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Microbiology (Bacteriology) > Bacterial Genetics, Metabolism, and Structure > Flashcards

Bacterial Genetics, Metabolism, and Structure Flashcards

1
Q

*the process of heredity and variation
*starting point from which all other cellular pathways,
functions, and structures originate

A

genetics

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2
Q

factor that contributes to the ability of a
microorganism to maintain viability, adapt, multiply, and
cause disease is determined by:

A

genetic composition

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3
Q

THREE major aspects of microbial genetic composition

A
  • The structure and organization of genetic
    material
    • Replication and expression of genetic information
    • The mechanisms by which genetic information is
    altered and exchanged among bacteria
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4
Q

most common macromolecule that encodes genetic

information

A

DNA (Deoxyribonucleic Acid)

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5
Q

plays an essential role in several of the
genetic processes in prokaryotic and eukaryotic cells,
including the regulation and transfer of information

A

RNA (Ribonucleic acid)

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6
Q

DNA structure:

A

deoxyribose sugars connected by phosphodiester bonds (Covalent linking of bases)

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7
Q

composition of an intact DNA

A

5’ (prime) phosphate

and a 3’ (prime) hydroxyl terminus (nucleotide polymers)

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8
Q

direction of 2 DNA strands

A

antiparallel direction

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9
Q

arrangements of strands

A

complementary:
adenine (purine)=thymine (pyrimidine) (2 hydrogen bonds)
cytosine (pyrimidine)=guanine (purine) (3 hydrogen bonds)

  • thymine is replaced by uracil in RNA sequence
  • hydrophobic in nature
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10
Q

structural conformation of DNA

A

twisted ladder/double helix

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11
Q

The three major types of RNA

A

messenger RNA [mRNA], transfer RNA
[tRNA], and ribosomal RNA [rRNA]

PLAY KEY ROLE IN GENE EXPRESSION

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12
Q

important fact about RNA

A

it is NOT double stranded

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13
Q

A DNA sequence that encodes for a specific product

RNA or protein

A

gene

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14
Q

All the genes in an organism comprise the organism’s:

A

genome

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15
Q

size of a gene and an entire genome is usually

expressed in:

A

base pairs (bp) present

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16
Q

organization/arrangement of a genome into discrete elements

A

chromosome (usually arranged in a linear fashion)

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17
Q

since bacteria are prokaryotes, the chromosome…

A

the chromosome is not located in a membrane-bound organelle

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18
Q

arrangement of the bacterial chromosome

A

doublestranded, closed, circular macromolecule

– extensively folded and twisted (i.e., supercoiled) — in order to fit the confined space of the bacterial cell

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19
Q

aside from the chromosome, bacterial genes may also be found in what extrachromosomal elements

A

plasmids and transposable elements

— not stable and may be lost during replication

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20
Q

structure of plasmids

A

double-stranded, closed, circular,

autonomously replicating extrachroosomal genetic elements ranging in size from 1 to 2 kilobases up to 1 megabase or more

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21
Q

other notable characteristics of plasmids:

A
  • do not code for cell viability
  • may also become incorporated into the
    chromosome
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22
Q

pieces of DNA that move from one genetic element to another, from plasmid to
chromosome or vice versa

A

transposable elements

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23
Q

other notable characteristics of transposable elements

A
  • they are unable to replicate independently

* do not exist as separate entities in the bacterial cell

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24
Q

two types of transposable elements

A

1) simple transposon or insertion sequence (IS)

2) composite transposon

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25
Q

transposon that is limited to containing the genes that
encode information required for movement from one
site in the genome to another

A

simple transposon/ insertion sequence

26
Q

transposon that is a cassette (grouping of genes) flanked by insertion sequences

A

composite transposon

27
Q

this is imbedded in the insertion

sequence encodes for an accessory function, such as antimicrobial resistance

A

internal gene

28
Q

four stages of replication:

A
  1. Unwinding or relaxation of the chromosome’s
    supercoiled DNA – allows enzymes and cofactors to access DNA
  2. Separation of the complementary strands of the
    parental DNA so that each may serve as a template
    (i.e., pattern) for synthesis of new DNA strands
  3. Synthesis of the new (i.e., daughter) DNA strands
  4. Termination of replication, releasing two identical
    chromosomes, one for each daughter cell
29
Q

the origin of replication is recognized by:

