Chapter 7: Bacterial and Viral Genetic Systems

Question 1

What did the microorganism experiment with leu- and leu+ bacterial colonies tell us regarding supplemental mediums?

Answer 1

A colony that grows ONLY on the supplemented medium has a mutation in a gene that encodes the synthesis of an essential nutrient

Question 2

Regarding medium consumption, which two types of bacteria exist?

Answer 2

1. Prototrophic
2. Auxotrophic

Question 3

Define prototrophic bacteria

Answer 3

Wild type, can eat anything, can survive off minimum medium

Question 4

Define auxotrophic bacteria

Answer 4

Cannot eat everything, needs a complete medium

Question 5

Define minimum medium

Answer 5

A medium with scarely any nutrients, only required by prototrophic bacteria

Question 6

Define complere medium

Answer 6

Contains all substances required by all bacteria, including auxotrophic bacteria

Question 7

Are wild type bacteria signaled with a + or a -, what about mutant bacteria?

Answer 7

Wild type: +
Mutant type: -

Ex:
met+ = wild type
met - = mutant type

Question 8

What does the symbol “s” mean regarding bacteria and antibiotics?

Answer 8

Sensitive to antibiotics

Ex: METs

Question 9

What does the symbol “r” mean regarding bacteria and antibiotics?

Answer 9

Resistant to antibiotics

Ex: METr

Question 10

Define plasmid

Answer 10

Extra-chromosomal small circles of DNA

Question 11

Define conjugation

Answer 11

Direct transfer of DNA from one bacterium to another

Question 12

What is the difference between transformation and transduction?

Answer 12

Transformation: Bacterium take up free DNA

Transduction: Bacterial viruses take DNA from one bacterium to another

Question 13

Who all played a role in the discovery of conjugation? (3 people)

Answer 13

William Hayes: Discovered the “F” facotr

Lederberg and Tatum: confirmed recombination took place between 2 mutant strains

Question 14

What is the F factor, and what does it mean?

Answer 14

F = fertility factor, which means one strain was always the donor while the other was always the recipient.

Question 15

How are the two strains (donor and recipient) depicted? (X+ and X-)

Answer 15

F+ = donor
F- = recipient

Question 16

What is an R plasmid?

Answer 16

Like an F plasmid it can rapidly replicate, but it also contains genes from many bacteria

Question 17

T/F: R plasmids play a role in antibiotic resistance

Answer 17

True

Question 18

What is the difference between a virus and a bacteriophage?

Answer 18

Virus: replicating structure (DNA/RNA) + protein cost

Bacteriophage: bacterial virus

Question 19

There are 2 types of “phages” what are they?

Answer 19

1. Virulent phage
2. Temperate phage

Question 20

Which reproduction cycle does virulent phage use?

Answer 20

Lytic cycle, always kills host cell

Question 21

Which reproduction cycle do temperate phages use?

Answer 21

Lysogenic cycle, inactive prophase, phage DNA integrates into bacterial chromosome

Question 22

T/F: Transduction usually occurs between bacteria of the same or closely related species

Answer 22

True

Question 23

How does cotransuction rate and distance between genes relate? (cotransduction is just genes transferred together)

Answer 23

Higher cotransduction rate = lower distance between genes

Question 24

Is influenza single or double-stranded?

Answer 24

Single

Question 25

What is a retrovirus?

Answer 25

A virus that reverses transcription from RNA to DNA

Question 26

A hypothetical bacterial colony grows well on minimal media plus raffinose. Select the genotype that most correctly represents this colony: A) raf+ B) raf- C) Raf^s D) raf^R Select the explanation of the genotype: A) The colony is resistant to raffinose B) The colony can utilize raffinose as a carbon source C) The colony cannot utilize raffinose as a carbon source D) The colony is sensitive to raffinose

Answer 26

A) raf+ and B) The colony can utilize raffinose as a carbon source Explanation: 1. The question stated nothing regarding sensitivity r resistance, so raf^S and raf^R can be eliminated. If the colony DIDN'T grow on raffinose, it would be raf-, but because it did, it is raf+ 2. With the previous knowledge, resistance, and sensitivity are removed, and sine the colony can grow on raffinose it can utilize it as a carbon source.

