Biology 11 Honours
NAME__________________
Biochemistry Review
Outlines: Experimental Design, Dehydration Synthesis and Hydrolysis, Proteins, Enzymes,
Nucleic Acids, DNA Replication, Protein Synthesis, Mutations.
1. Experimental Design: Enzymes are proteins that catalyze (speed up)
reactions in organisms. Since the average temperature of the human body
is 37℃, the enzymes in humans normally function at that temperature.
A scientist wonders if temperature affects the rate of an enzyme
catalyzed reaction. Design an experiment to answer the scientist’s
question.
Hypothesis: Temperature affects the ability of an enzyme catalyzed reaction
Testable prediction: If temperature affects the ability of an enzyme catalyzed
reaction then varying the temperature will vary the reaction rate.
Experimental Variable: Temperature
Dependent Variable: Reaction Rate
Control Group: Test Tubes at 37℃ with enzyme (min 10 samples)
Experimental Groups: Group 1- Test tubes at 20 ℃ with enzyme
Group 2- Test tubes at 30 ℃ with enzyme
Group 3- Test tubes at 50 ℃ with enzyme
(min 10 samples per group)
Constant Factors: Enzyme type, source of enzyme, amount of enzyme,
environment- pH, time of reaction, size of test tube, amount of solute and
substrate.
2. Illustrate and describe in words the formation of a dipeptide.
Dehydration Synthesis-a peptide bond is formed by removing a water, the
hydroxyl group from the carboxyl end of one aa and a hydrogen atom from the
amino end of the other aa.
3. Draw and label all parts of an amino acid and describe what happens to
each group in slightly acidic conditions.
4. Explain seven functions of proteins
a)
b)
c)
d)
Enzymes act as catalysts by speeding up chemical reactions.
Transport proteins carry molecules in organisms
Structural proteins are components of various structures
Some Hormones are proteins since they travel in the blood to target
tissues or organs where they stimulate certain responses
e) Receptor proteins on cell membranes allow chemical signals to binds to
the cell.
f) Contractile proteins allow movement
g) Some proteins provide protection against disease (antibodies)
5. Levels of Protein Structure:
Level of structure
Definition
Linear sequence of
Primary 1◦
amino acids in the
polypeptide
Orientation or pattern
Secondary 2◦
which the polypeptide
assumes, αhelix or
βpleated sheet
Folding upon itself,
forming a globular
Tertiary 3◦
structure
Quarternary 4◦
Combination or two or
more polypeptides to
form the final protein
Stabilizing bonds
peptide
hydrogen
Hydrogen, ionic,
covalent, hydrophobic
interactions
Hydrogen, ionic and
covalent
6. Define Anabolic and Catabolic reactions and give examples of each:
a. Anabolic- reorganize and combine smaller molecules into larger
molecules. Energy is required. Examples- protein synthesis or
photosynthesis.
b. Catabolic- break larger molecules into smaller molecules. Energy is
released. Examples- aerobic cellular respiration, fermentation.
7. Draw a labeled graph showing an exergonic reaction with and without a
catalyst (be sure to label axis and include Ea, ∆G)
8. What are the roles of Cofactors and Coenzymes in enzyme catalysis?
Cofactors are non-protein helpers which assist the enzyme in its catalytic function
by accepting or contributing atoms during the reaction.
Coenzymes are organic and are called coenzymes. Vitamins such as niacin,
riboflavin and thiamine are often components of coenzymes
9. Describe in detail why the following graph has the shape it does.
Enzymes have an optimal pH at which they exhibit maximum activity and
thus the reaction rate is maximized.
As pH increases above or below the optimal pH, the enzyme starts to
denature and the active site changes shape.
Therefore there will be a decreased rate of successful collisions and
formation of enzyme-substrate complexes.
Thus the reaction rate will decrease.
At extremes of pH, the enzyme becomes completely denatured, the active
site is completely destroyed and the reaction rate becomes almost zero.
10. Explain the change in reaction rate and how we could increase the rate of
the reaction.
As the substrate concentration increases, there will be an increased rate of
successful collisions and formation of enzyme- substrate complexes.
Thus the reaction rate will increase.
Once the substrate concentration has reached a certain level, however, all the
active sites of the enzymes will be occupied by substrate molecules at all times
and adding more substrate will not increase the reaction rate.
At this point, the enzyme is described as being saturated with substrate.
