Transcript INHERITANCE
INHERITANCE Interest Approach Pea plants Different colored flowers What was different about each plant?? History of Genetics 1670’s Scientists believed that each sperm contained a “little man” that would develop into a human Then mother only served as an incubator History of Genetics cont. 1750’s “Blending of Inheritance Theory” Example: Black animal mated to a white animal would produce a gray animal History of Genetics cont. 1850’s Gregor Mendel Austrian monk and worked in the monastery garden mating pea plants Determined that characteristic were inherited by discrete factors that would eventually become know as genes Gregor Mendel Discovered many principles Principle of segregation Principle of independent assortment Principle of Segregation Every individual carries pairs of factors for each trait and that the members of the genes segregate at random during the formation of gametes Since segregation is random, predictable ratios of traits are found in the offspring During segregation, chromosomes go from a pair (2n or diploid) to singles (1n or haploid). Good way to remember: “Hap a diploid is 1n” Principle of Independent Assortment Members of each pair of genes are distributed independently when the gametes are formed and are unaffected by other gene pairs on other chromosomes When pairs of genes on different chromosomes separate, they have an equal chance or probability of going to an individual gamete No predetermined order for the dividing pairs EVERY GENE FOR ITSELF Chromosomes Located in the nucleus of the cell and contain all of the genetic material in the cell Arranged in pairs Made up of a substance called DNA Two Types of Chromosomes Haploid Half the diploid or somatic (non-sex cell or gamete) number of chromosomes (n or 1n) Diploid Number of chromosomes found in the somatic or body cells (2n). Twice the number of chromosomes found in the gametes Chromosomes in Animals 1n 2n Cattle 30 60 Sheep 27 54 Goat 30 60 Swine 40 80 Horse 30 60 Human 23 46 DNA Deoxyribonucleic Acid Three Components Deoxyribose sugar Phosphate Four nitrogenous bases Adenine (A) Thymine (T) Guanine (G) Cytosine (C) Nucleotides Combination of the deoxyribose, phosphate and one of the four bases Nucleotides bond together to form one strand of the DNA molecule Two of the strands wind around each other in a double helix to form the DNA molecule In the two pairs of DNA C is always paired with G AND A is always paired with T The Gene Genes are points of activity found in each chromosome that govern the way in which traits develop. Genes are specific areas on each chromosome and are made up of DNA Protein Synthesis RNA (ribonucleic acid) is a group of molecules in charge of “reading” and “translating” the genetic code for the formation of new proteins RNA uses the DNA as a template to read the code in order to produce the right protein with the correct order and number of amino acids. Three Types of RNA Transfer RNA (t RNA) Plays a key role in protein synthesis (building). Each tRNA molecule can combine with one amino acid and can transport the a. a. to the new protein building site in the cytoplasm of the cell Three Types of RNA cont. Ribosomal RNA (rRNA) Also plays a key role in protein synthesis. It helps control the connecting of the parts of the protein (the amino acids) together. Three Types of RNA cont. Messenger RNA (mRNA) Helps complete the building of the protein Physically sequencing the amino acids that were carried to the building site by the tRNA and chemically connected by the rRNA The mRNA directs the sequence based on the order it obtains from the DNA molecule In RNA Translation. . . C is paired with G T is paired with A A is paired with U Activity: Building DNA Materials Needed: Several of each: Four different colored gumdrops or other material that a toothpick can be inserted into Toothpicks Activity cont. Instructions: Designate each color of gumdrops a different base (A=red, T=green, for example) Designate the toothpicks as the bonds between the bases Give the students a list of bases that ranges from 10 to 15 bases long The students will then lay out the sequence using the gumdrops and the sticking toothpicks into the sides Activity Instructions cont. The students must then decide the complimentary pair for each base and connect it to the given base (to make a double helix other toothpicks must be used on the outer sides of the bases to connect the pairs of bases together in a rotating matter) Example Given Gumdrops Toothpicks to hold bonds together in rotating matter T A A C Toothpicks T G Complimentary Gumdrops