Nucleic Acids Bio 14 DNA and RNA

Question 1

Chromosomes

Answer 1

Contain hereditary instruction for over 250k proteins unique to humans.

Question 2

All cells except ova and sperm

Answer 2

Contain 23 pairs of chromosomes, 46 total.

Question 3

A nucleis acids is a ________ made from monomeric units called ______.

Answer 3

Polymer, nucleotides

Question 4

To eat “py” you need to CUT it

Answer 4

Py for pyrimidines include C,U,T with 1 ring structures.

Question 5

Nucleotide, nucleoside components

Answer 5

Nucleotide : Sugar, phosphate, and N base (deoxyribose)
Nucleoside : Sugar and base (ribose)
2 position in chemical structure for nucleoside has OH, nucleotide has H.

Question 6

Furanose ring

Answer 6

5 Carbon sugar

Question 7

DNA

Answer 7

Helix structure. Sugar and phosphate makes up the backbone, held by H bonds. Rosalind Franklin produced a photograph which paved the way for Watson and Crick, double helix structure.

Question 8

H bonds in nucleotides

Answer 8

A=T H bonds
C=_G H bonds
Rules of Chargraff is A amount = T amount
G amount = C amount

Question 9

Double helix stabilization

Answer 9

H bonds and hydrophobic interactions between stacked bases

Question 10

A=T, C=_G

Answer 10

A purine pairs with a pyrimidine

Question 11

Why does purine pair always with a pyrimidine?

Answer 11

Limited space. Too large for two pyrimidines or two purines.

Question 12

What type of bond joins one nucleotide group to another?

Answer 12

Phosphodiester bond

Question 13

The bases along a backbone ware written

Answer 13

5’ to 3’ direction

Question 14

DNA structure

Answer 14

Purines and pyrimidines are on the inside, sugar and phosphate are outside. H bonds hold helix together and define its 2 prime structure.

Question 15

Increasing % of GC

Answer 15

Increase stability and melting point since more H bonds. A=T regions are first to melt and break.

Question 16

Length of DNA vs Melting Temp.

Answer 16

Stability of DNA is dependent on the H bonds present. H bonds increase with length, the melting temp increases as well.

Question 17

Amount of NaCl decrease, the melting temp decreases

Answer 17

DNA structure is highly negatively charged due to negative phosphodiester bonds (repelling each other). Positive Na+ cation shields the repelling charges, increasing stability. As NaCl conc decreases, the amount of shielding decrease and stability decreases.

Question 18

Renaturation of single strands to form double strands

Answer 18

Occurs more rapidly when the DNA conc is increased. Complementary sequences need to find each other.

Question 19

Melting temperature is reduced when Urea is added.

Answer 19

Urea is polar interfering with H bonds, decreasing stabilization.

Question 20

Water solubility of Phosphate group, ribosyl group, and the nitrogen bases.

Answer 20

Ribosyl group and phosphate group are hydrophillic. Located outside our helix and are water soluble.
Purines and pyrimidines are insoluble in water (hydrophobic), located interiorly of the helix.

Question 21

What technique is used to identify chromosomal material or DNA?

Answer 21

Feulgen stain. DNA stains reddish. Mild acid hydrolysis cleaves the molecule and reaction reveals the red.

Question 22

Histones

Answer 22

DNA is wrapped around a protein called histones. DNA and histone = nucleosome.
Rich in + charged aa lysine and arginine and this allows tight binding to negatively charged DNA.

Question 23

Nuclear DNA configurations

Answer 23

A) Euchromatin

B) Heterochromatin

Question 24

Heterochromatin

Answer 24

Dark staining in electron micrographs. DNA is not actively transcribed.

Question 25

Euchromatin

Answer 25

Eukaryotic, DNA is available for transcription. True chromatin, more dispersed and less compacted.

Question 26

Hershey- Chase experiment

Answer 26

Concluded that DNA is not a protein and is actually genetic info. Radioactive sulfer and phosphorus labelled proteins and DNA. Which molecules entered the bacterial cell. Page DNA entered the bacteria.

Question 27

Fred- Griffith Transformation Experiment

Answer 27

Two strains of bacteria: Pathogenic and nonpathogenic.
Mixed dead pathogen with living nonpathogenic and some became harmful. All further progeny were pathogenic. DNA is the culprit.

Question 28

Avery McCarty Macleod Experiment

Answer 28

1944 confirming Griffith DNA genetic material. Mitochondria and chloroplasts also contain their own DNA.

Question 29

RNA

Answer 29

single stranded, A, U ,C ,G
Ribose sugar ( lacking 2’ OH)
rRNA: physical makeup of ribosome, most abundant
mRNA: carries DNA info to ribosomes, shortest lived
tRNA: transports aa to ribosomes, lowest molecular weight
8x more RNA than DNA

Question 30

Transcription

Answer 30

Occurs in the nucleus.

Question 31

Why does alkaline conditions partially denature the helix?

Answer 31

Increasing the pH, ionizes some of the nucleic acid bases and the phosphate groups, thus increasing the # of negatively charged groups. This promotes unwinding of the helix to reduce charge repulsion.