1
The Twisting Tale
of DNA: Ted ED
DNA Vocabulary
quizzes
Quiz #1
1. Nucleotide
2. Base Pairing
3. Transformation
4. Deoxyribose
5. Double Helix
6. Chromatin
7. Replication
8. DNA Polymerase
9. Helicase
10. Chromosome
11. Complementary
12. DNA
2
UNIT GOALS
3
– Distinguish between DNA and RNA.
– Explain the role of DNA in storing and
transmitting cellular information.
– Describe the relationships between changes
in DNA and potential appearance of new
traits including – alterations during replication,
insertions, deletions, substitutions, mutagenic
factors, radiation, chemicals.
– Examine the use of DNA technology in
forensics, medicine and agriculture.
DNA
• Function:
Store &
Transmit
genetic
information
• Acts as a
library or
storehouse of
informtion.
CLIP
• DNA is located
in the nucleus.
4
Discovery of DNA
Many People contributed to
the discovery of DNA.
5
1928
Frederick Griffith
(Transformation)
6
Experiments with
Diplococcus pneumonia
(bacterium responsible for
witnessed a
transformation.
pneumonia),
•These experiments are
recognized as the first
in a series that lead to
the conclusion that
DNA is the carrier of
genetic information,
the genetic material.
DNA is the molecule of inheritance
1944
Oswald Avery
• Repeated Griffith’s
experiment
• Looking for “what” is
being transferred.
• Used enzymes to break up
carbohydrates, lipids and
proteins-transformation still
took place.
• Used enzymes to break up
DNA-transformation did not
happen.
• Conclusion: DNA is a
Nucleic Acid
7
1952
Rosalind Franklin & Maurice Wilkins
• Used x-ray
diffraction to
see DNA.
• Conclusions:
DNA is
twisted like a
spiral
staircase
Double helix 8
1952
Erwin Chargaff
• Discovered that the
– amount of Adenine = amount Thymine
– amount of cytosine = amount
of guanine.
• True in all organisms tested.
• Called Chargaff’s Rule.
• Conclusions:
1. amt A is = to amt of T
2. amt C is = to amt of G
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1953
Watson and Crick
“Put it all together”
Developed the
structure of DNA
that we know today.
Conclusions:
Described the
complete structure
of DNA.
CLIP
10
11
12
Structure of DNA
1. Double Helix.
-Twisted ladder
or spiral
staircase
2. Two stranded
3. Held together
by hydrogen
bonds
4. Made of four
Nucleotides
1. Phosphate
2. Base ( Nitrogen)
3. Sugar
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Structure of DNA
Remember:
• DNA is a
nucleic
acid.
• Nucleic
acids are
made of
nucleotides
14
Structure of DNA
Nucleotides
• Long chain of
Nucleotides
• There are four
nucleotide that make
up DNA
• Each nucleotide has
three parts:
1-Sugar,
2-Phosphate,
3-Base)
• The sugar is Deoxyribose
• There are four bases
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4 Bases
•
•
•
•
Adenine
Guanine
Cytosine
Thymine
14
Sides of the
“Ladder” are
made up of
sugar and
phosphate.
16
Adenine always pairs with Thymine
Cytosine always pairs with Guanine
17
Would
Thymine
be able
to pair
up with
Guanine?
18
19
CLIP
20
The sequence of nucleotides
forms the unique genetic
information of an organism.
Flashback
Before a cell
divides it needs
to make a copy
of its DNA.
(Remember Sphase?)
How does it
do that?
21
DNA has the unique ability to make an exact
copy of itself in a process called Replication.
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22
Chromosome
Structure
• DNA is packed
very tightly in
the nucleus.
• Human nucleus
has ~1 meter
of DNA!
• Smallest
human
chromosome
has 30 million
base pairs.
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• A chromosome has
DNA and proteinchromatin.
• Tiny sections of
DNA are called
genes
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DNA Replication
• Before Cell
Division, the
DNA must
be
replicated
exactly.
25.1
DNA Replication
Each
strand is
used to
make a
new
strand.
25.2
26
• Many
enzymes
are
involved.
Complementary
Strands
1.
Steps:
The two
parent
strands are
unwound
and
unzipped
with the
help of
DNA
helicases.
Replication
Bubble
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28
Steps:
2. DNA
polymerase
attaches new
nucleotides (base
paring) to the
parent strands
**Each new
strand formed
is a complement
of one of the
original, or
parent, strands.
