#___ Name:________________ Date:______ Period: _____
DNA: The Molecule of Heredity &
Understanding How Your Body Works!...“From Gene to Protein”
 Note-Taking Sheet- (Keep in your Notebook to study!) 
Today we will learn:
 The structure and purpose of DNA & RNA
 We will investigate 3 major processes that involve DNA & RNA
A. Semiconservative replication= the process of copying/doubling the
amount of DNA prior to cell division so the daughter cells both get a
full set.
The next two processes occur back to back, and this is how your genes
make your body work. Each gene codes for specific protein(s) each
individual cell needs to function properly and keep you alive.
This process of going from Gene to Protein occurs in two stages:
B. Transcription= process of copying the gene on the DNA strand into a
working copy of mRNA.
C. Translation=the process of building a protein using the “working mRNA
copy” of the original gene.
Ok, now on with the show!
So, what exactly is this DNA STUFF Anyway???
Official Name: Deoxyribonucleic acid
 is a type of nucleic acid
 is what chromosomes (and genes) are made of
 is made up of repeating _______________ subunits
 Each nucleotide represents half of the helix and consists of a phosphate
group, Sugar, and base.
Deoxyribose
Sugar
Phosphate
Group
Nitrogenous
Base
Adenine
Of bases: Guanine
Cytosine
Thymine
4 types

2 strands so bases can pair up
o A binds T only
o C binds G only
Strand 1
Strand 2
P
S
Phosphates + sugars
on the outside
Remember
P
A
T
P
S
(A)
(G)
(C)
(T)
S
DNA is like an Oreo
P
C
G
S
Phosphates + sugars = cookies
_______ = cream filling
Bases on the inside (Bases fit like puzzle pieces)
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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Shape is a double helix
o Double helix: 2 spirals wound around each other
o Rosalind _________ took an X-ray photo of DNA.
o James Watson and Francis
interpreted the
photo and discovered the double helix structure They won
the Nobel Prize.
_______: Group of 3
bases

Genes: stretch of DNA that codes for a _________.
o The code is the order of the bases (letters)
o Genes are hundreds or thousands of ________ long
Eye color gene
Dimples gene
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
Hair color gene
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Chargaff’s Rule
A scientist named Chargaff measured the amount of each base in DNA
samples and determined how they fit together based on the % of each.
 In DNA, the amount of A = the amount of T
the amount of C = the amount of G
So, they figured out that the DNA HELIX is complementary
 Complementary: bases on one strand of the helix match up with the bases
on the other strand (A-T and G-C)
 Example: Strand 1- ATG GGC CTA
Strand 2- TAC CCG GAT
During S-phase of Interphase, the DNA is copied so there are two
individual sets of DNA for each new daughter cell. This Synthesis phase is
when DNA Replication occurs. But it took a while for scientists to figure
out how it happened.
Replication
 Replication is the process by which DNA copies itself
 Happens during S-phase of Interphase when chromosomes copy
themselves before mitosis and meiosis.
 Semiconservative replication: Each new piece of DNA is made up of 1 old
strand and 1 new strand
Original DNA helix
DNA unzips
Each original strand
grows a new strand
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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DNA never ever leaves the nucleus
 DNA is the master copy of the directions a cell needs to live so it
needs to be protected
But DNA in
the cytoplasm
can be
destroyed
DNA in
the
nucleus is
safe
RNA is a working copy of DNA that goes out into the cytoplasm to tell the cell
what to do in order to stay alive & perform all of its duties.
 RNA: ribonucleic acid
 You can always make more RNA, so it’s ok if it gets destroyed
 RNA is divided into 3 types, each with a different job.
1. mRNA (message RNA)
2. tRNA (Transfer RNA)
3. rRNA (Ribosomal RNA)
DNA
2
How many
strands?
Nucleotide
subunit
Bases
Phosphate
Group
Deoxyribose
Sugar
RNA
1
Nitrogen
Base
Deoxyribose sugar
Thymine (T)
T–A
Adenine (A)
Guanine (G)
G–C
Cytosine (C)
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
Phosphate
Group
Ribose
Sugar
Nitrogen
Base
Ribose sugar
Uracil (U)
U–A
Adenine (A)
Guanine (G)
G–C
Cytosine (C)
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Transcription- the process of making a mRNA “working copy” of the
“master gene” made of DNA
 The type of RNA made is called mRNA (messenger RNA) because
it sends a message from DNA to the cytoplasm
DNA safe in the
nucleus

