Tuesday
July 29, 2014

Homework Help: Biology

Posted by Deepa on Thursday, May 8, 2014 at 10:41pm.

Hello, this is my biology assignment. I filled the answer's but I just need your help to correct me if I'm wrong Thank you.

1) The discovery of restriction endonucleases was crucial to the development of recombinant DNA technology because these enzymes.
a) always cut DNA at either end of a gene
b) always cut DNA leaving unpaired lengths of bases tht have a charge.
c) cut DNA at specific and predictable sequences of bases
d) tag DNA so that individual fragments can be identified
e) all cut DNA leaving sticky ends

My answer: b

2) The following are all steps in the production of a bacterium having recombinant DNA, which includes an inserted non bacterial gene. They are in random order.
1. gel electrophoresis of plasmid DNA from bacteria in colonies showing antibiotic resistance
2. sticky nds are allowed to pair up
3. a restriction endonuclease is used to remove the gene to be inserted from its source and also to cut open a plasmid that includes a gene for antibiotic resistance
4. the bacterial colonies are treated with antibiotic
5. treatment with ligase
6. transformation

The correct order of these steps is
a) 2,5,1,3,4,6
b) 4,3,6,2,5,1
c) 5,1,2,3,4,6
d) 3,2,5,6,4,1
e) 6,3,5,2,4,1

MY ANSWER : b

3) When recombinant DNA is formed, it is necessary to join the sugar-phosphate backbones of the plasmid DNA and the introduced DNA. Which of the following is used to do this?
a) heat
b) DNA polymerase
c) helicase
d) gyrase
e) ligase

MY ANSWER: d

4) You are a geneticist who is interested in a particular gene on human chromosome number eight. You have used a restriction endonuclease to produce fragments of the chromosome and cloned each fragment in a different culture of bacteria. You now need to find out which culture contains the fragment with the gene of interest. You have available to you a single-stranded radioactive DNA probe complementary to the template strand of the gene. In what order would you perform the following for each of the bacterial colonies?
1. Allow annealing between the probe and the DNA from the bacteria to occur
2. Flood the culture with the DNA probe.
3. Separate the strands of double-stranded DNA from the bacteria using heat.
4. Break open the bacteria.
5. Prepare an autoradiograph
6. Wash away unannealed probes.
a) 5,4,3,2,1,6
b) 4,3,2,1,6,5
c) 6,3,2,1,4,5
d) 2,1,3,6,5,4
e) 4,5,3,1,2,6
MY ANSWER: e

There aremore so I will be posting more :) pls help me.

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