Text book DNA

Question 1

Macromolecule

Answer 1

a large molecule

Question 2

Polynucleotide

Answer 2

made from a large sequence of nucleotides

Question 3

Chromosome

Answer 3

A molecule of DNA

Question 4

How is the structure of DNA suited to its function

Answer 4

: bases located inside the bases located inside the sugar-phosphate backbones and so they are protected and the integrity of the code is maintained

• molecules are long so they can store lots of genetic info
• hydrogen bonds between the bases can break
• enabling molecule to unzip for transcription and replication

Question 5

Meselson and Stahl experiment

Answer 5

• Only first gave access to N15
• Only gave e-coli N14 – The old version
• Old strand unwound then new ones wound repeat
• Then put in a centriguge

1) Just N15 so would have been heavier
2) Band would have been higher as mixture of the two – could be dispersive so doesn’t prove
3) Mixture of the two and the lighter band which is just the N14 - proves as there would have been mixture of all of them – here you have one as a mixture and one that is N14

Question 6

How a protein is made

Answer 6

Ribosomes act as catalysts, allowing (two) amino acids to align so that a peptide bond forms between them Nucleus/nucleolus – where mRNA is made (tRNAs and ribosomes are also made there)
Endoplasmic reticulum – newly made proteins pass into the cisternae and go to the Golgi apparatus to be modified/finished Mitochondria – make ATP.

Question 7

DNA rep

Answer 7

• two molecules of DNA, identical to eachother and the parent molecule
• DNA polymerase
• in nucleolus
• occurs during S phase of the cell cycle
• the whole DNA
• bases
• deoxyribose

Question 8

Transcription

Answer 8

• one molecule of mRNA, which is complementary to the template strand of the gene and, therefore, a copy of the coding strand of the gene
• RNA polymerase
• nucleolus
• G1 phase of) interphase, when a gene needs to be expressed (i.e. when the protein coded for by the gene needs to be made) in the cell
  ¬- bases
  -Ribose

Question 9

Degenerate

Answer 9

more than one codon, codes for the same amino acid which reduces the chances of point mutations

Question 10

Transcription

Answer 10

• A gene unwinds and unzips (enzymes = gyrase and helicase); H bonds break; exposing nucleotide bases; (activated) RNA nucleotides align to template strand; complementary base pairing; mRNA is a copy of the coding strand; mRNA uses U instead of T.

Question 11

Translation

Answer 11

mRNA at ribosome; tRNA brings an amino acid; anticodon–codon bonding via temporary H bonds; complementary base-pairing/U–A and C–G; 2 amino acids are located side by side and a peptide bond forms; via a condensation reaction; ribosome moves along mRNA; ATP needed

Question 12

Demonstrate the diff between DNA and RNA within cells

Answer 12

Using a thin section of tissue, on slide; methyl green pyronin stain; DNA stains green and RNA red