biological molecules 4

Question 1

what is dna( properties and name)

Answer 1

deoxyribose( deoxyribonuleicacid)
-hold genetic infomation
-double helix

Question 2

draw the structure of dna and rna

Answer 2

phosphate group attached by a phosphodiester bond to a pentose sugar( deoxyribose/ ribose-5 carbons), attached to a nitrogenous base

Question 3

how is a phosphodiester bond created

Answer 3

-Dna polymerease catalyses a condestion reaction
-condenstation reaction( water molecule is created)
-between deoxyribose and phosphate group

Question 4

what are the compemantry pairs and why are they important?

Answer 4

adenine and thymine/ uracil in rna
cytosine and guanine
- important for accurate replication

Question 5

How many amino acids make a nitrogenous base

Answer 5

3

Question 6

what dna is linked with protein

Answer 6

Histone dna ( provides structural support)

Question 7

what is the sugar phosphate backbone made out of

Answer 7

pentose sugar and the phosphodiester bond attaching to the phosphate group

Question 8

what is dna replication called

Answer 8

semi conservation

Question 9

what makes up the semi conservation dna

Answer 9

1 newly synthesised dna and 1 parental templete strand

Question 10

Describe stage 1 of semi conservation - hint hydrogen bond

Answer 10

-dna helicase breaks hydrogen bonds ( 2 inbetween a&t and 3 inbetween c& g)
- unwinds double helix exposing nucleotides

Question 11

Describe stage 2 hint dna polymerase

Answer 11

-new nucleotide bases are attracted to the exposed ones
-dna polymerase joins the new nuclotides in the new strand with a condesation reaction( releasing a water molecule)
- phosphodiester bond is created
-hydrogen bonds form between nitrogenous bases, to form the double helix structure again

Question 12

Action of dna polymerase

Answer 12

-dna polymerase can only work in a 3’ to 5’ direction, and the other strand goes in a 5’ to 3’ direction so it has to work in fragments

Question 13

EVidence for semi conservative replication?
hypothesis

Answer 13

• meselsons and stahl
• to see if dna was conservative or semi conservative

Question 14

INfomation about the experiment:

Answer 14

-dna bases contain nitrogen
- 2 isotopes of nitrogen was uses
-14N(lighter) and 15 N( heavy)
-bacteria was grown with 1 of the 2 isotopes
- menaing there dna was either heavy or light and this was tested in a centrifuge

Question 15

Looh at notes for practical