BIO 251 Quiz 2

Who discovered that adenine and thymine and cystosine and guannine have the same ratios in DNA which lead to double helix

Chargraff

Which group is on the 5” end

phosphate

which group is on the 3’ end

sugar/hydroxyl

purines

adenine and guanine

pryamidines

uracil, cytosine and thymine

nucleoside

base + sugar

Nucleotide

base + sugar + phosphates

antiparalell

5’ on one end, 3’ on the other and the 3’ end matches with the 5’ end and visa versa

what type of amino acids are in histones

positivly charged

what is a nucleosome?

8 histones

heterochromatin

More tightly packed DNA that is used by the cell less often.

euchromatin

DNA that is less tightly packed and used by the cell more

Conjugation

When bacteria get close and create a pilus or bridge between them where one can give the other a plasmid

What of the pRL27 plasmid is left behind

transposase gene

What did Griffith do?

He discovered that bacteria can share something between other bacteria and cause non-lethal bacteria to become lethal. Mice experiments.

Avery, Macleod and Mcarthy

Discovered the hereditary factor was DNA by replicating Griffith’s experiment, but isolating one macromolecule per experiment.

Hershey-Chase

Marked Phosphorus and Sulfur, and gave them to phages. Then the phages infected bacteria by inserting DNA. After centrifuging, the ghost phages had no marked Phosphorus, but still had Sulfur meaning sulfur is in proteins and phosphorus is in DNA.

semi conservative

One old and one new strand per DNA

Meselson-Stahl

Labeled Nitrogen and gave it to bacteria. Then centrifuged generations and recorded where Nitrogen fell. 1st gen was fully labeled N, 2nd was also fully labeled because it was bonded to the other strand. third was half and half.

Primase

Makes RNA primers for lagging strand so DNA polymerase can have a template

Which direction does the new strand get made from/ synthesized

5’ to 3’

What direction is the leading strand synthesized

towards the repllication fork

Nuclease

Destroys RNA primer

ligase

Using outside nuceotides, repairs phosphodi ester bonds between new DNA and okasaki fragments

sliding clamp

Keeps DNA polymerase on the DNA

single strand binding proteins

hold onto lagging strand so it doesn’t rebind with the other strand

topoisomerase

Nicks DNA pre unwinding so it doesn’t supercoil

How does DNA polymerase proofread

If a wrong nuceotide is there the H-bonds won’t work so DNA takes it away and replaces it with the closest and hopefully correct nucleotide

Temomerase

Extends telomeres,

problem with ending on the lagging strand

It lacks an OH group for the last okasaki fragment to hang onto to its sequence is copied and telomeres are extended

5’ GCGAT 3’

3’ CGCTA 5’

How many H-bonds do A and T make

two

How many H-bonds do C and G make

three

What do I need to remember about drawing DNA duplex?