Yesterday s Picture UNIT 3E

Transcription

1 Warm-Up The data above represent the results of three different crosses involving the inheritance of a gene that determines whether a certain organism is blue or white. Which of the following best explains the mechanisms of inheritance of the gene? a. The allele for white is an autosomal dominant allele because a 1:1 phenotype ratio of blue to white among both sexes is observed in cross 3. b. The allele for white is an autosomal dominant allele because an approximate 3:1 phenotype ratio of blue to white is observed in cross 1. c. The allele for white is an X-linked dominant allele because no white females are produced in cross 1. d. The allele for blue is an X-linked dominant allele because there are no blue male offspring in cross 2.

2 Yesterday s Picture

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4 with the RNA. protein protein RNA Host Cell

5 (RT) with the RNA. protein protein reverse transcriptase RNA Host Cell

6 (RT) with the RNA. RT makes DNA from RNA, which is then used in the lytic cycle. protein protein reverse transcriptase RNA DNA Replication and assembly of viral proteins Host Cell

7 (RT) with the RNA. RT makes DNA from RNA, which is then used in the lytic cycle. Retroviruses acquire mutations more quickly than DNA-based viruses because there is no RNA-error checking machinery. Host cell machinery, including errorchecking enzymes DNA Mutations! injected DNA RNA (gene expression) DNA-Based Virus

8 (RT) with the RNA. RT makes DNA from RNA, which is then used in the lytic cycle. Retroviruses acquire mutations more quickly than DNA-based viruses because there is no RNA-error checking machinery. No error checking! Mutations replicated and transcribed! Retrovirus RNA DNA Mutations! injected RNA RNA (gene expression)

9 (RT) with the RNA. retrovirus DNA virus RT makes DNA from RNA, which is then used in the lytic cycle. percentage of genome changed Retroviruses acquire mutations more quickly than DNA-based viruses because there is no RNA-error checking machinery. time Retroviruses reproduce (almost) as fast as DNA-based viruses, but more mutations = faster evolution.

10 (RT) with the RNA. RT makes DNA from RNA, which is then used in the lytic cycle. Retroviruses acquire mutations more quickly than DNA-based viruses because there is no RNA-error checking machinery. Retroviruses reproduce (almost) as fast as DNA-based viruses, but more mutations = faster evolution. Retroviruses such as HIV can quickly evolve drug resistance.

11 (RT) with the RNA. RT makes DNA from RNA, which is then used in the lytic cycle. Retroviruses acquire mutations more quickly than DNA-based viruses because there is no RNA-error checking machinery. Retroviruses reproduce (almost) as fast as DNA-based viruses, but more mutations = faster evolution. Retroviruses such as HIV can quickly evolve drug resistance.

12 CTQ #1 Explain how HIV strains can become resistant to anti-retroviral drugs.

13 CTQ #2 Draw the lytic cycle of the HIV virus (as you did yesterday), showing reverse transcriptase. Indicate the point at which the genetic material can acquire mutations much more rapidly than DNAbased viruses (LO 3.30).

14 Closure Explain why retroviruses evolve more rapidly than DNA-based viruses. (LO 3.29)