Once the enzyme is saturated with substrate, reaction rate can only be increased
by adding more enzymes.
11. Compare and contrast the structure of DNA and RNA
Similarities
Pentose sugars
Phosphate groups
Sugar-phosphate backbone
Phosphodiester bonds
Nitrogenous bases- A,G,C
Composed of nucleotides
Differences
DNA- double helix
RNA- linear or globular
DNA- double stranded
RNA- single strand
DNA- deoxyribose
RNA- ribose
DNA- thymine
RNA- uracil
12.
Draw a labeled DNA nucleotide, single strand of DNA and double
helix.
a. DNA nucleotide
b. Single strand of DNA
c. Double helix
13.
Draw a flow diagram included all the steps and enzymes involved
in DNA replication
 The enzyme DNA helicase unwinds and unzips the DNA by breaking
hydrogen bonds.
 Creates a replication fork which both parental strands serve as templates
 Enzyme DNA polymerase builds daughter strands using free floating DNA
nucleotides and the template.
 DNA ligase and polymerase join the daughter strand nucleotides by
creating phosphodiester bonds
 Each new strand and its complementary parent strand, linked by hydrogen
bonds, coil to form two new double helixes
14.
Explain what is meant by semi-conservative replication
Each new helix consists of one new strand and one old strand.
15.
What is the purpose of DNA replication and what is the purpose of
protein synthesis?
DNA replication occurs before mitosis, to provide daughter cells with the same
DNA that the parental cell had, allowing them to produce all the same proteins
that the parental cell could.
Protein synthesis occurs to produce proteins using the genetic information
contained in the DNA
16.
What are the 3 complementary base pairing rules?
a) Adenine always pairs with thymine. Forms 2 hydrogen bonds
b) Guanine always pairs with cytosine. Forms 3 hydrogen bonds
c) A two ring purine always pairs with a one ring pyrimidine.
17.
Describe all the steps in the following diagram: starting with DNA
ending with the polypeptide chain.
Transcription – RNA polymerase binds to the promoter
-RNA polymerase unwinds and unzips the DNA
-Only ONE strand used as the template
-RNA polymerase links RNA nucelotides together based on
the template stand
-Elongation continues until a termination site is reached on
the DNA
-The mRNA is released, travels from nucleus to cytoplasm
-DNA resumes its double helix configuration
Translation
-mRNA combines with the ribosome, sandwiched between the large and
small subunits
-The first two mRNA codons will be in the ribosome
-Two tRNA’s with complementary anticodons to the mRNA codons enter
the ribosome
-Each tRNA carries a specific amino acid
-A peptide bond forms between the aa and the ribosome shifts along the
mRNA, releasing the first tRNA.
-The third mRNA codon is now in the ribosome, and a third tRNA enters,
bringing its aa.
-A peptide bond will form between the second and third aa.
-The polypeptide will continue to be elongated until a termination codon is
reached, bringing in the release factor which causes the finished
polypeptide to be released, the ribosomal subunits to be released, and
mRNA to be realeased and broken down for reuse.
18.Describe the following types of point Mutations:
a. silent Mutation- no effect, due to the redundancy of the genetic
code, no change in the amino acid ( substitution mutation)
b. missense mutation- a substitution mutation that still codes for an aa
even though it’s a different one. May have a small effect or major
effect depending on the aa (similar or not in size and characterisitics)
and whether or not the aa lies in a part of the protein which is critical
for function.
c. nonsense mutation- Substitution mutation that codes for a stop
signal and thus ends protein synthesis. Often disastrous since the
resulting polypeptide is often missing several aa.
19.What are some examples of diseases causes by alternation in chromosome
number or structure
Aneuploidy- is the abnormal number of chromosomes example is
Downsyndrome, which is an example of trisomy having 47 chromosomes instead
of the normal 46.
Polyploidy- having 3 or 4 sets of chromosomes- rare in animals, sometimes in fish
or amphibians, common in plants and may contribute to the evolution of new
plant species.
20.
Describe the difference between karyotyping and nucleic acid
hybridaization
Karyotyping- does not allow detection of point mutations such as
substitutions and small insertions or deletions.
-Analyzing chromosome number by staining
Nucleic acid hybridization- can be used to detect point mutations if the
base sequence of the mutation is known.
-Detection of radioactive bound probe to known base sequence mutation.