Genetic code and DNA

Question 1

Nucleic acids

Answer 1

contain DNA and RNA
DNA: store and transmit
RNA: transcribe to make proteins

Question 2

The 4 nucleotides

Answer 2

-DNA encode info using 4 nucleotides (A, C, G, T (T is U in RNA)
- Generate all messages needed to build proteins and cells

Question 3

Nucleotides (have 3 parts)

Answer 3

1. nitrogenous base
2. pantose- 5 carbon sugar (In RNA, use 5-C sugar called ribose, in DNA use similar sugar but lack hydroxyl group)
3. at least 1 high-energy P group ( P group - change due to lots of electrons)

Question 4

Nucleosides

Answer 4

• nitrogenous base
• pentose sugar
• no p group

Question 5

ATP

Question 6

cAMP

Answer 6

cyclic adenosine monophospahte
- similar to ATP but include only 1 P group that is attached to pentose sugar at 2 point
cAMP: chemical signaling molecule inside cells

Question 7

Nitrogenous Base

Answer 7

• Experience. hydrophobic intercation with. adjacent bases stacked on top of each other. Enhancing stability of nucleic acid
  N base is what make DNA and RNA unique
• N base: cyclic with a lot of N base
• Pyrimidines are nitrogenous base with 1 ring
• Purines: 2 rings

Question 8

Nitrogenous base DNA pyrimidines

Answer 8

In DNA, the pyrimidines are cytosine and thymine

Question 9

Nitrogenous base DNA purine

Answer 9

adenine and guanine (PURE As Gold)

Question 10

Nitrogenous base RNA

Answer 10

Adenine, guanine, cytosine, uracil ( Cut the PY)

Question 11

Pairing

Answer 11

Thymine pair with Adenine (or uracil)
- Cytosine pair with Guanine ( 3 H bonds: complementry held by hydrogen bond, weak intercation but many togther form a stable molecule) Gc pairs stick best

Question 12

Chargaff’s Rule

Answer 12

• a double starnd DNA molecule contain 1:1 ratio of A:T; C:G
  ex: 20% A: 20% T

Question 13

how nucleotide held together?

Answer 13

Sugar phosphate backbone: a linear string: pento sugar and P group connected by a phosphodiester linkage
- the P group link nucleotide togther by binding 3’c to a 5’c

Question 14

complementary sequence

Answer 14

must be complementary and antiparallel running in the 3’ to 5’
- ex: 5’ ACTG-3’ (A=T, C=G, T= A, G=C) - 3’TGAC5’

Question 15

Separating 2 strands of double-starnds DNA molecule

Answer 15

• use heat or. urea to denature
• melting DNA:Tm
  overcoming the H bond that hold base pairs together
• Annealing: reverse process

Question 16

DNA double helix

Answer 16

have grooves:
- wider grooves are ‘major groove’
- narrower grooves: ‘ minor grooves”
- these grooves bind sites for transcription factors

Question 17

Central dogma:

Answer 17

DNA to RNA to proteins

Question 18

Alfred Hershey & Chase experiment

Answer 18

• DNA is inherited and source of genetic info
• viruses incubated with radioactive sulfur that labeled their proteins
  other viruses were incubated with radioactive phosphorus that labeled their DNA
• These viruses (microphages: were allowed to infect bacteria)
• ## after the infected bacteria is isolated, they contained radioactive material only when infected by the PHOSPHORUS-LABELED VIRUSES ( the DNA but not the protein was tranferred

Question 19

Heterogenous nuclear RNA (hnRNA)

Answer 19

precursor to mRNA that is modifies to the mature mRNA form

Question 20

mRNA

Answer 20

template to synthesis protein

Question 21

tRNA ( transfer RNA)

Answer 21

• transfer aminos to growing polypeptide chains
• recognize specific codons or sequences on mRNA

Question 22

Ribosomal RNA (rRNA

Answer 22

• synthesized in nucleoli
• making more than 50% of ribosomes by weight
  some molecules act as ribozymes have Inherent enzymatic activity
• siRNA and miRNA gene expression inhibit gene expression

Question 23

Reverse transcription

Answer 23

• enzymes reverse transcriptse in viruses reverse trasncriped rna back to DNA
  that help the virus propagate in its host

Question 24

genetic code: degenerate

Answer 24

• more than one different codon can encode for the same amino

Question 25

Conservative mechanism (DNA replication)

Answer 25

- the entire DNA molecule is completely duplicated to create a entire new DNA molecule

Question 26

Dispersive mechanism

Answer 26

the DNA backbone would be broken in multiple places as two strands unwind both the old and new molecule would contain section of old and new DNA

Question 27

Semi-conservative

Answer 27

the two DNA strands separate and each serve as a template for synthesis of a new strand \ - both old and new contain one old and one new strand

Question 28

Meselson-Stahl experiment

Answer 28

E.coli bacteria were grown in medium contain nitrogen-15 isotope( heaver than the much more nitrogen 14 isotope) - after many gen, the 15N had been completely incorporated into bacterial DNA The bacteria were transferred to medium contain the 14N and replicated - after centrfuging and testing on salt to see density: if the DNA replicated vis conservative mechanism: after 1 round replication, we expected to see 2 separate bands ( 1 for 15N and 1 14N) - instead all of the new DNA molecule had intermediate density (contain part of the old and new DNA)

Question 29

prokaryote replication:

Answer 29

- have 1 origin replication (specific sequence that recognized the pre-replc complex

Question 30

eukaryotic replc

Answer 30

- much more complex genomes - multiple origin replication - DNA replication produce identical sister chromatid connected to original DNA at chromosome centromere

Question 31

Helix unwinding

Answer 31

- accomplished by helicase enzyme which unwind 2 strands and the replication fork - single stranded binding proteins: prevent the new separated one from coming back together

Question 32

Topoisomerase enzyme (DNA gyrase)

Answer 32

- alleviate supercoiling created by helicase by making incision in 1 of the DNA strands and rotate the cut around the other then rejoin them to relax DNA

Question 33

primase

Answer 33

- synthesize a short RNA primer with free 3 hydroxyl group that is a starting point

Question 34

Prokaryotic DNA polymerases

Answer 34

- DNA polymerase I: removes rna primer, replace primer with DNA and repairs DNA - DNA polymerase II: repair DNA - DNA poly III: synthesizes new DNA and proofread DNA via 3'-5'

Question 35

eukaryotic DNA polymerase

Answer 35

- DNA poly alpha: initiate synthesis - DNA poly delta: synthesize new DNA and replace RNA primer with DNA - DNA poly ę epsilon: extend leading starnds and repair - DNA poly gamma: replicating mitochondrial DNA -DNA poly: beta: repair DNA

Question 36

Ligase:

Answer 36

responsible for joining DNA fragments or Okazaki fragments together that are produced as a result of the DNA replication process. As such, if a cell contains disconnected DNA fragments, nonfunctioning ligase may be the culprit.

Question 37

telomeres

Answer 37

- exetend telomeres to preventt chromoses arms from shortening that prevent loss of genetic materia - telomeres protect against degradation at end of chromoses in the cells that divide and replicate. Cells that divide have more telomeres activities

Question 38

telomeres

Answer 38

- exetend telomeres to preventt chromoses arms from shortening that prevent loss of genetic materia - telomeres protect against degradation at end of chromoses in the cells that divide and replicate. Cells that divide have more telomeres activities

Question 39

Stop codons

Answer 39

UGA, UAA, and UAG are all stop codons. - U go away U are annoying U are ghastly