TOPIC 6.1 DNA and RNA Structure
KEY Unit 6: Gene Expression and Regulation
ENDURING UNDERSTANDING IST-1 Heritable information provides for continuity of life.
LEARNING OBJECTIVE
IST-1.K Describe the structures
involved in passing hereditary What is the significance of this famous
information from one generation experiment (what does it demonstrate)?
to the next.
Radioactive protein did not show up
inside the bacteria, while radioactive
ESSENTIAL KNOWLEDGE DNA did. This demonstrates that it is
IST-1.K.1 DNA, and in some cases DNA, not proteins, that are
RNA, is the primary sourceof transforming bacteria, holding genetic
heritable information. information.
IST-1.K.2 Genetic information is
transmitted from one generation How did Crick, Watson, Franklin and Wilkins
to the next through DNA or contribute to our knowledge of DNA?
RNA—
Combined, they revealed the double helix
structure of the DNA molecule.
a. Genetic information is stored in
and passed to subsequent
generations through DNA
molecules and, in some cases, RNA Draw a plasmid. Where are plasmids found in Prokaryotic cells? Where are they found in Eukaryotic cells (HINT
molecules. consider the evolution of some Eukaryotic organelles!)?
b. Prokaryotic organisms typically Plasmids are small rings of DNA free floating inside Prokaryotes.
have circular chromosomes, while They are also found in mitochondria and chloroplasts (consider the
eukaryotic organisms typically Endosymbiotic Theory that these organelles were once free-living
have multiple linear chromosomes. prokaryotes)
Come up with some way to remember (to link the facts together) that A and G are Purines and have a double ring,
IST-1.K.3 Prokaryotes and while C, T, and U are Pyrimidines and have just one ring. Then share your idea with someone and see what idea
eukaryotes can contain plasmids, they came up with!
which are small
extra-chromosomal, Answers will vary! Some ideas: AU is the symbol for gold 'pure gold' two gold rings when you get
double-stranded, circular DNA married. Pyrimidines are one ring, like a pie, and you CUT the pie.
Science of Curiosity
,molecules.
Briefly explain in your own words how the base pairing rules of DNA lead to its ability to be used as the hereditary
material of life (aka, to be copied and passed to a resulting daughter cell).
LEARNING OBJECTIVE
IST-1.L Describe the The base pairing rules mean that one strand of DNA holds the information for making the opposite
characteristics of DNA that allow it strand. DNA is able to split down the middle and one strand becomes the template formaking the
to be used as the hereditary second strand, resulting in two copies of the DNA molecule- one for each daughtercell.
material.
ESSENTIAL KNOWLEDGE
IST-1.L.1 DNA, and sometimes A always matches with T, and G always matches with C…..but why?
RNA, exhibits specific nucleotide Proofreading enzymes run along the DNA molecule to be sure there are no mis-pairings between bases,
base pairing that is conserved but how do they know when a mistake has happened?
through evolution: adenine pairs
with thymine or uracil (A-T or A-U) Based on their structure (shape) explain why purines must always match with pyrimidines. In your explanation,
and cytosine pairs with guanine (C- include how a proofreading enzyme would identify a location where two purines are accidentally matched up, and
G)— a location where two pyrimidines are matched up.
a. Purines (G and A) have a A purine (two rings) always matches with a pyrimidine (one ring) making the 'rung of the DNA
double ring structure. ladder' three total rings across. If two purines were matched, there would be four rings across, and
two pyrimidines would be just two rings across. The proofreading enzyme would detect a bulge or a
b. Pyrimidines (C, T, and U) havea depression in the DNA strand at these locations respectfully, and correct it by replacingone base with
single ring structure. the correct matching base.
Okay, but why can't T (a pyrimidine) match with G (a purine)?
Based on the number of hydrogen bonds that are available in adenine, thymine, guanine and cytosine, explain
why A always matches with T, and C with G. In your explanation, include how a proofreading enzyme would
identify a location where G and T are accidentally matched up, and a location where A and C are matched up.
G and C form three hydrogen bonds together, while T and A form just two hydrogen bonds. If a C were
matched to an A, the C would have an open bond, which would be noticed by a proofreadingenzyme.
