Download Unit 5 DNA, RNA and Protein Synthesis

Unit 5 DNA, RNA and Protein Synthesis
Standards Addressed
BIO.B.1.2.1 - Compare cellular structures and their functions in prokaryotic and eukaryotic cells
BIO.A.1.2.2 - Describe and interpret relationships between structure and function at various levels of biological organization
(i.e., organelles, cells, tissues, organs, organ systems, and multicellular organisms).
BIO.A.2.2.1 - Explain how carbon is uniquely suited to form biological macromolecules.
BIO.A.2.2.2 - Describe how biological macromolecules form from monomers.
BIO.A.2.3.1 - Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction.
Essential Questions
Why is DNA called the “blueprint of life”?
How is structure related to function at all
biological levels of organization?
DNA and RNA
(Follows pages 1 – 7 in the reading packet)
Central Dogma of Molecular Biology
1. DNA is found in __________________________.
2. However, another nucleic acid carries the instructions from DNA to the ribosomes (where proteins are
manufactured) and this other nucleic acid is ________.
3. The phrase DNA
RNA
Protein is called the _________________ ___________________.
DNA
4. In the 1920’s, _________________ ___________________ studied two different strains of bacteria. He
injected the bacteria into mice. The mouse injected with the lethal strain died and the mouse with the other
strain did not.
5. In Griffiths experiment, he deduced that something in the ___________ S-strain was transferred to the harmless
_______________ strain, making the R-strain deadly.
6. In the 1940’s, the scientific team lead by _____________________________ tried to answer Griffith’s question.
7. The ultimate answer of the team lead by Avery was that ___________ is the _________________ material.
8. In the 1950’s, two additional scientists used radioactive tagged viruses to confirm DNA was the
________________________ __________________________.
9. State Erwin Chargaff’s Rules.
10. ____________ and _________ are given credit for discovering DNA structure of _______________ __________.
11. The discovery of the structure of DNA was based on the work of ____________ ________________.
12. The structure of the double helix is like a spiral staircase. There are three parts of a DNA nucleotide, the
____________________, the _____________________ and a ____________________.
13. Which two bases pair up in the DNA molecule?
14. These base pairs are called ______________________ bases.
DNA Replication
15. DNA replication is the process in which _________ is _______________.
16. An enzyme breaks the bonds between the ________________________ __________________ separating the
two sides of the DNA molecule.
17. Each side is read by another enzyme and is used to ______________ two new ________________ strands.
RNA
18. RNA is a __________________ acid.
19. Complete the chart below describing the differences between DNA and RNA.
Differences Between DNA and RNA
DNA
RNA
Number of Strands (chains)
Base differences
Type of sugar
20. List the three main types of RNA and give their function.
a.
b.
c.
History of DNA Structure and Function
Transformation
Which Molecule?
1.
1. Avery
What Kind of Molecule? 1951
1. Pauling / Corey
2. Transformation
2.
2.
3.
Which Molecule part 2?
1. Hershey / Chase
X-Ray Diffraction? 1952
1.
Base-pair Rules 1951
1. Chargaff
2.
2.
2.
3. Bacteriophage
3.
3.
Double Helix 1953
1.
RNA
1. Sidney Brenner
2.
2.
3.
3.
RNA and Protein Synthesis
I. The Structure of RNA
A. Consists of a long strand of nucleotides
B. Nucleotides consist of _______________, ________________, and a _______.
C. The sugar is ____________.
D. Bases are __________, __________, __________ and _____________.
E. Strand is single stranded.
II. Functions of RNA
A. Many different functions depending on the type of RNA it is
B. All RNA molecules are involved in ___________________.
a. Assembles amino acids into proteins
III. Types of RNA
A. Three main types
a. ________________________ (mRNA)
b. ________________________ (rRNA)
c. ________________________ (tRNA)
IV.
Messengerproduced
RNA
sequence of
in RNA
Transcription
A. Transcription –
Transfer
RNA
process by which RNA molecules are
from copying part of the nucleotide
DNA into a complementary sequence
B. Transcription requires the enzyme called RNA polymerase.
1. RNA polymerase binds to DNA and separates the DNA strands.
2. RNA polymerase then uses one strand of DNA as a template from which
nucleotides are assembled into a strand of RNA.
