Genetic Diversity: Natural and Artificial Means Honors Biology
Genetic Diversity The sorting and recombination of genes in sexual reproduction results in a great variety of gene combinations in the offspring of any 2 parents. Do you look EXACTLY like your brothers & sisters?
Genetic Diversity Genetically diverse populations are more likely to survive changing environments. Greater variation within the species makes a population better suited to adaptation to changes in the environment.
Leopards and Genetic Diversity Leopard populations around the world are in danger because of inbreeding. There is very little genetic variation between any 2 individuals.
Genetic Diversity This makes them VERY susceptible to disease & will likely lead to their extinction.
Genetics of Meiosis Recombination and mutation provide for genetic diversity. Inserting, deleting, or substituting DNA bases can alter genes. An altered gene in a sex cell may be passed on to every cell that develops from it, causing an altered phenotype.
Natural Recombination: Crossing Over Occurs in A A a a prophase of B B b b meiosis I C C c c D D d Generates d E E e e diversity F F f fCreates chromosomes with new combinations ofalleles for genes A to F.
recombinationLetters denote A a a Agenes B b bCase denotes B C C c calleles D D d d E E e e F F f f
recombination A a A a B b B bEND RESULT: Alleles C C c chave crossed over toproduce new genecombinations D D d d E E e e F F f f
Trisomy 21 Sometimes entire chromosomes can be added or deleted, resulting in a genetic disorder such as Trisomy 21 (Down syndrome).
Genetic Diversity Chromosomal Errors NONDISJUNCTION: the failure of chromosomes to separate properly in meiosis. Gametes with extra or too few chromosomes result. Can cause diseases such as Down’s Syndrome.
Other Chromosomal Mutations Chromosomal Errors POLYPLOIDY: organisms with entire extra sets of chromosomes Results in the death of the fetus in animals Often occurs in plants and causes the fruits and flowers to be larger. EX.: bananas, lilies
Genetic Diseases Turners Syndrome Turner’s syndrome is a genetic disorder affecting only females, in which the patient has one X chromosome in some or all cells; or has two X chromosomes but one is damaged.
Genetic Diseases Turners syndrome Signs of Turner syndrome include: short stature, delayed growth of the skeleton, shortened fourth and fifth fingers, broad chest, and sometimes heart abnormalities.
Genetic DiseasesTurners syndrome Women with Turner syndrome are usually infertile due to ovarian failure. Diagnosis is by blood test (karyotype).
Genetic Diseases Huntington’s Disease Huntington’s disease (HD) is an inherited disorder caused by the degeneration of certain nerve cells in the brain. The gene for Huntington’s disease is codominant. HD causes bizarre involuntary movements and loss of intellectual abilities (dementia).
Genetic Diseases Huntington’s Disease The condition begins most often in mid-adulthood and progresses slowly to death.
Genetic Diseases Tay-Sachs Disease A hereditary disease that affects young children almost exclusively of eastern European Jewish descent, in which an enzyme deficiency leads to the accumulation of fat in the brain and nerve tissue.
In the Laboratory: Changing DNA DNA technology is used to change life every day!!! Gel Electrophoresis Transgenic organisms (Gene Splicing)
GEL ELECTROPHORESIS A lab procedure that sorts portions of DNA by size Why? To determine gene length!!! (Number of base pairs present in gene)
STEPS OF GEL ELECTROPHORESIS DNA to be studied is cut into smaller portions by an enzyme DNA is now in fragments.
1. Fragments are placed in the (-) end of a gel and an electrical current is sent through the gelFACT:DNA is NEGATIVELY (-) charged. The electrical current causes DNA to move towards the (+) end of the gel, like a magnet attracted to its opposite pole
The electrical current separates DNA fragments by size “Short” genes travel a long distance across the gel “Long” genes travel a short distance across the gel THE SMALLER THE GENE, THE FURTHER IT CAN TRAVEL ACROSS THE GEL!!!
As DNA moves across the gel, itcreates visible bands. . .
APPLICATIONS OF GEL ELECTROPHORESIS DNA Fingerprinting: each individual’s genes will create different bands when put through electrophoresis Results can be used to: Determine a criminal’s innocence or guilt Determine the paternity of a child
TRANSGENIC ORGANISMS Created using GENE SPLICING Definition: Any organism that has foreign DNA in its cells Why would someone want to put foreign DNA in an organism?
WHY??? AGRICULTURAL IMPROVEMENT: growth-hormone gene added to organisms that don’t have it to increase weight. Common practice in livestock. MARKETING: jelly fish gene. . .
CLONING Definition: Producing an organism genetically identical to another organism 1997 – Sheep clone (Dolly) created by extracting cells from a female sheep What does the future of cloning hold for us???