DNA Structure and Replication

Question 1

Nucleic Acids

Answer 1

macromolecule that holds our genetic material

Question 2

Genes

Answer 2

sections of DNA that serve as instructions for making proteins (located on ribosome)

Question 3

Proteins carry out all _____ activity

Answer 3

cellular

Question 4

Two types of Nucleic Acids:

Answer 4

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)

Question 5

Nucleotides

Answer 5

monomer of Nucleic acids

Question 6

3 parts of a nucleotide

Answer 6

-Phosphate
-Sugar (DNA/RNA)
-Nitrogen Base (Adenine, Guanine, Cytosine, Thymine (DNA only), Uracil (RNA only)

Question 7

DNA structure

Answer 7

Double helix:
-Sugar/ phosphate form “sugar-phosphate backbone”
-Nitrogen bases bond in middle with weak hydrogen bonds
-All other bonds are strong covalent

Question 8

DNA Structure was discovered by:

Answer 8

James Watson and Francis Crick in 1953

Question 9

Nitrogen Bases (2 Types)

Answer 9

-weak hydrogen bond to their Complementary Base Pair
-A with T (double bond)
-C with G (triple bond)

Question 10

Purines

Answer 10

Adenine, Guanine

Question 11

Pyrimidines

Answer 11

Cytosine, Thymine

Question 12

DNA is ____parallel

Answer 12

Antiparallel

Question 13

Antiparallel

Answer 13

the strands run in opposite directions (antiparallel) directions
-1st strand in 5’ to 3’ direction
2nd strand in 3’ to 5’ direction
-Phosphate end is the 5’ end
-Deoxyribose sugar is the 3’ end

Question 14

RNA Structure

Answer 14

single strand of nucleotides with exposed bases
-RNA bases bond with DNA bases
-A binds with U
-C binds with G

Question 15

DNA Replication

Answer 15

when cell is ready to divide, it needs to copy its DNA
-happens in nucleus
-during S phase of Interphase

Question 16

Step 1: DNA Replication

Answer 16

Enzyme Helicase unzips the DNA into 2 strands
-several “Origins of Replication” will be unzipped at once

Question 17

Step 2: DNA Replication

Answer 17

Enzyme DNA Polymerase adds complementary nucleotides to the template strands (A-T, C-G)
-Only adds nucleotides to the free 3’ end of strand. This forms new DNA in the 5’-3’ direction ONLY

Question 18

What does Enzyme PRIMASE do in Step 2 of DNA Replication

Answer 18

-required for synthesis
-like a “key” for car ignition
-makes RNA primers

Question 19

What does enzyme DNA POLYMERASE do in Step 2 of DNA Replication

Answer 19

1: adds nucleotides to RNA primer- makes polynucleotides
2: removes RNA primer and replaces it with DNA
3: Proofreads the strand before backbone is finished

Question 20

What does Enzyme DNA LIGASE do in Step 2 of DNA Replication

Answer 20

-“seals” gaps in DNA (okazaki fragments)
-connects DNA by making phosphodiester bonds

Question 21

Leading Strand

Answer 21

-made toward Replication fork (in 5’-3’ direction from 3’-5’ strand
-needs ONE RNA primer
-made continuously

Question 22

Lagging Strand

Answer 22

-made away from Replication fork
-made discontinuously (makes Okazaki fragments)
-needs MANY RNA primers

Question 23

Step 3: DNA Replication

Answer 23

Two identical DNA molecules formed, with one “old” strand and one “new” strand. (Semi-Conservative Replication)

Question 24

Semi-Conservative Replication

Answer 24

each parent strand is now a template that determines the order of the new bases
-forms “complementary” strand to original strand
-new double helix is a combo of one “old” and one “new” strand