Transcript figure velo
Think for a second about the most crazy thing you have ever seen… Imagine in the future… when something like THIS could be possible… The future is now… How did the scientists do it? INTRO TO GENETICS GENETICS the study of how traits are passed from one generation to the next TRAIT a characteristic Examples: Plant size, seed color, pod shape GENES Each feature of the pea plants is controlled by a gene. It may have a gene that controls its color, another for size and another for shape. GENE the factors that control traits (found in the DNA) Above you see chromosomes. The circled area is a gene on chromosome #22. The absence of this gene causes velo-cardiofacial syndrome (VCFS) which may cause ADD and mental illness ALLELES Each gene comes in different forms called alleles, so the gene that controls flower color may come in two alleles: purple and white. ALLELES different forms of a gene GREGOR MENDEL • • • • The “father” of genetics Lived from 1822-1884 Austrian Monk Published his work in 1866, but no one took him seriously until 1900. • Studied Pea Plants! MENDEL’S EXPERIMENTS Mendel experimented with 7 different characteristics Mendel Got Lucky for 2 Big Reasons 1. First, he had a lot of time…he was a monk. This let him do LOTS of experiments with the peas! 2. Each trait had 2 options. This was key because he could tell if it was one way or the other. HOMOZYGOUS organism with two identical alleles for the same trait (TT or tt) HETEROZYGOUS organism with two different alleles for the same trait (Tt) DOMINANT allele that is expressed when in the presence of a recessive allele (TT or Tt = tall) RECESSIVE allele that is expressed only when homozygous (tt = short) PHENOTYPE physical characteristics (Tall, Brown) GENOTYPE the genetic makeup (TT, TtHh) GENE = Height ALLELE = Tall, Short Gene is represented by the letter “t” Dominant = T Recessive = t Remember you need 2 copies of every gene!!! How can we determine what the offspring are going to be? PUNNETT SQUARES Reginald C. Punnett • Inventor of the Punnett Square PUNNETT SQUARES chart showing the possible combination of alleles in a cross Punnett Squares show the probability of getting a certain type of offspring THE PARENTS GENOTYPES • DAD = Tt (heterozygous) • MOM = Tt (heterozygous) PHENOTYPES • DAD = Tall • MOM = Tall PUNNETT SQUARES THE OFFSPRING GENOTYPES 1TT:2Tt:1tt (1:2:1) • TT (homozygous dominant) • Tt (heterozygous) • Tt (heterozygous) • tt (homozygous recessive) THE OFFSPRING PHENOTYPES 3 Tall :1 Short (3:1) • TT (tall) • Tt (tall) • Tt (tall) • tt (short) Cross a homozygous dominant with a recessive (for height where T is dominant and tall). Find the genotype and the phenotype Cross a heterozygote with a recessive (for height where T is dominant and tall). Find the genotype and the phenotype Cross a heterozygote with another heterozygote (for skin color where Black is B, b = white). Find the genotype and the phenotype Cross a heterozygote with another heterozygote (for nose size where big nose is N and small nose is n). Find the genotype and the phenotype If we saw an organism that had round seeds (round is dominant), how could we figure out what its genotype is? Test Cross A cross between an unknown and a homozygous recessive Example of a Test Cross Unknown Incomplete Dominance When a combination of the dominant and recessive creates a new phenotype. RR = red, rr = white, and Rr = pink Incomplete Dominance RR Rr rr Incomplete Dominance Cross Incomplete Dominance Cross Co-dominance When an intermediate between the dominant and recessive is expressed. BB = black, Bb=spotted, bb=white Sex Linked Trait a trait that is found on either the X or Y chromosome Hemophilia is an example of a sex linked trait. Hemophilia a disease where your blood doesn’t clot. Hemophilia only occurs when all of the X chromosomes have a copy of the recessive gene. H h X X :female carrier h h X X :female hemophiliac H X Y:normal male h X Y:hemophiliac male ANTIBODY a protein produced by white blood cells in the body in response to the presence of an antigen, for example, a bacterium or virus ANTIGEN a substance, usually a protein, on the surface of a cell or bacterium that stimulates the production of an antibody Law of Segregation • The two alleles for a trait must separate when gametes are formed • A parent randomly passes only one allele for each trait to each offspring Law of Independent Assortment • The genes for different traits are inherited independently of each other. 200 B.C. Humans “clone” trees by cuttings 1950 Humans clone frogs 1980’s Humans clone mice! 1997 HUMANS CLONE SHEEP!!! 1998 Humans clone 8 copies of a cow!!! 20?? GENETIC ENGINEERING moving genes from one chromosome of one organism to the chromosome of another “Fat” Gene CLONING making an exact copy of another cell / organism Dolly—the first cloned sheep Ian Wilmut, the dude that did it Check out this short movie that talks about cloning… A dividing cell Read NYTimes Article "Despite Warnings, 3 Vow to Go Ahead on Human Cloning" a. What did three proponents of human cloning announce on August 7, 2001? b. Where did they make this announcement? c. Why did some scientists at the symposium object to the proponents' announcement? d. Why did Dr. Alan Colman object to the research by these proponents being done in secret? e. According to the article, what was the consensus among the panel and most of those who testified before it? Read NYTimes Article "Despite Warnings, 3 Vow to Go Ahead on Human Cloning" f. Who was "Dolly"? g. What animals have been successfully cloned? h. According to the article, what is involved in cloning a human? i. How did the three proponents say they would address the possibility of genetic abnormalities? j. How did other experts at the symposium respond to this statement? k. Why do the proponents need to conduct their research secretly? •http://www.biology.arizona.edu/human_bio/activities/karyot yping/karyotyping.html •http://www.pathology.washington.edu/galleries/Cytogaller y/cytogallery.html •http://www.biology.iupui.edu/biocourses/N100/2k2humancs omaldisorders.html •http://www.biology.washington.edu/bsa/karyotypeS.html •http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html AMNIOCENTESIS A technique used to determine the genetic traits of a baby before it is born Klinefelter Syndrome • Have male genitalia and internal ducts, but underdeveloped testes • Do not produce sperm • Slight enlargement of the breasts • 47,XXY • 1 out of every 500 male births Turner Syndrome • • • • • • • Has female external genitalia Underdeveloped ovaries Short (under 5 feed) Webbed Neck Broad, Shield-like chest 45,X 1 out of every 3000 female births Cri-du-Chat Syndrome • Partial monosomy (part of 1 chromosome is lost) • Loss of about 1/3 of the short arm of chromosome 5 • Anatomical malfomrations (gastrointestinal and cardiac complications) • Mentally retarded • Abnormal development of the larynx which makes the baby’s cry sound like a cat’s cry • 1 in 50,000 live births Down Syndrome • • • • • • • • • BKA trisomy 21 (47, 21+); 3 copies of the 21st chromosome Short Small round heads Protruding, furrowed tongues which cause mouth to remain partially open Retarded (IQ below 70) Shortened life expectancy (<50) Prone to reparatory disease and heart malformations Have 15x higher chance of getting leukemia Chance of having a baby with Down syndrome goes up as the mother gets older PEDIGREE chart that shows the relationships within a family Pedigree Basics • Males are squares, females are circles, and unborn babies are triangles or octagons • Shaded figures represent individuals with the trait, a carrier could be 1/2 shaded • Generations are numbered with roman numerals (I, II, II, IV) from top to bottom • People within generations are numbered (1,2,3) from left to right