Name: ___________________
Per. _____
Unit 7 Protein Synthesis & Mutation
Protein Synthesis
What does Protein
Synthesis mean?
The formation of proteins based on information in DNA and carried out by RNA.
(Gene expression)
Flow of Genetic Information
► DNA “unzips”
► Transcription- makes RNA
► Translation- makes protein
► Protein
DNA goes through
_________________ to
make RNA
Compare and Contrast DNA & RNA
DNA
RNA
RNA goes through
_________________ to
make Protein
What nitrogen base does
DNA have that RNA
doesn’t? _________
What nitrogen base does
RNA have that DNA
doesn’t _________
mRNA carries the
_______________
3 Types of RNA
1. Messenger RNA (mRNA)
2. Ribosomal RNA (rRNA)
3. Transfer RNA (tRNA)
rRNA makes up the
_______________
tRNA does what?
1. Messenger RNA (mRNA)- Carries the instructions from DNA
2. Ribosomal RNA (rRNA)- Make up Ribosomes
3. Transfer RNA (tRNA)- Transfers amino acids to the ribosome to make a
protein Has 3 nucleotides on one end (anticodon) and the corresponding amino
acid on the other (codon).
Draw and label a picture
of mRNA
Draw and label a picture
of tRNA
Draw and label a picture
of rRNA
What are 3 nitrogen
bases found in DNA or
mRNA called:
__________
What are 3 nitrogen bases
found in tRNA called?
____________________
With a partner, describe
mRNA’s function in your own
words
With a partner, describe tRNA’s
function in your own words
With a partner, describe rRNA’s
function in your own words
How do the ribosomes get instructions from DNA?
The Definition of Transcription:
Transcription
• The process by which RNA is made from part of the DNA sequence that codes for
a protein (gene)
• Transcription is taking the blueprint DNA and making a copy in the form of RNA
• This RNA blueprint will be used to assemble proteins
Steps of Transcription
1. An enzyme unzips the DNA molecule at the region of the gene that is being
transcribed
2. Free RNA nucleotides form base pairs with their complementary nucleotides on
the DNA strand
3. mRNA threads away and the DNA strand rejoins
4. mRNA leaves the nucleus and goes to the cytoplasm (ribosome)
•
Codon is a group of 3 nucleotides in mRNA that specifies an amino acid
(building blocks of protein)
•
Think of the codon as the drawings on the blueprint for the genetic code
Transcribe the
following DNA strand:
DNA mRNA
A
T
C
C
G
G
What process is shown
below?
Translate the Codon
from mRNA into an
Anti-codon found in
tRNA and then into the
Amino Acid using the
Codon Wheel:
With a partner describe Transcription in your own words:
mRNA tRNA
Amino
Acid
A
U
C
Translation Definition
• Use the codon of mRNA to specify the sequence of amino acids to build a protein
• It is time for the Blueprint (DNA-mRNA) to be read
• The Blueprint (mRNA) is sent to the construction site (Ribosome)
• Decoding of the genetic instructions
Steps of Translation
1. mRNA arrives at the Ribosome
2. tRNA Anti-codons are complementary to the mRNA codons
3. tRNA picks up an amino acid
4. tRNA delivers the amino acid to the ribosome
5. Amino acids are assembled into polypeptide chains, to form protein, held together
with peptide bonds
With a partner describe Translation in your own words:
G
A
U
What does a peptide
chain of Amino acids
make?
________________
During translation, the
amino acid will continue
to be added until a
__________ codon is
reached
How many codons are
needed to specify two
amino acids?
__________
What process is shown
above?
Where in the cell are
proteins made?
______________
When the mRNA is first transcribed, there are long sequences of
nucleotides that are not required for the synthesis of the protein
called introns. The DNA sequences that code for the protein are
known as exons. Introns are edited out (cut out) of the mRNA
before it leaves the nucleus and the remaining exons are spliced
together to form the final mRNA
How to use the Codon Wheel:
Take the codon from mRNA
Ex: AUC
The 1st letter will be in the center and work your way out with the
2nd and 3rd.
So AUC would code for the Amino Acid Isoleucine or ISO
NEVER USE tRNA on the Codon Chart!!!
Color the following diagram
Thymine = Yellow
Adenine = Orange
Guanine = Green
Cytosine = Red
D- Deoxyribose- Purple
R- Ribose- Blue
E- Nucleus- Black
Y- Ribosome- Pink
Uracil = dark brown
F- t RNA- Gray
M- amino acids- light blue
Mutations
A mutation is a __change in the DNA sequence_. Although many mutations are harmful, some
mutations are __silent__, and others may be very _beneficial__ to an organism. There are two categories of
Are all mutations
bad? ________
mutations:
A. Chromosomal Mutations
A chromosomal mutation involves a change in the structure of the entire chromosome or
a change in the total _number of chromosomes. Does not alter individual genes. These
errors generally occur during meiosis or mitosis_.
What phase of
Meiosis or Mitosis
would a
Chromosomal
Mutation occur?
_______________
Describe what
happens during each
type of Chromosomal
mutation in your own
words:
Deletion:
Duplication:
Inversion:
Translocation:
Describe what a
Chromosomal
Mutation is
B. Gene Mutations
A gene mutation is a change in one gene on an individual chromosome. This may
result in a change in only one nucleotide or many nucleotides making up that gene might be
altered. The incidence of gene mutations is relatively low due to the action of enzymes that
proofread the DNA sequence after replication. There are two types of gene mutations:
1. Point Mutations – This is a change in one or just a few _nucleotides_, but the
total number of nucleotides in the gene is not changed. This might have no effect, or
change one amino acid. Therefore, the resulting __protein_ may or may not be altered.
Example:
THE DOG BIT THE CAT
THE DOG BIT THE CAR
As you can see, changing a single letter changes the meaning of the sentence.
Describe what a
Gene Mutation is:
Which is worse a
Chromosomal
mutation or a Gene
mutation? Why?
Find the mRNA
and the Amino
Acid sequence for:
Original DNA Strand:
AGGCTTAAT
2. Frameshift Mutations – This involves the addition or deletion of a nucleotide.
When a nucleotide is inserted or deleted, this shifts the reading of the remainder of the
codons; therefore, the translation of the remainder of the mRNA is altered. This will usually
result in tremendous changes in the __amino acid__ chain and completed protein.
mRNA:
Example:
Mutation #1 DNA:
THE DOG BIT THE CAT
Deleting the G
THE DOB ITT HEC AT
– This mutation would cause nearly every amino acid after the deletion to be
changed.
________________
Amino Acid:
___________________
AGGGTTAAT
mRNA:
________________
Amino Acid:
___________________
What type of mutation
was that?
_______________
Mutation #2 DNA
AGCTTAAT
mRNA:
________________
Amino Acid:
___________________
What type of mutation
was that?
_______________
Mutation #3 DNA
AGGACTTAAT
mRNA:
________________
Amino Acid:
___________________
What type of mutation
was that?
_______________