Question 27

What is the definition of an auxotroph? A) an organism that grows well in the absence of a required metabolite B) an organism that produces complex compounds in order to grow C) an organism that uses organic carbon in order to grow D) an organs that lacks to the ability to synthesize a required metabolite

Answer 27

D) an organs that lacks to the ability to synthesize a required metabolite

Question 28

Which of the following are characteristics of F- bacterium? (2 correct answers) 1. Bacteria with F factor integrated into the genome 2. Contains a plasmid with only the F factor 3. Contains a plasmid with the F factor and some genomic DNA 4. Does not contain the F factor sequences 5. Recipient of DNA during conjugation

Answer 28

4. Does not contain the F factor sequences 5. Recipient of DNA during conjugation

Question 29

Which of the following is a characteristic of the F+ bacterium? 1. Bacteria with F factor integrated into the genome 2. Contains a plasmid with only the F factor 3. Contains a plasmid with the F factor and some genomic DNA 4. Does not contain the F factor sequences 5. Recipient of DNA during conjugation

Answer 29

2. Contains a plasmid with only the F factor

Question 30

Which of the following is a characteristic of F' (F-prime) bacterium? 1. Bacteria with F factor integrated into the genome 2. Contains a plasmid with only the F factor 3. Contains a plasmid with the F factor and some genomic DNA 4. Does not contain the F factor sequences 5. Recipient of DNA during conjugation

Answer 30

3. Contains a plasmid with the F factor and some genomic DNA

Question 31

Which of the following is a characteristic of the Hfr bacterium? 1. Bacteria with F factor integrated into the genome 2. Contains a plasmid with only the F factor 3. Contains a plasmid with the F factor and some genomic DNA 4. Does not contain the F factor sequences 5. Recipient of DNA during conjugation

Answer 31

1. Bacteria with F factor integrated into the genome

Question 32

Describe conjugation

Answer 32

DNA transferred from a donor to a recipient cell via direct connections

Question 33

Describe transduction

Answer 33

DNA transfer mediated through the action of a bacterial virus

Question 34

Describe transformation

Answer 34

Transfer of genetic material from the extra cellular environment

Question 35

Organize the 4 steps of bacterial transformation into order of occurrence Below are the steps organized alphabetically (not correctly) 1. An enzyme dissociated the DNA into single strands 2. A single-stranded fragment of DNA is imported into the cell 3. DNA binds to the DNA-binding complex 4. The DNA fragment recombines into a homologous region of the bacterial chromosome

Answer 35

1. DNA binds to the DNA-binding complex 2. An enzyme dissociated the DNA into single strands 3. A single-stranded fragment of DNA is imported into the cell 4. The DNA fragment recombines into a homologous region of the bacterial chromosome Shorted version: 1. DNA binding 2. Enyme separation 3. DNA enters cell 4. DNA enters chromosome

Question 36

How can the amount of frequencies in recombinants show the order of the recombinants?

Answer 36

The higher the frequencies, the closer to the reference point; the lower the frequency, the further. Ex: In STR there are 100 recombinants of b+, 50 recombinants of a+ and 25 recombinants of d+. So the order is b+, a+, d+ based of recombination

Question 37

Which of the following statements is true of plasmids? a. They are composed of RNA b. They normally exist outside bacterial cells c. They possess only a single strand of DNA d. They contain an origin of replication

Answer 37

d. They contain an origin of replication

Question 38

Which process of DNA transfer in bacteria requires a virus? a. Conjugation b. Transduction c. Transformation d. All of the above

Answer 38

b. Transduction

Question 39

Conjugation between and F+ and an F- cell usually results in a. two F+ cells b. Two F- cells c. An F+ and an F- cell d. an Hfr cell and an F+ cell

Answer 39

a. two F+ cells

Question 40

A bacterial strain with the genotype his-leu-thr- is transformed with DNA from a strain that is his+leu+thr+. A few leu+thr+ cells and a few his+thr+ cells are found, but no his+leu+ cells are observed. Which genes are furthest apart?

Answer 40

his and leu

Question 41

CRISPR-Cas systems are capable of remembering DNA from a specific pathogen by a. Modifying the bacteria's DNA by methylation b. Acquiring plasmids with antibiotic resistance c. Incorporating part of the pathogen DNA into the CRISPR array d. Cleaving foreign DNA with restriction enzymes

Answer 41

c. Incorporating part of the pathogen DNA into the CRISPR array

Question 42

In which bacteriophage life cycle does the phage DNA incorporate into the bacterial chromosome? a. Lytic b. Lysogenic c. Both lytic and lysogenic d. Neither lytic nor lysogenic

Answer 42

b. Lysogenic

Question 43

In gene mapping using generalized transduction, bacterial genes that are contrasduced are a. far apart on the bacterial chromosome b. on different bacterial chromosomes c. close together on the bacterial chromosome d. on a plasmid

Answer 43

c. close together on the bacterial chromosome

Question 44

What enzyme is used by a retrovirus to make a DNA copy of its genome?

Answer 44

Reverse transcriptase