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February 16, Week #
Learning Target: I will
6
NB-93
Agenda:
• Homework (NB-92 & 89)
• Define mutation.
• DNA mutations
• Define mutagen.
• Organize notebooks
• Explain 3 different types Essential Question:
of mutations.
• If both the father
Homework:
and mother are Tt,
• Read p. 194-200
what are the
• Answer questions 1-7 on chances of
p. 200
producing tt
offspring?
Learning Target: I will
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Complete a Punnett Square to predict
genotypes and phenotypes of offspring.
A genotype is
the DNA coding for a trait (EE)
A phenotype is
the trait we observe (free earlobes)
A percentage is
an amount compared to 100.
A ratio is a
relation between 2 numbers
Mutations
A change in DNA
Chromosomes and DNA
IIA. Mutations – Changes in DNA
Changes in DNA can cause changes in the amino acid sequence of proteins,
which can have effects on the shape and function of proteins.
Transcription
Translation
Normal DNA
Transcription
Mutated DNA
Normal
Functional
Protein
Shape
Translation
Different Shape-Different Function
2. No Function
1.
Ex: Sickle Cell Anemia
Caused by single amino acid change in hemoglobin
Q: Is this a gene or a chromosomal mutation?
A: Gene mutation.
Normal
RBC
Sickle
Cell
RBC
Ex: Down Syndrome
Caused by a 3rd copy of
chromosome 21
Q: Is this a gene or a
chromosomal mutation?
A: Chromosomal mutation.
Ex: Cancer
Cancer occurs when mutations cause cells to grow
in an uncontrolled way
Famous Mutants
IIB. Causes of Mutations (mutagens)
1. Environment
sunlight
smoke
Chemicals
Radiation
2. Mistakes during replication.
AAT
CTT
ATT
GCC
TGG
ACC
GGG
CAA
ATC
TAT
GGG
TAG
AAT
CGT
ATT
GCC
TGG
ACC
GGG
CAA
ATC
TAT
GGG
TAG
Types of Mutations
1. What is the difference between a gene
mutation and a chromosomal mutation?
A:
Gene Mutation
--Changes in single
gene/base
--3 types
Chromosomal
Mutation
--Changes in whole
chromosomes
--5 types
3 types of gene mutations
Substitution
Insertion
Deletion
IID. Types of Mutations – Substitutions
1. Replacement of 1 nucleotide and its partner with another
pair of nucleotides.
2. Effects of base pair substitutions
a. no change
b. insignificant change
c. alteration in structure and thus function of protein
IID. Types of Mutations – Substitutions
Analogy of a Base Pair Substitution Mutation
1) A Point Mutation:
Normal Sample Gene:
The fat cat ate the wee rat.
Gene with a Point Mutation:
The fat bat ate the wee rat.
The meaning of the sentence has changed with a 1 letter difference.
Lets apply that knowledge to DNA & Proteins
Green Fluorescent Protein (GFP) is produced by a number of organisms, such
as the jellyfish.
There are three amino
acids which are critical for
GFP’s green fluorescent
color.
Only a 1 amino acid difference
changes green to blue, and blue
to cyan.
Aequoria victoria
Why does this happen?
Production of wild type Green Fluorescent Protein
Part of a
normal GFP
Gene
Transcription
mRNA
produced
Translation at ribosomes
Green
Fluorescent
Protein
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
A Base Pair Substitution Mutation Occurs…
Production of Blue Fluorescent Protein
Part of a
mutated
Gene
Base Pair Substitution Mutation
Transcription
mRNA
produced
Translation at ribosomes
Blue
Fluorescent
Protein
IIC. Analogy of a Frameshift Mutation
Normal Sample Gene:
The fat cat ate the wee rat.
Gene with a Deletion Frameshift Mutation- 1 letter deleted.
The fat caa tet hew eer at
Regardless of the changes in the DNA, the mRNA is always read in 3
letter increments in the ribosomes.
The meaning of the sentence has changed dramatically with a 1 letter
difference.
A Deletion Mutation Occurs…
A Deletion Mutation Occurs…
A Deletion Mutation Occurs…
A Deletion Mutation Occurs…
A Deletion Mutation Occurs…
A Deletion Mutation Occurs…
A Deletion Mutation Occurs…
A Deletion Mutation Occurs…
A Deletion Mutation = Non functional protein
Site of
Deletion
Transcription
mRNA
produced
Translation at ribosomes
Nonfunctional Protein
no fluorescence
IIC. Analogy of a Frameshift Mutation
Normal Sample Gene:
The fat cat ate the wee rat.
Gene with an Addition Frameshift Mutation- 1 letter added.
The fat caa tat eth ewe era t
Regardless of the changes in the DNA, the mRNA is always read in 3
letter increments in the ribosomes.
The meaning of the sentence has changed dramatically with a 1 letter
difference.
What type of mutation?
• Gene or
chromosome?
• Insertion,
deletion, or
substitution?
What type of mutation?
• Gene or
chromosome?
• Insertion,
deletion, or
substitution?
What type of mutation?
• Gene or
chromosome?
• Insertion,
deletion, or
substitution?
Not all mutations are harmful!
IV. Why are Mutations Important?
A. Mutations provide the raw material for natural selection.
1. Changes in the bases of DNA may cause a change in a protein
which gives an organism an advantage:
a. Bigger teeth, faster runner, better vision,
different fluorescent colors etc.
b. Organisms with advantages may leave more offspring…
2. Directed Evolution
a. Now possible to produce optimal mutations.
Let’s return to Fluorescent Proteins…..
Learning Target: I will
•
•
•
•
•
•
•
•
•
•
Complete a Punnett Square to predict
genotypes and phenotypes of offspring.
A genotype is
the DNA coding for a trait (EE)
A phenotype is
the trait we observe (free earlobes)
A percentage is
an amount compared to 100.
A ratio is a
relation between 2 numbers
Organize Notebooks
10 minutes
Learning Target: I will
•
•
•
•
•
•
•
•
•
•
Complete a Punnett Square to predict
genotypes and phenotypes of offspring.
A genotype is
the DNA coding for a trait (EE)
A phenotype is
the trait we observe (free earlobes)
A percentage is
an amount compared to 100.
A ratio is a
relation between 2 numbers
Fill out the weekly planner.
Don’t forget the homework on
NB-92!
Essential Question:
What is the difference between
genotype and phenotype?