DNA: The Molecule of Heredity

DNA: The Molecule of Heredity
Answer the Following
• List the Functions of DNA
• The single unit of DNA is called
• DNA is located in which organelle of the cell?
• What is the basic unit of DNA made up of?
In all plant and animal cells, the nucleus contains long molecules of DNA.
Which of the following best describes the function of DNA?
a. DNA provides the shape and structure of the
b. DNA packages materials for transport through the
c. DNA carries materials into and out of the nucleus.
d. DNA contains the blueprint for producing the
whole organism.
All of the following are found in a DNA molecule except —
a. carbon dioxide
c. nitrogen
Which molecule is most responsible for determining an
organism’s eye color, body structure, and cellular enzyme
a. Complex starch
b.Fatty acid
c. Carbohydrate
d.Deoxyribonucleic acid
Name the four Nitrogenous base
present in DNA
Determine the complement strand of DNA for each
strand shown below:
In DNA, which of the following determines the traits of
an organism?
a. Amount of guanine
b.Number of sugars
c. Sequence of nucleotides
d.Strength of hydrogen bonds
Erwin Chargaff studied the DNA of organisms within a
single species. Chargaff discovered that the amount of
adenine is about equal to the amount of thymine. Which
of these explains why the ratio of adenine to thymine is
nearly 1:1?
Adenine and thymine pair with each other.
Adenine binds with phosphates, while thymine
binds with nitrates.
Adenine and thymine are identical in chemical
Adenine bases contain a form of thymine.
“Cytosine—guanine—thymine—guanine” describes —
a. nucleotides within an RNA strand
b. a sequence of bases within a DNA section
c. points of DNA separation during protein
d. tRNA codons for specific amino acids
What do you mean by DNA
• Replication takes place in the ___________ of
the cell.
Day 4 Notes “Steps of Replication” (record on
page 5)
1. DNA unwinds and
the two strands
2. DNA polymerase (an
enzyme) adds the
complementary base pairs to
each side.
3. Result: two identical
molecules of DNA, each
with one new and one
old strand of DNA
DNA molecules separate into single strands, which are then used
to construct two identical strands of DNA. This process ensures
that the —
a. cytoplasm is in equilibrium
b.mitochondria are genetically identical to the
c. parent cells use little ATP
d.daughter cells are genetically identical to the
parent cells
Which of the following best describes the question this set of procedures was
designed to answer?
Can a substance from dead bacteria transform living bacteria?
Can R bacterial cells survive heating?
Can dead bacterial cells confer immunity to a living host?
Can bacterial cells be isolated from a healthy host?
In Griffith’s experiment, what happened when heat-killed S-strain
pneumococcus were injected into a mouse along with live R-strain
• A) DNA from the live R-strain was taken up by the
heat-killed S-strain, converting them to R-strain
and killing the mouse
• B) DNA from the heat-killed S-strain was taken up
by the heat killed R-strain, converting them to Sstrain and killing the mouse
• C) Proteins released from the heat-killed S-strain
killed the mouse
• D) RNA from the heat-killed S-strain was
translated into proteins that killed the mouse.
• E) None of the above.
If DNA of a certain organism has guanine as 35% of its bases.
What percentage of its bases would be adenine?
Which is not found in DNA?
Deoxyribose sugar.
Phosphate group
Phospholipid group
If cytosine makes up 28% of the nucleotides in a sample of DNA from
an organism, then adenine would make up what percent of the bases?
• If cytosine makes up 22% of the nucleotides in
a sample of DNA from an organism, then
adenine would make up what percent of the
• 22
• 44
• 28
• 56
In DNA, phosphate groups bond to
Pyrimidine bases
Other phosphate groups
Complementary base pairs are held together by
Peptide bonds
Hydrogen bonds
Disulfide bonds
Covalent bonds
Ionic bonds
Semiconservative DNA replication means
The old DNA is completely broken down
The old DNA remains completely intact
A pairs with T and G pairs with C
Only half of the DNA is replicated
Each new DNA molecule has half of the old
This experiment was conducted by the
scientist __________
• _________ worked with two strains of a
bacterium, one pathogenic and one harmless.
• ___________ were responsible for the
discovery of the double helix structure of DNA
• The phosphate group of one nucleotide is
attached to the sugar of the next nucleotide
by a _________ bond.
Distinguish between
• Purines and Pyrimidines
• DNA and RNA
Answer the Following
• The model of DNA is known as a
____________________________ because it is
composed of two ___________________ chains
wrapped around each other.
• What makes up the sides of a DNA molecule?
• Name 2 purines.
. Name 2 pyrimidines
What makes up the "steps" of a DNA molecule?
• What enzymes help separate the 2 strands of
nucleotides on DNA? What bonds do
• they break?
• If the sequence of nucleotides on the original
DNA strand was A – G – G – C – T – A, what
would be the nucleotide sequence on the
complementary strand of DNA?
State what enzyme carries out the following
functions during DNA replication.
• A) Unwinds the helical DNA by breaking the
hydrogen bonds between complementary bases.
b) Adds DNA nucleotides to the RNA primer.
C). Digests away the RNA primer and replaces the
RNA nucleotides of the primer with the proper
DNA nucleotides.
D) . Links the DNA fragments of the lagging
strand together.
• The DNA strand replicated in short fragments
called Okazaki fragments is called the:
• a. lagging strand
b. leading strand
Draw Neat labeled diagrams of
• Structure of DNA
• DNA Replication
In double stranded DNA how do the four bases
(C,A,T,G) pair up with each other.
• C always pairs with T and A always pairs with
• A always pairs with T and C and G always pair
with themselves
• C always pairs with T and A and G always pair
with themselves
• A always pairs with T and C always pairs with
During DNA replication what is the first process
to occur?
• Sealing of the nicks between short DNA
• Synthesis of the lagging strand
• Unwinding of parental DNA
• Synthesis of the leading strand
DNA replicates through what
Semi-conservative replication
Dispersive replication
Conservative replication
Disparative replication
Which of the following enzymes is not as
involved in DNA replication as the others?
DNA Polymerase
DNA Ligase
What is the function of DNA
polymerase III?
• It adds nucleotide pairs to the growing DNA
• It adds single nucleotides to the growing DNA
• It unwinds the DNA
• It attaches the RNA primers to the DNA strand
Choose the Correct Answer
• Because DNA polymerase III can only act from 5'
to 3', continuous strand growth can be achieved
only along one of the template strands (Leading
strand) and strand growth along the other strand
must occur discontinuously resulting in the
production of a series of short sections of new
DNA called :
Ο Replicon fragments
Ο Okazaki fragments
Ο Klenow fragments
Ο None of the above
• The enzyme that stitches Okazaki fragments
together (along the lagging strand) is called :
Ο DNA Ligase
Ο DNA Polymerase II
Ο Topoisomerase
Ο Holoenzyme
• The enzyme that creates a short RNA
oligonucleotide at initiation sites where
replication is to be carried out is called :
Ο Primase
Ο DNA Ligase
Ο DNA Gyrase
Ο Exonuclease
• A major difference between DNA replication in
prokaryotes and eukaryotes is :
Ο there is only one replication origin in
Ο DNA amylase performs the function of DNA
helicase in prokaryotes
Ο replication is conservative in prokaryotes
Ο prokaryotes do not use Topoisomerase in
the replication process
Good Luck
• Make sure you go over the content in the text
book and the worksheet including the lab
worksheet (building a DNA model), and the
quiz on DNA And DNA Replication

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