Lecture 4 Unit 1

Question 1

what makes an RNA molecule slightly less stable

Answer 1

the oxygen molecule makes the RNA slightly more charged making it less stable

Question 2

what is the difference in the sugar in DNA and RNA

Answer 2

DNA the sugar is deoxyribose, RNA the sugar is ribose

Question 3

what is the difference in bases in DNA and RNA

Answer 3

DNA has thymine RNA has uracil

Question 4

what is the difference at the 5’ end in DNA and RNA

Answer 4

DNA has a monophosphate RNA has a triphosphate

Question 5

what is the difference in size between DNA and RNA

Answer 5

DNA is very large RNA is smaller

Question 6

what is the difference in strands of DNA vs RNA

Answer 6

DNA has double strands RNA has single strands

Question 7

how is the template strand read in transcription

Answer 7

from 3’ to 5’

Question 8

how is the RNA strand synthesized in transcription

Answer 8

5’ to 3’

Question 9

where does transcription start and end

Answer 9

starts at the promotor sequence ends at the terminator sequence

Question 10

what are housekeeping genes

Answer 10

genes that are needed for basic cellular function and are transcribed all of the time

Question 11

what happens in eukaryotic promotor recognition

Answer 11

1. general transcription factors bind to the promotor and transcriptional activator proteins bind to enhancers
2. transcriptional activator proteins, mediator complex, RNA pol 2, and general transcription factors are brought close

Question 12

what does RNA polymerase 2 do?

Answer 12

adds nucleotides to the 3’ end

Question 13

how does the polymerization reaction (the adding of nucleotides) occur?

Answer 13

1 incoming ribonucleotides are accepted if they correctly base pair

2. the 3’- OH of the growing strand attacks the high energy phosphate bond of the incoming ribonucleotide, providing the energy to drive the reaction
3. the two phosphates of the incoming ribonucleotides are released as pyrophosphate

Question 14

what does polycistronic mean

Answer 14

there are multiple genes on a primary transcript

Question 15

how does transcription and translation occur in prokaryotes

Answer 15

they are coupled, so translation begins before transcription is completed

Question 16

what does polyadenylation do

Answer 16

add a poly A tail to the 3’ end

Question 17

how is the 5’ end modified

Answer 17

adds a special nucleotide called the 5’ cap

Question 18

what do the 5’ cap and polyA tail do

Answer 18

stabilizes the RNA transcript since the single strand in unstable and susceptible to breakdown by enzymes

Question 19

what happens in RNA splicing

Answer 19

intron removal

Question 20

what catalyzes intron removal

Answer 20

spliceosomes

Question 21

what are spliceosomes made of

Answer 21

a complex of RNA and protein

Question 22

what does rRNA do

Answer 22

found in all ribosomes that aid in translation

Question 23

what does tRNA do

Answer 23

carries individual amino acids for use in translation

Question 24

what does snRNA do

Answer 24

found in eukaryotes and involved in spacing, polyadenylation, and other processes in the nucleus

Question 25

what does small regulatory RNA do

Answer 25

can inhibit translation or cause destruction of an RNA transcript