DNA, RNA, and DNA replication

Question 1

James Watson is…

Answer 1

a sexist asshole that stole info from people

Question 2

What did Rosalind Franklin do?

Answer 2

used X-ray diffraction data

Question 3

what are the purines?

Answer 3

adenine and guanine

Question 4

what are the pyrimidines?

Answer 4

cytosine, uracil, and thymine

Question 5

What are the complementary base pairs in DNA?

Answer 5

adenine-thymine (2 hydrogen bonds)
guanine-cytosine (3 hydrogen bonds)

Question 6

what is Chargaff’s rule?

Answer 6

A pairs to T and G pairs to C

Question 7

What is the basic chemical composition of DNA?

Answer 7

sugar phosphate backbone and a base combine to form a nucleotide
-nucleotides form to make a DNA strand
-make a double stranded DNA
-form a double helix

Question 8

What is a gene?

Answer 8

a unit of heratity

Question 9

How is DNA organized in prokaryotes?

Answer 9

linear or contiguous fashion

Question 10

Can transcription and translation occur on the same strand at the same time in prokaryotic organisms?

Answer 10

yes, because there is no nucleus , there is no separation between transcription and translation

Question 11

What are exons?

Answer 11

regions of DNA that will give rise to the protein sequence

Question 12

What are introns?

Answer 12

regions of DNA that do not code for protein

Question 13

What are UTR?

Answer 13

untranslated regions that are on the 5’ and 3’ ends of the DNA

Question 14

What is the process of removing introns from a transcript?

Answer 14

splicing

Question 15

Is there only one way to splice a transcript?

Answer 15

no, there are other regulatory elements that can alter the splicing (alternative splicing)
-this can create multiple proteins that can be made from one transcript

Question 16

How is DNA condensed in prokaryotes?

Answer 16

by a set of polyamines and proteins in back and forth loops
(look like a bobby pin)

Question 17

How is DNA condensed in eukaryotes?

Answer 17

first condensed with nucleosomes (involve about 200 bp each) and a set of core proteins
-nucleosomes looks like beads on a string and are packages together to give chromatin fiber structure

Question 18

What is euchromatin?

Answer 18

more relaxed structure and transcriptionally active

Question 19

What is heterochromatin?

Answer 19

more highly condensed and generally not transcriptionally active

Question 20

What are the even more condensed that heterochromatin form of DNA?

Answer 20

solenoids and then supersolenoids and then into chromosomes

Question 21

How were chromosomes arranged and numbered?

Answer 21

by size
-biggest is chromosome 1
-smallest chromosome 22 (or the Y chromosome)

Question 22

What is the DNA entity in bacteria called?

Answer 22

plasmids

Question 23

How many protein coding genes are in the human genome?

Answer 23

around 20,000-25,000

Question 24

How much of the DNA is made up of coding genes?

Answer 24

1%

Question 25

how many isoforms does the average gene give?

Answer 25

8

Question 26

How long is the average gene?

Answer 26

27,000 bp

Question 27

What is the proteome?

Answer 27

the complete set of proteins in an organism (more complex than the average estimate)

Question 28

How many bp is the human genome?

Answer 28

around 3.2 billion

Question 29

What is the smallest mutation that can cause disease?

Answer 29

1 bp

Question 30

What is the difference between siblings?

Answer 30

around 1-2 million bp

Question 31

What is the difference between unrelated humans?

Answer 31

around 6 million bp

Question 32

Base pair difference between humans and chimps?

Answer 32

around 50 million bp

Question 33

Base pair difference between humans and mice?

Answer 33

around 100 million bp

Question 34

Is only one strand of DNA able to be used for replication?

Answer 34

no, both strands are able to be used for replication

Question 35

What is the central dogma of genetic information flow?

Answer 35

DNA -> RNA -> protein

Question 36

What does DNA polymerase do?

Answer 36

makes new strand of DNA in the 5' - 3' direction -requires a template strand and a strand to build off of with a free 3' OH group -has 5'-3' polymerase activity and 3'-5' exonuclease activity

Question 37

Which direction is DNA made?

Answer 37

5'-3'

Question 38

What are the origins of replication rich in?

Answer 38

AT regions

Question 39

What is the active region of replication?

Answer 39

replication fork

Question 40

How many replication forks on a circular chromosome?

Answer 40

two replication forks moving in opposite directions

Question 41

What is the leading strand of DNA?

Answer 41

daughter strand that is synthesized continously

Question 42

What is the lagging strand of DNA?

Answer 42

daughter strand that is synthesized discontinously

Question 43

What are the fragments created on the lagging strand of DNA replication?

Answer 43

Okazaki fragments

Question 44

Why are Okazaki fragments created?

Answer 44

since DNA replication happens 5'-3', there are small fragments made that are then ligated together

Question 45

what attaches Okazaki fragments?

Answer 45

DNA ligase *requires ATP

Question 46

What are the general steps of DNA replication?

Answer 46

-DNA rich in A-T pairs (replication origin) -local opening of DNA helix -RNA primer synthesis -leading strand DNA synthesis begins -RNA primers start lagging strand synthesis

Question 47

How fast is DNA polymerase in bacteria?

Answer 47

500 nt/sec

Question 48

How fast is DNA polymerase in eukaryotes?

Answer 48

50 nt/sec

Question 49

What enzyme makes the RNA primers for DNA replication?

Answer 49

DNA primase -creates a new polynucleotide chain

Question 50

How long is the RNA primer?

Answer 50

10 nt

Question 51

Why is the RNA primer needed for DNA synthesis?

Answer 51

DNA polymerase is not able to start their own nucleotide chains

Question 52

Steps of lagging strand synthesis:

Answer 52

-RNA primer made by DNA primase -DNA polymerase adds to new RNA primer to start new Okazaki fragment -DNA polymerase finished DNA fragment -old RNA primer erased and replaced by DNA -nick sealing by DNA ligase joins new Okazaki fragment to the growing chain

Question 53

What enzyme seals that broken phosphodiester bond?

Answer 53

DNA ligase

Question 54

Is DNA replication accurate?

Answer 54

yes, there are a lot of mechanisms in place that remove the chance for a lot of mutations to cause huge harm -only 3 nucleotide changes at each time of cell division

Question 55

What is DNA helicase?

Answer 55

enzyme that moves along DNA strand and break any portions that are double stranded

Question 56

What do single strand DNA binding proteins do?

Answer 56

bind to exposed DNA strands -unable to open DNA strands themselves, but aid helicases by stabilizing unwound helix -binding coats and straightens out regions of single-stranded DNA on the lagging strand template -prevent formation of short hairpin helix

Question 57

What does the sliding clamp do for DNA replication?

Answer 57

holds DNA polymerase on the DNA

Question 58

What is Werner syndrome?

Answer 58

premature aging disease -cells divide more slowly -allow DNA damage to accumulate -impair normal cell activities and cause health problems

Question 59

How do retroviruses replicate?

Answer 59

use reverse transcriptase to turn their RNA into DNA that can be inserted into the human genome