DNA

Question 1

What is the molecule that binds chromatids at the centromere?

Answer 1

Cohesin

Question 2

Maternal and paternal pairs of chromosomes that contain similar but not identical genes are called what?

Answer 2

Homologous chromosomes.

Question 3

What is the chromatin that is complexed with proteins, highly condensed, transcriptionally inactive, and concentrated at the periphery of the cell?

Answer 3

Heterochromatin

Question 4

What is the translucent chromatin that is decondensed, is transcriptionally active, and is near the center of the cell?

Answer 4

Euchromatin

Question 5

What is the highly condensed structure with in the nucleus that contains genes for rRNA?

Answer 5

Nucleolus

Question 6

What is the meshwork of filaments that stabalize the nucelus?

Answer 6

Nuclear filaments

Question 7

The perinuclear space is contiguous with what structure?

Answer 7

The ER

Question 8

How do large molecules pass through the nuclear membrane?

Answer 8

Through specific channels

Question 9

How do small molcules pass through the nuclear membrane?

Answer 9

Freely –through small, non-specific opening

Question 10

What are the top three substances transported across the nuclear membrane?

Answer 10

mRNA, proteins, ribosomal subunits

Question 11

What protein transports mRNA out of the nucleus so that ribosomes may act on it?

Answer 11

Ran

Question 12

Where are ribosomal subunits synthesized? How does this aid in transcriptional regulation?

Answer 12

Cytoplasm

Prevents immediate translation

Question 13

What are the two proteins that are involved in transport into the nucleus?

Answer 13

Ran and importin

Question 14

True or false: the majority of mRNA is transported out of the nucleus by Ran-GTP

Answer 14

False–they go through a Ran-independent mechanism

Question 15

What is the protein that is involved in Ran-independent transport, and is on the cytoplasmic side of the nucleus?

Answer 15

Dbp5

Question 16

True or false: histones are recycled in the processing of new DNA

Answer 16

True

Question 17

Where does DNA polymerase gamma fuction?

Answer 17

In the mitochondria

Question 18

What do DNA polymerases need in order to begin synthesis of a new DNA strand?

Answer 18

An RNA primer

Question 19

What is the direction of DNA synthesis?

Answer 19

5’ to 3’ direction

Question 20

What is the driving factor of DNA replication?

Answer 20

Hydrolysis of pyrophosphate

Question 21

What do DNA helicases do?

Answer 21

Unwind the DNA molecule

Question 22

True or false: origins of replication can only be acted on once during DNA replication?

Answer 22

True–there are proteins that ensure this.

Question 23

What is the action of topoisomerases?

Answer 23

Prevent supercoiling of the DNA strand by cutting and re-ligating strands

Question 24

True or false: there are proteins that keep the DNA strands from re-associating once they are unwound

Answer 24

True

Question 25

Which DNA polymerase synthesizes a new RNA primer?

Answer 25

DNA polymerase alpha

Question 26

An RNA primer has what type of end to it?

Answer 26

3' OH group

Question 27

True or false: DNA polymerases can stay on DNA strands without the need for additional proteins

Answer 27

False

Question 28

What is the DNA polymerase that usually transcribes DNA

Answer 28

Pol epsilon

Question 29

What are the enzymes that remove the RNA primers?

Answer 29

ribonucleases

Question 30

What are the enzymes that bind DNA fragments from okazaki fragments together?

Answer 30

DNA ligases

Question 31

What is the action of telomerases?

Answer 31

They add additional DNA segments to the end of okazaki fragments so that it can be finished and not result in the shortening of the DNA strand.

Question 32

What is the group that is at the 5' end of a DNA molecule?

Answer 32

Phosphate group

Question 33

What is the group at the 3' end of a molecule?

Answer 33

Hydroxyl

Question 34

What is the type of RNA that is most drastically changed from the original transcription?

Answer 34

tRNAs

Question 35

What is the only modification of DNA

Answer 35

Methylation of Cytidine

Question 36

Which bases have 3 hydrogen bonds? Which form 2?

Answer 36

A and T have 2 | C and G have 3

Question 37

Which form of DNA is the most common: B, A or Z

Answer 37

B

Question 38

B form DNA helices are what "handed"? What about A? Z?

Answer 38

Right handed for B and A | Z is left handed

Question 39

What are the class of molecules that fit exactly on the rungs of the DNA ladder, and cause a distortion of the DNA helix?

Answer 39

Intercalcating agents

Question 40

What other structures can DNA be found in, besides the DNA helix?

Answer 40

Sequence dependent structures

Question 41

What are the structures that arise from palindromic DNA sequences? RNA?

Answer 41

Cruciform structures | Hairpin loops

Question 42

What are the structures that arise from long sequences of pyrimidines (and long purine sequences in the opposing strand)?

Answer 42

Triple helical structures

Question 43

What is negative supercoiling?

Answer 43

When the DNA is twisted in the direction that unwinds the helix

Question 44

What is positive supercoiling?

Answer 44

When the DNA helix is twisted in the direction that winds that helix further

Question 45

What is the action of Type I topoisomerases?

Answer 45

Make a single cut in the phosphodiester backbone of a DNA molecule

Question 46

What is the action of Type II topoisomerases?

Answer 46

Make a double stranded break

Question 47

Doxorubicn acts on which topoisomerase? What is the consequence of this?

Answer 47

topoisomerase II--leads to double stranded breaks and cell death.

Question 48

What are the four types of non-protein producing DNA sequences?

Answer 48

1. Spacer DNA 2. Introns 3. Non-protein encoding DNA (for rRNA) 4. Repetitous DNA sequences

Question 49

What is the type of DNA that does not code for proteins, and is found BETWEEN genes?

Answer 49

Spacer sequences

Question 50

What is the type of DNA that does not code for proteins, and is found WITHIN genes?

Answer 50

Introns

Question 51

What are pseudogenes?

Answer 51

Duplicates of genes that are not transcribed, and are free to mutate.

Question 52

What are the levels of chromatin?

Answer 52

11 nm (histone + DNA) 30 nm (nucleosomes together) 300 nm 700 nm

Question 53

DNA and histone complexes are called what?

Answer 53

nucleosomes

Question 54

How is the mitochondrial genome more closely related to prokaryotes than to humans (3)?

Answer 54

1. It is circular 2. Is present as multiple copies within a single mitochondria 3 .Has a very high gene density

Question 55

What are the four components of a nuclear pore?

Answer 55

1. Nuclear basket 2. Protein ring in the double membrane 3. Central transporter on the inside of the ring 4. filaments on the cytoplasmic side of the ring

Question 56

What is the action of Doxorubicin?

Answer 56

Acts on human topoisomerase II, causing double strand breaks in the DNA and cell death.

Question 57

What is the action of Nalidixic acid and ciprofoxacin?

Answer 57

They act on topoisomerase II of bacteria, and caused cell death through the introduction of double stranded breaks. These are Abx.