3. RNA polymerase starts at a promoter, which is a specific base sequence signal
that tells the enzyme to bind and make RNA. There are also stop regions which
signal termination.
C. RNA Editing
1. RNA molecules require editing, like a rough draft of a paper.
2. While still in the nucleus, introns are cut out of RNA. Introns are sequences
of nucleotides what are not involved in coding for proteins
3. After removal of introns, exons are what remains behind. Exons are coding
sequences; they are expressed in proteins.
4. Once the introns are cut out, the exons are joined together to form final mRNA
molecule.
V. Translation (or Protein Synthesis)
A. mRNA is transcribed (copied) from the DNA in the nucleus and released into the
cytoplasm.
1. sequences of bases in mRNA serves as instructions for the order in which
amino acids should be joined together to make protein.
B. Translation – cell uses information from mRNA and decoding it into proteins, takes
place in cytoplasm.
C. mRNA attaches to the ribosome; then each codon is moved through the ribosome.
1. Codons consist of 3 consecutive nucleotides that specify a single amino acid
D. tRNA delivers the proper amino acid to the ribosome.
(Each tRNA molecule carries only one type of amino acid and has three unpaired
bases called an anti-codon. Each anti-codon is complementary to only one mRNA
codon.)
E. In the polypeptide assembly line, ribosomes create peptide bond between the amino
acids brought to the ribosome by the tRNA and tRNA is released.
F. Polypeptide chain grows until ribosome reaches a stop codon, then the chain is
released.
VI. The Genetic Code
A. Proteins are made by joining amino acids into polypeptide chains.
B. There are 20 amino acids.
C. RNA codes for 3 bases at a time … or the word in the genetic code is 3 letters long.
D. A series of 3 bases is called a codon
E. With 4 different bases, there is a possible 64 three-base codons available to code for
amino acids.
Topic 6: DNA and its Processes
DNA Structure
Deoxyribonucleic acid (DNA) is an important
biomolecule that contains our genetic code. Here is
a diagram of the double helix model of DNA. Note
that the monomers/building blocks of DNA are
called nucleotides. Each nucleotide contains three
parts
 Sugar (deoxyribose)
 Phosphate group
 Nitrogenous base (4 kinds)
DNA Replication
In order for new cells to pass on the genetic code, DNA must be copied
inside of cells. In eukaryotic cells, this takes place inside of the
nucleus, which stores the cell’s DNA. In prokaryotes, the process of
copying DNA occurs in the cytoplasm. Regardless of location, the
process is known as replication. Two daughter strands are formed.
1. The double helix is opened up by breaking the weak hydrogen
bonds
2. An enzyme (DNA polymerase) comes in and adds new bases
to the open strand
a. It follows base pairing rules: Adenine pairs with
Thymine (straight letters A-T go together) and
Cytosine pairs with Guanine (curvy letters G-C go
together)
3. At the end, two identical strands of DNA are formed.
4. These strands are said to be complementary to each other
because they follow the base pairing rules
RNA Structure
Ribonucleic acid (RNA) is a similar molecule to DNA.
However, it has some key differences.
Deoxyribonucleic acid Ribonucleic acid
(DNA)
(RNA)
Number of strands
2
1
Sugar
Deoxyribose
Ribose
Base pairs
A-T G-C
A-U G-C
In addition to those differences, there are three different types of RNA. These different types have various shapes and
functions.
Messenger RNA (mRNA)
Transfer RNA
Ribosomal rna (rRNA)
carries the transcripted
(tRNA) brings the
is a component of the
message from DNA to
amino acids to the
ribosome and the site
the ribosome to make
ribosome for
of protein synthesis
proteins
protein synthesis
Transcription
This occurs in the nucleus of eukaryotes. In the process of transcription, an mRNA transcript is made using the double
helix as a template. The double-stranded molecule of DNA separates along the hydrogen bonds. An enzyme called RNA
polymerase adds in corresponding base pairs. However, instead of using Thymine to match up with Adenine, Uracil is
used. For RNA, the base paring rules are A-U and G-C. At the end of this process, one piece of mRNA is created. It is
complementary to the strand of DNA is was formed from.