Same holds true if a T were matched to a G.
Science of Curiosity
, Unit 6: Gene Expression and Regulation
TOPIC 6.2 Replication
ENDURING UNDERSTANDING IST-1 Heritable information provides for continuity of life
LEARNING OBJECTIVE
IST-1.M Describe the mechanisms by which In your own words, what does it mean that DNA replication is a ‘semiconservative’ process?
genetic information is copied for transmission
between generations. This means that one strand is conserved, the template strand
stays in tact, serving as a template for the opposite strand as it
ESSENTIAL KNOWLEDGE is constructed.
IST-1.M.1 DNA replication ensures continuityof
hereditary information—
a. DNA is synthesized in the 5’ to 3’ direction.
leading strand
b. Replication is a semiconservative process—
that is, one strand of DNA serves asthe template
for a new strand of complementary DNA.
c. Helicase unwinds the DNA strands. lagging strand
d. Topoisomerase relaxes supercoiling in front
of the replication fork.
e. DNA polymerase requires RNA primers to
initiate DNA synthesis.
f. DNA polymerase synthesizes new strands of
DNA continuously on the leading strand and Draw each of the following enzymes into the diagram where they would be working during DNA
discontinuously on the lagging strand. Replication. See the standards on the left for a description of their role.
Helicase Ligase (will need two) DNA polymerase (will need two) Topoisomerase
g. Ligase joins the fragments on the lagging
strand.
On diagram, label the leading strand and the lagging strand - briefly explain why Replication works a bit
X The names of the steps and particular enzymes differently on the leading vs. lagging strand. Use the word antiparallel
involved - beyond DNA polymerase,ligase, RNA
polymerase, helicase, and topoisomerase - are DNA polymerase can only lay down new DNA in a 5' to 3' direction. The leading strand runs
beyond the scope of the AP Exam in a 5' to 3' and can be made continually. The lagging strand is antiparrallel, so mustbe made
in pieces. DNA polymerase moves 5' to 3' as the replication fork opens it in a 3'to 5'
direction, DNA polymerase has to double back again and again as it opens..
Science of Curiosity
KEY Unit 6: Gene Expression and Regulation
ENDURING UNDERSTANDING IST-1 Heritable information provides for continuity of life.
LEARNING OBJECTIVE
IST-1.K Describe the structures
involved in passing hereditary What is the significance of this famous
information from one generation experiment (what does it demonstrate)?
to the next.
Radioactive protein did not show up
inside the bacteria, while radioactive
ESSENTIAL KNOWLEDGE DNA did. This demonstrates that it is
IST-1.K.1 DNA, and in some cases DNA, not proteins, that are
RNA, is the primary sourceof transforming bacteria, holding genetic
heritable information. information.
IST-1.K.2 Genetic information is
transmitted from one generation How did Crick, Watson, Franklin and Wilkins
to the next through DNA or contribute to our knowledge of DNA?
RNA—
Combined, they revealed the double helix
structure of the DNA molecule.
a. Genetic information is stored in
and passed to subsequent
generations through DNA
molecules and, in some cases, RNA Draw a plasmid. Where are plasmids found in Prokaryotic cells? Where are they found in Eukaryotic cells (HINT
molecules. consider the evolution of some Eukaryotic organelles!)?
b. Prokaryotic organisms typically Plasmids are small rings of DNA free floating inside Prokaryotes.
have circular chromosomes, while They are also found in mitochondria and chloroplasts (consider the
eukaryotic organisms typically Endosymbiotic Theory that these organelles were once free-living
have multiple linear chromosomes. prokaryotes)
Come up with some way to remember (to link the facts together) that A and G are Purines and have a double ring,
IST-1.K.3 Prokaryotes and while C, T, and U are Pyrimidines and have just one ring. Then share your idea with someone and see what idea
eukaryotes can contain plasmids, they came up with!
which are small
extra-chromosomal, Answers will vary! Some ideas: AU is the symbol for gold 'pure gold' two gold rings when you get
double-stranded, circular DNA married. Pyrimidines are one ring, like a pie, and you CUT the pie.
Science of Curiosity
,molecules.
