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College Biology > Lecture 7 > Flashcards

Lecture 7 Flashcards

1
Q

How many chromosomes do most Eukaryotes have in their body cells?

A

10-50.

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2
Q

How many chromosomes do humans have?

A

46 chromosomes in 23 almost identical pairs.

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3
Q

What is a karyotype?

A

A particular array of chromosomes in an individual organism.

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4
Q

What is diploid?

A

2 complete sets of chromosomes.

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5
Q

What is Haploid?

A

One set of chromosomes.

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6
Q

What are chromosomes made of?

A

Chromatin.

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7
Q

What makes up chromatin?

A

DNA and protein.

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8
Q

What else is associated with chromosomes?

A

RNA during RNA synthesis.

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9
Q

What are 2 types of chromosomes?

A
  1. Heterochromatin
  2. Euchromatin
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10
Q

What are heterochromatin chromosomes?

A

Ones that are compressed and not expressed (turned off, not accessible)

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11
Q

What are euchromatin chromosomes?

A

Chromosomes that are loose and expressed (turned on, accessible).

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12
Q

What is a nucleosome?

A

A complex of DNA and histone proteins.

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13
Q

What do histone proteins do?

A

Promote and guide coiling of DNA

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14
Q

What are histone core proteins?

A

Proteins that act as a bobbin for the DNA to wrap around.

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15
Q

What are histone link proteins?

A

It holds the DNA on the core protein (kind of like a crimp bead).

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16
Q

What is the most compact form of DNA?

A

Chromosomes.

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17
Q

How are chromosomes organized for replication?

A

Each sister chromatid is held together by proteins in an x shape to keep them organized before they are moved to the new cell.

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18
Q

What do chromosomes look like before and after replication?

A

Before each chromosome is composed of a single DNA molecule and after each is composed of 2 identical DNA molecules.

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19
Q

What 3 things are required for DNA replication?

A
  1. Something to copy
  2. Something to do the copying
  3. Building blocks to make copy
20
Q

What are the three things that are used for DNA replication?

A
  1. Parental DNA molecule
  2. Enzymes
  3. Nucleotide triphosphates
21
Q

What are 3 stages of DNA replication?

A
  1. Initiation - replication begins
  2. Elongation - new strands of DNA are synthesized by DNA polymerase
  3. Termination - replication is terminated
22
Q

What nucleotide bases are linked in DNA double helix?

A

CG and AT

23
Q

What is a DNA polymerase?

A

A protein that matches existing DNA bases with complementary nucleotides and links them.

24
Q

What are common features of polymerase?

A
  1. Adds new bases to 3 prime end of existing strands
  2. Synthesizes in 5’-3’ direction
  3. Requires a primer of RNA
25
Q

How do DNA polymerase and RNA polymerase work together?

A

The RNA polymerase makes the primer and the DNA polymerase extends the primer.

26
Q

What model does Prokaryotic replication use?

A

E. coli model.

27
Q

What is the E. coli model of replication?

A

Starts with a single circular molecule of DNA. Replication begins at the origin of replication and proceeds in both directions around the chromosome.

28
Q

What are the 3 DNA polymerases in E. coli?

A
  1. DNA polymerase 1
  2. DNA polymerase 2
  3. DNA polymerase 3
29
Q

What is DNA polymerase 1?

A

Acts on lagging strand to remove primers and replace them with DNA.

30
Q

What is DNA polymerase 2?

A

Involved in DNA repair processes.

31
Q

What is DNA polymerase 3?

A

Main replication enzyme.

32
Q

What do all three polymerase have?

A

3’-5’ exonuclease activity.

33
Q

What is 3’-5’ exonuclease activity?

A

Proofreading oved the DNA.

34
Q

What does DNA polymerase 1 also have?

A

5’-3’ exonuclease activity.

35
Q

What is 5’-3’ exonuclease activity?

A

It goes back and removes the RNA primers.

36
Q

What are helicases?

A

Enzymes that use energy from ATP to unwind DNA.

37
Q

What are Single-stand-binding (SSBs) proteins?

A

Enzymes that coat DNA strands to keep them apart. (keeps the DNA from going back to the double helix form.)

38
Q

What are topoisomerases?

A

Enzymes that prevent supercoiling (gets rid of knots and twists in the DNA).

39
Q

What is DNA gyrase?

A

The topoisomerase involved in DNA replication.

40
Q

What is a replication fork?

A

The partial opening of the DNA helix.

41
Q

What is DNA primase?

A

The RNA polymerase that makes RNA primer.

42
Q

How many directions can DNA polymerase synthesize in?

A

1.

43
Q

What is the leading strand in DNA replication?

A

The strand that synthesizes continuously from an initial primer.

44
Q

What is the lagging strand in DNA replication?

A

The strand that synthesizes discontinuously with multiple priming events.

45
Q

What are Okazaki fragments?

A

DNA fragments on the lagging strand.

46
Q
A

College Biology (24 decks)

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