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Flashcards in DNA Lecture 2 Deck (44):
1

It is the nucleic acid covalent structure and the nucleic acid sequence, and it stores genetic information

Primary Structure

2

What are three ways to represent pentadeoxyribonucleotide?

pA-C-G-T-A(OH)
pApCpGpTpA
pACGTA

3

a primary structure composed of less than or equal to 50 nucleotides is a(n)

oligonucleotide

4

a primary structure composed of more than 50 nucleotides is a(n)

polynucleotide

5

any regular, stable structure taken up by some or all of the nucleotides in a nucleic acid

Secondary Structure

6

Complex folding of large chromosomes within eukaryotic chromatin and bacterial nucleoids

Tertiary Structure

7

What did the experiments of Avery, MacLeod, and McCarty (1944) provide evidence of?

That DNA is the bearer of genetic information

8

How did Avery, MacLeod, and McCarty provide evidence that DNA is the bearer of genetic information?

DNA extracted from a virulent strain of bacterium was injected into a nonvirulent strain of the same bacterium, it genetically transformed the nonvirulent strain into the virulent strain

9

How did Hershey and Chase (1952) provide evidence that DNA carries genetic information?

they used radioactive phosphorous (32p) to tag the DNA and radioactive sulfur to tag the protein viral coat, and showed that when the virus infected its host cell (E. coli), the phosphorous containing DNA of the viral particle enters host cell and provides genetic information for viral replication

10

the sequences of bases from the 5' end to the 3' end in a nucleic acid
•e.g. pACGTA

Primary Structure

11

The sequence of nucleotide bases encodes the sequence of _______ in a protein

A sequence of three nucleotides provides a ____ for an amino acid

amino acids

codon

12

DNA of eukaryotes is in the

Protein synthesis occurs on ___ in the ____

what is the carrier molecule?

nucleus

ribosomes in the cytoplasm

messenger RNA (mRNA)

13

acts as an intermediary by using information encoded in DNA to specify the amino acid sequence of a functional protein

mRNA

14

The triplet codons in mRNA which specify a certain amino acid sequence are referred to as the

standard genetic code

15

T/F Most naturally occurring DNA molecules are too big to determine the sequence of the whole molecule in one operation.

True

16

How can the sequences of nucleotide bases (i.e. primary structure) in DNA be determined?

Chemical cleavage method (Maxam and Gilbert)
Dideoxy method (or chain-terminator method developed by Sanger)

17

Both the chemical cleavage method and the dideoxy method of determining the sequences of nucleotide bases in DNA depend upon starting with a ________, many molecules corresponding to one segment of the extended DNA molecule

homogenous sample of DNA

18

In the first step of DNA cloning, DNA is cut at precise locations. The DNA segment is prepared by treating the isolated DNA with ______

An enzyme

19

The enzyme that is used to prepare DNA segments in cloning catalyzes hydrolytic cleavage within a nucleic acid chain, called an

endonuclease

20

These nucleases cleave DNA only at specific recognition sequences to generate a set of smaller fragments

For example, the enzyme EcoR1 recognizes the sequence 5' GAATTC 3' and hydrolyzes what bond between G and A?

Restriction endonucleases

The phosphodiester bond

21

How many types of restriction endonucleases are there?

3 (Type I, II, and III)

22

These restriction endonucleases are large and cleave the DNA a certain number of base pairs away from the recognition sequence and require energy of ATP

Type I and III

23

This type of restriction endonuclease is simpler than the others, requires no ATP, and cleave the DNA within the recognition sequence itself

Type II

24

Treatment of DNA with restriction endonucleases will result in a finite number of fragments, which correspond to __________ at each of the recognition sites

Hydrolysis

25

Do restriction endonucleases cleave both strands of DNA?

What are at the ends?

Yes.

Fragments with unpaired nucleotides

26

Is it possible to separate all of the fragments from one another to gain more purity after treatment with restriction enzymes?

No. Impossible.

27

In step 2 of DNA cloning, a known small molecule of DNA is selected, and it is typically a plasmid or viral DNA

Cloning Vector

28

A circular DNA molecules that replicates separately from the host molecule and is typically selected for as a cloning vector

Plasmid

29

What is a cloning vector (plasmid) treated with?

What does this achieve?

The same restriction enzyme that the DNA was treated with

The ends of the cleaved plasmid DNA matches those of the unknown fragments

30

In step 3, the DNA fragments are joined covalently. What links the cloning vector and the DNA to be cloned? It's another 'special' enzyme

DNA ligase

31

What bonds are formed between the ends of the DNA fragments and the cleaved plasmid molecule?

What is the name of the structure that results?

Phosphodiester bonds

Recombinant DNA molecules

32

In step 4, recombinant DNA from the test tube is moved to the host cell where _______ can occur

DNA replication

33

When recombinant DNA is moved to the test tube suspension, the bacteria can take it up from the solution. How much DNA can a typical bacterium take up?

A single molecule

34

In step 5, the bacterial cell suspension is spread on an agar nutrient plate and allowed to grow. Colonies form which correspond to a single cell that has been multiplied.

T/F: Each cell contains one copy of one recombinant molecule

False. Each cell contains many replicated copies of one recombinant molecule. Molecules containing one fragment can then be isolated from a culture of a single colony.

35

Growing cells on an agar plate in the presence of an antibiotic allows for what?

Selections of colonies with and without the DNA

36

What are the most common vectors?


Why are they useful?

Plasmids and bacteriophage chromosomes

They replicate independently of the host cell

37

In our example of vectors, what E.coli plasmid is used as a vector? It contains a high origin of replication and genes conferring resistance to ampicillin and tetracycline (antiobiotics)

pBR322

38

To allow for further study, the recombinant DNA is separated from the plasmid. What can be used as a treatment to release the fragment from the plasmid?

The fragment can be separated from the plasmid by a technique called

The restriction enzyme used earlier (in our example, EcoRI)

Gel electrophoresis

39

What are the two types of gel electrophoresis?

Agarose and polyacrylamide

40

Type of gel electrophoresis that is a cross-linked polysaccharide

Type of gel electrophoresis that is a cross-linked polymer of acrylamide and N,N'-methylenebisacrylamide

When acrylamide is polymerized in water, what is formed?

Agarose

Polyacylamide

Gel

41

What cause the particles to migrate in gel electrophoresis?

An electric field, the particles are charged

42

What charge do DNA molecules have?

Therefore, they move towards the cathode or anode?

Negative

Towards the anode (anions move toward the anode)

43

In agarose and PAGE electrophoresis, the rate of movement of molecules depends upon what, due to the sieving effect of the gel?

Their size

44

Do larger or smaller molecules move more rapidly through electrophoresis?

The smaller/shorter molecules moved more rapidly and are found farthest down the gel.