1. MUTATIONS

2. Figure 10.15 Summary of transcription and translation.
DNA
mRNA is transcribed
from a DNA template. 1
mRNA
RNA
polymerase
Amino acid
Translation
Each amino acid
attaches to its proper
tRNA with the help of a
specific enzyme and
ATP. 2
Enzyme
ATP
tRNA
Figure Summary of transcription and translation.
This figure is an overview of the processes, emphasizing the participation of enzymes and the requirement of an energy source. Beyond its use for attaching amino acids to tRNAs, phosphate-bond energy is also needed during initiation, elongation, and termination of translation.
The need to obtain amino acids from the diet could be described along with this slide. If amino acids are present in sufficient amounts, they will be continually attached to tRNAs and available for protein synthesis. If one or more amino acids is low in quantity, the translation of any protein containing those amino acids will be terminated prematurely when the corresponding codon is reached and a tRNA fails to bind to the A site. For humans, animal protein sources have an appropriate profile of essential amino acids. Plant proteins can be combined to provide an adequate amino acid balance.
Anticodon
Initiator
tRNA
Large
ribosomal
subunit
Initiation of
polypeptide synthesis 3
The mRNA, the first
tRNA, and the ribosomal
sub-units come together.
Start Codon
Small
ribosomal
subunit
mRNA

3. Mutations can change the meaning of genes
A mutation is a change in the nucleotide sequence of DNA
Mutations can be
Spontaneous: errors in DNA replication or recombination (chromosomes)
Induced by mutagens
High-energy radiation
Chemicals
Student Misconceptions and Concerns
1. Beginning college students are often intensely focused on writing detailed notes. The risk is that they will miss the overall patterns and the broader significance of the topics discussed. Consider a gradual approach to the subjects of transcription and translation, beginning quite generally and testing comprehension, before venturing into the finer mechanics of each process.
2. Mutations are often discussed as part of evolution mechanisms. In this sense, mutations may be considered a part of a positive creative process. The dual nature of mutations, potentially deadly yet potentially innovative, should be clarified.
Teaching Tips
1. A simple way to demonstrate the effect of a reading frame shift is to have students compare the following three sentences. The first is a simple sentence. However, look what happens when a letter is added (2) or deleted (3). The reading frame, or words, are re-formed into nonsense.
(1) The big red pig ate the red rag.
(2) The big res dpi gat eth ere dra g.
(3) The big rep iga tet her edr ag.
2. The authors have noted elsewhere that “A random mutation is like a shot in the dark. It is not likely to improve a genome any more than shooting a bullet through the hood of a car is likely to improve engine performance!”
Copyright © 2009 Pearson Education, Inc.

4. POINT MUTATION Replacement of one nucleotide with another
Replacement of one nucleotide with another
ONLY MATTERS IF:
CHANGES Amino acid  CHANGES function of the protein
Normal hemoglobin DNA
Mutant hemoglobin DNA
Sickle-cell hemoglobin
Normal hemoglobin
mRNA
Val
Glu
Student Misconceptions and Concerns
1. Beginning college students are often intensely focused on writing detailed notes. The risk is that they will miss the overall patterns and the broader significance of the topics discussed. Consider a gradual approach to the subjects of transcription and translation, beginning quite generally and testing comprehension, before venturing into the finer mechanics of each process.
2. Mutations are often discussed as part of evolution mechanisms. In this sense, mutations may be considered a part of a positive creative process. The dual nature of mutations, potentially deadly yet potentially innovative, should be clarified.
Teaching Tips
1. A simple way to demonstrate the effect of a reading frame shift is to have students compare the following three sentences. The first is a simple sentence. However, look what happens when a letter is added (2) or deleted (3). The reading frame, or words, are re-formed into nonsense.
(1) The big red pig ate the red rag.
(2) The big res dpi gat eth ere dra g.
(3) The big rep iga tet her edr ag.
2. The authors have noted elsewhere that “A random mutation is like a shot in the dark. It is not likely to improve a genome any more than shooting a bullet through the hood of a car is likely to improve engine performance!”
Copyright © 2009 Pearson Education, Inc.