Briefly explain in your own words how the base pairing rules of DNA lead to its ability to be used as the hereditary
material of life (aka, to be copied and passed to a resulting daughter cell).
LEARNING OBJECTIVE
IST-1.L Describe the The base pairing rules mean that one strand of DNA holds the information for making the opposite
characteristics of DNA that allow it strand. DNA is able to split down the middle and one strand becomes the template formaking the
to be used as the hereditary second strand, resulting in two copies of the DNA molecule- one for each daughtercell.
material.
ESSENTIAL KNOWLEDGE
IST-1.L.1 DNA, and sometimes A always matches with T, and G always matches with C…..but why?
RNA, exhibits specific nucleotide Proofreading enzymes run along the DNA molecule to be sure there are no mis-pairings between bases,
base pairing that is conserved but how do they know when a mistake has happened?
through evolution: adenine pairs
with thymine or uracil (A-T or A-U) Based on their structure (shape) explain why purines must always match with pyrimidines. In your explanation,
and cytosine pairs with guanine (C- include how a proofreading enzyme would identify a location where two purines are accidentally matched up, and
G)— a location where two pyrimidines are matched up.
a. Purines (G and A) have a A purine (two rings) always matches with a pyrimidine (one ring) making the 'rung of the DNA
double ring structure. ladder' three total rings across. If two purines were matched, there would be four rings across, and
two pyrimidines would be just two rings across. The proofreading enzyme would detect a bulge or a
b. Pyrimidines (C, T, and U) havea depression in the DNA strand at these locations respectfully, and correct it by replacingone base with
single ring structure. the correct matching base.
Okay, but why can't T (a pyrimidine) match with G (a purine)?
Based on the number of hydrogen bonds that are available in adenine, thymine, guanine and cytosine, explain
why A always matches with T, and C with G. In your explanation, include how a proofreading enzyme would
identify a location where G and T are accidentally matched up, and a location where A and C are matched up.
G and C form three hydrogen bonds together, while T and A form just two hydrogen bonds. If a C were
matched to an A, the C would have an open bond, which would be noticed by a proofreadingenzyme.
Same holds true if a T were matched to a G.
Science of Curiosity
, Unit 6: Gene Expression and Regulation
TOPIC 6.2 Replication
ENDURING UNDERSTANDING IST-1 Heritable information provides for continuity of life
LEARNING OBJECTIVE
IST-1.M Describe the mechanisms by which In your own words, what does it mean that DNA replication is a ‘semiconservative’ process?
genetic information is copied for transmission
between generations. This means that one strand is conserved, the template strand
stays in tact, serving as a template for the opposite strand as it
ESSENTIAL KNOWLEDGE is constructed.
IST-1.M.1 DNA replication ensures continuityof
hereditary information—
a. DNA is synthesized in the 5’ to 3’ direction.
leading strand
b. Replication is a semiconservative process—
that is, one strand of DNA serves asthe template
for a new strand of complementary DNA.
c. Helicase unwinds the DNA strands. lagging strand
d. Topoisomerase relaxes supercoiling in front
of the replication fork.
e. DNA polymerase requires RNA primers to
initiate DNA synthesis.
f. DNA polymerase synthesizes new strands of
DNA continuously on the leading strand and Draw each of the following enzymes into the diagram where they would be working during DNA
discontinuously on the lagging strand. Replication. See the standards on the left for a description of their role.
Helicase Ligase (will need two) DNA polymerase (will need two) Topoisomerase
g. Ligase joins the fragments on the lagging
strand.
On diagram, label the leading strand and the lagging strand - briefly explain why Replication works a bit
X The names of the steps and particular enzymes differently on the leading vs. lagging strand. Use the word antiparallel
involved - beyond DNA polymerase,ligase, RNA
polymerase, helicase, and topoisomerase - are DNA polymerase can only lay down new DNA in a 5' to 3' direction. The leading strand runs
beyond the scope of the AP Exam in a 5' to 3' and can be made continually. The lagging strand is antiparrallel, so mustbe made
in pieces. DNA polymerase moves 5' to 3' as the replication fork opens it in a 3'to 5'
direction, DNA polymerase has to double back again and again as it opens..
Science of Curiosity