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• This process will continue until the entire
molecule has been unzipped and replicated.
30
Each new strand formed is
a complement of one of the
original, or parent strands.
The replication of DNA is called
Semi-conservative replication
DNA replication website
31
When all of the
DNA in the
chromosomes of
the cell have been
copied by
replication, there
are now two copies
of the genetic
information that
will be passed on
to new cells during
mitosis or to new
generations
through the
process of meiosis.
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Review Clip
DNA Vocabulary
quiz
2
Quiz#2
1. Messenger RNA
2. Transfer RNA
3. Transcription
4. Translation
5. Codon
6. Anti-Codon
7. Promoter
8. Intron
9. Exon
10.Genetic Code
11.Amino Acid
12.Protein
13.Polypeptide
14.Mutation
15.DNA
16.RNA
DNA stores the information needed by
a ribosome to make a protein.
• How does the ribosome get the
information?
• How does the ribosome read the
information?
• How does it make the protein?
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UNIT GOALS
3
– Distinguish between DNA and RNA.
– Explain the role of DNA in storing and
transmitting cellular information.
– Describe the relationships between
changes in DNA and potential appearance
of new traits including – alterations during
replication, insertions, deletions, substitutions,
mutagenic factors, radiation, chemicals.
– Examine the use of DNA technology in
forensics, medicine and agriculture.
EQ: How does a protein
get made?
“PROTEIN SYNTHESIS”
34
DNA contains the code for
all of the cell proteins.
35
Flashback:
• DNA is located in the Nucleus
• Proteins are made on the ribosomes.
• DNA makes a copy (send a message) called
“mRNA”
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Two Steps of Protein Synthesis
1. Transcription
2. Translation
LOCATIONS
Where do the steps take place?
37
1. Transcription:
Nucleus
Animation
• During transcription a
“backwards copy” of the DNA
is made…the copy is called
messenger RNA or mRNA.
• The mRNA takes the code to
the ribosome.
• During transcription the DNA
unwinds and RNA nucleotides
are paired up with DNA
bases.
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DNA vs. RNA
• Double
Stranded
• AGTC
• Deoxyribose
• NEVER!
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• Single
Stranded
• AGUC
• Ribose
• YES!
1. Transcription:
Nucleus
• The section that is copied
is called a gene.
• The gene contains the
code for a protein.
“backwards copy”
During transcription
the DNA opens up
and RNA
nucleotides are
paired up with the
DNA bases.
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2. Translation:
• Once the
mRNA
copy is
made, it
can go to
the
ribosome
and be
used to
make a
protein
(translated)
Cytoplasm
41
2. Translation:
Cytoplasm
• To have the correct translation of the code,
mRNA codons must join with the correct
anticodon
of the tRNA.
Ribosome
tRNA anticodon
mRNA codons
The ribosome
reads every 3
letters
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2. Translation:
Cytoplasm
To have the correct translation of the code, mRNA
codons must join with the correct anticodon of the tRNA.
tRNA
brings the
amino acids
to the
ribosomes
tRNA anticodon
mRNA codons
A codon is a group of 3 nitrogenous bases on an mRNA molecule that
carries the code for a specific amino acid.
An anticodon is a set of 3 nitrogenous bases on a tRNA molecule that
matches a codon on an mRNA molecule.
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animation
• Remember
….Proteins
are made
out of
amino
acids.
• There are
20
different
amino
acids.
• 3 bases
code for
each amino
acid.
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mRNA codons
The Genetic Code
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Another
version of
the
Genetic
Code
In summary:
•Messenger RNA (mRNA) carries the message of
the genetic code from the DNA in the nucleus to
the ribosomes in the cytoplasm.
•At the ribosomes, the mRNA sequence is
translated into a protein in a process known as
translation. Transfer RNA (tRNA) transfers the
amino acids in the cytoplasm to the ribosomes.
•The amino acids are lined up in the coded
sequence to form a specific protein.
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Review Clip
47
Review link
(in Spanish, but GREAT animation)
Animation “in real time”
“Stated Clearly” Review of Protein
Synthesis
Eukaryotic DNA processing
Sometimes the DNA is cut up before it leaves the nucleus.
Exon - RNA
sequences in the
primary transcript
that are found in the
mRNA
Intron - RNA
sequences between
exons that are
removed by splicing
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EOCT Questions
Which of the following shows how
information is transformed to make
a protein?
