DNA Replication Notes

Question 1

Nuclear Chromosomes/Eukaryotic DNA

Answer 1

Have a linear structure
• Compacted by interaction with
proteins
• Many hundreds or thousands of genes
each

Question 2

Different forms of DNA

Answer 2

• Nuclear Chromosomes/Eukaryotic DNA
  -Mitochondrial Chromosomes/Prokaryotic
  DNA

Question 3

Mitochondrial Chromosomes/Prokaryotic

DNA

Answer 3

Circular DNA molecule
• Not compacted with protein
• Similar to prokaryotic chromosomes
• Reflects evolutionary history of
mitochondria
• Not many genes (37 in humans)

Question 4

Deoxyribonucleic Acid

Answer 4

Controls production of proteins within cell

Question 5

Chromatin

Answer 5

DNA is never found alone!, it is a complex association of DNA and proteinthat makes up chromosomes in nondividing cells

Question 6

Chromosomes

Answer 6

Tightly wound chromatin
Chromatid: one of two identical parts of a
chromosome - occurs during cell division.

Question 7

Histones

Answer 7

DNA-binding proteins that assist
in compacting and folding DNA into a
chromosome.

Question 8

Nucleosomes

Answer 8

Bead-like structures composed of histones wrapped with DNA.

Question 9

Structure pf DNA is related to function. What are the functions of DNA

Answer 9

• Store and use information to direct cell activities

- Copy ITSELF EXACTLY for new cells

Question 10

What parts is DNA made of

Answer 10

Polymer made of monomers called nucleotides. Each
nucleotide is made of 3 parts
1. 5-Carbon Sugar (Deoxyribose)
2. Phosphate
3. Nitrogen Base

Question 11

DNA (twisty) structure

Answer 11

DNA molecule forms double helix (twisted ladder shape)
Sugar and Phosphate alternate to make up side or backbone of
ladder
-Held together by a sugar-phosphate bond called a phosphodiester bond
Base Pairs make up rungs of ladder
-Hydrogen bonds hold the bases together
Sugar in backbone is bonded to the nitrogen base of the rung
-Covalent bond holds the sugar and base together

Question 12

What are the nucleotide bases for DNA

Answer 12

• Adenine
• Guanine
• Cytosine
• Thymine

Question 13

Purines

Answer 13

• Double ring of C and N

- Adenine and Guanine

Question 14

Pyrimidines

Answer 14

• Single ring of C and N

- Thymine and Cytosine

Question 15

How do nucleotide bases pair

Answer 15

A purine always pairs with a
pyrimidine, to keep all rungs equal
 A-T
 G-C
- The strands are complementary
because of A-T and G-C

Question 16

DNA scientists

Answer 16

• Miescher 1860
• Frederick Griffith 1928
• Avery, Macleod & McCarty 1944
• Hershey-Chase 1952
• Chargaff 1949
• Rosaline Franklin and Maurice Wilkins 1953
• Watson and Crick 1953

Question 17

Miecher

Answer 17

-DNA first isolated (called it
nuclein) from cells in 1860’s by
Friedrich Miescher
-shown to contain C, H, O, N and P
-it wasn’t until the 1940’s and 1950’s
that DNA was shown to be the genetic
material

Question 18

Frederick Griffith

Answer 18

Studying how bacteria caused pneumonia
– believed proteins, NOT DNA, were units
of heredity.
– Determined some factor was being
transmitted from non-living bacteria to
living bacteria

Question 19

1944: Oswald Avery

Answer 19

designed an
experiment to further test Griffith’s
findings
-Avery concluded genes are made of DNA

Question 20

Hershey and Chase

Answer 20

Used viruses called bacteriophages to confirm that DNA is the genetic material

Question 21

Chargaff

Answer 21

Determined the Base Pair Composition of DNA through analysis of data

Question 22

Rosalind Franklin and Maurice Wilkins

Answer 22

Used a technique called X-ray diffraction (crystallography)
to study DNA
– These pictures suggested a highly coiled helix

Question 23

James Watson and Francis Crick

Answer 23

-Develop the double-helix model of the structure of DNA
-To construct this model, they use information about
bonding, Chargaff’s rules, pictures from x-ray
diffraction

Question 24

DNA replication Helicase

Answer 24

• 1st thing that happens
  -“unzips” ladder by breaking
  hydrogen bonds
  point at which two strands
  separate is called the
  “Replication Fork”
  Multiple replication forks form
  along DNA strand

Question 25

DNA Polymerase

Answer 25

-2nd thing that happens
-Holds two strands apart
-Assembles and proofreads
strands
-Free-floating nucleotides
join unpaired bases on the
2 single strands with help
of DNA Polymerase and
Primase.
-DNA moves 5’ to 3’ and when 3’ to 5’ its okazaki fragments

Question 26

DNA Ligase

Answer 26

-3rd thing that happens
-Uses ATP as an energy source to seal copies
together

Question 27

DNA replication accuratcy

Answer 27

• Replication is extremely accurate: 1 error
  per 1 Billion nucleotides
• DNA is able to repair damage from heat,
  radiation, and chemicals
• There are many enzymes that help with
  accuracy and DNA repair

Question 28

PCR

Answer 28

Polymerase Chain Reaction: Allows a short
strand of DNA to be amplified about a
million fold