SBI4U1 EXAM SHORT ANSWERS

Question 1

o Identifying types of macromolecules, functional groups and polarity/solubility

Answer 1

Types of macromolecules:
Carbohydrates(polar):
Simple sugars: monosac and disacc as an energy source
Complex sugars: polysac, energy source(second) structural support and cell to cell communication
Polar molecules soluble in water except if very large
Polysac are carbohydrate molecules of glucose (monosac) joined together
Types of polysac are:
Starch:glucose is stored in plants
Glycogen: glucose is stored in animals
Cellulose:provides structural support in plant cell walls and humans have hard time breaking it down
Lipids(non polar):
Insoluble in water
Four major types: fats, oils, steroids and phospholipids
Functions are:
Long term energy sources(stored), cushion vital organs, insulate against heat loss
Hydrolysis reaction of glycerol and 3 fatty acids create triglyceride
Unsaturated contain a kink bcuz of a double bond between carbons
- phospholipids are half polar and half non polar
- composed of glycerol, 3 fatty acids and a negative phosphate group
- phosphate group gives a hydrophilic water loving head
- fatty acids are hydrophobic water fearing
The phosphate group is attached to an r group to various atoms

Steroids are composed of 4 rings attached and the most abundant steroid in our body is cholesterol
Proteins:
Composed of amino acids
Must contain an amino group and carboxyl group
Bond linking 2 amino groups is a peptide bond

Question 2

3. Factors that affect reaction rates (4), collision model and enzyme function

Answer 2

3. Factors that affect reaction rates (4), collision model and enzyme function
   Reaction rates:
   Temperature
   The higher the temperature, the faster the rxn.

Concentration
The higher the concentration, the faster the rxn.

Surface Area
The larger the TOTAL SA, the faster the rxn.

Catalysts
A substance that speeds up the rate of a chemical reaction by lowering the activation energy for the reaction.

Not consumed in the reaction.

Collision Theory:
A chemical reaction must involve COLLISIONS of particles with
each other or the walls of the container.
An EFFECTIVE collision has sufficient energy and correct orientation of colliding particles so that bonds can be broken and new bonds formed.
The RATE of a reaction depends on the FREQUENCY of collisions and the FRACTION of those collisions that are effective.

Question 3

Gene cloning using bacteria STEP 1

Answer 3

Gene cloning using bacteria
Recombinant DNA technology allows scientists to produce several identical copies of a gene in a process called GENE CLONING.
Step 1: Insertion of Gene into a Vector:
Insert the gene of interest into a plasmid.
The plasmid has selectable markers such as:
Genes for antibiotic resistance
lacZ gene that codes for an enzyme that breaks down galactose.
The gene of interest is inserted into the plasmid so that it disrupts the
lacZ gene to make it inactive.
Step 2: Transformation:
DNA is taken up by the bacteria (host cell) through transformation.
The bacterial cells are plated on a Petri dish containing
growth media supplemented with:
The antibiotic ampicillin
A galactose derivative, Xgal, which causes bacterial
colonies to turn blue when the lacZ is active.

Question 4

STEP 2

Answer 4

Step 2: Selection of hosts:
The bacterial colonies that have the recombinant DNA are identified:
Blue colonies have an active lacZ gene and contain plasmid only – no recombinant DNA.
White colonies contain the recombinant DNA of interest since they have
an inactive lacZ gene.

Question 5

STEP 3

Answer 5

Step 3: Make multiple copies:
Cells from the colonies that contain recombinant DNA are transferred to a liquid to grow in larger quantities.
The recombinant DNA is:
isolated and purified from the bacterial cells
analyzed to confirm that the correct recombinant DNA molecule was made
Challenges of gene cloning:
The bacteria may not always take the plasmid. Scientists need to figure out if the bacteria took the plasmid by putting the plasmid into bacteria (host cell) and seeing if it has an active or inactive lacz gene (colonies= blue, then it is active, colonies= white, than it is inactive) and by testing if the bacteria is antibiotic resistant. If it did not take the plasmid it will die.