Viruses 7.6-7.7

Question 1

Human Genome Project

Answer 1

the joint government and private sector research project that sequenced the human genome

Question 2

Variable number tandem repeats (VNTRs)

Answer 2

non-coding, repeating sequences of DNA that vary in length between homologous chromosomes and between individuals

Question 3

LINEs (long interspersed nuclear elements)

Answer 3

repetitive DNA sequences, approximately 6500 bp in length on average, interspersed throughout the genome

Question 4

SINEs (short interspersed nuclear elements)

Answer 4

repetitive DNA sequences, approximately 500 bp in length on average, interspersed throughout the genome

Question 5

Transposon

Answer 5

a small segment of DNA that can move to a different position in the genome

Question 6

Comparative genomics

Answer 6

the study of the organization, functions, and relationships of the genomes of different species

Question 6

Pseudogene

Answer 6

a sequence of DNA that is similar to an existing gene but does not code for proteins

Question 7

Retrovirus

Answer 7

a virus that uses reverse transcriptase for replication

Question 8

Reverse transcriptase

Answer 8

a viral enzyme that uses RNA as a template strand to synthesize complementary DNA

Question 9

Transduction

Answer 9

the use of viral vectors to introduce new genetic material into a cell

Question 10

Lytic cycle

Answer 10

the replication process in viruses in which the virus’s genetic material uses the copying machinery of the host cell to make new viruses

Question 10

Lysogenic cycle

Answer 10

the replication process in viruses, in which the viral DNA enters the host cell’s chromosome; it may remain dormant and later activate and instruct the host cell to produce more viruses.

Question 12

Provirus

Answer 12

The viral DNA that has become part of the host chromosome. It can invade a cell but does not kill it.

Question 12

Life Cycle of a Bacteriophage

Answer 12

1. A bacteriophage locks onto the bacterium’s cell wall and deposits its DNA inside the cytoplasm.
2. The viral DNA then controls the functioning of the bacterium’s cell parts.
3. Even though the number of genes of a phage virus is small, the DNA it contains is enough to prevent the host bacterial cell from performing its normal life functions.

Question 12

The Lytic Cycle In detail

Answer 12

1. Attachment: A phage virus attaches to a host bacterial cell.
2. Entry: The phage’s DNA is injected inside the bacterium.
3. Replication: The host cell replicates the phage DNA and produces phage protein coats.
4. Assembly: The phage cells are assembled inside the bacterium cell.
5. Lysis and Release: The host cell is destroyed, and the phage cells are released.

Question 12

Interruption of the Production of a Host’s Protein
Synthesis by RNA retrovirus

Answer 12

a) Retroviral RNA uses reverse transcriptase to
make retroviral DNA using host cell materials
b) New retroviral DNA splices into host
chromosome and becomes dormant
c) Dormancy period of variable length
d) Spliced retroviral DNA becomes active again
e) Deactivates mRNA of host cell
f)Makes retroviral mRNA from host cell materials
g) Host ribosomes “read” retroviral mRNA code
h) Ribosomes produce retroviral protein

Question 12

The Lysogenic Cycle in detail

Answer 12

1. Attachment: A phage virus attaches to a host bacterial cell.
2. Entry: The phage’s DNA is injected inside the bacterium.
3. Provirus Formation: viral DNA becomes part of the host cell’s chromosome for many generations.

Question 12

Interruption of the Production of a Host’s Protein
Synthesis by DNA Virus

Answer 12

a) Viral DNA released into host cell
b) Replication of viral DNA
c) Deactivates mRNA of host cell
d) Makes viral mRNA using host cell materials
e) Host ribosomes “read” viral mRNA code
f)Ribosomes produce viral protein

Question 12

How do retroviruses leave the host

Answer 12

extrusion

Question 12

Host cell 3 functions while infected

Answer 12

1. Manufacturing hundreds of copies of viral DNA
2. Producing new proteins for viral protein coats
3. Producing a powerful enzyme that dissolves the bacterium’s cell wall.

Question 12

Interruption of the Production of a Host’s Protein
Synthesis by RNA Virus

Answer 12

a) Viral RNA released into host cell
b) Replication of viral RNA
c) Deactivates mRNA of host cell
d) RNA serves as mRNA
e) Host ribosomes “read” viral mRNA code
f)Ribosomes produce viral protein

Question 13

Retroviruses using reverse transcriptase

Answer 13

To hijack a host cell’s machinery, certain RNA viruses employ reverse transcriptase, an enzyme that converts viral RNA into complementary DNA (cDNA). This cDNA enables the host cell’s ribosomes to recognize and utilize the viral genetic information, reversing the typical DNA-to-RNA sequence.