Transcript Gene mutations

BIOTECHNOLOGY
The future is here!
MUTATIONS
 Mutation
- changes in the DNA
sequence that affect genetic
information
 Types of mutations:
 Gene
mutations - changes within a
single gene
 Chromosomal mutations - changes
within a whole chromosome (affects
multiple genes)
Gene Mutations
 Point
Mutation - a change in
a single nucleotide (example:
changing an A to a C)
 Frame-shift Mutation - an
insertion or deletion of a
nucleotide that causes a
different reading of codons
from the point of the change to
the end of the gene
Point Mutations
 Normal
AAT TAA TAG GAT TTT AAA
 Mutation
AAT TAG TAG GAT TTT AAA
The G was used instead
of an A.
Frame-Shift Mutations
 Usually
occurs as a result of an
insertion or deletion
 Normal
TAC GCA TGG ATT
 Insertion
TAT CGC ATG GAT T
T was inserted after the A.
Example using words:

THE FAT CAT ATE THE RAT

THE FAT C AT A TE T HE R AT
DELETION of H
TEF ATC ATA TET HER AT
 Just like this mutated sentence does not
make sense, frameshift mutations make
nonsense proteins that cannot do their
jobs correctly.

Chromosomal Mutations
Deletion – when part or all of a chromosome
is lost
 Duplication – when part of a chromosome is
mistakenly repeated
 Inversion – when part of a chromosome
becomes oriented in reverse of its normal
direction
 Translocation – when one part of a
chromosome breaks off and attaches to
another nonhomologous (not the partner)
chromosome

Chromosomal Mutations
Deletion
Duplication
Inversion
Translocation
When do mutations occur?
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During DNA replication, mistakes can be
made when DNA polymerase adds
complementary nucleotides.
If this mutation or mistake happens very early
on in a baby’s development, the mutation can
affect the entire baby. The rest of the cells
will have that same mutation.
Remember, we all start off as one cell that
must make many news cells through mitosis.
Every time your cells divide, DNA has to copy
itself and mistakes can be made.
If a one of your skin cells divides right
now and a mutation occurs, this is
probably not a problem.
 However, if the mutation causes
certain genes to change, the new,
mutated skin cell can become a
cancer cell.

Cause of mutations

Mutagen – any agent that causes
DNA to mutate
 UV light
 Radiation
 Smoking
 Many different chemicals
Mutations gone wide

Cats
Gene Regulation
Only some of your genes are being
expressed (used to make protein) at any
given time.
 Your body needs mechanisms to “turn
on” or “turn off” genes.
 Chemicals can act as blocks or starters.
 Some cancers are caused by genes
being turned on that should not have
been! For example, these genes can be
turned on by smoking, which mutates
DNA.

Types of Genetic Disorders
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Autosomal Dominant gene
 Example: Huntington’s Disease
Autosomal Recessive gene
 Examples: Tay Sachs, Sickle Cell Anemia, and
Albinism
Sex-linked Genes (usually recessive)
 Examples: Hemophilia and color-blindness
Chromosomal – entire chromosome or large areas
of a chromosome is affected
Random mutations
 Example: Progeria
Genetic Engineering
Manipulating DNA
Working with DNA
 DNA
Extraction
 Cells
are chemically opened and
the DNA is pulled out.
 Cutting
 DNA
DNA
strands from most organisms
are much too large to be analyzed
all at once.
 Somehow we must cut the DNA
into smaller fragments.
 Special
enzymes are used to cut
the DNA in specific places.
 These special enzymes are called
restriction enzymes.
 These restriction enzymes cut the
DNA molecule at specific
sequences of nucleotides.
Recognition sequences
How do we separate the DNA
fragments?
 ELECTROPHORESIS
Electrophor-what?!?
Electrophoresis is a technique that
separates DNA fragments (using
electricity) in a jello-like slab based on
the size of the fragments.
 Smaller fragments are able to travel
longer distances more quickly.
 DNA has a negative charge so the
fragments will flow toward the positive
electrode (opposites attract).

DNA plus
restriction
enzyme
Mixture of
DNA
fragments
Power
source
Gel
 If
you were to compare two
samples of the same DNA using
the same restriction enzymes, the
banding pattern would be the
same.
 Different people make different
banding patterns.
And why would we do this?
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DNA Fingerprinting
 Paternity Tests
 Children have a banding that is a
combination of their mom’s and dad’s
banding.
 Crime solving
 Identify the person who committed a crime
(no two people have the same DNA)
 Medical diagnosis
 Determine if you have the gene that
causes a disease or disorder.
Transgenic organisms
 Transgenic
organisms contain
genes from other organisms.
 Genes from one organism can be
inserted into another organism.
Transgenic Bacteria
 Used
to make:
 Insulin
 Human
Growth Hormone
 Clotting Factors
Transgenic Animals
 Used
to study genes and improve
the food supply
 Mice with human-like immune
systems.
 Livestock with extra copies of
growth hormone genes.
 Sheep and pigs that produce
human proteins in their milk.
Transgenic Plants
 Used
for food supply and medical
supplies
 Soy
and corn
 Rice with additional Vitamin A
 Plants that produce blood proteins
Cloning
Producing genetically identical
organisms from one original cell.
 We have successfully cloned pigs,
cows, mice, sheep, and monkeys.
 The first animal cloned was a sheep
named Dolly in 1997.

A donor cell is taken
from a sheep’s udder.
Donor
Nucleus
These two cells are
fused using an
electric shock.
Fused Cell
An egg cell is taken from an adult
female sheep.
Egg Cell
The nucleus of the
egg cell is removed.
Cloned Lamb
The fused cell
begins dividing
normally.
Foster
Mother
Embryo
The embryo develops
normally into a lamb—Dolly
The embryo is placed in
the uterus of a foster
mother.