bio hl test -- dna
Outline the primary structure of proteins.
number/sequence/order of amino acids «in a protein/polypeptide chain»
Identify two hydrolysis reactions that occur in the small intestine.
polysaccharides to disaccharides/monosaccharides like sucrose to glucose AND fructose
State one similarity and one difference between the structure of genes and short tandem repeats.
similarity:
both made of DNA/nucleotides
difference:
genes are longer/have longer DNA/base sequences «without repeats»
Outline the role of short tandem repeats in DNA profiling.
tandem repeats are used to identify the source of a DNA sample
Explain how model making helped Watson and Crick to establish the structure of DNA.
built scale models of components of DNA
Outline the role of the enzyme helicase in replication.
unwinds/separates strands/double helix (by breaking hydrogen bonds)
Outline the role of the enzyme DNA polymerase in replication.
makes covalent bonds between nucleotides
Outline the role of tRNA activating enzymes in translation.
they attach amino acid to all of the tRNA molecules that have anticodon corresponding to that amino acid
Nitrogen is part of many important substances in living organisms. Distinguish between transcription and translation.
transcription produces RNA AND translation produces polypeptide/protein
Nucleosomes help to regulate transcription in eukaryotes. State the components of a nucleosome.
DNA and histone
State a chemical modification of a nucleosome that could impact gene expression.
methylation
Outline the process of DNA profiling.
sample of DNA obtained from person/hair/blood/mouth/crime scene , PCR used to amplify/make copies of DNA (in sample)
Outline the role of DNA polymerase III in DNA replication.
binds to template strand , adds nucleotides to template strand/to single stranded DNA using complementary base pairing
Describe the structure of the DNA molecule.
two stranded/double helix , one strand organized 5’ to 3’ and the other 3’ to 5’
Outline the role of three enzymes used in the replication of DNA.
a. helicase to separate/unwind DNA strands
b. gyrase / toposiomerase to relax the tension as bacterial DNA is being uncoiled / prevent supercoiling
c. primase to synthesise primers
d. polymerase (I) removes primers and replaces with nucleotide
e. polymerase (III) adds nucleotides (in a 5' to 3' direction)
f. ligase joins (Okazaki) fragments together
Explain how a polypeptide chain is synthesized in a eukaryotic cell.
translation occurs on ribosomes
Outline the stages in the production of mRNA by transcription
DNA is unwound/strands are separated by RNA polymerase
b. new nucleotides attached to template strand by RNA polymerase
c. complementary base pairing/base pairing
Outline the roles of helicase and ligase in DNA replication.
Helps to form and join okazaki fragments , breaks hydrogen bonds
Explain DNA replication
helicase unwinds the double helix
gyrase prevents DNA from recoiling
helicase separates the two strands of DNA/breaks hydrogen bonds
DNA polymerase III can only add nucleotides to the end of an existing chain
(DNA) primase adds RNA primer/short length of RNA nucleotides
DNA polymerase (III) adds nucleotides in a 5’ to 3’ direction
complementary base pairing / adenine to thymine and cytosine to guanine
DNA polymerase I replaces primers/RNA with DNA
ligase joins the fragments together/seals the nicks
Outline how translation depends on complementary base pairing.
translation converts a sequence of mRNA nucleotides/codons to a sequence of amino acids/polypeptide/protein