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3 DVM - MICROBIO > LESSON 14: BACTERIAL GENETICS > Flashcards

LESSON 14: BACTERIAL GENETICS Flashcards

1
Q

is the science of heredity; it includes the study of genes and information it carries.

A

Genetics

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2
Q

How genes are replicated and transferred to other organisms
or how particular genes are expressed in an organism and how does it influence its
characteristics

A
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3
Q

is the genetic information that a cell carry that includes chromosomes and plasmid.

A

genome

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4
Q

are containing DNA that carry
hereditary information; the chromosomes carry the genes.

A

Chromosomes

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5
Q

are segments of DNA (except in RNA viruses) that code for functional products.

A

GENES

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6
Q

A DNA or deoxyribonucleic acid is a macromolecule composed of repeating units called

A

nucleotides

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6
Q

nucleotide is consist of of a

A

Nitrogenous base (adenine, thymine, cytosine or guanine),
Deoxyribose (a pentose sugar), and a Phosphate group

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6
Q

The cells DNA exist as long strands of nucleotides twisted together in pairs to form a

A

Double helix

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7
Q

Each strand has a string of sugar and phosphate group and nitrogenous base attached to each sugar.

A
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7
Q

The two strands are held together by

A

hydrogen bonds

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8
Q

DNA
The base pairs are
(Thymine and adenine)
(Cytosine and guanine)

A
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9
Q

These strands have two designated ends called 5’ and 3’ (you can read that as 5 prime end and 3 prime end).
These numbers indicate end-to-end chemical
orientation.

A
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10
Q

is the end, which joins a phosphate group that attaches to another nucleotide.

A

5

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10
Q

end is important as during replication the new nucleotide is added to this end.

A

3

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11
Q

In terms of direction, if one strand is 5’ to 3’ while reading from left
to right, the other strand will be 3’ to 5’. Simply put, the strands run in opposite
directions. This orientation is kept for easy binding between nucleotides of the
opposite strands.

A
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11
Q

is the genetic makeup of an organism that codes for all its characteristics.
It is the organisms collection of genes.

A

Genotype

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12
Q

actual expressed properties of an organism
or the manifestation of a genotype

A

phenotype

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13
Q

A typical bacterial chromosome have a single circular DNA molecule and associated proteins.

A
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14
Q

The chromosome is folded and looped and attached to the plasma membrane of a bacteria.

A
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14
Q

The flow of genetic information from one generation to the next is made possible through DNA replication, or mRNA transcription.

A
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14
Q

If there is adenine in the parent or old
strand, complementary thymine will be added to the new strand.
Similarly, if there is cytosine in the parent strand, complementary guanine will be copied into the new daughter strand.

A
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14
Q

To summarize DNA replication

A

-the two strands uncoil and permanently
separate from each other.
- The base sequence of parent or old strand directs the base sequence of new or daughter strand.

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15
Q

initiated at the origin of replication.

A

DNA replication

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15
Q

Before the DNA synthesis begins, both the parental strands must unwind (due to an enzyme called
and separate permanently into single stranded state made possible by enzyme helicase

A

topoisomerase or gyrase

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16
Q

Primers are short sequences of RNA, around 10 nucleotides in length

A
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17
Q

Primase synthesizes the primers.

A
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18
Q

The next step involves the addition of new complementary strands.
The choice of nucleotides to be added in the new strand is dictated by the sequence of
bases on the template strand.

A
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19
Q

New nucleotides are added one by one to the end of growing strand by an enzyme called D

A

DNA polymerase

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20
Q

The strand, which is synthesized in the same direction as the replication fork, is known as the

A

‘leading’ strand.

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21
Q

The DNA polymerase has to attach only once and it can continue its work as the replication fork moves forward.

A
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22
Q

for the strand being synthesized in the other direction, which is known as the —-
the polymerase has to synthesize one fragment of DNA thus creating many fragments as it moves towards the replication fork.

A

‘lagging’ strand

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22
Q

These fragments are known as

A

Okazaki fragments

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22
Q

These gaps are filled by

A

ligase

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23
Q

Reiji okazaki

A
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23
Q

When DNA polymerase is adding nucleotides to the lagging strand and creating Okazaki
fragments, it at times leaves a gap or two between the fragments

A
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24
Q

The Replication process is finally complete once all the primers are
removed and Ligase has filled in all the remaining gaps.

A
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25
Q

This process gives us two
sets of genes, which will then be passed on to two daughter DNA molecules which
are identical to the parent molecule.

A
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25
Q

The information in a DNA are used to make proteins that controls cell activities.

A
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26
Q

the synthesis of a complimentary strand of RNA from a DNA template.

A

transcription

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26
Q

The encoded information is then used by cell to synthesize protein in a process called

A

translation

26
Q

wherein genetic information in DNA is
copied or transcribed into a complimentary base sequence of RNA.

A

transcription

27
Q

carries the coded
information for making specific proteins from DNA to ribosomes, where proteins are
synthesized.

A

Messenger RNA (mRNA)

27
Q

There are three types of RNA in a bacterial cell:

A

messenger RNA,
ribosomal RNA, and transfer RNA

28
Q

The process of transcription is similar to DNA replication wherein it also uses complementary base pairing as a guide, except that thymine is replaced by a uracil to pair with adenine in an RNA strand

A
29
Q

Protein synthesis is called

A

translation

29
Q

because it decodes and translates the genetic codes (codons) made during transcription into specific proteins which consists of a series of amino acids.

A
29
Q

Sense codons codes into a particular amino acid
while nonsense codons signal the ends of protein synthesis thus it is also called

A

stop codons

29
Q

The site of translation is the

A

ribosomes

29
Q

while transfer RNA (tRNA) recognize the specific codon and transport the corresponding

A

amino acid

30
Q

The functions of the
ribosomes are to direct the orderly binding of tRNAs to codons and to assemble the
amino acids brought there into a chain, ultimately producing protein.

