Chapter 21.1

Question 1

learning objective 1 - outline the procedure for cloning a gene into a vector

Answer 1

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Question 2

learning objective 2 - describe how cDNA is made

Answer 2

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Question 3

learning objective 3 - compare and contrast a genomic library with a cDNA library

Answer 3

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Question 4

how is researching proteins compared to finding a needle in a hay stack?

Answer 4

because in all species, any given cell can express hundreds or thousands of different proteins

Question 5

what is gene cloning?

Answer 5

refers to the process of making copies of a gene, which can be done through techniques like PCR or introduction of a gene into a vector

Question 6

what are the benefits of DNA sequencing?

Answer 6

cloned genes provide enough DNA for sequencing, which helps find the sequence of a gene’s promoter, regulatory sequence, and coding sequence, as well as identifying alleles that can cause cancer and disease

Question 7

what is a vector?

Answer 7

a small segment of DNA that a gene is inserted into

Question 8

When is a vector used?

Answer 8

When a gene is removed from its native site within a chromosome, it is inserted into vector

Question 9

what is the function of a vector?

Answer 9

it can function and replicate independently of chromosomal DNA and produce copies, so it can act as a carrier of the DNA segment that is going to be cloned.

Question 10

where is a vector replicated?

Answer 10

a vector is replicated within a living cell, also called the host cell. when the vector is replicated, so is the DNA it holds

Question 11

where are vectors commonly derived from?

Answer 11

plasmids or viruses

Question 12

most vectors are ____

Answer 12

plasmids

Question 13

what is a plasmid?

Answer 13

small circular pieces of DNA

Question 14

what kind of genes to plasmids carry?

Answer 14

plasmids tend to carry genes that confer resistance to antibiotics or other toxic substances - these are called R factors

Question 15

what else do plasmids carry?

Answer 15

they also contain an origin of replication sequence

Question 16

what does the origin of replication sequence within a plasmid determine?

Answer 16

whether or not the vector can replicate within a particular type of host cell

Question 17

while some plasmids have a _______ range of origins of replication, many vectors have _____ range

Answer 17

broad, limited

Question 18

some plasmids can make ______ copies, while others can only make ____ or _____ copies

Answer 18

100-200, one or two

Question 19

what is a selectable marker?

Answer 19

when the expression of the gene selects for the growth of the host cells, such as the ability to grow in toxic environments

Question 20

how do viral vectors work?

Answer 20

because viruses infect living cells and propagate within them, a gene can be inserted into a viral genome, where the gene is then replicated once the viral DNA is replicated

Question 21

what is used to clone large pieces of DNA?

Answer 21

cosmids, bacterial artificial chromosomes (BACs), and yeast artificial chromosomes (YACs)

Question 22

how does DNA get inserted into a vector?

Answer 22

by cutting and pasting of the DNA fragments using enzymes called restrictions endonuclease/restriction enzymes

Question 23

how do restriction enzymes work?

Answer 23

the restriction enzymes bind to a specific base sequence, then cleave the DNA backbone at two locations

Question 24

what are sticky ends?

Answer 24

single stranded DNA regions, which holds DNA strands together

Question 25

what are sticky ends for?

Answer 25

two dna sequences that have been cut will have sticky ends, which will be put together to form one larger DNA sequence. dna ligase forms hydrogen bonds and puts them back together

Question 26

palindromic

Answer 26

the sequence in one strand is the same as that in the complimentary strand when read in the opposite direction