DNA Flashcards

1
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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2
Q

What is extranuclear DNA?

A

Small amounts of DNA that are found:
- outside the nucleus in mitochondria (in plants & animals)
- in chloroplasts (in plants)

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3
Q

What is the shape of DNA like?

A
  • a long, twisted ladder
  • the two strands twist to form a stable, 3-dimensional double helix
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4
Q

What is a DNA molecule made up of?

A
  • a long chain (polymer), which is made up of small units (monomers)
  • ie, building blocks called nucleotides
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5
Q

What is a nucleotide made up of?

A
  • sugar molecule - deoxyribose (S)
  • phosphate molecule (P)
  • nitrogenous base
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6
Q

What are the different nitrogenous bases?

A
  • adenine (A)
  • thymine (T)
  • guanine (G)
  • cytosine (C)
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7
Q

What is the importance of the four nitrogenous bases?

A
  • these are the foundation of the genetic code
  • they instruct cells on how to synthesise enzymes and other proteins
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8
Q

How are the outer two strands of the ladder of the double helix made up?

A
  • formed by a chain of alternating sugar/phosphate links
  • the bonds between the sugar and phosphate molecules are strong
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9
Q

How are the rungs of the ladder of the double helix made up?

A
  • formed from pairs of bases linked by weak hydrogen bonds
  • the base pairs are attached to the sugar molecules
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10
Q

How do the four nitrogenous base pairs link up?

A
  • adenine with thymine or uracil, using 2 hydrogen bonds
  • cytosine with guanine, using 3 hydrogen bonds
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11
Q

What are the different groups in which nitrogenous base pairs are classified?

A
  • purines
  • pyrimidines
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12
Q

What are purines made up of?

A
  • two fused rings of nitrogen, carbon and hydrogen atoms
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13
Q

Which nitrogenous bases are classified as purines?

A
  • guanine
  • adenine
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14
Q

What are pyrimidines made up of?

A
  • one ring of similar atoms
  • (therefore much smaller than purines)
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15
Q

Which nitrogenous bases are classified as pyrimidines?

A
  • thymine
  • cytosine
  • uracil
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16
Q

What are the two main constituents of base pairs?

A
  • one purine and one pyrimidine
17
Q

Do the nitrogenous bases differ in different organisms?

A

No, these four nucleotides are the same in all animals and plants.

18
Q

How do nucleotides in organisms differ?

A
  • they differ in terms of the sequence in which the nucleotides are strung together
19
Q

What determines the genetic code of an organism?

A
  • the sequence of the nucleotides
20
Q

What is the role of DNA in terms of carrying information?

A
  • to carry hereditary information in each cell in the form of genes
21
Q

What is the role of DNA in terms of providing a blueprint?

A
  • to provide a blueprint for an organism’s growth and development by coding for protein synthesis
22
Q

What is the role of DNA in terms of replication?

A
  • can replicate so that a copy of the genetic information is passed on to each daughter cell formed during cell division
  • this ensures that the genetic code is passed on from generation to generation
23
Q

How much of human DNA codes for proteins?

A
  • less than 2%
  • the rest consists of non-coding DNA
24
Q

What are the protein-coding regions of a DNA molecule called?

A
  • exons
25
Q

What are the non-coding regions of a DNA molecule called?

A
  • introns
26
Q

How does DNA differ in complex organisms compared to less complex organisms?

A
  • complex organisms contain much more non-coding DNA than less complex organisms
27
Q

What do the non-coding regions of DNA do?

A
  • they form functional RNA molecules which have regulatory functions
28
Q

What should an ideal technique for extracting DNA from organic matter do?

A
  • release as much DNA as possible
  • minimize DNA degradation
  • be efficient in terms of cost, time, labour, and supplies
29
Q

Where is the majority of DNA found?

A
  • in the chromosomes in the nucleus of nearly every cell of an organism