Module 2 Flow of Genetic Information in the Cell

Question 1

The Flow of Genetic Information or also known as _________

Answer 1

Central Dogma of Life/Biology

Question 2

What happens to RNA during cell division?

Answer 2

synthesized in interphase then gets distributed in daughter cells

Question 3

Where is RNA stored in a cell?

Answer 3

nucleus, cytoplasm and mitochondria

Question 4

types of RNA (8)

Answer 4

• mRNA
• tRNA
• rRNA
• snRNA
• snoRNA
• miRNA
• siRNA
• IncRNA

Question 5

type of RNA that encodes proteins

Answer 5

mRNA

Question 6

type of RNA that acts as adaptor between mRNA and amino acids

Answer 6

tRNA

Question 7

type of RNA that forms the ribosome

Answer 7

rRNA

Question 8

type of RNA that functions in various nuclear process (e.g splicing)

Answer 8

snRNA

Question 9

type of RNA that facilitates chemical modification of RNAs

Answer 9

snoRNA

Question 10

type of RNA that regulates gene expression (2)

Answer 10

miRNA
IncRNA

Question 11

type of RNA that silences gene expression

Answer 11

siRNA

Question 12

3 proposed Models of Replication

Answer 12

• semiconservative (pd + pd) -> (dd + pd)
• conservative (pp + dd) -> (pp + pp)
• dispersive (mekus2) (pd + pd) -> (pd + pd)

Question 13

demonstrated semiconservative replication

Answer 13

Meselson and Stahl (1958)

Question 14

Meselson and Stahl Experiment

Answer 14

centrifuged bacteria cultured in medium containing nitrogen

Question 15

summary of DNA replication

1. ________ unwind the parental double helix
2. ________ stabilize the unwound parental DNA
3. The leading strand is synthesized continuously in the _______ direction by ________
4. The lagging strand is synthesized discontinuously. ______ synthesizes a short _______, which is extended by ___________ to form an ________.
5. After the RNA primer is replaced by DNA, ________ joins the Okazaki fragment to the strand.

Answer 15

1. Helicase
2. Single-strand binding proteins
3. 5’ -> 3’ , DNA polymerase
4. Primase synthesizes short RNA primer, which is extended by DNA polymerase to form an Okazaki fragment.
5. DNA ligase

Question 16

DNA polymerase and function

Answer 16

1 - repair
2 - cleans up Okazaki fragments
3 - main polymerase

Question 17

Enzyme that prevents tangling upstream from the replication fork

Answer 17

gyrase or topoisomerase

Question 18

why is RNA primer needed?

Answer 18

DNA polymerase 3 (enzyme that builds new DNA strand) can only add nucleotides to existing strands of DNA

Question 19

Replacement of RNA primer by DNA is done by ________.

Answer 19

DNA polymerase I

Question 20

Enzymes do make mistakes at a rate of about _____________. In humans, with our 6 billion base pairs in
each diploid cell, that would amount to about __________ every time a cell divides!

Answer 20

1 per every 100,000 nucleotides
120,000 mistakes

Question 21

Explain the three (3) main steps in DNA replication.

Answer 21

initiation
elongation
termination

Question 22

the enzyme that is responsible for the polymerization of nucleotides to nucleic acid during the elongation phase of DNA replication

Answer 22

DNA polymerase

Question 23

________ is the first DNA polymerase was discovered by ______- in _____ for which he received the 1959 Nobel Prize in Chemistry.

Answer 23

DNA polymerase I
Arthur Kornberg
E.coli

Question 24

DNA pol 1 has 3 enzymatic activies

Answer 24

• polymerization (5’ -> 3’)
• exonuclease (3’ -> 5’) - proofreading
• exonuclease (5’ -> 3’) - edit out sections of damaged DNA

Question 25

discovered DNA pol II and III

Answer 25

Thomas Kornberg son of Arthur Kornberg

Question 26

DNA Pol III is highly "______" while DNA pol I is "____"

Answer 26

processive distributive

Question 27

Fidelity of DNA replication can be traced to three distinct activities:

Answer 27

* accurate selection of nucleotides * immediate proofreading * post-replicative mismatch pair

Question 28

Types of DNA Damage or Lesion

Answer 28

1. loss of amino group (deamination): C - > U 2. mismatches 3. breaks in the backbone 4. crosslinks

Question 29

is a frequent cause of breaks in backbones, but some chemicals produce breaks as wells

Answer 29

ionization radiation

Question 30

two types of crosslinks

Answer 30

intrastrand - same DNA strand interstrand - opposite DNA strand

Question 31

DNA damaging agents (5)

Answer 31

* DNA replication stress * ionizing radiation * UV light * oxygen radicals * polyaromatic hydrocarbon

Question 32

repairs base mismatch (insertion/deletion)

Answer 32

mismatch repairre

Question 33

repairs ssDNA breaks

Answer 33

base-excision repair

Question 34

repairs intrastrand crosslinks

Answer 34

nucleotide-excision repair

Question 35

repairs interstrand crosslink

Answer 35

dsDNA break repair

Question 36

Each time a cell divides, the telomeres get _____.

Answer 36

shorter

Question 37

When telomeres get too short, the cell can no longer divide; it becomes _______ or it dies

Answer 37

inactive or "senescent"

Question 38

associated with aging, cancer, and a higher risk of death.

Answer 38

telomere shortening

Question 39

some factors of aging (4)

Answer 39

* **telomere shortening** * **chronological age** - risk factors increase overtime * **oxidative stress** - oxidants damage DNA, proteins, lipids * **glycation** - glucose sugar bind and inhibits DNA, proteins, lipids

Question 40

DNA to protein: * When a gene is switched on, ________ attaches to the start of the gene. It moves along the DNA making a strand of ______. This process is called ________. * ________ is the removing and adding sections of RNA. * mRNA moves out of the nucleus out to the ______. * ______ binds to mRNA and reads the code in mRNA to produce a chain made up of _____. * ______ carry the amino acids to the ribosome

Answer 40

* RNA polymerase, mRNA, Transcription * RNA splicing * cytoplasm * ribosome, amino acids * tRNA

Question 41

_______ repeats that bind a set or proteins called _______and protect the DNA by forming a closed telomere 'cap'

Answer 41

TTTAGGG shelterin

Question 42

- enzymes that lengthens telomeres - prevents progressive shortening of lagging strand

Answer 42

telomerase

Question 43

- are unique DNA segments that contain multiple short repeated sequences - AT-rich stretch

Answer 43

replication origin

Question 44

control the initiation of DNA replication by directing assembly of the repeat on machinery to specific sites on the DNA chromosome

Answer 44

Origin-binding proteins