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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 geneChromosomal mutations - changes
within a whole chromosome (affects multiple genes)
Gene MutationsPoint 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
NormalTAC 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
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.
DELETION of H
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? 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
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 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
Gel
Power source
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?
DNA Fingerprinting Paternity Tests
Children have a banding that is a combination of their mom’s and dad’s banding.
Crime solvingIdentify 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 supplyMice 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
The fused cell begins dividing normally.
Embryo
The embryo is placed in the uterus of a foster mother.
Foster Mother
The embryo develops normally into a lamb—Dolly
Cloned Lamb
Egg CellAn egg cell is taken from an adult female sheep.
The nucleus of the egg cell is removed.
