Exam 2 long answer questions

Question 1

List the steps required to clone a gene

Answer 1

1. isolate plasmid DNA from bacterium
2. isolate target DNA in organisms of interest
3. cut both DNA’s with the same enzyme
4. mix DNA fragments and join them together
5. bacteria take up recombinant plasmids
6. allow bacteria to replicate themselves and the plasmid containing the gene of interest

Question 2

List the potential steps required for human gene therapy

Answer 2

1. Gene from a normal individual is cloned. The cloned gene is inserted into a virus.
2. Cells from the patient are collected and infected with a harmless virus
3. The virus inserts its genes and the healthy human gene into the patient cell’s chromosomes
4. The engineered cells are injected into the patient

Question 3

List and describe Darwin’s two observations and his inference (conclusion) that pertain to natural selection.

Answer 3

1. all species tend to produce excessive numbers of offspring
2. organisms vary, and much of this variation is heritable
   Interference: those individuals best suited to survive the given environment generally survive the most offspring, can lead to adaptation of the population to the environment over time

Question 4

List and describe five reproductive barriers between species. For each reproductive barrier, include whether it is prezygotic or postzygotic.

Answer 4

Prezygotic barriers include

• temporal isolation
• habitat isolation
• behavioral isolation
• mechanical isolation
• gametic isolation.

Postzygotic barriers include
-reduced hybrid viability
-reduced hybrid fertility
hybrid breakdown