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. 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? Do you look EXACTLY like your brothers & sisters?

Genetic Diversity Genetically diverse populations are more likely to survive changing environments. 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. 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. Leopard populations around the world are in danger because of inbreeding. There is very little genetic variation between any 2 individuals. 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. This makes them VERY susceptible to disease & will likely lead to their extinction.

Genetics of Meiosis Recombination and mutation provide for genetic diversity. Recombination and mutation provide for genetic diversity. Inserting, deleting, or substituting DNA bases can alter genes. 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. An altered gene in a sex cell may be passed on to every cell that develops from it, causing an altered phenotype.

Occurs in prophase of meiosis I Occurs in prophase of meiosis I Generates diversity Generates diversity Creates chromosomes with new combinations of alleles for genes A to F. a b c d e f A B C D E F A B C D E F a b c d e f Natural Recombination: Crossing Over

Letters denote genes Case denotes alleles A B C D E F a b c d e f c d e f A B a b C D E F recombination

END RESULT: Alleles have crossed over to produce new gene combinations A B C D E F a b c d e f c d e f A B a b C D E F recombination

Trisomy 21 Sometimes entire chromosomes can be added or deleted, resulting in a genetic disorder such as Trisomy 21 (Down syndrome). Sometimes entire chromosomes can be added or deleted, resulting in a genetic disorder such as Trisomy 21 (Down syndrome).

Genetic Diversity Chromosomal Errors Chromosomal Errors NONDISJUNCTION: the failure of chromosomes to separate properly in meiosis. Gametes with extra or too few chromosomes result. 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. Can cause diseases such as Down’s Syndrome.

Other Chromosomal Mutations Chromosomal Errors Chromosomal Errors POLYPLOIDY: organisms with entire extra sets of chromosomes POLYPLOIDY: organisms with entire extra sets of chromosomes Results in the death of the fetus in animals 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 Often occurs in plants and causes the fruits and flowers to be larger. EX.: bananas, lilies

Karyotype Boy or Girl?

Genetic Diseases Turner's 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. 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 Turner's syndrome Signs of Turner syndrome include: Signs of Turner syndrome include: short stature, short stature, delayed growth of the skeleton, delayed growth of the skeleton, shortened fourth and fifth fingers, shortened fourth and fifth fingers, broad chest, broad chest, and sometimes heart abnormalities. and sometimes heart abnormalities.

Genetic Diseases Turner's syndrome Women with Turner syndrome are usually infertile due to ovarian failure. Women with Turner syndrome are usually infertile due to ovarian failure. Diagnosis is by blood test (karyotype). Diagnosis is by blood test (karyotype).

Turner’s Syndrome

Genetic Diseases Huntington’s Disease Huntington’s disease (HD) is an inherited disorder caused by the degeneration of certain nerve cells in the brain. 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. The gene for Huntington’s disease is codominant. HD causes bizarre involuntary movements and loss of intellectual abilities (dementia). 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. The condition begins most often in mid-adulthood and progresses slowly to death.

Huntington’s Disease

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. 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.

Genetic Diseases Tay-Sachs Disease Tay-Sachs results in: Tay-Sachs results in: mental retardation, mental retardation, convulsions, convulsions, blindness, blindness, and ultimately death. and ultimately death.

Genetic Diseases Tay-Sachs Disease

In the Laboratory: Changing DNA DNA technology is used to change life every day!!! DNA technology is used to change life every day!!! Gel Electrophoresis Gel Electrophoresis Transgenic organisms (Gene Splicing) Transgenic organisms (Gene Splicing)

GEL ELECTROPHORESIS A lab procedure that sorts portions of DNA by size A lab procedure that sorts portions of DNA by size Why? To determine gene length!!! (Number of base pairs present in gene) Why? To determine gene length!!! (Number of base pairs present in gene)

STEPS OF GEL ELECTROPHORESIS 1. DNA to be studied is cut into smaller portions by an enzyme 2. DNA is now in fragments.

2. Fragments are placed in the (-) end of a gel and an electrical current is sent through the gel FACT: 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

3. The electrical current separates DNA fragments by size “Short” genes travel a long distance across the gel “Short” genes travel a long distance across the gel “Long” genes travel a short 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, it creates visible bands...

APPLICATIONS OF GEL ELECTROPHORESIS DNA Fingerprinting: each individual’s genes will create different bands when put through electrophoresis DNA Fingerprinting: each individual’s genes will create different bands when put through electrophoresis Results can be used to: Results can be used to: Determine a criminal’s innocence or guilt Determine a criminal’s innocence or guilt Determine the paternity of a child Determine the paternity of a child

TRANSGENIC ORGANISMS Created using GENE SPLICING Created using GENE SPLICING Definition: Any organism that has foreign DNA in its cells Definition: Any organism that has foreign DNA in its cells Why would someone want to put foreign DNA in an organism? 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. AGRICULTURAL IMPROVEMENT: growth-hormone gene added to organisms that don’t have it to increase weight. Common practice in livestock. MARKETING: jelly fish gene... MARKETING: jelly fish gene...

CLONING Definition: Producing an organism genetically identical to another organism Definition: Producing an organism genetically identical to another organism 1997 – Sheep clone (Dolly) created by extracting cells from a female sheep 1997 – Sheep clone (Dolly) created by extracting cells from a female sheep What does the future of cloning hold for us??? What does the future of cloning hold for us???