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Microbio > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

The basic unit of heredity is the _____, the segment of DNA that encodes for a gene product

A

gene

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2
Q

The ___ is the whole genes (coding regions of DNA) and the noncoding regions constituent of an organism

A

genome

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3
Q

What process is accomplished by RNA polymerase enzymes to give mRNA?

A

Transcription

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4
Q

What process is performed by ribosomes (rRNA + proteins) in the cytoplasm of the cell?

A

Translation

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5
Q

______ participate in the translation (polypeptide synthesis) by transferring the amino acids from the cytoplasm to the ribosomes and binding them to the peptide chain according to the mRNA codon

A

Transfer RNAs (tRNA)

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6
Q

___ and _____ tend to be stable and together account for more than 95% of the total RNA in a bacterial cell

A

rRNA and tRNA

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7
Q

How many chromosomes in the nucleus is the eukaryotic genome carried on?

A

Two or more linear chromosomes

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8
Q

Diploid eukaryotic cells contain two homologues of each chromosome. The gene that does not achieve phenotypic expression in the presence of it’s homologue is __, and the gene that overrides the effect of its homologue is ___

A

recessive, dominant

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9
Q

What are introns?

A

intervening sequences of DNA that are missing in the processed mRNA when it is translated

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10
Q

Most prokaryotic genomes consist of what type of DNA?

A

Single circular DNA

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11
Q

What are some examples of bacteria that have two chromosomes?

A

-Brucella melitensis
-Burkholderia pseudomallei
-Vibrio cholerae

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12
Q

What are some examples of bacteria that have linear chromosomes?

A

-Actinomycetes
-Myobacteria

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13
Q

Bacterial genes are:
a) diploid
b) haploid

A

Haploid

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14
Q

In contrast to eukaryotic genomes, 98% of bacterial genomes are ___________

A

coding sequences

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15
Q

What are housekeeping genes?

A

They are genes essential for bacterial growth and reproduction

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16
Q

What are housekeeping genes carried on?

A

Bacterial chromosomes

17
Q

________
-Have double-stranded DNA that can exist and replicate independently
-Some can integrate into the host’s chromosome
-Are not required for bacterial growth

A

Plasmids

18
Q

Plasmids carry genes that give their host a selective advantage. What advantages do these hosts have?

A

-render bacteria drug-resistant
-Give them new metabolic abilities
-Make them pathogenic
-Provide them with other properties

19
Q

Plasmids mediate their transfer from one organism to another through:

A

conjugation and sex pili formation

20
Q

A cluster of genes in the chromosome (up to 200 kbp) and encodes a collection of virulence genes

A

Pathogenicity Islands (PAIs)

21
Q

What are 4 important components of PAIs?

A
  1. They have different G+C Content from the rest of the genome
  2. Are closely linked on the chromosome to tRNA genes
  3. Are flanked by direct repeats (allow the PAIs to be copied and inserted at a different location in the genome)
  4. Contain diverse genes important for pathogenesis, including antibiotic resistance, adhesions, invasions, exotoxins, and genes involved in genetic mutation
22
Q

-A class of genetic elements that can move or “jump” to different locations within a genome.
-They are always integrated into the genome (chromosomes or plasmids) and can not replicate by themselves
-Most eventually become inactive and no longer move

A

Transposons (transposable elements)

23
Q

Are the simplest transposable elements (0.72-2.0 kbp long), which are found in almost all bacteria, viruses, and some eukaryotes.
They create insertion mutations

A

Insertion sequences elements (IS)

24
Q

Are elements that could have antibiotic resistance or toxic genes

A

Composite transposons

25
Q

How does DNA replication in prokaryotes occur?

A

-Begins at one point (oriC) and moves in both directions and terminates in a region called (ter)
-The two old strands of DNA are separated and used as templates to synthesize new strands (semiconservative replication)
-The structure where the two strands are separated is referred to as the replication fork

26
Q

_____ is a large protein complex that carries out DNA replication and has several enzymatic activities ( DNA I, II, and III)

A

Replisome

27
Q

____ are enzymes that alter the supercoiling of ds DNA, by cutting the DNA to relax the coil and extend the DNA molecule
Are targets of antibiotics

A

Topoisomerases

28
Q

What are the two mechanisms of gene transfer?

A
  1. Vertical gene transfer: vertical inheritance of parental genes from the parent cells to the progeny cells
  2. Horizontal gene transfer (HGT): can be transferred from one organism to another. The DNA can be stably incorporated into the recipient permanently changing its genetic composition
29
Q

What are the 3 broad mechanisms that mediate HGT?

A

Conjugation, transduction, transformation

30
Q

How does the conjugation of DNA work?

A

It requires donor cell-to-recipient cell contract to transfer only one strand of DNA
The recipient completes the structure of dsDNA by synthesizing the strand that complements that strand acquired from the donor

31
Q

What part of the DNA is most frequently transferred by conjugation?

A

Plasmids

32
Q

What are fertility factors responsible for?

A

The formation of sex pilus and the extracellular multimeric proteins that attach donor cells to the recipient cells

33
Q

How does the transduction of DNA work?

A

Transduction is a phage (virus) mediated genetic recombination in bacteria
The phages infect bacterial cells and propagate inside them. When they leave the cell to infect other cells, they take some bacterial genes with them.

34
Q

In nature, ________ are often transported by phages

A

pathogenicity islands

35
Q

How does the transformation of DNA work?

A

It is a direct uptake of extracellular “naked” DNA by the recipient cell.

36
Q

Can the transformation of DNA be natural, forced, or both?

A

Both

37
Q

How can forced transformation be induced?

A

In a laboratory. After treatment with high salt and temperature shock, many bacteria are rendered competent for the uptake of extracellular plasmids.
The competency for transformation is varied between bacterial spaces

Microbio (7 decks)

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