5. DELETION INSERTION A BASE IS LOST AN EXTRA BASE IS INSERTED
A BASE IS LOST
INSERTION
AN EXTRA BASE IS INSERTED
RESULT: FRAME-SHIFT (HOW YOU READ); DOWNSTREAM
AMINO ACID CHANGES
WRONG PROTEIN
NO PROTEIN
Student Misconceptions and Concerns
1. Beginning college students are often intensely focused on writing detailed notes. The risk is that they will miss the overall patterns and the broader significance of the topics discussed. Consider a gradual approach to the subjects of transcription and translation, beginning quite generally and testing comprehension, before venturing into the finer mechanics of each process.
2. Mutations are often discussed as part of evolution mechanisms. In this sense, mutations may be considered a part of a positive creative process. The dual nature of mutations, potentially deadly yet potentially innovative, should be clarified.
Teaching Tips
1. A simple way to demonstrate the effect of a reading frame shift is to have students compare the following three sentences. The first is a simple sentence. However, look what happens when a letter is added (2) or deleted (3). The reading frame, or words, are re-formed into nonsense.
(1) The big red pig ate the red rag.
(2) The big res dpi gat eth ere dra g.
(3) The big rep iga tet her edr ag.
2. The authors have noted elsewhere that “A random mutation is like a shot in the dark. It is not likely to improve a genome any more than shooting a bullet through the hood of a car is likely to improve engine performance!”

6. The big red pig ate the red rag. The big res dpi gat eth ere dra g.
INSERTION
The big red pig ate the red rag.
The big res dpi gat eth ere dra g.
DELETION
The big red pig ate the red rag.
The big rep iga tet her edr ag.

7. SUBSTITUTION A SINGLE BASE CHANGES RESULT:
A SINGLE BASE CHANGES
RESULT:
MISSENSE MUTATION- WRONG AMINO ACID
WRONG PROTEIN
SILENT MUTATION- SAME AMINO ACID
CORRECT PROTEIN
NONSENSE MUTATION- EARLY STOP CODON
SHORTENED/WRONG PROTEIN
Student Misconceptions and Concerns
1. Beginning college students are often intensely focused on writing detailed notes. The risk is that they will miss the overall patterns and the broader significance of the topics discussed. Consider a gradual approach to the subjects of transcription and translation, beginning quite generally and testing comprehension, before venturing into the finer mechanics of each process.
2. Mutations are often discussed as part of evolution mechanisms. In this sense, mutations may be considered a part of a positive creative process. The dual nature of mutations, potentially deadly yet potentially innovative, should be clarified.
Teaching Tips
1. A simple way to demonstrate the effect of a reading frame shift is to have students compare the following three sentences. The first is a simple sentence. However, look what happens when a letter is added (2) or deleted (3). The reading frame, or words, are re-formed into nonsense.
(1) The big red pig ate the red rag.
(2) The big res dpi gat eth ere dra g.
(3) The big rep iga tet her edr ag.
2. The authors have noted elsewhere that “A random mutation is like a shot in the dark. It is not likely to improve a genome any more than shooting a bullet through the hood of a car is likely to improve engine performance!”

8. The big red pig ate the red rag. The big res pig ate the red rag.
MISSENSE
The big red pig ate the red rag.
The big res pig ate the red rag.
NONSENSE
The big red pig ate the red rag.
The big re.

9. Normal gene mRNA Protein Base substitution Base deletion Missing Met
mRNA
Protein
Met
Lys
Phe
Gly
Ala
Base substitution
Met
Lys
Phe
Ser
Ala
Figure 10.16B Types of mutations and their effects.
This figure contrasts the multiple amino acid changes caused by a deletion with the single amino acid change caused by a substitution.
Base deletion
Missing
Met
Lys
Leu
Ala
His