Chapter 4 - DNA, RNA

Question 1

The central dogma

Answer 1

DNA -> RNA -> Protein

Question 2

Nucleotide

Answer 2

Sugar, a phosphate, and one of four bases

Question 3

DNA

Answer 3

Has a deoxyribose sugar and lacks an OH at carbon 2

Question 4

Phosphodiester bridges

Answer 4

The 3’hydroxyl group of the sugar moeity of one nucleotide is joined the the 5’ group of the adjacent sugar

Question 5

RNA

Answer 5

Is a long unbranched polymer with phosphodiester linkages. Ribose contains a 2’-hydroxyl group. RNA is uracil instead of thymine

Question 6

Phosphodiester bridges

Answer 6

Have a negative charge. This negative charge repels nucleophilic species such as hydroxide ions, which are capable of hydrologic attack on the phosphate backbone

Question 7

Nucleoside

Answer 7

Base and sugar joined by a glycosidic linkage

Question 8

Nucleotide

Answer 8

Sugar, base and phosphate. Joined by ester linkages

Question 9

Nucleotide triphosphates

Answer 9

The monomer that are linked to form RNA and DNA. The energy, ATP, released from it is used to power many cellular processes

Question 10

Nucleotide functions

Answer 10

Energy for metabolism
Enzyme cofactors
Signal transduction

Question 11

Nucleic acid function

Answer 11

Storage of genetic information
Transmission of genetic info (mRNA)
Processing of genetic info
Protein synthesis tRNA, rRNA

Question 12

Double helix structure

Answer 12

Double helical structure facilitates the replication of genetic information

Question 13

Watson Crick model of DNA

Answer 13

Right handed screw
Anti parallel strands, opposite directionality
Sugar phosphates on the outside, and purine and pyrimidines on the inside

Question 14

Length of DNA

Answer 14

Bases are separated 3.4A
10.4 bases per turn of helix
20A diameter
Intermediate shape

Question 15

The base pairs are held by

Answer 15

Hydrogen bonds which contribute stability in the helix due to their large numbers in a DNA molecule

Question 16

Stacking of base pairs

Answer 16

Millions of bases together become very strong
Rings are planar.
Held by van der Waals

Question 17

For,action of the double helix

Answer 17

Is facilitated by the hydrophobic effect

Base stacking is favored by the confirmations of the somewhat rigid five ,embedded rings of th backbone sugars

Question 18

Supercooling is important because

Answer 18

Is more compact and less reactive

May hinder the capacity of the double helix to unwind

Question 19

DNA denaturing

Answer 19

Can happen by heating DNA or changing the ph.

Question 20

Melting temperature

Answer 20

When half of the DNA molecule helical structure is lost

Question 21

Helicases

Answer 21

Use chemical energy from ATP to disrupt the helix

Question 22

Denaturing

Answer 22

Covalent bonds stay intact
Hydrogen bonds are broken
Base stacking is lost

Question 23

Hydro chronic effect

Answer 23

Increase in absorption upon denaturing due to release of base pairing

Question 24

DNA is replicated by polymerase

Answer 24

Promote the formation of the bonds joining unite of the DNA backbone

Question 25

DNA synthesis needs

Answer 25

Deoxynucleoside triphosphates
-dATP, dGTP, dCTP, dTTP and Mg ion
Preexisting DNA template
Primer having a free 3’ hydroxyl

Question 26

Nucleases

Answer 26

Enable DNA fidelity because it enables mismatched nucleotides

Question 27

Polymerization is driven forward by

Answer 27

The hydrolysis if pyrophosphate to yield PPi

Question 28

Where do you want to radiolabel?

Answer 28

In the alpha carbon

Question 29

Reverse transcriptase

Answer 29

Makes viral DNA
Possess several activities and catalyze the synthesis of a complementary DNA strand, the digestion of the RNA and the subsequent synthesis of the DNA strand

Question 30

RMA polymerase

Answer 30

The synthesis of RNA from DNA is called Transcription and is catalyzed by the RNA polymerase enzyme

Question 31

RNA synthesis

Answer 31

Does not require a primer of nuclear activity

Fidelity by base sequence studies

Question 32

If RNA polymerase doesn’t have a promoter, how does it bind?

Answer 32

Bonds to promoter site

Question 33

Cap structure

Answer 33

Guanosine nucleotide with a 5’-5’ triphosphates linkage

Question 34

PolyA tail

Answer 34

Important to have because the cell can tell whether the mRNA was made correctly

Question 35

Genetic code is degenerate

Answer 35

Amino acids are encoded by more than one codon

Question 36

Important of degenerate code

Answer 36

The probability of mutation to chain termination would be much higher

Question 37

What physical property is going to change between the prokaryotic start signal and eukaryotes?

Answer 37

There’s going to be a charge difference.

The N terminator, for euk, must be able to interact with glutamate so its needs that positive charge.

Question 38

Splicing is carried out by

Answer 38

Spliceosomes

Question 39

Introns

Answer 39

Start with GU and end with AU that precedes by a pyrimidine rich tract