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Microbiology > Topic 7 - Microbial genetics > Flashcards

Topic 7 - Microbial genetics Flashcards

1
Q

What are: Genetics Genomes Genomics Chromosome Gene Genotype Phenotype

A
  • Genetic: study of what genes are, how genetics are expressed and how they are replicated - Genome: all genetic material in a cell - Genomics: molecular study of genomes - Chromosomes: carries hereditary information, in bacteria it is circular and humans linear. - Gene: DNA that carries a function or produces a functional product -Genotype: Genetic makeup of an organism (all genes) -Phenotype: the physcial expression of genes
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2
Q

What are the three categories for genes and functions?

A

Structural genes - code for proteins RNA - code for RNA Regulatory genes - control gene expression

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3
Q

What are the characteristic of eukaryotic chromosome?

A
  • Multiple and linear - Diploid
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4
Q

What are the characteristic of prokayotic chromosomes

A
  • Single and circular - Haploid - Looped and folded - Attached to one or several places to cell membrane
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5
Q

What is the difference between vertical and horizontal transmission?

A

Vertical transmission is between two generations of cells horizontal is within the same generation.

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6
Q

What kind of genetic transmission is portrayed here?

A

Vertical transmission as it is between two generations.

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7
Q

What are the propeties of DNA?

A
  • Double stranded
  • nucleotides
  • Strands held together by hydrogen bonds
  • phosphates are on the outside of the helix
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8
Q

Nucleotide properties?

A
  • 3 types:

deoxyribose (5 carbon sugar)

phosphate group

Nitrogenous bases (Adenine, guanine, cytosine and thymine).

  • Bond together to make sugar-phosphate backbone
  • Each sugar attaches to two phosphate
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9
Q

What does DNA polymerase do?

A

Copies DNA only from 5 -3 direction.

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10
Q

What is the difference between leading and lagging strands?

A

Leading - is synthesized by continously and only needs one RNA primer

Lagging - synthesized discontuniely and requires multiple RNA primers

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11
Q

What do RNA primers do?

A

Intitiate leading and lagging synthesize in DNA.

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12
Q

What are okazaki fragments?

A

Short fragments of DNA.

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13
Q

What are okazaki fragments used for?

A

RNA primers are removed and okazaki frgaments are then used to fill in the gaps by DNA polymerase.

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14
Q

What are some important enzymes for DNA?

A
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15
Q

What is the process of DNA replication?

A
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16
Q

What is semiconservavtive?

A

In DNA replication where each chromosome ends up with one new strand and one old one.

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17
Q

What are the nucleotides of RNA?

A
  • Uracil
  • Adenine
  • Cystocin
  • Guanine
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18
Q

What are the three main types if RNA’s?

A

mRNA- messeger

tRNA - transfer

rRNA - ribosomal

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19
Q

Why is DNA transcribed?

A

To make RNA which uses mRNA, rRNA, tRNA.

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20
Q

How does transcription begun?

A

RNA polymerase binds to promoter sequence.

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21
Q

What does the terminator sequence do?

A

It stops transcription.

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22
Q

What is the process of transcription?

A
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23
Q

What is the process of RNA processing in eukaryotes?

A
24
Q

What happens in translation?

A

mRNA is translated into into codons. mRNA begins at AUG and ends at UAA, UAG and UGA

25
Q

What is the process of translation?

A
  1. Ribosomes which need translation connect
  2. tRNA carries the first amino acid to the mRNA where it pairs with the start codon. A tRNA with the second amino acid approaches.
  3. The p-site is where the first amino acid is and the a-site is where the second one.
  4. First amino acid joins the second via peptide bond and the first tRNA is released.
  5. Process continous as second tRNA moves into the p-site.
  6. Ribosomes continue to move along mRNA and new amino acids are connected to polypeptide.
  7. Ribocome reaches the stop codon and polypeptide is released.
  8. tRNA is released and the ribosomes detach. Polypeptide makes a protein.
26
Q

What are operons?

A

These are gene regulators for when products are needed.

27
Q

What are constitutive and regulated enzymes?

A
  • Enzymes that are expressed at a fixed rate.
  • Regulated enzymes are only expressed when needed.
28
Q

What are some examples of regulated enzymes?

