Chapter 9.5: Finding the Genes in Genomes

Question 1

What is the annotation of the genome?

Answer 1

parsing out which sequences of DNA do which tasks

Question 2

Describe retroviruses

Answer 2

 Retroviruses carry their genetic information in molecules of RNA  As part of their gene-transmission, retroviruses contain the unusual enzyme known as RNA-dependent DNA polymerase, or simply reverse transcriptase  After infecting a cell, a retrovirus uses reverse transcriptase to copy its single strand of RNA into a mirror-image strand of complementary DNA (cDNA)

Question 3

When is DNA a homolog?

Answer 3

 A segment of DNA is said to be a homolog of a sequence in another species when the two show evidence of derivation from the same DNA sequence in a common ancestor

Question 4

After Obtain mRNA from red blood cell precursors, what is step 2 of making a cDNA library?

Answer 4

Create a hybrid cDNA-mRNA molecule using reverse transcriptase and oligo-dT primer

Question 5

After Heat the mixture to separate mRNA and cDNA strands, and then eliminate the mRNA transcript. The 3’ ends of the cDNA strands loop around and bind by chance to complementary nucleotides within the same strand, forming a “hairpin loop” that serves as the primer for DNA polymerization, what is step 4 of making a cDNA library?

Answer 5

Create a second cDNA strand complementary to the first. After the reaction is completed, the enzyme S1 nuclease is used to cleave the hairpin loop.

Question 6

Define open reading frames (ORFs)

Answer 6

stretches of nucleotides that have a reading frame of triplets uninterrupted by a stop codon

Question 7

When is a DNA sequence said to be conserved?

Answer 7

 When homologs of a DNA sequence are found in many different species, the sequence is said to be conserved

Question 8

After Create a second cDNA strand complementary to the first. After the reaction is completed, the enzyme S1 nuclease is used to cleave the hairpin loop., what is the final step of making a cDNA library?

Answer 8

Insert the newly created double-stranded DNA molecule into a vector for cloning.

Question 9

What is step 1 of making a cDNA library?

Answer 9

Obtain mRNA from red blood cell precursors

Question 10

After Create a hybrid cDNA-mRNA molecule using reverse transcriptase and oligo-dT primer, what is step 3 of making a cDNA library?

Answer 10

Heat the mixture to separate mRNA and cDNA strands, and then eliminate the mRNA transcript. The 3’ ends of the cDNA strands loop around and bind by chance to complementary nucleotides within the same strand, forming a “hairpin loop” that serves as the primer for DNA polymerization