Nucleic acids Flashcards

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1
Q

What are the components of a nucleotide?

A

Pentose sugar, phosphate plus organic base which contains nitrogen.

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2
Q

What are the components of ATP?

A

Ribose sugar, adenine and three phosphate groups joined together

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3
Q

Why is ATP formation endergonic?

A

Because energy is stored in the bond between the second and third phosphate.

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4
Q

Why is ATP hydrolysis exergonic?

A

Energy is released when the bond is broken between the second and third phosphate

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5
Q

Why is ATP known as the universal energy currency?

A

It is used by all living organisms to provide energy for nearly all reactions

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6
Q

Name three cellular processes that require ATP

A

Active transport, muscle contraction, protein synthesis, cell division, bulk transport.

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7
Q

Which bases are pyramidines and how many rings to they have?

A

Cytosine, Thymine, Uracil, they have one ring

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8
Q

Which bases are purines and how many rings to they have?

A

Guanine and Adenine, they have two rings

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9
Q

What are the base pairs and how do they join together?

A

Adenine and Thymine, Cytosine and Guanine. Joined by H bonds

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10
Q

How do you describe the different directions in which the two DNA strands run?

A

One runs from the 5 prime end to the 3 prime end, the other from the 3 prime end to 5 the prime end.

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11
Q

What are the two functions of DNA?

A

replication in dividing cells and coding for the order of amino acids in protein synthesis

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12
Q

Which enzymes are involved in DNA replication and what do they do?

A

DNA helicase breaks the H bonds to separate the strands, DNA polymerase catalyses the condenstation reaction to join the sugar phosphate backbone

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13
Q

Which isotopes were used in Meselson and Stahl’s experiment?

A

Nitrogen 14 and 15

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14
Q

If bacteria were given only N15 with which to form DNA bases, then DNA was extracted and centrifuged, where would the band be in the tube?

A

At the bottom

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15
Q

If bacteria grown in N15 were allowed to divide once in N14, then DNA was extracted and centrifuged, where would the band be in the tube?

A

In the middle

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16
Q

What does it mean that the DNA code is degenerate?

A

There is more than one DNA triplet coding for each amino acid

17
Q

What do you call three bases of mRNA?

A

A codon

18
Q

Which areas of DNA code and which don’t?

A

Exons code, introns don’t

19
Q

What is the name for the process in which non coding parts of the mRNA are removed after transcription?

A

mRNA splicing of introns

20
Q

Which enzymes are involved in transcription and what do they do?

A

DNA helicase breaks the H bonds to separate the DNA strands, RNA polymerase catalyses the condenstation reaction to join the sugar phosphate backbone

21
Q

What do m, r and t RNA stand for?

A

messenger, ribosomal and transfer RNA

22
Q

How many activated tRNA molecules can bind to a ribosome at one time?

A

Two

23
Q

Describe a tRNA molecule

A

It is a clover leaf shape, with an anticodon (three bases) at the bottom and an amino acid attachment site at the top

24
Q

Where does transcription happen? Where does translation happen?

A

In the nucleus and at the ribosome

25
Q

What is a gene?

A

A section of DNA that codes for one polypeptide chain