Transcript 3.1 Mutations_Gene Expression

What is a gene and what
is Gene Expression?
 A Gene is the molecular unit of heredity
in a living organism!
 Gene expression is the process by
which information from a gene is used
in the synthesis of a functional gene
product. These products are often
proteins.
Gene Expression
Operons
 Gene expression requires an operons!
 A segment of DNA to which a transcription
factor can bind!
 Also called a lac operon
 The operon regulates gene expression!
Control of Gene
Expression
 Cells differ in which genes are being
expressed
 It is based on cell function (nerve vs muscle)
 Levels of control in eukaryotes
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Transcriptional
Post transcriptional
Translational
Post translational
 May rely on signals from outside or inside
Don’t let this happen to you!!
Types of Control
 Transcriptional control
 Determines the rate of transcription or if
transcription even occurs
 The organization of chromatin (form that
chromosomes take in non-dividing cells)
 Regulator proteins are called transcription
factors
 Signals from inside/outside cell
Types of Control
 Post transcriptional
 Involves process of mRNA
 Translational control
 Involves the ability of the mRNA to bind to
ribosomes
 Post translational
 Involves changes needed for the polypeptide
to become functional
 Polypeptide: long, continuous chain of amino
acids
Closing Question #1
 Explain how gene expression plays a role
in this scenario.
 At 21oC, a bread mold can often be seen
growing on bread as a dark-colored mass.
 At 15oC the same bread mold can often be
seen growing as a red mass.
Closing Question 2
 The chart shows the relationship between
inherited genes, environment and the physical
appearance of a sweet potato vine. Determine
which gene is most influenced by environment
and defend your answer.
MUTATIONS
Changes in DNA that affect genetic
information
Gene Mutations
 Point Mutations – changes in
one or a few nucleotides
 Substitution
 THE FAT CAT ATE THE RAT
 THE FAT HAT ATE THE RAT
 Insertion
 THE FAT CAT ATE THE RAT
 THE FAT CAT XLW ATE THE RAT
 Deletion
 THE FAT CAT ATE THE RAT
 THE FAT ATE THE RAT
Gene Mutations
 Frameshift Mutations – shifts
the reading frame of the
genetic message so that the
protein may not be able to
perform its function.
 Insertion
 THE FAT CAT ATE THE RAT
 THE FAT HCA TAT ETH ERA T
 Deletion
H
 THE FAT CAT ATE THE RAT
 TEF ATC ATA TET GER AT
H
Chromosome Mutations
 Changes in number and structure of entire
chromosomes
 Original Chromosome ABC * DEF
 Deletion
AC * DEF
 Duplication
ABBC * DEF
 Inversion
AED * CBF
 Translocation
ABC * JKL
GHI * DEF
Significance of Mutations
• Most are neutral
• Eye color
• Birth marks
• Some are harmful
• Sickle Cell Anemia
• Down Syndrome
• Some are beneficial
• Sickle Cell Anemia to Malaria
• Immunity to HIV
What Causes Mutations?
 There are two ways in which DNA can
become mutated:
 Mutations can be inherited.
 Parent to child
 Mutations can be acquired.
 Environmental damage
 Mistakes when DNA is copied
Chromosome Mutations
 Down Syndrome
 Chromosome 21 does
not separate correctly.
 They have 47
chromosomes in stead
of 46.
 Children with Down
Syndrome develop
slower, may have heart
and stomach illnesses
and vary greatly in their
degree of inteligence.
Chromosome Mutations
 Cri-du-chat
 Deletion of material on 5th
chromosome
 Characterized by the cat-like
cry made by cri-du-chat
babies
 Varied levels of metal
handicaps
Sex Chromosome
Abnormalities
 Klinefelter’s
Syndrome
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XXY, XXYY, XXXY
Male
Sterility
Small testicles
Breast enlargement
Sex Chromosome
Abnormalities
 XYY Syndrome
 Normal male traits
 Often tall and thin
 Associated with antisocial and behavioral
problems
Sex Chromosome
Mutations
 Turner’s Syndrome
 X
 Female
 sex organs don't
mature at
adolescence
 sterility
 short stature
Sex Chromosome
Mutations
 XXX
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Trisomy X
Female
Little or no visible differences
tall stature
learning disabilities
limited fertility
Some mutations even
make it on SNL!