Biochemistry - Ch 24 - Dna Structure And Interactions With Proteins

Front 1

What is the central dogma of molecular biology?

Back 1

DNA ---> RNA --> Protein

*with some molecules being able to go from RNA to DNA, or RNA transcribing itself.

Front 2

State (briefly) the function, and where it occurs:

Replication

Back 2

Funciton:
Duplicating genome (DNA)

Location:
Nucleus

Front 3

State (briefly) the function, and where it occurs:

Transcription

Back 3

Function:
Copy DNA ---> RNA

Location:
Nucleus

Front 4

State (briefly) the function, and where it occurs:

Splicing

Back 4

Function:
Remove pieces of transcript

Location:
Nucleus

Front 5

State (briefly) the function, and where it occurs:

Translation

Back 5

Function:
RNA ---> Protein

Location:
Cytoplasm

Front 6

What are 4 characteristics of Nucleic Acids?

Back 6

1) Information storage - stable

2) Decoding - transcription and translation

3) Information must be accessible to proteins and other nucleotides

4) Must be able to make copies

Front 7

What are 8 characteristics of the geometry of DNA?

Back 7

1) 2 antiparallel polynucleotide chains

2) Wind around common axis (20Å diameter helix)

3) Bases in the center

4) Sugar phosphate backbone on the outside

5) Planes of bases perpendicular to the axis of helix

6) Strands held together by h-bonds and non-polar interactions between bases

7) G-C and A-T

8) Ideal B-DNA helix is 10 b.p./turn

Front 8

What are 5 characteristics of the geometry of base pairs?

Back 8

1) H-bonding between the bases

2) A-T is 2 h-bonds

3) C-G is 3 h-bonds

4) Interfaces are complementary

5) Base pairs have same width

Front 9

What are the 3 types of DNA?

What is the difference between them (generally)?

Which is the most common (i.e. the one we know and love)

Back 9

A-DNA:
Squashed B-DNA structure. right handed helix.

B-DNA:
Normal right-handed helix DNA structure.

Z-DNA:
left handed-helix

Front 10

What is the term for when DNA become extremely twisted (or untwisted)?

Back 10

Supercoiling

or

Superhelicity

Front 11

What type of supercoiling (negative or positive) is essential for DNA transcription?

Back 11

negative supercoiling

Front 12

Describe in general how topoisomerase works, and the 2 different types of it.

Back 12

- Introduces a cut
- Twists (or untwists) DNA
- Repairs the cut

Type I:
Acts through single strand cuts

Type II:
Acts through double strand cuts

Front 13

What are 5 factors the affect the melting temperature (Tm) of DNA.

Back 13

1) G-C content

2) Nature of ions

3) ion concentration

4) pH

5) length of DNA

Front 14

What are 2 forces that stabilize the double helix of DNA?

Back 14

1) Hydrogen bonds

2) Stacking interactions between consecutive base pairs

Front 15

Protein-DNA interactions:

What is the difference between "non-sequence specific" and "sequence specific" interactions?

Back 15

Non-Sequence specific:
- proteins that help DNA fold up
- Proteins bind to sugar-phosphate backbone

Sequence Specific:
- Proteins that recognize specific sequence
- Protein binds to edges of the bases
* Major or minor groove
* can distinguish all 4 base pairs

Front 16

Eukaryotic DNA:

DNA in a human cell is usually how long?

Back 16

1 meter

Front 17

Eukaryotic DNA:

Chromosomes are composed of _____ and _____.

Back 17

...protein...

...DNA...

Front 18

Eukaryotic DNA:

What are nucleosomes?

Back 18

DNA wrapped around protein complexes.

Protein complexes are composed of 8 histones.
- 2 of each {H2A, H2B, H3, H4}