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Bacteriology > C. Bacteriology Module 2.3 > Flashcards

C. Bacteriology Module 2.3 Flashcards

1
Q

[T or F] Bacterial reproduction is asexual.

A

True.

Bacteria reproduce asexually so progeny cells are identical to the parent cell.

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2
Q

[T or F] Bacteria reproduce asexually which prevents them from forming new genetic combinations.

A

False - Bacteria can still form new genetic combinations

(The bacterial genome may be subject to different forms of alterations that give rise to expression or appearance of characteristics not previously seen or observed in a species. )

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3
Q

Genetics came from the Latin word “genesis”, which means ______.

A

Birth/Generation

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4
Q

The science of inheritance or heredity.

A

Genetics

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5
Q

covers study ofthe composition of genes, how they carry information, how they are replicated and passed down through generations of cells or between organisms, and how the expression of their information within an organism affects the organism’s particularfeatures.

A

Genetics

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6
Q

A macromolecule composed of repeating units called nucleotides, hence a polynucleotide.

A

deoxyribonucleic acid (DNA)

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7
Q

[DNA] Each nucleotide consists of a ___________, ______________, and ____________.

A

pentose sugar (deoxyribose)
phosphate group
nitrogen-containing nucleobase

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8
Q

[DNA] What are the purine base nitrogen-containing nucleobase? What are the pyrimidine base nitrogen-containing nucleobase?

A

purine base: adenine (A), and guanine (G)

pyrimidine base: cytosine (C), and thymine (T).

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9
Q

The nucleotides are joined to one another in a chain by ___________ between the sugar of one nucleotide and the phosphate of the next, resulting in an ___________.

A

covalent bonds

alternating sugar-phosphate backbone

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10
Q

[T or F] According to base pairing rules, nitrogenous bonds bind the hydrogen bases of the two separate polynucleotide strands to make a double-stranded DNA. Thus, the sequence on one strand is complementary to that on the other.

A

False - hydrogen bonds bind nitrogenous bases

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11
Q

[T or F] Two strands of nucleotides are coiled around each other to form a double helix, a structure like a spiral ladder forming a double-stranded DNA that is helical.

A

True

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12
Q

Small sections of the DNA molecule that codes for production of proteins

A

Genes

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13
Q

Small sections of the DNA molecule that codes for production of proteins

A

Genes

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14
Q

the fundamental units of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

A

Genes

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15
Q

The sum total of genes present in cell or organism

A

Genome

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16
Q

[T or F] Each genotype contains all of the information needed to build and maintain that organism.

A

False - Each genome […]

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17
Q

The genome size is expressed in _______.

A

Base pairs

For example, in humans, 3 billion base pairs (3 gbp) is are contained in all cells that have a nucleus.

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18
Q

The inheritable genetic makeup of an organism that codes for a particular trait.

A

Genotype

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19
Q

Refers to actual, expressed or observable trait and is governed by the genotype.

A

Phenotype

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20
Q

Among the bacteria, ___________, _________, _________, _________ are some of the environmental influences that may dictate whether the
genetic trait may be expressed or not.

A

temperature
pH
age
humidity

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21
Q

[T or F] Serratia marcescens form white colonies at 24 oC, and red colonies at 37 oC.

A

False - Serratia marcescens form red colonies at 24 oC, and white colonies at 37 oC.

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22
Q

Different types of DNA may be found in a bacterial cell. The genes are carried on: ___________, __________, ___________, or ___________.

A

bacterial chromosome
plasmid
phage
transposon.

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23
Q

Bacterial cell has ________ chromosome(s), which consists of a double-stranded DNA molecule arranged in a circular form.

A

Only one

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24
Q

[T or F] Most bacterial chromosomes are large, up to 1,000 um long, about 10 times the diameter of the cell.

A

False - 1,000 times the diameter of the cell

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25
Q

Bacterial chromosomes can range in size anywhere from about ____ kbp to ____ mbp, with 3,000 to 10,000 genes.

A

130 kbp to 14 mbp

Escherichia coli is about 4.6 mbp

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26
Q

Bacterial chromosome is found in the region of the

cytoplasm called ________.

A

nucleoid

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27
Q

All genes essential for bacterial growth are carried on ___________.

A

Chromosome

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28
Q

They are circular, double-stranded DNA.

A

Plasmids

They are small ranging from 1.5 to 400 kbp

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29
Q

[T or F] Plasmids are extra-chromosomal and can replicate autonomously in bacterial cells.

A

True

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30
Q

also known as bacteriophage, a bacterial virus

A

Phage

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31
Q

This are stable pieces of phage DNA

A

prophage

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32
Q

The process where stable pieces of phage DNA are inserted into bacterial chromosome.

