Protein Synthesis

Notes: The Big Picture
• All cells in an organism contain an
__________________ of that organism ’ s genetic code.
• Restate:

Where do all of the cells in your body come from?

Questions
Do all of the cells in your body have the same:
• Structure?
• Function?
Neuron
• Deoxyribonucleic Acid?
Epithelial Cells (Skin)

Example:
• The Pancreas contains a complete copy of your DNA, but the gene for insulin (among others) is activated (on).
• Would the adrenal gland have an entire copy of your DNA?
• Would your adrenal gland have the gene for insulin activated (on)?

Notes: The Big Picture
• How do specialized cells know which part of the genetic code they are responsible for?
• Specialized cells have different genes expressed (turned on). Those genes allow specific proteins to be synthesized, which aides their function.
• This process is CALLED:
Cell
Differentiation

HOW do genes become activated?
Any ideas?

What conclusion can you make based on the data below?
Warmer T = More Males
Colder T = More Females

Conclusion:
Male
Female

Huh?
• How did this happen?
• What did the temperature “ do ” to the baby turtles?
• Increased temperatures activate the genes that allow the turtles to become males .
True for Ridley Sea
Turtle…but NOT
Humans

Notes: The Big Picture
• How can genes be activated?
• Environmental Factors
– Temperature
– Smoking/pollutants
– Light
• Chemicals
– Oxygen
– Drugs

Summary-
• Use the terms cell differentiation, genetic code, and expressed to summarize today ’ s lesson.
• Cell differentiation allows the genetic code to have certain parts expressed.

Protein Synthesis Unit
Learning Targets
• The point is to understand how cells use DNA to create traits.
• By the end of this unit you will describe how
DNA codes for traits, the steps of protein synthesis, & how environmental and chemical factors affect gene expression in organisms.

DNA Characteristics
• Basic Central Dogma or idea:
________  Proteins 
Traits

Our DNA
• Each cell contains 2 meters (6 ft) of DNA
• All combined it could reach from the Earth to the sun over 600 times!!
– The sun is 98 million miles away
How does it all fit?

• DNA is found in the nucleus
• Its shape is a double helix
– Twisted ladder
• The double helix further coils into strands called chromatin.
• The chromatin are wound even further into chromosomes.
– Humans have 23 pairs of chromosomes

Chromatin
Double helix
Chromosome

• Sugar (Deoxyribose)
• Phosphate
• Nitrogen base
Nitrogen Base + Sugar
+ Phosphate = a Nucleotide

• The order of the nitrogen bases tell your cells to make certain proteins.
• There are ~ 3 billion bases in the
DNA code in each cell of your body.
Each cell has enough bases to fill
200 pages of this book in small font.

• DNA codes for PROTEINS.
• DNA Proteins

DNA
Nucleus
Transcription mRNA
Translation
Ribosome
Protein
Traits

• Added mRNA
DNA mRNA

Will this be true for all kingdoms?
Yes, except for bacteria.

Protein Synthesis

Compare/ Contrast DNA & mRNA.

mRNA vs. DNA mRNA is very similar to DNA….but there are differences.
How many strands does DNA have?
2 strands, DNA is double stranded.
mRNA has only 1 strand. mRNA is single stranded.

mRNA vs. DNA
What kind of sugar is found in DNA?
Deoxyribose is the sugar in DNA.
mRNA has a different sugar.
Ribose is the sugar in RNA

mRNA vs. DNA
What are the 4 nitorgen bases in DNA?
A- Adenine
G- Guanine
C- Cytosine
T- Thymine
What do each pair up with?
A—T G—C

mRNA vs. DNA mRNA does not have a “ T ” (Thymine) and instead has a “ U ” for Uracil. Therefore, what are the four nitrogen bases for RNA?
DNA RNA
U
A 
T 
G 
C 
U
A
C
G
T

mRNA vs. DNA
What is DNA’s job/function?
It is your genetic information that codes for mRNA. mRNA’s job is to code for specific proteins. What do the proteins eventually make?
Traits

mRNA vs. DNA
Where is DNA always located?
Nucleus.
Can DNA ever leave the nucleus?
No, its too large.
Nucleus must code for another form to leave the nucleus.

Compare DNA & RNA
• Similarities:
They both have nucleotides.

Differences:
Strands:
Sugar:
Nucleotides:
Job:
Location:
Compare DNA & RNA
Double
Deoxyribose
DNA  DNA
A  T
C  G
T  A
G  C codes for mRNA nucleus
Single
Ribose
DNA  RNA
A  U
C  G
T  A
G  C codes for proteins nucleus & cytoplasm - ribosomes

Explore
You just ate ice cream and drank a Dr.
Pepper. Your body must secrete Insulin
(a protein).
Where are the instructions?
Where are proteins made?
What are the specifics?

DNA
Nucleus
Transcription mRNA
Translation
Ribosome
Protein
Traits

Transcription
Transcription=
The process of making mRNA from DNA.
Is transcription happening in every gene every second? Yes
If DNA cannot leave the nucleus, then where must transcription occur?
In the nucleus.
***mRNA is the blueprint for converting the message of DNA into proteins.

