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Mutation and Biotechnlogy Notes packet
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April 18, 2012
I. Mutations: changes in DNA
A. Causes of Mutations
1. Environmental (mutagenic agents)
a. Radiation, such as ultraviolet (UV) radiation, X-rays, and gamma rays
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b. Certain chemicals, such as
Carcinogens (cancer-causing):
Ex: asbestos, formaldehyde, tobacco smoke (contains many)
Teratogens (cause birth-defects):
Ex: alcohol, cocaine, methylmercury, lead
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c. Some viruses, such as Hepatitis B (liver cancer) and some human papillomaviruses (HPV) (cervical cancer -
Gardasil)
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2. Internal to the bodya. Random errors in DNA replication during mitosisb. Random errors in DNA replication during meiosis
(because these processes happen quickly all the time)
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B. Types of Gene Mutations1. Substitutions:
one nucleotide is switched with anotherthis MAY cause a change in the amino acid the codon codes forthis may result in a change (good or bad) in the protein that is made
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Original: The fat cat ate the wee rat.Substitution Mutation: The fat hat ate the wee rat.
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Ex:Original DNA: C T G G A G Mutation: C T G G G G mRNA: mRNA: Amino Acids: Amino Acids:
Original DNA: A G A G A G Mutation: A G G G A G mRNA: mRNA: Amino Acids: Amino Acids:
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B. Types of Gene Mutations
2. Insertions: extra nucleotides are put into the genethis causes a change in the rest of the amino acids the gene codes forthis may result in a change (good or bad) in the protein that is made
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Original: The fat cat ate the wee rat.Insertion: The fat cat xlw ate the wee rat.
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Original DNA: C T G G A G Mutation: C T G T G G A G mRNA: mRNA:
Amino Acids: Amino Acids:
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B. Types of Gene Mutations3. Deletions:
a nucleotide is missingthis causes a change in the rest of the amino acids the gene codes forthis may result in a change (good or bad) in the protein that is made
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Original: The fat cat ate the wee rat.Deletion: The fat ate the wee rat.
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Original DNA: C T G G A G A A C mRNA:
Amino Acids:
Mutation: C T G G G A A C mRNA:Amino Acids:
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C. Effects of Mutations
Mutations à CHANGES IN DNA à
CHANGES IN PROTEIN STRUCTURE AND FUNCTION
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Types of proteins that can be affected by mutations in DNA:
1) STRUCTURAL– movement (muscle); protective covering (skin, hair, nails)
2) HORMONES– chemical messengers
3) ANTIBODIES– fight invading bacteria & viruses
4) RECEPTOR MOLECULES(embedded in cell membranes) – receive chemical messages
5) ENZYMES = biological catalysts– speed up chemical reactions
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If a mutation changes a protein’s structure (shape), this will affect its function (what it can do)
change DNA --> change amino acids -->change protein
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*Mutations can be* a. Lethal – lead to death of the organism
b. Harmful/Deleterious – negatively affect the health or the ability of an organism to reproduceEx: *cancers (cancerous mutations cause uncontrolled cell division)
genetic disorders
c. Neutral – have No effect on the health or the ability of an organism to reproduce
d. Beneficial – give the organism a reproductive advantage*important in the process of evolution**mutations increase VARIETY within a species**how asexually reproducing organisms can change*
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*IMPORTANT IN TERMS OF EVOLUTION*
In asexually reproducing species, any mutation in
the parent cell can be passed on to offspring
But in sexually reproducing species (like humans),
a mutation can ONLY be passed on to offspring if it occurs in a
SEX CELL/GAMETE, such as an egg or sperm .
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Mutations SexualReproduction
AsexualReproduction
Lethal Harmful/Deleterious
Neutral Beneficial
CancerGenetic
DisordersChromosomalAbnormalities
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II. Genetic Disorder: a disease that is caused by chromosomal abnormalities
Abnormalities in DNA can range from a small mutation in a single base to the addition or subtraction of an entire chromosome.
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A. Types of Genetic Disorders1. Sex-linked (abnormalities involving the sex
chromosomes)
a. Sex-linked recessive (must carry one or both alleles)Ex: hemophilia – genotypes: X
hX
h or X
hY
b. Monosomy (mono = 1, only one chromosome – the other copy is missing)
Ex: Turner Syndrome – genotype: X
c. Trisomy (tri = 3, an extra chromosome)
Ex: Klinefelter’s Syndrome – genotype: XXY
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2. Autosomal (abnormalities involving the body chromosomes)
a. Autosomal dominant HH or Hh
Ex: Dwarfism
b. Autosomal recessive cc
Ex: Cystic Fibrosis
c. Trisomy an extra autosomal chromosome
Ex: Down's syndrome, Trisomy 13, Trisomy 18
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B. Testing for Genetic Disorders
Amniocentesis: a medical test performed during pregnancy to diagnose chromosomal abnormalities
usually done when a woman is 15 - 20 weeks pregnant
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· a sample of the developing embryo's (fetus') cells are taken from the amniotic sac (the fluid-filled sac that protects and cushions the embryo)
· the DNA in the embryo's cells is extracted
· Chromosomes are arranged in order of decreasing size to produce a karyotype (a picture of the pairs of homologous chromosomes in an individual)
Procedure for Amniocentesis
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Biotechnology = the application of technology to the biological sciences
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a. Ex: genetic engineering (gene splicing), gel electrophoresis, bioremediation, genetically modified organisms
b. Has been around for hundreds of yearsEx: cheese and bread
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Selective breeding = a process that produces domestic animals and new varieties of plants with traits that are particularly desirable
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a. Ex: animals bred to have less fat; sweeter, juicier or hardier fruits or vegetables
b. Process:i. Select a trait (or two) that you would like – sweet,
juicy strawberriesii. Cross parents that expresses each trait – cross a
sweet strawberry plant with a juicy strawberry plant
iii. Results – sweet, juicy strawberriessweet strawberry x juicy strawberry --> sweet, juicy strawberries
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http://www.dnatube.com/video/574/Dog-Breeding
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Genetic Engineering = a set of technologies that humans use to alter the genetic instructions of an organism by substituting DNA molecules
a. Ex: plants that contain genes with instructions for making chemicals that kill the insects that feed on them; bacteria to clean up oil spills or ones that produce human growth hormone
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b. Process:i. Cut out gene of interest from one organism using a
restriction enzymeii. Insert (Splice) that gene of interest into another
organism using another enzymeiii. Result: organism with gene of interest from another
organism in its DNA, it can now reproduce with that gene of interest in it and make the protein coded for by that gene
iv. Take human insulin –producing gene, cut it out of human cell and splice it into bacteria cell that can reproduce quickly and make lots of insulin. This insulin is the same as human insulin.
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Draw a picture of gene splicing from a human to a bacteria:
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V. Applications of Biotechnology
a. Purpose: i. Disease research – understand disease,
locate and decode its genes, how to treat itb. Ways to diagnose:
i. Karyotypingii. DNA fingerprinting using gel electrophoresis
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http://learn.genetics.utah.edu/content/labs/gel/
http://www.monsanto.com/biotech-gmo/asp/default.asp
http://www.brainpop.com/health/geneticsgrowthanddevelopment/stemcells/
http://www.ncbi.nlm.nih.gov/mapview/maps.cgi?taxid=9606&CHR=17&maps=genes-r,pheno,morbid,genec&R1=on&query=BRCA1&VERBOSE=ON&ZOOM=3