Highlights Lecture #23 Spring 2017

1. DNA fingerprinting relies on short repeated DNA sequences that vary between individuals. Using PCR, one can amplify these sequences and identify from a crime scene (for example) if a suspect’s DNA matches the DNA at the scene. It can also be helpful in paternity testing.

2. Microarrays are modern techniques for analyzing all of the sequences of an organism simultaneously. Sequences analyzed can be the RNA collection of a cell. The key to microarrays is the ability to attach specific sequences precisely on a grid. To do microarray analysis, you would do the following things.

a. Synthesize a collection of nucleic acids complementary to each of the mRNAs that a cell could theoretically produce and then sort them out and precisely put copies of each one in its own spot on a grid

b. Take a batch of mRNAs made by one cell, put a dye on them (blue, for example)

c. Take a batch of mRNAs made by another cell and put a different dye on them (yellow, for example)

d. Mix the mRNAs from the two cells and then let them anneal to their complementary sequences on the grid.

e. mRNAs common to the two cells would show color green color. mRNAs found only in the first cell will show blue color. mRNAs from cells only in the second cell will show yellow color. The intensity of each color would tell the amount of mRNA and the position of the color on the grid would tell exactly which mRNA it was.

Highlights Viruses

1. Viruses infects cells of all types.

2. Viruses contain nucleic acid (RNA or DNA, single-stranded or double-stranded, depending on the virus) and have a protein coat.

3. The protein coat comes from a gene encoded by the virus and it allows the virus to attach to the cell(s) it infects.

4. Viral infection includes the steps of 1) attachment; 2) injection of the viral nucleic acid; 3) replication and translation of the viral information by the cell; 4) packaging of the viral nucleic acid into coat proteins; and 5) bursting of the cell to release viral particles for more infection.

5. HIV is a retrovirus, meaning it has an RNA genome and an enzyme called reverse transcriptase that converts the viral RNA into double-stranded DNA. HIV has a protein that attaches to CD-4 (a protein found on the membrane of immune system cells).

6. When double-stranded viral HIV DNA is made, an enzyme called integrase inserts (attaches) the viral DNA inside of the host chromosome where it stays. The inserted DNA has a strong promoter that RNA polymerase uses to make more copies of the viral RNA, which continues the cycle.

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