A

repressible (inhibit gene expression) and induced enzymes (turn on transcription).

29
Q

What is the operon model based on and what is it used for?

A

It is based on the repression and induction of structural genes and it is used for the regulation of bacterial protein synthesis.

30
Q

What does the operon model consist of?

A
  • Promoter where RNA polymerase binds and makes mRNA
  • Operator transcription on and off
  • Control region this is the promoter + operator
  • Operon control region and the genes to be expressed
31
Q

What does the lac operon consist of?

A

It refers to a gene that is only swtiched on when milk sugar (lactose) is present. If there isn’t lactose then the enzyme isnt synthesied. This gene synthesises an enzyme, beta-galactosidase or Lac Z, which breaks down lactose to glucose and galactose.

32
Q

What does the lac operon have?

A

A promoter, operator and structural genes.

33
Q

What happens when the lac operon is repressed?

A

Repressor protien binds to operator whic block RNA transcription.

34
Q

What happens when lac operon is induced?

A

Allolactose attaches to the repressor which inactivates it (in the presence of lacotse) which then produces the enzymes needed to break down lactose.

35
Q

What is a mutation?

A

A change in the DNA sequence.

36
Q

What is a mutagen and what is spontaneous mutation?

A

A mutagen is the agent that causes mutagens (radiation or chemical).

Spontaneous mutation is a mutagen that occurs without a mutagen (errors in DNA replication or repair).

37
Q

What is point mutation?

A

It is a base substitution and is also known as missense mutation.

38
Q

What is nonsense mutation?

A

Changes a normal codon to a stop codon.

39
Q

What is frameshift mutation?

A

Insertion or deletion of one or more nucleotide pairs. Changes mRNA frame.

40
Q

What are silent and back mutations?

A

Silent - altes the base but doesn’t change the amino acid and back is a mutated gene which is reversed to original base composition.

41
Q

What causes mutation?

A

Ionizing radiation which causes ions to react with nucleotides and deoxyribose backbone.

42
Q

What repairs inionizing radiation mutations?

A

nucleotide exicision repair.

43
Q

What causes thymine dimers and what do they do?

A

Thymine dimers block transcription and replication.

44
Q

What are light repair and excision repair involved with?

A

These repair mutations done my thymine dimers.

Light repair seperates the thymine dimers and excision repaire remove and repair damaged bases.

45
Q

What is the frequency of mutation?

A

1 in 10^9 base pairs or 1 in 10^6 genes

46
Q

What can cause mutagens?

A

UV light, X-rays, base analogs and deaminating agents.

47
Q

What detects mutagenic compounds?

A

The AMES test and this determines if a mutagen (carcinogenic) is at work. This is seen with salmonella mutation which can’t break down histadine, however when mutation is added revertants take place and and it retains the ability to produce histadine.

48
Q

What are the three forms of genetic recombination?

A

Transformation, Conjugation and Transduction

49
Q

What is recombination?

A

Organism attains and expressed genetic material from another organism.

50
Q

What is transformation?

A

Chromosomes fragments are lysed and recipient cell picks those up and aquires them (capsulated).

51
Q

What is conjugation?

A

A plasmid is put into recipient cell which doesn’t originally have a plasmid and therefore both the donor and recipent have the plasmid. It require cell to cell contact.

52
Q

What is transduction?

A

This uses bacteriophage as a carrier from donor to recipent and it transfers DNA.

53
Q

What is genetic recombination?

A

This is when two chromosomes cross, break and join.

54
Q

What is a plasmid?

A

A circular DNA material found in the cytoplasm, it is self replicating and can move to other cells via conjugation and transformation.

55
Q

What is a Transponson?

A

A small segment of DNA which moves from one region of the DNA molecule to another. They can excise out of one part of DNA and recombine to another. They allow for cutting and resealing.

56
Q

What types of plasmids are there?

A

conjugative - used as sex pili

dissimilation plasmids - used to encode for enzymes in catabolism reactions

R factors - encode for antibiotic resistance

Virulence genes- pathogenic

Bacteriocine genes - kill competing bacteria.

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Microbiology (10 decks)

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