A

several initiation proteins, followed by the separation of the complementary strands of parental DNA

30
Q

site of active replication

A

replication fork (bidirectional forks)

31
Q

notable on replication forks:

A
  • each replication fork moves through the parent DNA molecule in opposite directions so that replication is a bidirectional process
  • involves different cofactors and enzymes, with DNA polymerases playing a central role
32
Q

termination of replication happens when:

A

when the replication forks meet

33
Q

the processing of information encoded
in genetic elements (i.e., chromosomes, plasmids, and
transposons), which results in the production of biochemical molecules, including RNA molecules and proteins

A

gene expression

34
Q

complex steps in gene expression (in order)

A

transcription and translation

35
Q

beginning of transcription:

A

DNA -> mRNA (complementary to to gene’s DNA sequence)

— only one of the two DNA strands become the sense strand - encodes for functional gene product and template for mRNA synthesis

36
Q

enzyme central to the transcription process

A

RNA polymerase

37
Q

composition of RNA polymerase

A

sigma factor and 4 protein subunits

38
Q

role of sigma factor in RNA polymerase

A

to identify the appropriate site
on the DNA template where transcription of mRNA is
initiated

39
Q

other name for initiation site

A

promoter sequence

40
Q

direction of transcription

A

5’ to 3’ direction

41
Q

In bacteria, the mRNA molecules that result from the

transcription process are:

A

polycistronic — encode for several gene products

42
Q

When a cluster of genes is under the
control of a single promoter sequence, the gene group
is referred to as:

A

operon

43
Q

phase in gene expression that involves protein synthesis

A

translation — responsible for protein structure and function

44
Q

genetic code consists of triplets of nucleotide

bases, referred to as:

A

codons

45
Q

Ribosomes (compact nucleoproteins) components

A

rRNA and proteins

  • – central to translation
  • – assisting with coupling of all required components and controlling the translational process
46
Q

three steps of translation

A

initiation
elongation
termination

47
Q

association of ribosomal subunits, mRNA, formylmethionine tRNA ([f-met] carrying the initial amino acid of the protein to be synthesized), and various initiation factors

A

initiation

48
Q

involves tRNAs mediating the sequential
addition of amino acids in a specific sequence that is
dictated by the codon sequence of the mRNA molecule

A

elongation

49
Q

arrangement wherein multiple
ribosomes may be simultaneously associated with
one mRNA molecule

A

polysome

50
Q

appearance of polysome

A

string of pearls

51
Q

the final step in translation, occurs when
the ribosomal A site encounters a stop or nonsense
codon that does not specify an amino acid (stop codons)

A

termination

52
Q

process wherein most proteins must undergo modification, such as folding or enzymatic trimming, so that protein function,transportation, or incorporation into various cellular structures can be accomplished

A

posttranslational modification

53
Q

Genetic alterations and diversity in bacteria are accomplished by three basic mechanisms:

A

mutation
genetic recombination
exchange between bacteria (with or without recombination)

54
Q

defined as an alteration in the original nucleotide sequence of a gene or genes within an organism’s
genome

A

mutation

— arise spontaneously

55
Q

In this process, some segment
of DNA originating from one bacterial cell (i.e., donor)
enters a second bacterial cell (i.e., recipient) and is
exchanged with a DNA segment of the recipient’s
genome

A

homologous recombination

—occurs frequently

56
Q

protein that plays a central role in genetic recombination

A

RecA protein

57
Q

three mechanisms by which bacteria physically

exchange DNA

A

transformation
transduction
conjugation

58
Q

involves recipient cell
uptake of naked (free) DNA released into the environment when another bacterial cell (i.e., donor) dies and undergoes lysis

A

transformation

— genomic DNA exists as fragments in the environment

59
Q

second mechanism by
which DNA from two bacteria may come together in one cell, thus allowing for recombination

process is mediated through viruses capable of
infecting bacteria (i.e., bacteriophages)
A

transduction

60
Q

process occurs
between two living cells, involves cell-to-cell contact,
and requires mobilization of the donor bacterium’s chromosome

A

conjugation

61
Q

considered the utilization of metabolic pathways involved in the acquisition of nutrients from the
environment, production of precursor metabolites, and
energy production

A

fueling

Microbiology (Bacteriology) (21 decks)

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