Microbial genetics

Question 1

Define a gene

Answer 1

Segment of the genome that Codes for a specific protein, or stable RNA molecule

Question 2

Define a chromosome

Answer 2

The overall structure of DNA within cells that control cellular activity. In prokaryotes the Chromosomes are circular.

Question 3

Define a promoter

Answer 3

A sequence of DNA where RNA polymerase binds; to initiate transcription.

Question 4

Define an operator

Answer 4

A DNA sequence to which a repressor protein may bind.

Question 5

Define a codon

Answer 5

Groups of 3 nucleotide bases on mRNA. Each codon codes for an amino acid.

Question 6

Define a mutation

Answer 6

A random change in the DNA sequence of the nucleotide bases.

Question 7

Define a point mutation

Answer 7

A random change in the DNA sequence. Changing one nucleotide base for another.

Question 8

Define a missense mutation

Answer 8

Caused by a point mutation; One amino acid is substituted for another.

Question 9

Define a nonsense mutation

Answer 9

Caused by a point mutation; A premature STOP codon is introduced.

Question 10

Define a frameshift mutation

Answer 10

Caused by an insertion or deletion mutation; A change in the translational reading frame

Question 11

Define a silent mutation

Answer 11

Caused by a point mutation; There is no change in the amino acid sequence.

Question 12

Define a mutagen

Answer 12

Agent that increases the mutation rate by 10 to 1000 times (Radiation or various chemicals)

Question 13

Define a plasmid

Answer 13

Circular, extrachromosomal DNA molecules. Thought to give advantage over microbes without a plasmid. (Could code for genes for F factor pili, or R Factors, or Virulence factors)

Question 14

Describe how strands of DNA are held together

Answer 14

The strands are held together by hydrogen bonds between based pairs (A-T, and C-G).

Question 15

What is the backbone of DNA?

Answer 15

Sugar (Deoxyribose-phosphate)

Question 16

What are the nucleotide bases of DNA?

Answer 16

Adenine (A), Thymine (T), Cytosine (C), Guanine (G)

Question 17

What is the role of the promoter sequence during transcription?

Answer 17

Binding site for RNA polymerase. Attrachs RNA polymerase to the gene so transcription can occur.

Question 18

What is the product of transcription?

Answer 18

RNA

Question 19

What is the product of translation?

Answer 19

Proteins

Question 20

What is the product of DNA replication?

Answer 20

A new copy of DNA

Question 21

What is the name of the enzyme that performs trancription?

Answer 21

RNA polymerase

Question 22

What is the role of ribosomes during translation?

Answer 22

Forms the bonds between the amino acids during Translation. Building up the protein.

Question 23

What is the role of mRNA during translation?

Answer 23

Acts as a blueprint that is read by the ribosome to build proteins.

Question 24

What is the role of Codons during translation?

Answer 24

Codons code for amino acids, also tell the Ribosome when to start and stop protein synthesis.

Question 25

Decribe the operon structure of gene regulation.

Answer 25

Composed of the control region (promoter, and operator), and the Structural genes.

Question 26

What is the role of a repressor protein regulating gene expression?

Answer 26

Repressor protein are able to bind to the operator region of the operon, preventing RNA polymerase from reading the gene.

Question 27

Describe how genes can be regulated based on the needs of the cell?

Answer 27

Repressor proteins can be activated or deactivated based on substrates present or not present. (For lac operon repressor gets deactivated when lactose is present. For Trp operon repressor gets activated when excess amounts of tryptophan is present.)

Question 28

Decribe how a lac operon is regulated

Answer 28

For lac operon repressor gets deactivated when lactose is present.

Question 29

Describe how a trp operon is regulated

Answer 29

Trp operon repressor gets activated when excess amounts of tryptophan is present.

Question 30

What are the three mechanism that bacteria use for horizontal gene transfer?

Answer 30

Transformation, Conjugation, Transduction

Question 31

Describe the flow of genetic information within a cell.

Answer 31

Transcription then Translation to proteins.

Question 32

Describe the flow of genetic information of genetic information between generations of cells

Answer 32

Through Cellular replication, and passing copies of DNA to the daughter cells. (DNA replication)

Question 33

Describe the flow of genetic information between cells of the same generation

Answer 33

Through mechanisms of horizontal gene transfer

Question 34

What is the Enzyme that performs DNA replication?

Answer 34

DNA polymerase

Question 35

What is the difference between gene and genome

Answer 35

A gene is a segment of the genome that codes for a specific protein. A geneom is a collection of all the genes.

Question 36

What gets copied during DNA replication?

Answer 36

DNA

Question 37

What gets read during Transcription?

Answer 37

DNA

Question 38

What gets read during Translation?

Answer 38

mRNA

Question 39

m in mRNA stands for what?

Answer 39

Messenger

Question 40

When does transcription begin?

Answer 40

When RNA polymerase binds to the promoter sequence of a gene.

Question 41

True or false: Is mRNA immediately ready for translation in prokaryotes?

Answer 41

True

Question 42

Define constitutive proteins

Answer 42

Proteins that are expressed at a fixed rate. (genes are always on)

Question 43

Define regulated proteins,

Answer 43

Proteins are expressed only as needed. (Genes can be turned on and off depending the cellular needs for the protein)

Question 44

Define Repressible genes

Answer 44

Gene expression is normally on, but can be repressed. (if there are excess amounts of proteins.)

Question 45

Define Inducible genes

Answer 45

Gene expression is normally off, but can be turned on (if the cell needs the protein in certain circumstances)

Question 46

Define Structural genes

Answer 46

Genes that code for proteins. ( enzymes that work in a metabolic pathway)

Question 47

What are the mechanisms for bacteria to acquire new genotypes?

Answer 47

Mutation, Plasmids, Transformation, Conjugation, Transduction

Question 48

Why are mutations important for a population?

Answer 48

Mutations are necessary for adaptation and evolution. (Gives genetic variation)

Question 49

Define spontaneous mutations

Answer 49

Occurs due to errors by DNA polymerase

Question 50

Define vertical gene transfer

Answer 50

Transfer of genes that occurs during reproduction, between generations of cells.

Question 51

Define horizontal gene transfer

Answer 51

Transfer of genes between cells of the same generation. 3 Mechanisms

Question 52

Define transformation

Answer 52

Genes are transfered by DNA fragment being excreted into the environments. The DNA fragment is enveloped by another cell. The DNA fragment aligns with complementary bases of the original DNA, and recombination occurs between DNA fragment and original DNA.

Question 53

Define Conjugation

Answer 53

A cell to cell transfer of plasmids through a pili. The Conjugating cells must be of opposite mating types. Donors F+, Recipients F-.

Question 54

Define transduction

Answer 54

Bacterial DNA is transferred from a donor cell to a recipient cell inside a bacteriophage.

Question 55

What is F factor?

Answer 55

A gene on a plasmid that could code for a pili allowing to transfer the plasmid itself.

Question 56

What is R factors?

Answer 56

A gene on a plasmid that could code for antibiotic resistance.

Question 57

What is virulence factors?

Answer 57

Encodes for factors that increase the pathogenicity of an organism? (Toxins)

Question 58

What is the difference between a promoter and a start codon?

Answer 58

A promoter is on DNA and acts as binding site for RNA polymerase. A start codon is on mRNA and signals to a ribosome that it should start translating and building the proteins.