CHEM 1040 Lecture 3: SBI4UC UNIT 3 MARKED
11 Oct 2018
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UNIT 3
Lesson 9: Question 28
a)
According to Watson and Crick model of the DNA, indicates that the DNA molecule is a twisted helix ,
where each side of the helix is running anti-parralel to each other. Another model of DNA discovered by
Watson and Crick is how the complementary base are being paired such as Adenine(A) pairing to
Thymine (T) and Guanine(G) pairing to Cytosine(C) .
Teacher Comments:
You are missing- nucleotides are attached to phosphate and sugar which compose the backbone of the
molecule.
Mark: 3/6
b)
The work of the scientist called Franklin was used to assist Watson and Crick work, when the X-ray
diffraction photographs used by Franklin revealed that the wet form of DNA likely had a double helix, that
made Watson and Crick realized that the two strand model was right as they have discovered a structure
of a twisted helix, and had to reworked their model based on this result and found more insights from
Franklin and other scientist to produce their own discoveries.
Teacher Comments:
good.
Mark: 3/3
Lesson 9 : Question 29
The chemical features of DNA and protein that permitted Hershey and Chase to prove that DNA was the
only molecule that carried hereditary information is the DNA from the bacteriophage and not of protein,
that goes into the bacteria to take over the synthesis of the new viruses.
Teacher Comments:
This answer is very convoluded and I can't understand what you're trying to say.
The chemical feature of each moleucule was that DNA contained phosphate but no sulphur and protein
contains
sulphur but not phosphate. Radio isotope tags were used to trace the path of the two moleucules during
the lytic
cycle.
Mark: 0/2
Lesson 9 : Question 30
According to the DNA extraction activity, the two methods used to separate the strawberry DNA from the
rest of the cell are as follows;
By mashing the strawberry that is bagged with a resalable plastic with lysis solution for two minutes will
help separate the strawberry DNA from the other cell. Another method of separation is cutting one bottom
corners of the resealable bag and squeezes the strawberry pulp together with the liquid into a paper towel
or a coffee filter and sieve for about a minute and then pour about 10 ml of water to rinse out the
strawberry, thus will help separate the strawberry DNA for other cell.
Teacher Comments:
mashing the strawberries
adding the lysis solution.
Mark: 2/4
Lesson 9 : Question 31
Teacher Comments:
good.
Mark: 2/2
Lesson 10 : Question 32
The DNA code is the same in every somatic cell in the human body, because this code stores the
information code from one generation to another except for some cells in reproductive system which
produces an enzyme called telomerase, where the DNA needs to be replicated more times than the
somatic cells.
Teacher Comments:
you should include information about the replication being used to provide daughter cells with an exact
copy of the
parent cell's DNA.
Mark: 2/3
Lesson 10 : Question 33
If the replication were dispersive, there would be a mixture of parental and newly synthesized DNA in the
centrifuge tubes.This would be because the parental DNA molecule would be divided into fragments,and
each daughter DNA molecule would be a mixture of the parental and newly synthesized DNA, where only
one band of the intermediate-weight DNA would be created from the two weights of the parental DNA.
Teacher Comments:
good.
Mark: 3/3
Lesson 10 : Question 34
a) Helicase helps in the unwinding and unzipping of the DNA.
Teacher Comments:
and breaking the hydrogen bonds.
Mark: .5/1
b)
Gyrase is a type of enzyme that moves along the DNA and help cuts the DNA and relaxes the coils that
has been caused by the helicase in twisting and supercoiling the DNA.
Teacher Comments:
good.
Mark: 1/1
c)
DNA polymerase 1 replaces the RNA in the primer with DNA
Teacher Comments:
good.
Mark: 1/1
d)
DNA ligase bind the pieces of DNA together that is created by polymerase 1 and 111
Teacher Comments:
joins the okazaki fragments together on the lagging strand.
Mark: .5/1
Lesson 10 : Question 35
DNA replication is very essential, because it helps to store genetic information from one generation to
another in each daughter cell. This information comprises of genes in organisms as well as growth,
reproduction and repair needed in the functioning of the human body system.
Teacher Comments:
watch that your answers are written clearly. The second sentence doesn't make any sense.
Mark: ½
Lesson 10 : Question 36
Work Submitted by Student: 1 images.