Process of Transcription
• Transcription Animation

Draw Transcription

Elaborate:
• Have we made a protein yet?
• What if this was a fungi?
• Bacteria?
• Plant?

Elaborate
• Predict what would happen if the gene for insulin was added to a bacterial cell.

Skip Page 10
• We will come back to this page tomorrow

Complete Venn Diagram
DNA vs. RNA
• Double strand
• Thymine
• Nucleus
• Strores genetic info
• Double helix shape
• Goes through
Replication
• Deoxyribose sugar
• Adenine
• Guanine
• Cytosine
• Comprised of
Nucleotides
• Single strand
• Uracil
• Cytoplasm
• Made of 3 base units = codons
• Ribose sugar

Translation
Each codon codes for a specific amino acid. A codon chart is used to easily determine the amino acid that each codon codes for.
Practice: Which amino acid do each of these codons code for?
UUA CCC AGA GAC

Determine which amino acid UUA codes for?

Translation
Each codon codes for a specific amino acid. A codon chart is used to easily determine the amino acid that each codon codes for.
Practice: Which amino acid do each of these codons code for?
UUA
Leucine
CCC AGA GAC

Determine which amino acid CCC codes for?

Translation
Each codon codes for a specific amino acid. A codon chart is used to easily determine the amino acid that each codon codes for.
Practice: Which amino acid do each of these codons code for?
UUA
Leucine
CCC
Proline
AGA GAC

Determine which amino acid AGA codes for?

Translation
Each codon codes for a specific amino acid. A codon chart is used to easily determine the amino acid that each codon codes for.
Practice: Which amino acid do each of these codons code for?
UUA
Leucine
CCC
Proline
AGA
Arginine
GAC

Determine which amino acid GAC codes for?

Translation
Each codon codes for a specific amino acid. A codon chart is used to easily determine the amino acid that each codon codes for.
Practice: Which amino acid do each of these codons code for?
UUA
Leucine
CCC
Proline
AGA
Arginine
GAC
Aspartic
Acid

Translation
Notice: multiple codons code for the same amino acid.
Practice: Which two codons code for histidine?
CAU & CAC

DNA
Central Dogma?
RNA
Protein

DNA
Nucleus
Transcription mRNA
Translation
Ribosome
Protein
Traits

Translation

Translation
Translation Animation
Translation=
The process where mRNA codes for proteins using tRNA.
Is translation occuring
In every gene every second?
Yes, when proteins are needed

Translation
How mRNA codes for proteins using tRNA.
Amino acid tRNA
Anti codon mRNA
Codon

Translation
Key players in Translation:
Codon: 3 mRNA bases.
Anticodon: 3 tRNA bases that match the mRNA sequence.

Protein: A chain of amino acids made in the ribosome ( in the cytoplasm).
aa aa aa aa
Protein

Amino Acid:
Translation
Attached to the end of tRNA, monomer of a protein tRNA : Translation uses another
RNA called tRNA.
Shape
Like a cloverleaf or t

Draw Translation.

Elaborate:
• Have we made a protein yet?
• What if this was a fungi?
• Bacteria?
• Plant?

Elaborate
• Could a plant do the same thing with the gene for insulin?

Protein Synthesis

Central Dogma?

DNA
Nucleus
Transcription mRNA
Translation
Ribosome
Protein
Traits

Can any step in the process of protein synthesis be regulated?
Yes
What is the result if any step in the process does not occur correctly?
The protein might be incorrect which will affect the trait.

Mutation
What is a mutation? A change in DNA.
NOVA Video: ONE WRONG LETTER , Watch part 3.
Mutation during replication:
What happens during replication?
DNA copies itself. Sometimes DNA copies itself incorrectly; then mRNA is made & it is incorrect.

Mutations
There are 3 types of mutations:
1. Substitution:
Question: If a codon ACA changes to
AUA will the codon change?
Yes.
Question: If a codon ACA changes to
AUA will the amino acid change?
Yes.

Mutations
1. Substitution: (Continued)
Question: If a codon ACA changes to
ACU will the amino acid change?
NO.
Question: If a codon ACA changes to
ACU what will happen to the proteins?
Nothing will happen to the protein because the codons code for the same amino acid.

Mutations
1. Substitution: (Continued)
Will a change in mRNA change the codon?
Yes.
Will a change in mRNA always change the amino acid? NO, not always.
Will a change in amino acid change the protein? Yes.

Mutations
2. Insertion:
Example:
A THE CAT ATE THE RAT
Does the sentence now mean the same thing?
NO.
Which codons changed?
All codons to the right of the insertion change.

Mutations
3. Deletion:
Example:
AUG ACA GGU UGU UGA
MET THR GLY CYS STOP
Order: aa ’ s:
AUG AAG GUU
MET LYS VAL
GUU
VAL
GA

Mutations
Example:
Original DNA:
G A T T A C A
Mutated DNA:
G G T T A C A mRNA:
C U A AUG U C C A A U G U aa ’ s:
LEU MET PRO
Did the protein change?
Yes.
MET