Translation
This process occurs in the cytoplasm. In the process of translation, the piece of mRNA is read by the ribosome in groups
of three letters (codons). Each 3-letter portion of mRNA is referred to as a codon and codes for a specific amino acid.
These codes match up to the anticodons on the bottom of the tRNA molecules. The corresponding tRNA molecule brings
in the correct amino acid (building block of proteins). The ribosome joins the amino acids together to make a protein.
The diagram on the left shows replication, transcription, and translation all happening in the cell. The diagram on the right
shows a chart of the 64 codons that make up the genetic code and the 20 amino acids that match up.
Each 3-letter portion of mRNA is referred to as a codon and codes for a specific amino acid. These codes match up to the
anticodons on the bottom of the tRNA molecules.
Mutations
Many different types of mutations can occur. They can either affect a few nucleotides (point mutations) or affect large
portions of DNA (chromosomal mutations). These will ultimately affect the shape and size of the protein constructed, and
the appearance of the cell or organism.
AMOEBA SISTERS: VIDEO RECAP
DNA VS. RNA AND PROTEIN SYNTHESIS
Amoeba Sisters Video Recap: DNA vs RNA and Protein Synthesis
Whose Show Is This?
Directions: DNA shouldn’t get all the credit! For this page, you will need to watch the video clip “Why RNA is Just as Cool as DNA.”
Label the two cartoons below. For the following comments, write a “D” inside the speech bubble if for DNA, “R” inside the speech
bubble if for RNA, or “BOTH” if the statement applies to both.
1. I am single stranded.
4. I am arranged as a double
helix or “twisted ladder.”
2. I am found only in the
nucleus of eukaryote cells
(exception during mitosis
when nucleus is
temporarily disassembled).
3. I am a nucleic acid.
5. I have the
sugar ribose.
6. I have the
sugar
deoxyribose.
7. I include the
bases Guanine,
Cytosine, and
Adenine.
8. In eukaryote cells, I
travel out of the nucleus
to a ribosome.
9. I have the
base Thymine.
10. I have the base
Uracil.
There are 3 types of RNA. Fill in any missing information in the chart below:
Type: mRNA
13. Stands for:
11. Type: ___________________
Stands for: Transfer RNA-transfers message.
12. Type: ____________________
14. Stands for:
AMOEBA SISTERS: VIDEO RECAP
DNA VS. RNA AND PROTEIN SYNTHESIS
Amoeba Sisters Video Recap: DNA vs. RNA and Protein Synthesis
Protein Synthesis Summary
Directions: Fill in any missing information in the summary chart below after watching “Protein Synthesis and the Lean, Mean
Ribosome Machines.”
Where is this
process located
(assuming
eukaryote cell)?
Is DNA
directly
involved in
process?
Which
types of
RNA are
involved?
End Result
and Purpose
Transcription
15.
16.
mRNA
only
17.
Translation
18.
No, as DNA 19.
remains in
the nucleus
and this
process is
not in the
nucleus.
Name of Process:
20.
Worksheet: Mutations Practice
There are three ways that DNA can be altered when a mutation (change in DNA
sequence) occurs.
1. Substitution – one base-pairs is replaced by another:
Example: G to C or A to G
C G T
C
2. Insertion – one or more base pairs is added to a sequence:
Example: CGATGG –– CGAATGG
GCTACC
GCTTACC
3. Deletion – one or more base pairs is lost from a sequence:
Example: CGATGG –– CATGG
GCTACC
GTACC
There are five possible results of a mutation.
1. Silent mutation: When a base pair is substituted but the change still codes
for the same amino acid in the sequence:
Example: TCT and TCC both code for the amino acid Serine
2. Substitution: When a base pair is substituted for another base pair
a. If the substitution changes the amino acid, it is called a MISSENSE
mutation:
Example: TCT codes for Serine and CCT codes for Proline
b. If the substitution changes the amino acid to a STOP, it is called a
NONSENSE mutation.
