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AS Biology > BM: DNA & RNA > Flashcards

BM: DNA & RNA Flashcards

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1
Q

Name two types of nucleic acid:

A

DNA and RNA

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2
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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3
Q

What does RNA stand for?

A

Ribonucleic acid

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4
Q

What is the function of DNA?

A

To store genetic information.

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5
Q

What is the main function of RNA?

A

Transfers genetic information from DNA to the ribosomes.

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6
Q

What do ribosomes do with the genetic information they receive from RNA?

A

They read the RNA to make polypeptides/proteins in a process called translation.

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7
Q

What are ribosomes made of?

A

RNA and proteins

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8
Q

What monomer makes up DNA and RNA?

A

Nucleotides

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9
Q

What are nucleotides?

A

A type of biological molecule that is the monomer of nucleic acids.

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10
Q

Draw a nucleotide and list its components:

A
  • A pentose sugar
  • A nitrogen-containing organic base
  • A phosphate group
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11
Q

What is a pentose sugar?

A

A sugar that contains 5 carbon atoms.

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12
Q

How do they parts of a nucleotide join together?

A

Through condensation reactions to form a mononucleotide.

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13
Q

How do two nucleotides join together?

A

Through a condensation reaction between the pentose sugar of one nucleotide and the phosphate group of another nucleotide.

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14
Q

What bond forms between two nucleotides?

A

Phosphodiester bond.

(The bond is classed as the entirety of the phosphate group, and the two ester bonds on either side, joining the phosphate to the two pentose sugars).

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15
Q

What is the pentose sugar in DNA?

A

Deoxyribose

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16
Q

What are the four possible bases in DNA?

A
  • Adenine
  • Thymine
  • Cytosine
  • Guanine
17
Q

What pentose sugar does RNA have?

A

Ribose

18
Q

What are the four possible bases in RNA?

A
  • Adenine
  • Uracil
  • Cytosine
  • Guanine
19
Q

The chain of sugar and phosphates formed as a result of condensation reactions between nucleotides, is known as what?

A

Sugar-phosphate backbone.

20
Q

What structure does DNA have?

A

Double-helix

21
Q

What is a DNA molecule?

A

A double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs.

22
Q

What is an RNA molecule?

A

A relatively short polynucleotide chain.

23
Q

How is the double-helix structure of DNA formed?

A
  • Two DNA polynucleotide strands join together by hydrogen bonding between the bases - via complementary base pairing.
  • The two antiparallel polynucleotide strands twist to form the double-helix.
24
Q

What is complementary base pairing?

A

Where bases only pair with one other type of base.

A & T (U)

G & C

25
Q

What does complementary base pairing mean for the amount of each base in a DNA molecule?

A

There will always be equal amounts of adenine and thymine and equal amounts of cytosine and guanine.

26
Q

How many hydrogen bonds form between adenine and thymine?

A

Two

27
Q

How many hydrogen bonds form between cytosine and guanine?

A

Three

28
Q

When was DNA first observed?

What did scientists first believe about it?

A

The 1800s.

Scientists doubted it could carry genetic code because it has a relatively simple chemical composition. Some thought genetic info must be carried by proteins which are much more chemically varied.

29
Q

When was it shown that DNA carried the genetic code?

What was also discovered at this time?

A

1953.

Also the year that Watson and Crick determined the double-helix structure, which helps DNA to carry out its function.

30
Q

Why is DNA a stable molecule?

A
  • Phosphodiester backbone protects the more chemically reactive bases within the double helix.
  • Hydrogen bonds linking bases form bridges between backbones, offering stability - higher proportion of C & G pairings, the more stable the molecule (as this pairing has higher amount of bonds).
31
Q

How is DNA adapted to carry out its function?

A
  • Very stable structure which passes from generation to generation unchanged - mutations are repaired, so persistent mutations are uncommon.
  • Two strands are joined with weak hydrogen bonds allowing for easy separation during replication and protein synthesis.
  • Extremely large molecule, so carries lots of genetic information.
  • Base pairs are within the helical cylinder of deoxyribose-phosphate backbone, so genetic info is somewhat protected from being corrupted by chemical or physical forces.
  • Base pairing leads to DNA being able to replicate and to transfer information as mRNA.
32
Q

What are the similarities and differences between RNA and DNA?

A

AS Biology (51 decks)

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