experiments and DNA replication

Question 1

nucleotide

Answer 1

nucleoside: nitrogenous base and pentose sugar
+ 1 or more phosphate group
- covalent bods between -OH group and 3’ end and the phosphate on the 5’carbon end of next

Question 2

DNA

Answer 2

• double helix
• antiparallel (opposite 5’->3’ directions)
• thymine
• sugar phosphate backbone
• deoxyribose

Question 3

genomics

Answer 3

approach used to analyze large sets of genes or compare the genomes of different species

Question 4

proteomics

Answer 4

analysis of large sets of proteins or compare the proteins

Question 5

Griffith experiment

Answer 5

• 2 strand of bacteria: one pathogenic and one harmless
• when he mixed heat-killed remains of the pathogenic train with living cells of the harmless strain, some living cells became pathogenic
• transformation: a change in genotype and phenotype due to assimilation of foreign DNA

Question 6

Hershey and Chase experiment

Answer 6

DNA is genetic material not proteins
- Sulfer 35 and Phosphorus 32
- DNA contains phosphorous, protein does not
- S35 found in supernatant, P32 found in pellet

Question 7

Chargaff’s rules

Answer 7

1. the base composition of DNA varies between species
2. any species has equal percentage amounts of A and T as G and C

Question 8

Wilkins and Franklin

Answer 8

X-ray crystallography
- photo of DNA and helped Watson and Crick with their discovery

Question 9

Watson and Crick experiment

Answer 9

DNA antiparallel helix
- x-ray enabled them to see spacing of nitrogenous bases and width of helix
- Purine (A,G) + Pyrimidine (T,C) for base pairing
- A and T pair, G and C pair

Question 10

DNA replication: definiton

Answer 10

parent molecule unwinds, and two new daughter strands are synthesized based on base-pairing rules
- semiconservative model: one new strand and one old one

Question 10

conservative model and dispersive model

Answer 10

conservative: 2 parent strands rejoin
dispersive: each strand is a mix of old and new

Question 11

Origin of replication

Answer 11

replication begins here, where two DNA strands are separated, opening up a replication “bubble”

Question 11

Meselson and Stahl

Answer 11

disproved conservative theory
- N15(heavy N) and N14 (light N)
- centrifuge
- 2 hybrid, and 2 N14 (light)
- No purely heavy

Question 11

replication fork

Answer 11

a Y-shaped region where the parental strands of DNA are being unwound

Question 12

topoisomerase

Answer 12

relieves the coils of DNA

Question 12

initiation of DNA replication steps

Answer 12

topoisomerase -> helices -> single strand binding proteins -> primate -> RNA primer

Question 13

DNA polymerase I

Answer 13

replaces RNA nucleotides with DNA

Question 14

DNA polymerase III

Answer 14

elongates the DNA from the primer

Question 14

Helicase

Answer 14

creates the replication bubble

Question 14

primer

Answer 14

initial nucleotide strand short RNA and starts at 3’ end

Question 15

DNA polymerase

Answer 15

cannot initiate synthesis of a polynucleotide; they can only add nucleotides - catalyzes elongation of new DNA at replication fork
- requires a primer
- proofreads newly made DNA, and corrects it

Question 16

Primase

Answer 16

An enzyme that starts a. RNA chain with a single RNA nucleotide and adds using parental DNA as template

Question 17

dATP

Answer 17

is used to make DNA, dATP = deoxyribose, ATP = ribose

Question 18

As each monomer nucleotide joins the DNA strand it loses…

Answer 18

2 phosphate group as a molecule of pyrophosphate

Question 19

A new DNA strand can elongate only in the...

Answer 19

5' to 3' direction

Question 20

Synthesis of leading stand

Answer 20

- continuous - towards replication fork - DNA Pol III

Question 21

Synthesis of lagging strand

Answer 21

- Okazaki fragments - away from replication fork

Question 22

lagging strand steps

Answer 22

primate -> primer -> DNA Pol III -> Okazaki fragments -> DNA polymerase I removes the RNA primers and replaces the RNA nucleotides with DNA -> DNA ligase seals the gaps

Question 23

mismatch repair

Answer 23

other enzymes correct errors in base pairing

Question 24

nucleotide excision repair

Answer 24

nuclease cuts out and replaces damaged stretches of DNA - DNA polymerase corrects it and DNA ligase seals it

Question 25

bacterial chromosome

Answer 25

a double-stranded, circular DNA molecule associated with a small amount of protein - bacterial DNA is supercoiled and found in a region of the nucleoid

Question 26

Eukaryotic chromosomes

Answer 26

linear DNA molecules associated with a large amount of protein

Question 27

chromatin

Answer 27

a complex of DNA and protein, in nucleus of eukaryotic cells - multilevel system of packing

Question 28

histones

Answer 28

proteins responsible for DNA packing in chromatin - H2A, H2B, H3, H4

Question 29

nucleosome

Answer 29

DNA wound twice around a protein core of 8 histones, 2 of each of the types

Question 30

DNA packing levels

Answer 30

DNA < histones < nucleosome < 30nm fiber < looped domain < scaffold < 300nm fiber < chromatid < chromosome

Question 31

heterochromatin and euchromatin

Answer 31

hetero: condensed chromatin euchro: dispersed, less compacted chromatin

Question 32

nucleic acid hybridization

Answer 32

the base pairing of one strand of a nucleic acid to another complementary strand

Question 33

DNA cloning

Answer 33

production of multiple copies of a single gene

Question 33

genetic engineering

Answer 33

the direct manipulation of genes for practical purpose

Question 34

cloning vector

Answer 34

the plasmid that carries the cloned DNA

Question 35

restriction enzymes

Answer 35

cut DNA molecules at specific DNA sequences called restriction sites - create restriction fragments - fragment form different DNA molecule replaces, DNA ligase seals

Question 36

gel electrophoresis

Answer 36

can use to see the fragments produced

Question 37

The polymerase chain reaction (PCR)

Answer 37

can produce many copes of a specific target segment of DNA - 3 step cycle: denaturation, annealing, extension - heat stable DNA polymerase called Taw polymerase

Question 38

PCR primers are synthesized to include a restriction site that...

Answer 38

matches the site in the cloning vector - are cut and ligated together