Exam 2

Question 1

Kinetochores

Answer 1

-fomred on the centromere region of the chromosome
-spindle microtubules attatch to the kinetochore

Question 2

What is the differences between meiosis and mitosis?

Answer 2

-two daughter cells, each 2n are produced in mitosis
-four daughter cells, each n are produced in meiosis
-Meiosis has two different separations stages while mitosis only has one

Question 3

What is the relationship between being haploid and meiosis?

Answer 3

-Haploid: n, has only 1 copy of the chromosome

Question 4

When do the cells in meiosis become haploid?

Answer 4

after meiosis II

Question 5

What is the relationship between diploid and mitosis?

Answer 5

Diploid: 2n in mitosis for a total of 46 chromosomes; this is when the cell has two sets of chromosmes

Question 6

Sugoshin

Answer 6

protein that prevents cohesin degradation during meiosis I

Question 7

What does sugoshin help protect?

Answer 7

cohesin at the centromere
-it is eventually degraded and allows the cohesin at the centromeres to break down and allows the chromosomes to seperate

Question 8

Template Strand in Transcription

Answer 8

the strand that is transcribed
-contains the transcription unit: a promoter, RNA coding sequence, terminator

Question 9

Non-Template Strand in Transcription

Answer 9

not usually transcribed

Question 10

What is the function of the sigma factor?

Answer 10

binding to the promoter when transcription starts

Question 11

What is created when the sigma factor binds to the core enzyme and what is the function?

Answer 11

-holoenzyme
-capable of binging promoter and initiating transcription as it is one of many transcription factors

Question 12

Eukaryotic promoters

Answer 12

-direct RNA polymerase to know where to go (not transcribed)
-normally negative and upstream

Question 13

Prokaryotic Promoters

Answer 13

-consensus sequences are used as promoters
- -10 consensus: 10 bp upstream of the start site
- -35 consensus sequence: TTGACA
-Location of sequence determines start site of transcription

Question 14

What has been shown experientally to influence transcription?

Answer 14

Base mutations in promoters

Question 15

What binds to the promoter in prokaryotic transcription?

Answer 15

holoenzyme

Question 16

How does termination occur in rho-dependent termination?

Answer 16

uses a terminator sequence to cause polymerase to pause
-Rho protein binds to the rut site and moves toward the 3’ end
-When RNA polymerase encounters a terminator sequence it pauses and allows rho to catch up and unwind the DNA-RNA hybrid stopping transcription

Question 17

How does termination occur in rho-independent transcription?

Answer 17

hairpin structure, followed by a string of uracils
-transcription terminates when inverted repeats form a hairpin followed by a string of U’s because it destabilizes DNA-RNA pairing

Question 18

How are -10 and -35 useful to promoters?

Answer 18

both are consensus sequences and are found upstream of the start site
-sigma factor binds to core enzyme creating a holoenzyme. This then binds to the -10 and -35 sequence

Question 19

Basal Transcription Apparatus is found where and what is its function?

Answer 19

-general transcription factor and RNA polymerase
-these are only found in eukaryotes and bind to the promoter to recruit RNA polymerase

Question 20

What is the role of the 5’ and 3’ UTR?

Answer 20

-help initiate translation
-5’ end is bound by proteins that are recognized by the 5’ cap and 3’ tail
-have clear distinction where coding stops and UTR starts which sets the reading frame

Question 21

What is an intron?

Answer 21

-intervening sequences that are removed by DNA splicing
-rare in prokaroytes; all classes of eukaryotic genes contain introns
-variable length; 200 to over 50,000 bp

Question 22

What is an exon?

Answer 22

expressed coding region

Question 23

What is the splice some?

Answer 23

removes introns and rejoins exons

Question 24

Where does the splicesome remove introns at?

Answer 24

-5’ consensus sequence: GU A/G AGU (where splicing occurs on 5’ end)
-3’ consensus sequence: CAGG

Question 25

What is the branch point in the splicesome mechanisim?

Answer 25

the adnenine that is ~18-40 NT’s upstream of 3’ splicing site

Question 26

What can happen if the branch point is deleted or mutated?

Answer 26

splicing is prevented

Question 27

What is the splicesome made out of?

Answer 27

five RNA molecules + 300 proteins which controls the process of splicing

Question 28

What does splicing require?

Answer 28

consensus sequense that are present at the 5’ splice site and the 3’ splice site, with a weak one at the branch point

Question 29

How many steps is splicing? What is it facilitated by?

Answer 29

-5 snRNAs
-2 step process

Question 30

siRNA function

Answer 30

triggers degradation of other RNA molecules in eukaroytic cells in the nucleus and cytoplasm

Question 31

miRNA function

Answer 31

inhibits translation of mRNA in eukaryotic cells in the nucleus and cytoplasm

Question 32

E site function

Answer 32

exit site

Question 33

P site function

Answer 33

peptidyl site occupies fMET-tRNA

Question 34

A site function

Answer 34

aminoacyl site; EF-Tu, GTP, and charged tRNA form a complex