cell differentiation
TRANSCRIPT
Cell Differentiation http://www.youtube.com/watch?
v=cyaVEotYsY0
Cell Specialization & Gene Expression We have 100 trillion cells, but they don’t all
look the same (200 types):
Neuron Cell
Epithelial (Skin) CellsRed Blood Cells
Muscle CellSperm Cell
Cell Specialization & Gene Expression All of these cells contain the same exact copy of DNA (except sperm and
egg), BUT:
Image Source: questgarden.com
Same DNA, but only
some genes are
expressed
Definitions
**Gene: a portion of DNA that codes for a
protein
**Gene Expression: the proteins formed by
the decoding of specific genes in a cell
Exhibition Step 1 Pick a cell Answer questions on planning sheet Use as introduction to your hero and story
10 Human Mutations http://
io9.com/10-unusual-genetic-mutations-in-humans-470843733
Mutations Mutation: A change in a DNA sequence. May
or may not affect gene expression (the protein).
Mutagen: something that causes a mutation
Mutations
Point
Silent Not Silent
Frameshift
Insertion Deletion
Mutations & Gene Expression
Mutations & Gene Expression
Image Source: waynesword.palomar.edu
Recall: 64 codons, only 20
amino acids.
Mutations
Point Mutation: Change in one nucleotide
1. T H E / F A T / C A T / A T E / T H E / R A T
T H E / F A T / K A T / A T E / T H E / R A T
2. T H E / F A T / C A T / A T E / T H E / R A T
T H E / F A T / B A T / A T E / T H E / R A T
“Silent Mutation”
Not Silent
Message still sounds the
same
Message sounds
different
Mutations & Gene Expression Point Mutations (cont.)
Normal:
Point (Silent):
Point (not silent):
DNA Template Strand
T A C G T G C G A A C C T G A A T T
mRNA Strand A U G C A C G C U U G G A C U U A A
Protein Methionine
Histidine AlanineTryptopha
nThreonine STOP
DNA Template Strand
T A C G T G C G C A C C T G A A T T
mRNA Strand A U G C A C G C G U G G A C U U A A
Protein Methionine
Histidine AlanineTryptopha
nThreonine STOPRecall: 64 codons, only 20 amino acids; helps prevent protein changes!
DNA Template Strand T A C G T G C G A A C G T G A A T T
mRNA Strand A U G C A C G C U U G C A C U U A A
Protein Methionine
Histidine Alanine Cysteine Threonine STOPJust one amino acid change can change an entire protein!
Sickle Cell Anemia
Mutations & Gene Expression
Frameshift Mutations: insertion or deletion of
nucleotide(s) results in the reading of codons
to shift.
1. T H E / F A T / C A T / A T E / T H E / R A T
T H E / F A E / T C A / T A T / E T H / E R A / T
2. T H E / F A T / C A T / A T E / T H E / R A T
T H E / A T C / A T A / T E T / H E R / A T
Insertion
Letters after insertion are shifted to the right
All Nonsense = Message Destroyed
Deletion
All Nonsense = Message Destroyed
Letters after insertion are shifted to the left
Mutations & Gene Expression Frameshift Mutations (cont.)
Normal:
Frameshift Insertion:
Frameshift Deletion:
DNA Template Strand
T A C G T G C G A A C C T G A A T T
mRNA Strand A U G C A C G C U U G G A C U U A A
Protein Methionine
Histidine AlanineTryptopha
nThreonine STOP
DNA Template Strand
T A C A G T G C G C A C C T G A A T T
mRNA Strand A U G U C A C G C G U G G A C U U A A
Protein Methionine
Serine Arginine LeucineAspartat
eLeucine
DNA Template Strand
T A C T G C G A A C G T G A A T T
mRNA Strand A U G A C G C U U G C A C U U A A
Protein Methionine
Threonine
Leucine Glycine Leucine
No Stop
Completely Different!
Completely Different!
Example Cystic Fibrosis
You try it… Write: THE BOY HAD THE FLU Do two types of frameshift mutations:
Insertion of a single base Deletion of a single base
In each case, how many amino acids would be affected during translation?
Mutations & Gene Expression Which is more destructive? Point OR
FrameshiftChanges MANY amino acids
Mutations
Point
Silent Not Silent
Frameshift
Insertion Deletion
Can be a “silent mutation” or only
changes one amino acid
What Causes Mutations?
There are two main ways in which DNA can become mutated:
Mutagens: agents that cause changes in DNA:
Chemical exposure: pH, poisons, toxins, factory waste, pollution
Radiation: nuclear fallout, X rays, UV sun exposure
http://www.cnn.com/2014/10/29/health/oregon-brittany-maynard-video/index.html
Are mutations good or bad?
Both…. Mutations can lessen chances of survival
A mutation that makes a rabbit white instead of brown may make it easier to catch because it stands out in its environment.
Mutations can help chances of survival and increase genetic diversity in a species Over millions of years, mutations have caused
different colors in bear fur, and bears have evolved as different species in different environments (polar, forest)
Exhibition Step 2 Pick a mutagen Research how it affects cells, and apply it to
your selected cell This is the conflict and introduction of the
villain in your story