A
31
Q

is a regulatory mechanism
that inhibits gene expression and decreases synthesis of enzymes, usually in response to overabundance of an end-product (protein).

A

repression

32
Q

RNA synthesis starts at a site in the strand called

A

promoter

33
Q

until it reaches a site on the DNA called

A

terminator

34
Q

is the process that
turns on the transcription of genes.

A

induction

34
Q

is a change in the base sequence of a DNA which sometimes cause a change in the end-product (protein)

A

mutation

34
Q

a single base in one point of a DNA is
replaced with another

A
  1. Base mutation (point mutation):
35
Q

Types of mutation:

A
  1. Base mutation (point mutation):
  2. Missense mutation:
  3. Frame-shift mutation:
35
Q

happens when as a result of base mutation, an
incorrect amino acid is inserted into the synthesized protein.

A

Missense mutation

36
Q

when one or a few nucleotide pairs are inserted or
deleted in the DNA

A

Frame-shift mutation

36
Q

are environmental agents that directly or indirectly cause mutations

A

Mutagens

36
Q

mutagens examples:

A

1.Chemical mutagens
2. Radiation

37
Q

Examples of chemical mutagens:

A
  1. nitrous acid
  2. nucleoside analog
  3. aflatoxins
38
Q

exposure of bacteria to nitrous acid can convert the base adenine (A) to a form no longer unpairable with thymine at a random location.

A
39
Q

also have altered base-pairing property

A

nucleoside analog

40
Q

Radiation examples:

A

1.Xrays and gamma rays
2. . Ultraviolet (UV) light

40
Q

are potent mutagens due to their ability to ionize
atoms

A

Xrays and gamma rays

40
Q

a frame-shift mutagen and also a potent carcinogen.

A

aflatoxin

40
Q

harmful (at 260 nm wavelength) due to its ability to form covalent bonds between bases.

A

ultraviolet (UV)

41
Q

Cell damage due to UV light can be repaired by photolyases or light repair enzymes by destroying covalent bonds to return its original sequence.

A
41
Q

is the exchange of genes between two DNA
molecules to form new combinations of genes on a chromosome that results to
genetic diversity in a population.

A

Genetic recombination

42
Q

occurs when genes are passed from an organism to
its offspring (plants and animals).

A

Vertical gene transfer

42
Q

the transfer involves a donor cell that gives a portion of its DNA to a recipient cell.

A

Horizontal gene transfer

42
Q

The recipient cell that incorporates donor DNA to its own DNA is called

A

recombinant

43
Q

In bacteria, genetic recombination results from these three types of
gene transfer :

A
  1. Transformation
  2. Conjugation
  3. Transduction
43
Q

is the transfer of genes from one bacterium to another as “naked” DNA in a solution.

A

Transformation

44
Q

in bacteria is a mechanism by which genetic material is
transferred by a plasmid.

A

conjugation

45
Q

A is a circular piece of DNA that replicates
independently from the cells chromosome.

A

plasmid

46
Q

is a genetic transfer wherein bacterial DNA is transferred
from a donor cell to recipient cell inside a virus that infects bacteria called
bacteriophage,

A

transduction

46
Q

requires cell to cell contact, only donor cell must carry the plasmid.

A

conjugation

47
Q

is an extrachromosomal genetic element that is capable of autonomous replication in the cytoplasm of a bacterial cell.

A

plasmid

48
Q

The plasmids can also be
present as integrated with bacterial chromosomes, and plasmids integrated with host chromosome are known as

A

Episomes

49
Q

Plasmids are present in both Gram-positive
and Gram-negative bacteria.

A
50
Q

Many plasmids control medically important properties of pathogenic bacteria.
These include

A

(a) resistance to one or several antibiotics,
(b) production of toxins, and
(c) synthesis of cell surface structures required for adherence or colonization.

50
Q

transfer antibiotic resistant genes to some
organism.

A

R plasmid

51
Q

2 categories of plasmid:

A
  1. Transmissibility
  2. Nature of plasmid
52
Q

cell to cell genetic transfer through conjugation

A

Transmissible

53
Q

Responsible for synthesis of the sex pilus and
for the synthesis of enzymes required for their transfer.

A

a. transmissible

54
Q

empty of genes, thus unable to transfer

A

b. non- transmissible

55
Q

nature of plasmid

A

a. F factor
b. R (resistance) factor
c. Col factor

56
Q

contains the genetic information, essential for controlling mating process of the bacteria during conjugation.

A

f factor

56
Q

These genes determine
(a) expression of pili,
(b) synthesis and transfer of DNA during mating,
(c) interference with the ability of F bacteria to serve as recipients, and
(d) other functions.

A
57
Q

2 sizes; large plasmid (mol. wt. 60 million); contains R factor and are conjugative, while small plasmids (mol. wt. 10 million)contains
“r” factor and non-conjugative

A
58
Q

is responsible for conjugational
transfer

A

resistance transfer factor

59
Q

R factor consists of two components:

A

The resistance transfer factor (RTF)
and resistant determinant (r)

60
Q

carries resistance for one of the several
antibiotics

A

R determinants

60
Q

or colicinogenic factor, resembles the F factor in promoting conjugation, leading to self-transfer and also at times transfer of segments of
chromosomes

A

col factor

61
Q

encodes for production of colicins, which are antibiotics-like substances that are specifically and selectively lethal to other enteric
bacteria.

A
62
Q

They also encode for production of diphthericin and pyocyanin
produced by
which are substances similar to colicins.

A

diphtheriae and Pseudomonas pyocyanea,

3 DVM - MICROBIO (15 decks)

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