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Biochemistry Exam 3 > Chapter 33: Nucleic Acids > Flashcards

Chapter 33: Nucleic Acids Flashcards

1
Q

What is the first level of DNA packaging?

A

Wrapping of DNA around histones to create a nucleosome structure

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2
Q

What is the second level of DNA packaging?

A

“Beads on a string” form of chromatin
Beads = nucleosomes
String= linker DNA

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3
Q

_____ are the major proteins of chromatin

A

Histones

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4
Q

What are the five different histones of most eukaryotic species?

A

H1, H2A, H2B, H3, & H4

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5
Q

Histones are small basic proteins with many _____ and _____ residues

A

Lysine and arginine

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6
Q

Histones are ____ charged particles

A

Positively

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7
Q

DNA is _____ charged

A

Negatively

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8
Q

+ charge of Histone allows interaction with - charged ___

A

DNA

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9
Q

What histones make up a histone octamer?

A

2 each of H2A, H2B, H3, & H4

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10
Q

What does DNA wrap around to form a nucleosome?

A

Histone octamer

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11
Q

Histone modifications can lead to…

A

Gene activation or gene repression

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12
Q

Study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than alterations to the DNA sequence is ____

A

Epigenetics

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13
Q

Histone tails are important in

A

Epigenetic regulation

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14
Q

Epigenetic “marks” tell your genes to

A

switch on/off & to speak loud/soft

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15
Q

What does “beads on a string” consist of?

A

Nucleosomes connected by linker DNA

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16
Q

Chromatosomes are part of the ___ level

A

Second

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17
Q

What is a chromatosome?

A

Nucleosome (DNA wrapped around histone octamer) with one bound linker histone (H1)

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18
Q

H1 binds the ____ and exit/entry of the nucleosome dyad (center DNA of the nucleosome)

A

Linker DNA

19
Q

Chromatin unfolds when treated with

A

Low ionic strength solution

20
Q

What is the third level of packaging?

A

30nm fiber

21
Q

With what can’t the 30nm fiber form?

A

H1

22
Q

H1 histones from _____ bind to each other

A

Adjacent nucleosomes

23
Q

What are the two models for the third level?

A

Solenoid and Zig-Zag

24
Q

What is the fourth level?

A

Looped domains

25
Q

Looped domains attached to

A

Chromosome scaffold

26
Q

What can cause loop domains to open up?

A

Histone, modifying enzymes, chromatin, remodeling complexes, & RNA polymerase

27
Q

In prokaryotes, DNA is ____ and there is no nucleus

A

Smaller

28
Q

The presence of 2 ___ groups on RNA greatly affects its properties

A

-OH

29
Q

2-OH can form hydrogen bonds. When treated with 0.1 M NaOH, what are the results?

A

Rapid degradation. DNA would remain stable.

30
Q

Because RNA has 2-OH groups, it can participate in certain ____ and ____ reactions

A

Chemical and Enzyme-catalyzed

31
Q

DNA is ____stable than RNA and is ____susceptible to alkaline attack

A

More, less

32
Q

It is important for DNA to be stable because its role as the primary ____

A

Genetic material

33
Q

What do nucleases catalyze?

A

Hydrolysis of phosphodiesters

34
Q

Exonucleases work from the ___

A

Ends

5’ to 3’ or 3’ to 5’

35
Q

Endonucleases work ____ the chain

A

Within

36
Q

What are the 3 properties of restriction endonucleases?

A
  1. Recognition of short sequences on DNA and cleavage of DNA at that site
  2. Palindromic sequences
  3. Bacteria use these enzymes to destroy invading genomes by cleaving their DNA’s
37
Q

What is an example of DNA recognition & cleavage?

A

EcoR1 Restriction Endonuclease

38
Q

Palindromic means it can be read _____ forward and backward

A

The same.
5’-GAATTC-3’
3’-CTTAAG-5’

39
Q

Bacteria can protect its own DNA from being cut by

A

Methylation of adenine residues which prevents EcoR1 cleavage

40
Q

Restriction enzymes are important in

A

Molecular biology - cloning
DNA fingerprinting
DNA profiling- forensics and paternity tests

41
Q

You can use restriction enzymes to

A

Generate fragments of a certain size

42
Q

After digestion of restriction enzymes, fragments are run through a gel. The fragments travel from the ____ end to the ____ end.

A

Negative, positive

43
Q

Which fragments travel farther in the gel? Long or short

A

Short

44
Q

For DNA profiling, a band present in the child must be present in either their ___ or ___

A

Father, mother

Biochemistry Exam 3 (10 decks)

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