exam Q's

Question 1

explain why at the end of the day only a small proportion of the student mass was ATP

Answer 1

-provides energy for metabolic reactions
-ATP is broken down
-it is constantly recycled

Question 2

explain why some gene mutations do not affect the function of a protein?

Answer 2

-the genetic code is degenerate, different codons can code for the same amino acid
-silent mutations lease primary structure unchanged
-some dependent on tertiary structure
-substitution of amino acids with similar properties to original might leave tertiary structure/secondary structure unchanged.

Question 3

compare DNA replication and transcription by describing the similarities and differences

Answer 3

similarities:
-in both helicase enzyme breaks hydrogen bonds between DNA bases
-both use polymerase enzymes to join nucleotides
-in both DNA helix unwinds

differences:
-transcription uses free RNA nucleotides whereas replication uses free DNA nucleotides
-in transcription mRNA copy is made in replication two identical double helices are made
-transcription only a certain section of DNA unwinds whereas replication whole two strands are unwind.

Question 4

outline how the process of DNA replication is completed following the paring of nitrogenous bases

Answer 4

-DNA polymerase joins free nucleotides forming phosphodiester bonds
-sugar-phosphate backbone is formed
-the two polynucleotide strands wind together forming a double helix

Question 5

explain how pairing of nitrogenous bases allows identical copies of DNA to be made?

Answer 5

-adenine always pairs with thymine and cytosine always pairs with guanine
-bonded by hydrogen bonds
-purines can only bind to pyrimidines because they are different sizes

Question 6

suggest why using pineapple juice as a source of protease enzyme is not appropriate when attempting to produce a pure sample of leek DNA

Answer 6

-because it will contain DNA from the pineapple and the pH may be too low