Module 2-4

Question 1

Structure of nucleotides

Answer 1

A nitrogen base
Ribose (5 carbon sugar)
A phosphate group

Question 2

What are the two nitrogen base categories?

Answer 2

Purines -have 2 rings (Adenine & Guanine are Purines)

Pyrimidines -have one ring (Cytosine, Uracil, and Thymine are Pyrimidines)

Question 3

What are the two ribose?

Answer 3

Ribose (RNA)

2-deoxyribose (DNA)

Question 4

What are 5’ and 3’

Answer 4

These are labeled carbons in rivose, 5’ end it where phosphate is attached

Question 5

What are phosphates?

Answer 5

In DNA, phosphates are the “sugar-phosphate backbone”

Question 6

What is step 1 of the DNA strand formation?

Answer 6

A nucleotide is added to the 3’ of an existing chain.

Its phosphate binds to the oxygen on the 3’ sugar

Question 7

What is step 2 of the DNA strand formation?

Answer 7

A diphosphate is formed as a byproduct

Question 8

What is step 3 of the DNA strand formation

Answer 8

A phosphodiester bond is formed between the new nucleotide and the existing strand of DNA

Question 9

What direction are nucleotides attached?

Answer 9

5’ to 3’

Question 10

Why does DNA form a double helix?

Answer 10

Nitrogen bases are hydrophobic

Phosphate backbone is hydrophilic

Question 11

What are genes?

Answer 11

Small pieces of DNA that contain information to make a protein. (Coding DNA)

Question 12

What amount of a gene is used to make protein?

Answer 12

Most of a gene isn’t used

Question 13

Who solved the structure of DNA?

Answer 13

James Watson & Francis Crick

Question 14

What is the fundamental structural unit of DNA?

Answer 14

Deoxyribonucleotides

Question 15

What is RNA?

Answer 15

RNA is a nucleic acid similar to DNA, primarily tells the cell what kinds of proteins to make

Question 16

Structural differences of DNA and RNA.

Answer 16

RNA uses Uracil instead of Thymine
RNA uses ribose instead of deoxyribose
RNA is single-stranded, therefore it is less stable

Question 17

What are the 3 types of RNA?

Answer 17

Messenger (mRNA)
Transfer (tRNA)
Ribosomal (rRNA)

Question 18

What does mRNA do?

Answer 18

carries instructions to making protein in the cell

Question 19

What does tRNA do?

Answer 19

tRNA brings amino acids to ribosomes to build protein

Question 20

What does rRNA do?

Answer 20

rRNA is a part of ribosomes

Question 21

What are the 5 levels of DNA packaging

Answer 21

1. Double Helix
2. Nucleosomes (beads on a string)
3. Chromatin fiber
4. Looped domains
5. a) Folded looped domains
6. b) Chromosomes

Question 22

What is the central dogma?

Answer 22

A set of principles that explain how DNA contains instructions for building RNA & Proteins

Question 23

What are the 3 components of the central dogma?

Answer 23

1. Replication (DNA -> DNA)
2. Transcription (DNA -> RNA)
3. Translation (RNA -> Protein)

Question 24

What is DNA replication?

Answer 24

DNA is copied during cell division, the major enzyme is DNA polymerase

Question 25

What is DNA transcription?

Answer 25

A section of DNA info is transcribed into RNA so the info can leave the nucleus, the major enzyme is RNA polymerase

Question 26

What is RNA translation?

Answer 26

RNA is read and translated to produce proteins, the major enzymes are ribosomes

Question 27

When is DNA most vulnerable?

Answer 27

During replication. Bonds are broken

Question 28

Why is DNA replication semi-conservative

Answer 28

The original strand is conserved

Question 29

What are the 4 steps of DNA replication?

Answer 29

1. Unwinding the DNA 2. RNA primers bind to unwound strands 3. Elongation 4. Termination

Question 30

How is DNA unwound?

Answer 30

DNA helicase unwinds the 2 strands

Question 31

What enzyme allows for DNA replication to begin?

Answer 31

Primase

Question 32

What enzyme copies single strands of DNA?

Answer 32

DNA polymerase

Question 33

What direction does DNA polymerase move

Answer 33

3' -> 5'

Question 34

What are the Okazaki fragments?

Answer 34

OFs are fragments of DNA synthesized off of primers on the lagging strand

Question 35

What joins the Okazaki fragments?

Answer 35

Ligase

Question 36

What prevents DNA shortening at the end of the replication

Answer 36

Telomeres, which are attached with telomerase