Chapter 18 Part 2

Question 1

Transposable elements

Answer 1

DNA sequences that can move about in the genome

Question 2

Interesting fact –> flip the back

Answer 2

Transposition often cause mutations, either by inserting into a gene and disrupting it or by promoting chromosome rearrangements, such as deletions, duplications, and inversions

Question 3

Flanking Direct Repeats

Answer 3

Short, directly repeated sequences from 3 to 12 bp long – present on both sides of most transposable elements

Question 4

What steps are required to create flanking direct repeats

Answer 4

1. Staggered cuts are made in the target DNA
2. A transposable element inserts itself into the DNA
3. The staggered cuts leave short single-stranded pieces of DNA
4. Replication of the single-stranded DNA

Question 5

Terminal Inverted Repeats

Answer 5

Sequences from 9-40 base pairs in length that are inverted complement of each other

5’-ACA …..CTG-3’
3’-GTC……ACA-5’

Notice…how the sequence from left to right in the top strand is the same as the sequence from right to left in the bottom

Question 6

Why do we need terminal inverted repeats

Answer 6

The two sequences are not simple inversions, as their name might imply; rather, they are both inverted and complementary

They are important so enzymes that catalyze transposition – enzymes required for transpositions to take place – recognize that specific region of the DNA

Question 7

Transposition

Answer 7

The movement of a transposable element from one location to another

Question 8

How do transposable elements move?

Answer 8

1. First, staggered breaks are made in the target DNA
2. The transposable element is joined to a single-stranded ends of the target DNA
3. DNA is replicated at the single-stranded gaps

Question 9

Transposase

Answer 9

An enzyme that often encoded by the transposable element, is used to make the staggered breaks in DNA and to integrate the transposable element into a new site