Download Genes & Genetic Engineering

Genes & Genetic Engineering
Contents
Genetic Code
 Cell Cycle
 Sexual Reproduction
 Applications of Gene Technology
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Genetic Code
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Sequence of bases on DNA
These code the sequence of amino acids in proteins
1st 2 are most important
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20 amino acids
4 bases
grouped into 3s  64 combinations
Codon
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Genetic code
Universal Code: The code is used between species. Each
base sequence codes for the same amino acid
Many base sequences can code for the same amino acid
“Stop” (UAG, UGA, UUA) does not code for an amino acid
Genetic Code
Amino Acid mRNA Codons
Cell Cycle
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Cell cycle varies from hours to years
- Bacterial cells divide every 30 minutes
- Liver cells divide every 2 hours
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Four cycles:
- Gap 1, Synthesis, Gap 2, Mitosis
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Mitosis has four phases:
- prophase, metaphase, anaphase, telophase
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Mitosis results in 2 daughter cells, genetically identical to
each other. Used for growth and asexual reproduction
Cell Cycle
Cell grows & produces
Gap 2
proteins for cell division.
Determines if cell can
undergo mitosis.
mitosis
Gap 1
Interphase:
Gap 1 + synthesis + Gap 2
DNA synthesis
DNA synthesis
(replication).
Cell size increases
RNA and synthesise
proteins produced.
Preparations for DNA
synthesis.
Cell stops dividing.
Gap 0 Temporary or permanent.
Meiosis (Sexual Reproduction)
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Mitosis produces 2 genetically identical daughter cells
Meiosis occurs directly afterwards with 2 further divisions
Meiosis therefore results in 4 daughter cells with:
- half the number of chromosomes (diploid 2n  haploid n)
- new combinations of genes so no two will be identical
Meiosis (Sexual Reproduction)
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Advantages:
- genetic variation and wide diversity of life
- allows species to adapt and evolve
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Disadvantages:
- complex
- slower than mitosis
Applications of Gene Technology
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3 main applications to date:
- Gene Products: using genetically modified (GM)
organisms (usually microbes) to produce chemicals for
medical or industrial applications
- New Phenotypes: using gene technology to alter the
characteristics of organisms such as crops
- Gene Therapy: using gene technology on humans to
treat diseases
Gene Products
GM Product
Application
Host Organism
AAT
Cystic fibrosis
Sheep
Anti-thrombin
Anti-blood clotting
(surgery)
Goats
BST
Increase cows’ milk yields
Bacteria
Factor VIII
Human blood clotting
(haemophiliacs)
Bacteria
HGH
Human growth hormone
Bacteria
Penicillin
Antibiotic to kill bacteria
Fungi
Vaccines
Hep B antigen
Yeast
Rennin
Manufacture of cheese
Bacteria
New Phenotypes
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These include:
- Fast-growing sheep & fish
- Crops resistant to insects, herbicides & viruses
- Long life tomatoes & some fruit
- Crop improvement & nitrogen-fixing crops
- Cattle resistant to mastisis ( higher yield of milk)
- Sheep resistant to ticks ( may not need sheep dip)
Gene Therapy
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Altering the genotype of a tissue or organ
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In early stages but treatments hope to include:
- GM white blood cells that produce proteins that kill
cancer cells
- targeting genes at cancer cells to kill them or revert
them back to normal cells
- white blood cells that would not reproduce if infected
with HIV
- germ-line modification (only present in animals) which
is currently illegal
- at present, only somatic cell therapy is legal which
alters only specific cells in the body
Summary
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Genetic code: Sequence of 20 amino acids & 4 bases,
grouped into 3s. It is a universal code (all species)
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Cell cycle: Interphase = Gap 1 + synthesis + Gap 2
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Sexual reproduction, meiosis produces non-identical
daughter cells and is vital for organisms to evolve
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Applications of gene technology include gene products (e.g.
penicillin), new phenotypes (long life tomatoes) and gene
therapy (in early stages)