Chapters 16-18 Flashcards Preview

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Flashcards in Chapters 16-18 Deck (94)
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phosphodiester bonds

bonds formed between the phosphate on the 5' carbon of one nucleotide and the 3' carbon of the next nucleotide

1

purine

nitrogenous base with two rings, includes adenine and guanine

2

pyrimidine

nitrogenous base with single ring structure, includes thymine, cytosine and uracil

3

nucleotide

3 phosphate groups + pentose sugar + nitrogenous base

4

nucleoside

pentose sugar + nitrogenous sugar

5

nucleotide residue

1 phosphate, pentose sugar, and nitrogenous base

(the bond holding phosphates breaks to make energy for building process)

6

first scientists credited with DNA structure

James Watson and Francis Crick

7

polarity of nucleotide chain

one end contains the roof of the pentose sugar (5' carbon) and the other end is the left base of the pentose sugar (3' carbon)

8

how many nucleotides chains are in RNA?

1

9

how many nucleotide chains are in DNA?

DNA is a double helix formed by combining two chains

10

how are two nucleotide chains linked?

hydrogen bonds between their bases (A,G,T,C)

11

antiparallel

run in opposite directions. 5' end and 3' end of opposite nucleotide chains are side-by-side

DNA is antiparallel

12

how does the sugar-phosphate backbone remain straight?

A purine always bonds with pyrimidine. always 3 rings in any pair, providing consistent width

13

What complementary base pair has 2 hydrogen bonds?

Adenine and Thymine

NOT URACIL because only DNA does this

14

What complementary base pair has 3 hydrogen bonds?

Guanine and Cytosine

15

angstrom

equal to 0.1 nanometers. used to measure wavelengths of EM radiation

16

distance between base pairs (steps of ladder)

3.4 angstroms

17

distance between sugar-phosphate backbones

20 angstroms

18

distance between every complete twist of helix

34 angstroms

3.4 angstroms between pairs, so 10 pairs per twist

19

Chargaff's Rule

#purines = #pyrimidines
#adenines = #thymines
#cytosines = #guanines

ratio is very unlikely to be 1:1:1:1

20

Scientists used to think genetic material was ______

proteins

21

First proof that nucleic acid was genetic material and not protein

Bacterial transformation studies ny Frederick Griffith - 1928

Involved bacteria with glyco protein coats and without

22

Denaturation study by Oswald Avery, Colin Macleod, and Maclyn McCarty - 1944

Protein was destroyed with enzyme but bacteria transformation occurred

RNA was destroyed but bacteria transformation occurred

DNA was destroyed and transformation didn't occur

Genetic material must be DNA

23

bacteriophage labeling by Hershey and Chase - 1952

radioactive sulfur was put into bacteriophage making protein coat radioactive

radioactive phosphorous was put into virus making nucleic acid radioactive

phosphorus was found in new phages, so DNA is genetic material

24

Tobacco Mosaic Virus Study by Fraenkel-Conrat and Singer - 1957

TMV protein coat put onto HRV RNA to make hybrid.

When virus replicates it is HRV RNA and protein coat. Therefore RNA was genetic material.

25

replication

when DNA makes copies of itself during synthesis stage of the cell cycle

semiconservative

26

Conservative

Two strands of DNA reassociate, therefore parental double helix is always together.

27

semiconservative

two strands of parental DNA molecule separate and act as a template for new complementary strand.

therefore each DNA strand is half parental and half new material

28

dispersive

each strand of DNA contains both old and newly synthesized DNA

old is dispersed throughout the strand

29

Matthew Meselson and Franklin Stahl - 1958

Grew E. coli in heavy isotope of nitrogen N (15) for several generations to make DNA heavy

Allow heavy DNA to replicate one time in normal nitrogen (14). Take sample and let it replicate one more time in normal nitrogen and take another sample.

Centrifuge spins DNA in Cesium Chloride

results: There was a single band midway in the tube after first replication. There were two bands, one midway and one higher up, in the tube after second replication

First replication was half and half heavy and nonheavy, second replication was one half and half and one all normal. Therefore semiconservative.