From Gene to Protein

Question 1

Are DNA molecules found in eukaryotes and prokaryotes the same?

Answer 1

Yes

Question 2

What are genes?

Answer 2

sections of DNA containing information that is transcribed into RNA for proteins

Question 3

What are genes?

Answer 3

sections of DNA containing information that is transcribed into RNA for proteins

Question 4

What is the central dogma?

Answer 4

DNA is transcribed into RNA which is translated into an amino acid sequence

Question 5

What is different about the structure of RNA and of DNA

Answer 5

-DNA is 2 stranded, RNA is one stranded
-RNA contains a ribose sugar and uracill instead of deoxyribose and thymine

Question 6

What is the promoter region

Answer 6

Transcription start point situatied upstream (5’), RNA polymerase attaches there

Question 7

Which direction does RNA polymerase read and write

Answer 7

Reads template srands in a 3’-5’ direction

Writes the RNA strand in the 5’-3’ direciton

Question 8

What is the consensus nuelceotide sequence in prokaryotes

Answer 8

TATAAT positioned 10 base pairs upstream and serves as part of the promoter region

Question 9

What is the second consensus nucleotide sequence in prokaryotes

Answer 9

TTGCCA 35 base pairs upstream of the transcription start point

Question 10

What is the structure of RNA polymerase in prokaryotes

Answer 10

They have 1 type of RNA polymerase, a globular protein with channels running through it, with the active site where phosphodiester bonds are formed found at channel intersections

Question 11

What are sigma factors

Answer 11

Found in prokaryotes, helps RNA polymerase bind to DNA at promoter regions

Binds with RNA polymerase to create a holoenzyme

Question 12

What is a holoenzyme

Answer 12

Binds to and unwinds DNA
Made of RNA polymerase and sigma factor

Question 13

How do incoming nucleotides attach themselves to the growing strand

Answer 13

-3’-OH separates phosphate bond from triphosphate, creating a phosphodiesterr bond between the incoming nucleotide and growing strand
-Two phosphates are released as pyrophosphate

Question 14

What is a Rho-independent terminator sequence

Answer 14

-Contains inverted repeat followed by a string of 6 adenines
-Inverted repeats are transcribed and fold in on themselves into a hairpin loop
-This pauses RNA and releases the mRNA

Question 15

What is a rho-dependent terminator sequence

Answer 15

-Uses a rho factor protein
-Binds to and uses ATP to move along RNA and unwinds it from DNA template

Question 16

What allows rapid reproduction in prokaryotes?

Answer 16

-Transcription and translation can happen at the same time
-Processes happen in the same area due to lack of nucleus

Question 17

What ar transcription factor proteins

Answer 17

-Found in eukaryote (instead of sigma)
-Helps RNA polymerase bind

Question 18

what is RNA polymerase I

Answer 18

transcribes genes for rRNA

Question 19

What is RNA polymerase II

Answer 19

transcribes mRNA for proteins

Question 20

What is RNA polymerase III

Answer 20

transcribes genes for tRNA and small regulatory RNA molecules

Question 21

How is RNA modified in eukaryotes to leave the nucleus

Answer 21

-5’ cap and poly A tail

Question 22

What is a 5’ cap

Answer 22

-Attached when transcription begins
-7-methylguanosine
-Guanosyl enzyme attaches 5’ cap

Question 23

What is a poly-A tail

Answer 23

-Attached to 3’ end of mRNA following polyadenylation sequence
-Once AATAAA is transcribed, mRNA is cleaved and poly(A) polymerase adds 150-200 adenines

Question 24

How does the polyAtail and 5’ cap protect the mRNA

Answer 24

-Prevents ribonuccleasee enzymes from targeting phosphodiester bonds
-Helps with ribosome attachment

Question 25

What kind of termination does RNA polymerase I use

Answer 25

similar to rho-dependent

Question 26

What kind of termination does RNA polymerase II use

Answer 26

termination coupled with polyadenylation

Question 27

What kind of termination does RNA polymerase III use

Answer 27

termination sequence similar to rho-independent

Question 28

What are spliceosomes

Answer 28

Location of splicing, made up of 5 small ribonucleooproteins (snRNPs)

Question 29

How does the splicing of introns happen

Answer 29

-RNA in spliceosomes recognizes and pairs with nucleotides at the ends of introns -Cut end forms a loop -New phosphodiester bond is formed between the 3' upstream exon and 5' downstream exon

Question 30

why did Gamow decide there must be 3 nucleotides in a codon

Answer 30

1 would make no sense because there would only be 4 possible amino acids, 2 was also not enough becuase there would be only 16

Question 31

How can there be 64 possible combinations yet only 20 amino acids?

Answer 31

Some codons code for the same amino acid, but no codons code for multiple amino acids

Question 32

What did Nirenberg and Matthaei determine

Answer 32

-Put all components necessary for protein synthesis into tubes -Only uracil resulting in only phenylalanine -Uracil and cytosine alternating gave serine and leucine alternating -Proved there are 3 nucleotides in a codon, more trials found other combinations

Question 33

What is the template strand

Answer 33

-Non-coding -Minus strand -Antisense strand -Complimentary to RNA

Question 34

What is the non-template strand

Answer 34

-Coding strand -Plus strand -Sense strand -Same code as RNA except for thymine

Question 35

What does AUG code for

Answer 35

-Start codon -Methionine

Question 36

What are the stop codons

Answer 36

UAA UAG UGA

Question 37

What is the open reading frame

Answer 37

sequence of a gene from the triplet start codon to the triplet stop codon

Question 38

How many possible reading frames are there if a DNA molecule is unknown

Answer 38

6

Question 39

What are the steps of prokaryotic protein synthesis

Answer 39

transcription-initiation-elongation-termination-translation

Question 40

What are the steps of eukaryotic protein synthesis

Answer 40

transcription-initiation-elongation-termination-mRNA processing-RNA export-translation

Question 41

What changes phenotype for hair colour

Answer 41

Amino acid variation in melanocortin receptors

Question 42

Why does transgenics work

Answer 42

-The genetic code is shared almost universally -There are genetic similarities but there are limitations -Some species have the same codons, but they may code for different amino acids

Question 43

What is retinoblastoma

Answer 43

cancer caused by disruption of Rb protein in eye

Question 44

What does the Rb protein do

Answer 44

Regulates cell cycle (apoptosis) If it fails, cancer/cell division occurs

Question 45

Metastasis

Answer 45

cancer spreads through blood and lymphatic system to other areas

Question 46

How does chemotherapty work

Answer 46

-Drugs travel via liposomes to areas of cancer growth to reduce cell division -Inhibit topoisomerases needed to unwind DNA for replication

Question 47

What makes triple -ve breast cancer aggressive

Answer 47

-Rapid spreading and cell diviison -No estrogen and progesterone receptors making it difficult to treat via hormonal/lipid medicaiton -Radiation and chemotherapy are the only current options

Question 48

How can triple -ve breast cancer risk be determined

Answer 48

-Kaiso expression levels -Prevalent in black and hispanic women

Question 49

What is kaiso

Answer 49

-Transcription factor -Regulates expression of how cells grow, adhere, and die -Malfunction leads to tumours and agressive cancer spread