nucleic acids and DNA replication

Question 1

what does DNA do

Answer 1

holds genetic info

Question 2

what does RNA do

Answer 2

transfers genetic info from DNA to ribosomes

Question 3

what makes up a DNA nucleotide

Answer 3

• deoxyribose as a pentose sugar
• nitogen containing bases ( adenine, thymine, cytosine and guanine)
• contains a phosphate group

Question 4

what does a RNA nucleotide contain

Answer 4

• ribose as the oentose sugar
• nitrogen bases ( adenine, uracil, cytosine and guanine)
• contains a phosphate group

Question 5

what is the structure of DNA

Answer 5

• polynucleotide
• phosphodiester bonds between adjacent nuclotides, formed by condensation reactions
• double helix with two polynucleotide chains held togather by hydrogen bonds between specific complementary base pair

Question 6

what is the structure of RNA

Answer 6

• short polynucleotide chain
• 3 different types ;
  messengar RNA ( mRNA )
  transfer RNA ( tRNA )
  ribosomal RNA (rRNA)

Question 7

what is the structure of mRNA

Answer 7

• linear in shape
• no hydrogen bonds
• contains codons

Question 8

what is the structure of tRNA

Answer 8

• clover leaf shape
• contains H bonds
• contains anticodons
• has an amino acid binding site
• transports amino acids

Question 9

what is the structure of rRNA

Answer 9

• contains H bonds

Question 10

what are the differences between DNA and mRNA

Answer 10

DNA ;
- deoxyribose
- thymine
- long
- double stranded
- contains H bonds

mRNA ;
- ribose
- uracil
- short
- single stranded
- does not contain H bonds

Question 11

what is the structure of prokaryotic DNA ( how is it different to DNA)

Answer 11

• shorter
• fewer genes
• circular not linear
• not associated with histones
• no introns present
• sometimes there are additional plasmids

Question 12

what is the process of semi conservative replication

Answer 12

1) DNA helicase is an enzyme which unwinds the DNA double helix by breaking the H bonds between complementary bases in the polynucleotide strands
2) this gives a single stranded DNA with exposed bases that act as a template determining the order of nucleotides on the newly synthesised strand.
3) new DNA nucleotides are attracted to exposed bases on template strands and form complementary base pairs
4) DNA polymerase joins adjecent nucleotides by condensation reaction forming phosphodiester bonds.
5) after replication each DNA molecule contains one original template strand and one newley synthesised strand