semester 2, day 8
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Semester 2, Day 8. Cell Specialization and Gene Expression. Agenda. Review Central Dogma Turn in HW (Packets 11.4-11.5) Quiz on Central Dogma Lecture on Cell Specialization and Mutations Reading/Work Time. Review. What is the definition and diagram of the central dogma? - PowerPoint PPT PresentationTRANSCRIPT
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Semester 2, Day 8
Cell Specialization and Gene Expression
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Agenda Review Central Dogma Turn in HW (Packets 11.4-11.5) Quiz on Central Dogma Lecture on Cell Specialization and Mutations Reading/Work Time
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Review What is the definition and diagram of the central dogma? What are the roles of DNA, RNA and protein in the central
dogma? What is the first “step” of the central dogma? Know the steps! What is the second “step” of the central dogma? Know the
steps! What is a codon? Be able to use scientific language! Which amino acid do all proteins begin with? (Hint: look at
the genetic code chart) If given a strand of DNA, can you determine what the mRNA
strand should be? (Hint: don’t use T, use U!) With that mRNA strand, be able to use the genetic code chart
to determine the chain of amino acids. (Remember: which amino acid comes first???)
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Homework Due Annotate the packet Sections 11.4-11.5
Do all concept checks Chapter 11 Review
#3-6, 12, 14, 15, 19, 20, 22-24
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Cell Specialization & Gene Expression We have 100 trillion cells, but they don’t all
look the same (200 types):
Neuron CellEpithelial (Skin) Cells
Red Blood Cells
Muscle CellSperm Cell
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Cell Specialization & Gene Expression All of these cells contain the same exact copy of DNA (except sperm), 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
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Cell Specialization & Gene Expression Zygote: first cell of an organism
Day 0
Image Source: www.bbc.co.uk Image Source: commons.wikimedia.org
Morula (16-64 cells)
All of these cells are TOTIPOTENT: capable of differentiating (specializing) into any and all types of cells
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Cell Specialization& Gene Expression
Blastocyst (70-100 cells)
Embryoblast cells are PLURIPOTENT: capable of
differentiating into the cells of one of three groups.
Image Source: www.boundless.com Image Source: www.scq.ubc.ca
**Stem cell therapy can
use embryoblast
cells!
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Mutations & Gene Expression Mutation: A change in a DNA sequence. May
or may not affect gene expression (the protein). Point Mutation
1. T H E / F A T / C A T / A T E / T H E / R A TT 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 TT 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
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Mutations & Gene Expression
Image Source: waynesword.palomar.edu
Recall: 64 codons, only 20
amino acids.
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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 AProtein Methionin
e Histidine Alanine Tryptophan Threonine 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 AProtein Methionin
e Histidine Alanine Tryptophan Threonine 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 AProtein Methionin
e Histidine Alanine Cysteine Threonine STOPJust one amino acid change can change an entire protein!
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Mutations & Gene Expression
Mutations
Point
Silent (doesn’t
affect gene expression)
Not Silent (affects
gene expression)
?
? ?
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Mutations
Point
Silent Not Silent
Frameshift
Insertion Deletion
Mutations & Gene Expression
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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 TT H E / A T C / A T A / T E T / H E R / A T
InsertionLetters after insertion are shifted to the right
All Nonsense = Message Destroyed
Deletion
All Nonsense = Message Destroyed
Letters after insertion are shifted to the left
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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 AProtein Methionin
e Histidine Alanine Tryptophan Threonine 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 AProtein Methioni
ne Serine Arginine Leucine Aspartate Leucine
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 AProtein Methionin
eThreonin
e Leucine Glycine Leucine
No Stop
Completely Different!
Completely Different!
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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
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Reading/Work Time Section 11.3
Cornell Notes #1-6
Chapter 11 Assessment #2, 4, 12, 13, 14, 25