3.1.5 nuclecic Acid

Question 1

Structure of DNA

Answer 1

Phosphate group
Pentose sugar (ribose, or deoxyribose)
Nitrogen, organic base

Question 2

Pyrimidines

Answer 2

Cytosine
Thymine
Uracil
(Single Ring)

Question 3

Purines

Answer 3

Adenines
Guanine
(Double Ring)

Question 4

Phone between adjacent phosphate group and sugar

Answer 4

Phosphodiester linkage

Question 5

Bond between bases

Answer 5

Weak hydrogen bond

Question 6

Which pair of DNA is more stable?

Answer 6

CG has three hydrogen bond, more stable
AT/ UT less stable

Question 7

Three types of RNA

Answer 7

Messenger, RNA
Ribosomal, RNA
Transfer RNA

Question 8

How is nucleotides join together?

Answer 8

Ester Bond

Question 9

DNA and RNA comparison

Answer 9

Double-stranded vs single-stranded
Deoxyribose sugar vs ribose sugar
ATCG vs AUCG
Long Vs short
Contain histone protein vs do you not contain protein

Question 10

How DNA structure is related to its function?

Answer 10

Stable structure, allowed it to pass from generation to generation rally mutate
2 strand hold together by hydrogen bond, separation in replication and protein synthesis
Backbone act as protection for bases
Many week hydrogen bond is strong together (provide strength)
Extremely large molecule, which is compact, allowed it to carry a huge amount genetic information
Complimentary pair allow DNA replication, accurately

Question 11

Role of DNA and RNA

Answer 11

DNA: Protein synthesis, DNA replication
mRNA: copy section of DNA (gene)
rRNA : be part of ribosome
tRNA: bring a amino acid to make protein

Question 12

Whole process of DNA replication

Answer 12

1. The enzyme DNA Helicase cause the DNA double helix to unwind and separate into two strands by breaking the hydrogen bonds between complementary base pairing, exposing the base.
2. Both separated Strand, then act as a template for DNA replication to occur
3. Free activated DNA nucleotides in the nucleoplasm are attracted to and hydrogen bond to the complimentary base on the exposed at templates strands by complementary base pairing
4. The newly added nucleotides are then joined together by the enzyme DNA polymerase, which catalyse the formation of phosphodiester bond between adjacent nucleotides.
5. The result into identical DNA molecule being produced. Each of which contain one of the original DNA strand and one newly synthesised DNA strand. (semi-conservative)

Question 13

How can Meselson and Stahl tell what nitrogen isotope the DNA contain when extract from bacteria?

Answer 13

1. The extracted DNA is spun in the centre of the road in the solution of cesium chloride.
2. When spinning, the DNA molecule move in the tested based on their density.
3. Molecule with a higher density will settle further towards the bottom of the test tube.
4. The results from the centrifugation are then analysed.
5. Provide understanding about the DNA molecule and what nitrogen isotope they are made from.

Question 14

Describe the meselson and stahl experiment

Answer 14

Stage 1 bacteria grows from circle generation in growth medium contain heavy nitrogen (N15) [bottom]
Stage 2 bacteria from the end of stage, one I transferred and grow for one generation in Grove, medium contain light nitrogen (N14) [ intermediate ]
Stage 3 the bacteria from the end of stage to a grown for one more generation in growth medium containing light nitrogen (N14) [light and intermediate]