A

lysogeny

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33
Q

a repressed virus — carried passively without replication and causing lysis of the infected bacterium

A

temperate phage

34
Q

The ability of gene products to make bacteria more pathogenic.

A

lysogenic conversion

35
Q

large, mobile genetic elements, with DNA sequences of several kbp , that can move themselves or a copy from one molecule of DNA to another, so are referred j to as “jumping genes”.

A

Transposons

36
Q

referred j to as “jumping genes”.

A

Transposons

37
Q

The process of transferring of transposons which can occur: plasmid to plasmid or plasmid to chromosome within bacterial cell.

A

transposition

38
Q

genetic determinant in bacteria that can carry genes for specialized functions

A

plasmids and transposons

However, in contrast with plasmids, transposons do not contain genetic information for replication.

39
Q

The unilateral transfer of genetic information from a donor cell to a recipient cell

A

Genetic exchange

40
Q

Transferred genes can be stably incorporated into the recipient’s chromosome by ___________.

A

recombination

41
Q

[T or F] Genetic exchange is not an essential step in the life cycle of bacteria.

A

True

(But, it is beneficial and may bring together combination of genes that enables the recombinant bacteria to carry out a valuable new function.)

42
Q

the gene transfer from one bacterial cell to another involving direct cell-to-cell contact.

A

Conjugation

43
Q

[Conjugation] F factor stands for ___________.

A

fertility plasmid

44
Q

Conjugation is controlled by ____________ that carries the genes that code for sex pili formation which bring the two cells in physical contact.

A

F factor (fertility plasmid)

45
Q

[T or F] Donor (male) cells have F factor, therefore form sex pili, meanwhile, Recipient (female) cells lack F factors and are called F- cells.

A

True

46
Q

__________ have F factor in its “free state” (not incorporated into the bacterial chromosome); __________ have F factor that is “integrated” into the bacterial chromosome.

A

F+ cells; Hfr cells

47
Q

The term Hfr denotes _______________, referring to the fact that Hfr cells donate copies of genes on the bacterial chromosome

A

high frequency of recombination

48
Q

Two types of conjugal crosses:

A

a. F+ x F- conjugation

b. Hfr x F- conjugation

49
Q

[Reading: not a question] Main difference between Hfr x F- conjugation to F+ x F- conjugation:

Note:
Hfr x F- conjugation
Transfer order: 
1.first half of F factor 
2.bacterial genes 
3.integrated F factor

F+ x F- conjugation
transfer is quick so it is transferred in its entirety.
No genetic recombination and no transfer of bacterial genes.

A

Transfer in Hfr x F- conjugation takes approximately 90 mins and conjugative bridge is fine, so transfer is usually interrupted causing the entire genome of the donor cell not to be transferred completely which becomes a recombinant F-cell.

50
Q

The uptake of free (or naked) extracellular DNA in the environment by a competent cell and subsequent integration into its chromosome by a competent

A

transformation

The recipient cell often acquires new characteristics as a result

51
Q

[T or F] When a cell is destroyed, its genetic material is also destroyed.

A

False - Destruction of cell does not necessarily destroy its genetic material.

52
Q

Competency is dependent on several factors. State the three:

A

• Stage of growth — logarithmic phase
• Alterations in the cell membrane that makes it permeable to the
DNA molecule
• Synthesis of receptor sites on the bacterial cell surface

53
Q

Only a few bacterial species are capable of natural transformation since specific DNA sequences is required. Naturally competent transformable bacteria, of medical importance, are found in several genera and include:

A

Haemophilus influenzae
Neisseria gonorrhoeae
Neisseria meningitidis
Streptococcus pneumoniae

54
Q

The procedure involves extraction of the DNA, and “treatment of cells with high salt” (e.g., CaCl2 ) and
“temperature shock” to render the cell membrane more permeable to DNA and make them readily take up DNA.

A

Artificial (or forced) transformation

55
Q

transfer of DNA between bacteria by means of a phage (bacteriophage)

A

Transduction

56
Q

Two major types of phage:

A

Virulent phage

Temperate phage

57
Q

often have repressor genes to prevent phage replication; integrates their DNA into the bacterial chromosome where it stably stays as a prophage without lysing the host bacteria.— lysogeny

A

Temperate phage

58
Q

infects bacterial cells, replicates, and and kills the

host bacteria, usually by lysing — lytic cycle.

A

Virulent phage

59
Q

What are the two types of transduction?