Uses mRNA
(working copy of the gene)
To send a
message to the
cytoplasm
Transcription- Happens Like This:
o Enzyme unzips one gene in DNA
o Match up bases to one side of a gene in
DNA
o mRNA detaches from the DNA
o mRNA moves out of the nucleus through
nuclear pores and into the cytoplasm
What is different about the RNA bases?
DNA: GAG AAC TAG TAC
RNA: CUC UUG AUC AUG
That is right! RNA doesn’t have __; it has __
For figuring out RNA:
A binds U
C binds G
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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DNA
mRNA
mRNA
A
Cytoplasm
of cell
Nucleus
Transcription
happens in the
nucleus. An
RNA copy of a
gene is made.
Then the mRNA
that has been
made moves out
of the nucleus
into the
cytoplasm
Once in the
cytoplasm, the
mRNA is used to
make a protein.
Which is called
Translation!
How does mRNA tell the cell what to do?
 mRNA is a message that codes for a protein
 Proteins are made in the cytoplasm and then work to keep the
cell alive
Translation (protein synthesis): Process of making a protein
 Proteins are made up of amino acids (small building blocks)
 There are 20 different types of amino acids
Protein
Amino Acids
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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Nucleus
Process of Translation
1. mRNA moves out of
nucleus and into
cytoplasm
Cytoplasm
2. mRNA attaches
to a ribosome
Ribosome
3. Transfer RNA (tRNA)
decodes the mRNA
and brings amino acids
to build up the protein
tRNA
Amino
acid
Anticodon (3 bases on
tRNA): Matches up to
codons on mRNA
4. Protein (chain of amino
acids) detaches from
ribosome and goes off to
work in the cell
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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Genetic Code- Code that matches codons on mRNA to complementary
anticodons on the tRNA which carries the correct amino acid for
making the protein. The chain of amino acids is the protein.
mRNA
codons
(3 bases)
Pairs with
anticodons on
tRNA thus
delivering
the next
Amino acid.
Start codon- indicates the beginning
of the gene and the
Stop codon – codes for the end of the
mRNA (no amino acid added)
1. Read your mRNA codon 
ACU
2. Find 1st base on the left, 2nd base on the top, 3rd base on the
right. Find where they all cross in the chart.
3. Read your amino acid.

Threonine
Different codons code for different amino acids!!!
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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Central dogma of molecular biology
Transcription
DNA
Directions to
make proteins are
safely stored in
the nucleus
Translation
RNA
Carries the
directions to
the cytoplasm
Protein
Work to keep
the cell alive
**Now lets talk about when things don’t work as planned…
Mutations
 a change in the DNA sequence
 It’s a mistake that’s made during replication or transcription
 can be harmful: diseases or deformities
helpful: organism is better able to survive
neutral: organism is unaffected
 if a mutation occurs in a sperm or egg cell, that mutation is
passed onto offspring
 if a mutation occurs in a body cell, that mutation affects only the
organism and is not passed onto offspring
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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Types of mutations
1. Point mutations: Bases are mismatched
 Harmful when: a mistake in DNA is carried into mRNA and
results in the wrong amino acid
Correct DNA
Correct mRNA
GAG
CTC
Correct amino acid
CUC
Point mutation in DNA
GCG
CTC
Leucine
Mutated mRNA
Wrong amino acid
CGC
Arginine
A should pair with T, but instead C is mismatched to T

Not harmful when: a mistake in DNA is carried into mRNA
but still results in the correct amino acid

2. Frameshift mutations: bases are inserted or deleted
 Are usually harmful because a mistake in DNA is carried
into mRNA and results in many wrong amino acids
Correct DNA:
ATA
TAT
CCG
GGC
TGA
ACT
Correct mRNA:
UAU
GGC
ACU
Correct amino acids: Tyrosine
Glycine
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
Threonine
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Extra inserted base shifts how we read the codons (3
bases), which changes the amino acids
Frameshift mutation
in DNA:
ATG
TAC
ACC
TGG
GTG
CAC
A
T
Mutated mRNA:
UAC
UGG
CAC
U
Wrong amino acids: Tyrosine Tryptophan Histadine
3.



Chromosomal mutations
chromosomes break or are lost during mitosis or meiosis
broken chromosomes may rejoin incorrectly
almost always lethal when it occurs in a zygote
Causes of mutations
 mutagens: anything that causes a change in DNA
 examples: X rays, UV light, nuclear radiation, asbestos, cigarette
smoke
Mrs. Lambert’s Note-taking Sheet: From Gene to Protein
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