A
B
C
D
DNA→RNA→protein
gene→chromosome→protein
cell respiration→ATP→protein
ATP→amino acid→protein
49
Information on mRNA is used to make
a sequence of amino acids into a
protein by which of the following
processes?
A replication
B translation
C transcription
D transference
50.1
A characteristic of RNA is that it
A remains in the chromosomes in the nucleus
B is involved in translating information in DNA
into proteins
C undergoes crossing-over during meiosis
D is replicated during the process of mitosis
50.2
51
Which of the following
is the correct basepairing rule for DNA?
A A-U; C-G
B A-G; T-C
C A-T; G-C
D A-C; T-G
52
Mutations
Describe the relationships between changes
in DNA and appearance of new traits
Mutations: Youtube
53
Mutations
• Every so often genes do change.
• A sudden change in the genetic
code is called a mutation.
• Most mutations have little or no
effect on the organism.
• Mutations can be spontaneous or
may be caused by environmental
factors called mutagens.
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Mutations in DNA usually occur
through one of two processes:
1- DNA damage from environmental agents
such as :
•
•
•
•
UV light
Radiation
Free radicals
Chemicals (ex: substances in tobacco products)
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2- Errors that occur when a cell replicates its
DNA in preparation for cell division.
• Spontaneous
• An enzyme may “fix” the wrong base.
Types of Mutations
1.Base pair substitutions
• (Aka Point mutation)
2.Frameshift mutation
• deletions or insertions
CLIP
56
Point
mutation
Base pair substitutions
The substitution
of one amino acid
for another
during protein
synthesis.
Can be harmless
or it change the
entire protein.
57
Point
mutation
Base pair substitutions
The inherited disorder
sickle-cell anemia is
caused by a this type
of mutation.
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59
Frameshift mutations
-deletions or insertions
• When one or more
base pairs are inserted
into a DNA molecule or
deleted from it.
• Causes a reading
frame shift during
translation.
ACTIVITY
CLIP
DNA TECHNOLOGY
genetic recombination.
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Forensics
There are many uses for DNA
technology. Police labs use DNA
technology to identify people
through a process known as DNA
fingerprinting.
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How to make a
DNA fingerprint
• Scientist cut up DNA into pieces using enzymesRestriction Enzymes
• Then load the pieces into a well.
• Electricity is run through the gel.
• The pieces of DNA move to the other end of
the gel with the + charge.
• Smaller pieces move farther.
• The gel is then compared to
a known sample
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Who doesn’t belong?
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Who done it?
• A blood stain
was found at a
crime scene.
Who is the
perpetrator of
the crime?
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•Researchers use recombinant DNA
technology to analyze genetic
changes.
•They cut, splice together, & insert
the modified DNA molecules from
different species into bacteria or
another type of cell that rapidly
replicates and divides.
•The cells copy the foreign DNA
right along with their own DNA.
•An example of this is the gene for
66
human insulin inserted
into a bacterium. This is
how human insulin is mass produced.
CLIP
Click
on
Picture
Restriction
Enzyme
animation
Cloning a Gene
67
Bacteria DNA that has DNA
from another organism
spliced in to it.
•Sheep are used in the 68.1
production of alpha-1
antitrypsin, which is used in
the treatment of
emphysema.
•Goats are also producing
the CFTR protein used in
the treatment of cystic
fibrosis.
Called Transgenic Organisms
68.2
In the plant world, the buds of cotton
plants are vulnerable to worm
attacks. The buds of a modified
cotton plant resist these worms,
resulting in increased cotton
production.
These gene insertions are
ecologically safer than pesticides.
They affect only the targeted pest.
68.3
Plant biologists have used DNA
technology to produce plants
with many desirable traits.
These include increased disease
resistance, herbicide resistance,
and increased nutritional
content.
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Golden Rice
23 times more Vitamin A
Called a Transgenic Organism
Transgenic Organisms
Transgenic Tobacco, from
1986. This is an ordinary
photographic image of a tobacco
plant engineered to express a
firefly gene which produces
luciferase.
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Clip
Scientists today have developed genetically
altered bacteria.
Among them are strains of bacteria that
eat up oil spills
manufacture alcohol and other chemicals
process minerals.
Make human proteins.
There is concern about possible risks to the
environment and the general population as
genetically engineered bacteria are introduced.
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Cloning
Bill
Nye
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