Download Retroviruses - stephen fleenor

Warm-Up (12/02)
On the piece of white paper from the back, answer
the following question.
Explain the difference between
the lytic cycle and the lysogenic
cycle. What do they both have
in common?
Name
Date
Period
Retroviruses
• Normal viruses contain DNA and inject that DNA
into a host cell.
• Retroviruses
contain RNA.
RNA
injected RNA
DNA
reverse
transcriptase
RNA
(gene expression)
Retroviruses
• Normal viruses contain DNA and inject that DNA
into a host cell.
• Retroviruses
contain RNA.
RNA
injected RNA
DNA
reverse
transcriptase
RNA
(gene expression)
If I wanted to target HIV
fight it without hurting
human enzymes, which
enzyme should I target?
HIV
HIV goes through the lytic cycle and acquires
mutations very rapidly.
∴, it evolves very rapidly.
“retroviral” drugs
HIV
HIV goes through the lytic cycle and acquires
mutations very rapidly.
∴, it evolves very rapidly.
“retroviral” drugs
HIV
HIV goes through the lytic cycle and acquires
mutations very rapidly.
∴, drug resistance can happen easily.
“retroviral” drugs
Critical Thinking Question #1
Discuss this question with your partner and write or
represent it. I will call on three people to share their
partners’ answers.
Explain how HIV strains can become resistant to
anti-retroviral drugs.
What makes HIV so bad?
DNA
RNA
injected DNA
injected RNA
Host cell machinery,
including errorchecking enzymes
RNA
(gene expression)
Host cell machinery,
including errorchecking enzymes
DNA
RNA
(gene expression)
What makes HIV so bad?
RNA
DNA
Mutations!
Mutations!
injected DNA
injected RNA
No error checking!
Host cell machinery,
including errorchecking enzymes
RNA
(gene expression)
Host cell machinery,
including errorchecking enzymes
DNA
RNA
(gene expression)
Critical Thinking Question #2
Discuss this question with your partner and write or
represent it. I will call on three people to share their
partners’ answers.
Draw the lytic cycle of the HIV virus (as you did
yesterday), showing reverse transcriptase. Also
indicate the point at which the genetic material
can acquire mutations much more rapidly than
DNA-based viruses.
Closure
On the piece of white paper from the
back, answer the following question:
Why do retroviruses evolve more
rapidly than DNA-based viruses?
Name
Date
Period
Scale
1 – 10