Transcript PIG - enzymes

PIG - enzymes
What are enzymes? [3]
3 of the following:
• Biological catalysts
• Globular proteins
• Increase the rate of (chemical)
reaction
• Complimentary substrate shape to its
active site
• Have an active site
What is activation energy? [2]
• Energy ‘barrier’
• Molecules must overcome this barrier
in order to take part in the reaction
Name the 2 enzyme theories & explain
them. [4]
Lock & Key theory [1]
Active site and substrate are
complimentary shapes
Induced fit theory [1]
Arrival of the substrate causes a change
in the shape of the active site
Which inhibitor fits the enzyme’s active
site? [1]
Competitive inhibitor
Explain how a non-competitive inhibitor
affects the rate of an enzyme related
reaction. [3]
• Reduces rate of reaction
• Fits into site on enzyme away from the
active site
• Attaches to tertiary structure of enzyme
• Changes shape of the active site
• Substrate can no longer bind with active
site
• Permanent
Why does increasing substrate
concentration eventually have no
effect on the rate of reaction? [2]
• V max
• All active sites are occupied at all
times
What are coenzymes? [2]
• Organic, non-protein molecule
• (Often) carry chemical groups
between enzymes
• So enzyme controlled reactions can
link together in sequence
What is a prosthetic group? [1]
A coenzyme that is a permanent part of
an enzyme molecule.
What is it called when an enzyme and
substrate fit together? [1]
Enzyme-substrate complex
How does lowering the pH of a solution
affect an enzyme’s tertiary structure?
[3]
• Increased concentration of H+ ions means
lower pH
• Hydrogen ions are positive so are
attracted to negatively charged molecules
• Hydrogen bonds hold tertiary structure in
place
• Hydrogen ions react with hydrogen bonds
which alters the tertiary structure
What is an enzyme inhibitor? [1]
A substance or molecule which slows
down the rate of an enzyme
controlled reaction.
Nucleic Acid PIG
Describe the structure of DNA
Polynucleotide
Contains bases adenine, guanine,
cytosine and thymine
Double stranded
Name some differences between
DNA and RNA
RNA contains:
Ribose sugar
Has uracil instead of thymine
Single stranded
Exist in 3 forms: Mrna, tRNA and rRNA
Explain how DNA replicates
During interphase
Double helix untwisted
Hydrogen bonds broken
DNA unzips
Free DNA nucleotides hydrogen
bonded onto exposed bases
Covalent bonds between phosphates
and sugars forming backbone
Explain the term anti-parallel
The strands lie opposite each other,
parallel, but run in opposite directions
(the 3’ end goes with the 5’ end)
What is complementary base
pairing
Complementary base pairs pair up
C-G
A-T or U in RNA
Hydrogen bonds link base pairs
What is a gene
A sequence of DNA nucleotides that
codes for a polypeptide
Outline the role of DNA in protein
synthesis
DNA provides the template strand for
mRNA and determines the sequence
of amino acids and therefore the
structure of proteins
What is mRNA for?
Messenger RNA
Complementary to the DNA Strand
Contains Uracil instead of Thymine
Passes through the nuclear pore and
attaches to a ribosome
What happens at the ribosome and
what is the role of tRNA
tRNA brings amino acids to the
ribosome in the right order according
to the base sequence on the mRNA
Amino acids then joined together by
peptide bonds to give a protein