Download F4-6 Gene Regulation and Mutation Ch12,13

Gene Regulation and Mutation Ch13 F4-6
I.
Gene Regulation
A. Prokaryote Gene Regulation
1. Gene regulation – abiity of organism to control which genes are
transcribed (turned on) in response to the environment
2. Operon
a. Section of DNA that contains genes needed to produce
particular proteins
b. Operon responds to changes in environment
3. Parts of an operon
a. Operator – segment of DNA that acts as on/off switch for
transcription
b. Promotor – section of DNA where RNA 1st binds
c. Regulatory gene – makes repressor proteins to prevent or allow
transcription
d. Genes coding for proteins
B. Lac Operon (Example of gene regulation)
1. When E-coli bacteria is exposed to lactose (milk sugar) it makes
enzymes to break down lactose for an energy source
2. Lac (tose) Operon – contains a promoter, an operator, a
regulatory gene and 3 enzyme genes to control lac digestion
3. When lactose is present:
a. Regulatory gene’s repressor protein inactivated
b. RNA then allowed to begin transcription
c. Enzymes are created to digest lactose
4. When lactose gone
a. Regulatory gene’s repressor protein activated
b. RNA transcription blocked
c. No enzymes created
C. Eukaryote Gene regulation
1. Much more complex
2. Still requires control over when various proteins activated
D. Mutations – causes by errors in copying or mutagens (chemicals, etc.)
1. Mutation – change in DNA
2. Point mutation – change in one base pair
3. Substitution
a. one base exchanged for another
b. may create wrong amino acid
c. may change to stop codon – no amino acid created
4. Insertion – addition of nucleotide
5. Deletion – loss of nucleotide
Applied Genetics Ch13
I.
DNA Technology
A. Genetic Engineering
1. Selective Breeding
a. Old way to achieve desired traits
b. Only breed animals/plants with desired traits
c. After many generations – new pure breed
2. Genetic Engineering
a. manipulate DNA of one organism to insert DNA of another
b. Restriction enzymes – recognize specific DNA sequences and
cut out the DNA
c. Gel electrophoresis – used to separate DNA fragments by size
(DNA placed in gel with electric current)
d. Recombinant DNA technology – DNA fragments of certain
sizes are removed and replaced with desired DNA from other
organisms
e. Viruses used to insert new DNA into host cell
f. Host cell cloned to produce many copies
B. Benefits of bioengineering
1. Transgenic animals
a. Research organisms – carry desired traits for study
b. Livestock – improve food supply
c. Animals that produce needed chemicals/drugs
2. Transgenic plants
a. Resistant to disease
b. Resistant to pests
c. Resistant to weather extremes
d. Grown with added vitamins or nutrients
3. Transgenic bacteria
a. Produce human drugs (insulin)
b. Produce biomarkers (jellyfish phospholuminesence)
c. Clean oil spills
d. Clean trash/toxic chemicals
C. Human Genome
1. Genome – complete genetic info in a cell
2. Human genome project – completed 2003
a. determine sequence of 3 billion nucleotides
b. ID 20-25,000 human genes
3. Accomplished
a. Used restriction enzymes to cut all genes from 46
chromosomes
4. Findings
a. less than 2% of nucleotides code for proteins
b. Remainder – “junk DNA” or non-coding sequences
c. Non-coding sequences – unique to each individual
D. DNA fingerprinting
1. Use restriction enzymes to cut non-coding sequences
2. Use gel electrophoresis to separate by size
3. DNA segments labeled with radioactive compounds
4. X-Rays provide a “picture” of the fragments
5. Used to ID paternity, human remains and criminal suspects.