A 
Generalized transduction (mediated by virulent phages)
Specialized transduction (mediated by temperate phages)
60
Q

Occasionally, bacterial DNA are
packaged in a phage capsid by mistake —
these are called ______________.

A

transducing particles

61
Q

Generalized transduction process:

A
  1. Attachment and infection
  2. Replication of the phage DNA
  3. Assembly and package
  4. Lysis of the host bacterium

summary: virulent phage DNA is injected into the bacterium where it replicated, packaged with bacterial phage, and then released. The released transducing particle infects other bacterium by injecting DNA and not viral nucleic acid since it cannot kill its host bacterium.

62
Q

Specialized transduction process:

A
  1. Attachment and infection
  2. Lysogeny and lysogenic conversion
  3. Replication (entire bacterium)
  4. Continuous cell division showing no evidence of viral infection.
  5. Spontaneous induction
  6. Reactivation of phage DNA, assembly and package.
  7. Lysis of the host bacterium

The temperate phage is injected into the bacterium and instead of replicating, it integrates into the bacterium’s chromosome, leading the bacteriumto acquire new features. The bacterium is then replicated with the host chromosome, resulting in daughter cells that can produce temperate phages but lack evidence. The prophage DNA gradually cutsitself out of the bacterial chromosome,then replicates, while the progeny temperate phages accumulate within a capsid and detach from the bacterial chromosome with abacterial DNA, allowing them to become specialized transducing particles. The host bacterium is then lyzed, allowing infectious phages to escape.

Summary: The temperate phage is injected into the bacterium and instead of replicating, it integrates into the bacterium’s chromosome, leading the bacteriumto acquire new features. The bacterium is then replicated with the host chromosome, resulting in daughter cells that can produce temperate phages but lack evidence. The prophage DNA gradually cutsitself out of the bacterial chromosome,then replicates, while the progeny temperate phages accumulate within a capsid and detach from the bacterial chromosome with abacterial DNA, allowing them to become specialized transducing particles. The host bacterium is then lyzed, allowing infectious phages to escape.

63
Q

Phage-coded pathogenic factors:

A
  • O antigen of Salmonella
  • Botulinum toxin of Clostridium botulinum (causing botulism)
  • Erythrogenic toxins of Streptococcus pyogenes (causing scarlet fever)
  • Diphtheria toxin of Corynebacterium diphtheriae
64
Q

a permanent alteration in the base sequence of the gene (DNA) resulting in phenotypic change

A

Mutation

65
Q

3 Mechanisms of mutation:

A
  1. Insertion
  2. Deletion
  3. Substitution
66
Q

takes place when a nitrogenous base (nucleobase) is “added” to the nucleotide sequence.

A

Insertion.

67
Q

the “removal” of a nucleobase from the nucleotide chain.

A

Deletion

68
Q

arise when there is mispairing between complementary bases. It occurs when one or more nucleobases in a
nucleotide sequence is replaced with another base.

A

Substitution

69
Q

[T or F] Mutations can be spontaneous, or induced by a mutagen in the environment.

A

True

70
Q

a random, undirected alteration of the DNA base sequence that arise as a consequence of mistakes in DNA replication.

A

Spontaneous mutation

71
Q

[T or F] Spontaneous mutation is natural.

A

True

72
Q

caused by exposure to external influences or agents that result in the DNA to breakdown.

A

Induced mutation

73
Q

agents that induce mutations are collectively referred to as

A

mutagens

74
Q

external influences that causes induced mutation

A 
chemicals
radiation
viruses
diet
lifestyle.
75
Q

converts the nucleobase adenine (A) to a form that no longer pairs with thymine (T) but cytosine (C). Thus, when DNA containing such modified adenines replicates, one daughter DNA molecule will have a base-pair sequence different from that of the parent DNA.

A

Nitrous acid (HNO2)

76
Q

ionize atoms and molecules with the formation of highly reactive ions and free radicals. Some of these ions can combine with bases in DNA, resulting in errors in DNA replication and repair that produce mutations.

A

X rays and gamma rays

77
Q

a non-ionizing component of ordinary sunlight. Its most important effect on DNA is the formation of harmful covalent bonds between certain bases. Adjacent thymines in a DNA strand can cross-link to form thymine dimers. Such dimers, unless repaired, may cause serious damage or death to the cell because it cannot properly transcribe or replicate such DNA.

A

Ultraviolet (UV) light

78
Q

The transfer of either a chromosomal DNA or plasmid through a sex pilus is called

A

Conjugation

79
Q

Genetic recombination requires a competent cell

A

Transformation

80
Q

results from a permanent change in the base sequence of a gene through natural or artificial means

A

mutation

Bacteriology (1 decks)

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