Example: GTGGTCCGAAACACC –– GTGGTCTGAAACACC
Val-Val-Pro-Asn-Thr
Val-Val-STOP
c.If the substitution does not change the amino acid, it’s called a SILENT
mutation.
Example: GTGGTCCGAAACACC – GTGGTACGAAACACC
Val-Val-Pro-Asn-Thr
Val-Val-Pro-Asn-Thr
3. Codon Deletion or Insertion: A whole new amino acid is added, or one
is missing from the mutant proton:
Example: GTGGTCCGAAACACC –– GTGGTCTGCCGAAACACC
Val-Val-Pro-Asn-Thr
Val-Val-Cys-Pro-Asn-Thr
4. Frame Shift: When a deletion or insertion results in a different base pair
being the beginning of the next codon, changing the whole sequence of
amino acids
Example: GTGGTCCGAAACACCT –– GTGGTCGAAACACCT
Val-Val-Pro-Asn-Thr
Val-Val-Glu-Thr-Pro
1. Below is the base sequence for the normal protein for normal hemoglobin and the base
sequence for the sickle cell hemoglobin.
Normal: GGG CTT CTT TTT
Sickle: GGG CAT CTT TTT
a. Transcribe and translate the normal and sickle cell DNA.
b. Identify this as a point or frameshift mutation. Explain.
c. If the base sequence read GGG CTT CTT AAA instead, would this result in sickle cell
hemoglobin? Explain.
2. There are several types of genetic mutations. List two. What do they have in common?
How are they different? Give an example of each.
3. A geneticist found that a particular mutation had no effect on the protein coded by a gene.
What do you think is the most likely type of mutation in this gene? Why?
4. Name one amino acid that has more than one codon. Name an amino acid that has only
one codon
5. Look at the following sequence: THE FAT CAT ATE THE RAT. Delete the first H and
regroup the letters in groups of three- write out the new groups of three. Does the sentence
still make sense? What type of mutation is this an example of?
You have a DNA sequence that codes for a protein and is 105 nucleotides long. A frameshift mutation
occurs at the 85th base- how many amino acids will be correct in this protein?
6. Given the following three mRNA sequences, 2 code for the same protein. Which two?
#1. AGU UUA GCA ACG AGA UCA
#2 UCG CUA GCG ACC AGU UCA
#3 AGC CUC GCC ACU CGU AGU
Original DNA Sequence:
T A C A C C T T G G C G A C G A C T
mRNA Sequence:
Amino Acid Sequence:
Mutated DNA Sequence #1: T A C A T C T T G G C G A C G A C T
What’s
the
mRNA
What
will
be
sequence?
the
(Circle
the
amino
acid
change)
sequence?
Will there likely be effects?
What kind of mutation is this?
Mutated DNA Sequence #2: T A C G A C C T T G G C G A C G A C T
What’s
the
mRNA
What
will
be
sequence?
the
(Circle
the
amino
acid
change)
sequence?
Will there likely be effects?
What kind of mutation is this?
Mutated DNA Sequence #3: T A C A C C T T A G C G A C G A C T
What’s
the
mRNA
What
will
be
sequence?
the
(Circle
the
amino
acid
change)
sequence?
Will there likely be effects?
What kind of mutation is this?
Mutated DNA Sequence #4: T A C A C C T T G G C G A C T A C T
What’s
the
mRNA
What
will
be
sequence?
the
(Circle
the
amino
acid
change)
sequence?
Will there likely be effects?
What kind of mutation is this?
Mutated DNA Sequence #5: T A C A C C T T G G G A C G A C T
What
What
will
be
will
the
be
corresponding
the
amino
Will there likely be effects?
What kind of mutation is this?
mRNA
acid
sequence?
sequence?
1. Which type of mutation is responsible for new variations (alleles) of a trait?
2. Which type of mutation results in abnormal amino acid sequence?
3. Which type of mutation stops the translation of the mRNA?