6. BACTERIAL GENETICS Flashcards

1
Q

discovered DNA

A

Frederick Miescher(1869)

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2
Q

discovered that DNA contained phosphates, five-carbon sugars (cyclic pentose), and nitrogen containing bases

A

Phoebus A. T. Levine (1920s)

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3
Q

→ discovered the helical structure by x-ray crystallography

A

Rosalind Franklin

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4
Q

described the three-dimensional structure of the DNA molecule

A

James Watson and Francis Crick (1950s )

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5
Q

What does genetics study?

A

Heredity and variation

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6
Q

What determines an organism’s ability to maintain viability, adapt, multiply, and cause disease?

A

Genetic composition

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7
Q

What are the three major aspects of microbial genetics?

A

Structure and organization of genetic material,

replication and expression of genetic information,

mechanisms of genetic information alteration and exchange

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8
Q

What is the structure of a DNA molecule?

A

Double helical chain of nucleotides

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9
Q

How is the DNA helix described?

A

Double strand twisted together, referred to as a “spiral staircase”

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10
Q

What determines the information contained in DNA?

A

Base sequence (Genetic Code)

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11
Q

What process involves DNA in the production of RNA?

A

Genetic information processing

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12
Q

What are the components of a nucleotide?

A

A phosphate group (PO4),

a cyclic five-carbon pentose sugar (deoxyribose),

and a nitrogen-containing base

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13
Q

What are the two types of nitrogen-containing bases in nucleotides?

A

Purine and pyrimidine

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14
Q

What is the structure and length of an RNA molecule compared to DNA?

A

RNA is single-stranded and short

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15
Q

What sugar is present in RNA molecules?

A

Ribose

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16
Q

What are the three major types of RNA?

A

Messenger RNA (mRNA),
Transfer RNA (tRNA),
Ribosomal RNA (rRNA)

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17
Q

A DNA sequence that encodes for a specific product (RNA or protein)

A

gene

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18
Q

What term refers to all the genes in an organism?

A

Genome

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19
Q

What organizes the genome into discrete elements?

A

Chromosomes

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20
Q

What type of chromosome do bacteria have?

A

Single, unpaired (haploid), double-stranded, closed, circular

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21
Q

What are double-stranded, closed, circular, autonomously replicating genetic elements called?

A

Plasmids

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22
Q

What are the size ranges of plasmids?

A

1 to 2 kilobases up to 1 megabase

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23
Q

What do plasmids encode for?

A

Replication and transfer products, specialized functions

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24
Q

Do plasmids encode essential viability products?

A

No

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25
Q

What are pieces of DNA that move between genetic elements called?

A

Transposable elements

26
Q

What are the two types of transposable elements?

A

Simple Transposon, Composite Transposon

27
Q

What do Simple Transposons (Insertion Sequences) contain?

A

Movement genes

28
Q

What characterizes Composite Transposons?

A

Cassette flanked by insertion sequences

29
Q

What do internal genes in insertion sequences often encode?

A

Accessory functions (e.g., antimicrobial resistance)

30
Q

Extrachromosomal Elements

A

Plasmids
Transposable Elements

31
Q

What is the complex process mediated by various enzymes for DNA replication?

A

Replication

32
Q

What enzyme is crucial for DNA replication?

A

DNA polymerase

33
Q

What is the first step in DNA replication?

A

Unwinding of the chromosome’s supercoiled DNA

34
Q

What happens after unwinding the DNA in replication?

A

Separation of the complementary strands of the parental DNA

35
Q

What is the third step in DNA replication?

A

Synthesis of the new DNA strands

36
Q

What marks the end of the DNA replication process?

A

Termination of replication, releasing two identical chromosomes

37
Q

How long does the replication process typically take in rapidly growing bacteria like E. coli?

A

Approximately 20 to 40 minutes

38
Q

Expression of Genetic Information

A

Transcription
Translation

39
Q

→processing of information encoded in genetic elements (i.e., chromosomes, plasmids, and transposons)

→results in the production of biochemical molecules, including RNA molecules and proteins

A

Gene expression

40
Q

What is the synthesis of single-stranded RNA from a DNA template called?

A

Transcription

41
Q

mRNA are considered as __________ due to their ability to encode for several gene products

A

Polycistronic

42
Q

What process involves translating mRNA into amino acid sequences?

A

Translation

43
Q

GENETIC EXCHANGE AND DIVERSITY
Three basic mechanisms:

A

Mutation
Genetic Recombination
Genetic Exchange

44
Q

Genetic Exchange
Three mechanisms:

A

Transformation
Transduction
Conjugation

45
Q

What is the alteration in the original nucleotide sequence of a gene called?

A

Mutation

46
Q

What effect does a mutation have on an organism’s genotype?

A

It changes the genotype

47
Q

What can induce mutations?

A

Chemical or physical factors (mutagens) or biologic factors

48
Q

What is the process where a segment of DNA from one bacterial cell is exchanged with a segment of another cell’s DNA?

A

Genetic recombination

49
Q

What type of recombination involves DNA segments with extensive nucleotide sequence similarities?

A

Homologous recombination

50
Q

What protein plays a central role in homologous recombination?

A

RecA

51
Q

What is the uptake of naked DNA from the environment by a recipient cell called?

A

Transformation

52
Q

What happens to DNA during transformation after a bacterial cell dies and lyses?

A

It is released into the environment and can be incorporated into the recipient’s genome

53
Q

What term describes cells that can take up naked DNA during transformation?

A

Competent

54
Q

What is the transfer of bacterial genes by a bacteriophage from one cell to another called?

A

Transduction

55
Q

What happens in generalized transduction?

A

Bacterial DNA may be randomly incorporated with viral DNA

56
Q

What happens in specialized transduction?

A

Bacterial DNA is incorporated along with adjacent viral DNA

57
Q

What mechanism involves the transfer of genetic material between two living bacterial cells through direct contact?

A

Conjugation

58
Q

What structures are involved in the transfer of plasmids and transposons during conjugation?

A

Plasmids and transposons

59
Q

What mediates contact between donor and recipient cells in conjugation?

A

Sex pilus

60
Q

What does the sex pilus establish between the donor and recipient cells?

A

A conjugative bridge for DNA transfer