Overview of DNA and structure

Question 1

What gets packaged to make chromosomes?

Answer 1

DNA

Question 2

What are the three required properties of dna?

Answer 2

1. Must allow for accurate replication (when cells divide each cell needs accurately replicate to be in the new cell)
2. Must contain information
   3.Must be able to change (rarely)- has to give mutations

Question 3

What are the three basic components of dna?

Answer 3

phosphate back bone, sugar (deoxyribose), and base

Question 4

What kind of bases are in dna?

Answer 4

Purines and Pyrimadines

Question 5

What are the type of purines?

Answer 5

A and G

Question 6

What are the type of pyrimidines?

Answer 6

C and T

Question 7

Nucleotides must have how may phosphates? How many can they have upto?

Answer 7

Must have 1, can have upto 3

Question 8

Where is the OH on the sugar in DNA? Is this important?

Answer 8

on the three prime carbon, is important for synthesis

Question 9

In double stranded DNA, how much A+G and T+C is there?

Answer 9

An equal amount, A+G = T+C

Question 10

In double stranded DNA, is there equals amounts of paired nucelotides?

Answer 10

Yes, G= C and A=T

Question 11

What does it mean if an organisms DNA is GC rich?

Answer 11

It means that some organisms have more GC content

Question 12

After every _____ base pairs, dna twists

Answer 12

10 bp

Question 13

In what direction does DNA twist?

Answer 13

Right

Question 14

What are phosphodiester bonds?

Answer 14

Is the 3’ carbon of sugar of one nucletide, bonding to the 5’ carbon of another sugar via a phosphate group

Question 15

What kind of orientation does the two dna strands show?

Answer 15

antiparrellel, one is 5’ to 3’ other is 3’ to 5’

Question 15

Why is dna with more GC content stronger?

Answer 15

Is more GC rich, G-C has three bond smore H bonds so stronger

Question 16

Whats the difference betwen purine and pyrimidines?

Answer 16

purine- two rings
pyrimadine- one ring

Question 17

What experiment confirmed that dna replicates in a semi conservative manner?

Answer 17

meselson-stahl experiment

Question 18

What replicates DNA?

Answer 18

DNA polymerase

Question 19

What happens in catalyzing DNA that produces energy for the rxn?

Answer 19

pyrophosphate (two extra phosphates) gets cleaved, this produces energy to drive dna synthesis

Question 20

new nucleotides can only be added in what direction?

Answer 20

The 5’ to 3’ direction, because the 3’ sugar needs to bond to the phosphodiester which bonds to the 5’ of the next sugar.

Question 21

How does DNA get synthesized?

Answer 21

unwinding- single strand DNA binding proteins unwind DNA, helicase facilitates this by disrupting H bonds
Leading strand gets synthesized- leading strand template in 3’ to 5’ serves as template for leading strand in 5’ to 3’ direction, DNA polymerase three does this by building off primers made by primase
Lagging strand gets synthesized from template in 5’ to 3’ direction, so the lagging strand gets synthesized in chunks by poleymerase three working off primer.
B Clamp starts DNA synthesis, and okazaki fragmets are refined by polymerase 1 as it removes primer with nucelotides and fills gaps, and ligase joins the fragments
gyrase rejoins dna strands

Question 22

What kind of bonds does DNA ligase catalyze?

Answer 22

phosphodiester bonds

Question 23

How long are primers made by rna primase?

Answer 23

11 bp long