Genetics Beyond Mendel Betsy Sanford 7th Grade Life Science Lost Mountain Middle School

Human Chromosomes karyotype – an image showing the chromosomes in an organism

Human Chromosomes mutation – a change in a chromosome may be helpful, harmful, or have no noticeable effect

Human Chromosomes mutation may cause disease or disorder melanoma (skin cancer) – a deletion in #9

Human Chromosomes Down’s Syndrome – an extra copy of chromosome #21

Sex Determination 23rd pair of chromosomes causes an organism to be either male or female two X chromosomes = female An X and a Y chromosome = male women always pass their offspring an X men pass their offspring either an X or a Y therefore, the father determines the sex of the offspring even though these are whole chromosomes (long strands of DNA, thousands of genes), a Punnett square can be used to show these results

23rd Pair of Chromosomes

Sex-linked Gene any gene found on the 23rd pair of chromosomes X chromosome is dominant over Y chromosome any disease or disorder carried on the X will appear in males to appear in females, both X’s would have to have the disease or disorder example = females who can see color can pass color-blindness to their sons.

Color-blindness is a Sex-linked Gene

Co-Dominance neither allele is strong enough to overcome the other both alleles attempt to show up

Multiple Alleles more than two different forms of a gene example = blood type A = dominant B = dominant O = recessive 6 possible genotypes (letter combinations) 4 phenotypes (results)

Multiple Alleles

Polygenic Inheritance one trait produced from many genes several sections of DNA cause the result of a single trait examples = shades of eye color, shades of hair color, fingerprints

Polygenic Inheritance

Pedigree a chart that shows the genetic history of an entire family

Pedigree Analysis All pedigrees use common symbols. Answer the following questions. What does an empty square represent? What does a shaded square represent? What does a ½ shaded square represent? What does shaded circle represent? What does an empty circle represent? What does a ½ shaded circle represent?

I = grandparents II = parents III = children

Pedigree Analysis Based on the pedigree in the previous slide, answer the following questions. In row I, how many males can roll their tongue? In row I, how many females can roll their tongue? In row II, how many males can roll their tongue? In row II, how many females can roll their tongue? In row III, how many males can roll their tongue? In row III, how many females can roll their tongue? How is a pedigree different from a Punnett square? Why would it be useful or important to see several generations of characteristics at one time?

Selective Breeding mating organisms with desirable characteristics pets (personality, ability, appearance) produce (insect resistant, increased size and amount of fruits and vegetables) livestock (more meat in cows and chickens; more eggs from chickens)

Genetic Engineering actually changing/manipulating the DNA of organism inside the cell new products = food, fabrics, medicines example: insulin production by bacteria the human gene that produces insulin has been identified the human gene for insulin is isolated and inserted into a bacteria the bacteria produces human insulin the synthetic insulin is used to treat diabetes in humans