. The function of the 16s rRNA gene over time has nit changed, suggesting that random sequence changes are a more accurate measure of time/ evolution
  3. The 16s rRNA gene (1,500 bp) is large enough for informatics purposes
51
Q

Highlight the structure of eukaryotic ribosomal RNA

A
  • 60s and 40s (Svedberg units) ribosomal units

- They join during protein synthesis to form 80s ribosome

52
Q

Why is the 40s eukaryotic small ribosome small?

A

The 40s subunit (containing 18s rRNA) recognizes the the 7-methylguanosine cap on the eukaryotic mRNA

53
Q

Differentiate the sizes of ribosomal RNA size in eukaryotes and prokaryotes

A

Prokaryotic- 70s

Eukaryotic- 80s

54
Q

Differentiate the small subunits of rRNA in prokaryotic and eukaryotic cells

A

Prokaryotic- 30s: contains 16s associated with ribosomal proteins

Eukaryotic- 40s: contains 18s rRNAs combined with ribosomal proteins

55
Q

Differentiate the large subunit of rRNA between eukaryotes and prokaryotes

A

Prokaryotes: 50s contains 5s and 23s rRNAs associated with ribosomal proteins

Eukaryotes: 60s contains 5s, 5.8s and 28s rRNAs co,pleaded with ribosomal proteins

56
Q

What is an operon?

A

A group of metabolically related genes that are co-expressed under the same

- operator
- promoter
57
Q

Explain operons being comprised of multiple genes

A
  • controlled as a unit to produce single mRNA

- used for metabolic reactions of the same pathway

58
Q

How much of E. coli genome is composed of operons?

A

27% of E, coli genome is composed of 600 operons

59
Q

State what is polycistronic mRNA synthesis

A

Bacterial regulation occurs at a transcriptional level by controlling a couple of related genes in a single operon

60
Q

Is eukaryotic mRNA monocistronic?

A

Typically eukaryotic is mRNA is monocistronic but some eukaryotes contain operons and undergoes polycistronic translation

61
Q

Describe the discovery of Francois Jacob and Jacque Monod in 1962

A

The Lac operon in E. coli- the first thoroughly characterized gene regulation system by Francis Jacob and Jacque Monod

62
Q

What is a Regulon?

A

When a single event triggers a coordinated expression of different operons

E.g. maltose regulation

63
Q

What are the structural genes that make up the Lac operon structure?

A

Z gene

Y gene

A gene

64
Q

What is the Z gene of the Lac operon structure?

A

Z gene- structural gene for B-galactosidase- breaks down the lactose

65
Q

What is the Y gene of the Lac operon structure?

A

Y gene- Structural gene for B-galactosidase permease - allows lactose to enter the cell easier

66
Q

Describe the Lac operon structure as a start sequence

A
  • regulator region-start sequence
  • Controls the expression (next to the structural gene)- DNA polymerase binds to start transcribing the gene

Promoter (P)- set of sequences where RNA polymerase binds

Operator(O)- if open RNA polymerase will transcribe all the DNA to RNA

67
Q

What is a promoter in the Lac operon structure?

A

Promoter (P)- set of sequences where RNA polymerase binds

68
Q

What is an operator in the Lac operon structure?

A

Operator(O)- if open RNA polymerase will transcribe all the DNA to RNA

69
Q

What is the A gene of the Lac operon structure?

A

Structural gene for B-galactosidase transacetylace-keeps lactose in the cell

70
Q

What is the function of the I gene?

A

I gene -codes for a rep press or protein (regulatory gene)

  • Not part of the operon- far away from the operon
  • Can block the polymerase from acting by binding to the operator
  • regulatory gene
71
Q

Lac operon can be under BOTH ____________ and ______________ control

A

Positive

Negative

72
Q

What is the negative control?

A

If lactose is available it can bind to the repressor molecule and blocks it from binding to the operator, so it comes off from the operator.

Now the gene is ready to be transcribed. Turned off until the cell needs to transcribe the lactose genes

73
Q

What is positive regulation?

A

When glucose is high, cAMP is low

When the cell runs out of glucose the cAMP goes up and binds to a protein that is a positive regulator

This positive regulator sets into the promoter sequence and that helps the promoter binds to the RNA polymerase(boosts transcription)

74
Q

How is a premature mRNA converted into a mature one?

A

Exons and introns are transcribed into a single pre-mRNA which is followed by the removal of introns(splicing) before the mature mRNA leaves the nucleus

The mature mRNA is translated in the cytoplasm by eukaryotic ribosomes

75
Q

Describe eukaryotic mRNA and differe it’s polyadenylation tail with prokaryotic mRNA

A
  • 5’ cap structure ( RNA-7-methyl-guanosine

- Longer polyadenylation tail : 100-200 NT vs 15-60 NT in only 2-60% of prokaryotic mRNA species

Microbiology PMY 3 (24 decks)

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