Genetics: The Science of Heredity 3.1 What is Heredity? What did Mendel observe? _____________________________: Known as the Father of Genetics, he unlocked the key to understanding heredity using pea plants. He was able to obtain predictable, repeatable results using plants that could both self-pollinate & cross-pollinate. ______________________ the passing of traits/physical characteristics from parents to offspring _____________________ the scientific study of heredity ___________________________ the joining of egg and sperm cell (the beginning of the formation of new organism) _____________ segments of DNA that carry hereditary instructions located on chromosomes & passed from parent to offspring(factors that control a trait) __________________ alternative forms of a gene that govern the same characteristics (ex. eye color) How do alleles affect inheritance? An organism’s ______________ are controlled by the __________________ it inherits from its parents. Some alleles are __________________________ , while other alleles are ___________________________ . ______________________________________ trait observed when at least one dominant allele for a characteristic is inherited ______________________________________ trait that is apparent only when 2 recessive alleles for the characteristic are inherited ____________________________/__________________________having 2 copies of the same allele for a trait (ex. HH or hh) _____________________________/___________________ having 2 different alleles for a trait (ex. Rr or RW) 3.2 Probability & Heredity How is probability related to Inheritance? In a _______________ _____________ , the combination of _________________ that ____________________ can pass to an __________________________ is based on _______________________________ . _______________________________ the mathematical chance that an event will occur/number that describes how likely it is that an event will occur ________________________________________ (designed by Reginald C. Punnett) a chart that shows all the possible ways alleles can combine in a genetic cross Parent generation (true breeding purple PP x true breeding white pp) P p p P Pp Pp Pp Pp = _________________________ First generation (self pollination of the offspring from the parent generation Pp x Pp) P P p p PP Pp Pp pp = ________________________ ________________________ (recessive trait reappears) What are phenotype and genotype? _________________________________ the inherited combination of alleles; genetic make up ________________________________ an organism’s inherited appearance; visible appearance 3.3 Patterns of Inheritance How are most traits inherited? Most traits are the result of ____________________ _______________________ of ____________________________ . ____________________________ both alleles for a gene are expressed equally (and individually) ____________________________________ one allele is only partially dominant (blending occurs) ___________________________________ three or more possible alleles determine the trait (an organism can still only inherit 2 alleles for a gene, one from each parent, but there are more possible genotypes with multiple alleles than with just 2 alleles) __________________________________ more than one gene affects a trait (broad range of geneotypes: human height, skin color, and eye color) __________________________ traits organisms are born with (height, freckles, eye color) ________________________________ traits organisms acquire (language a person speaks, haircuts, piercings, tattoos) How do genes and the environment interact? _____________________________ factors can _______________________ the way genes are __________________________________ . List some examples of factors in your environment that can affect how genes are expressed: _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Changes in _________________ ____________ cannot be passed to offspring. Only changes in the sex cells - ____________ & ____________ can be passed to offspring. 3.4 Chromosomes & Inheritance How are chromosomes, genes, & inheritance related? According to the _____________________________ ___________________ of ______________________________ , genes pass from parents to offspring on ______________________________ . __________________________________ coiled structure of DNA & protein that forms in the nucleus during cell division; passed from one generation to the next What happens during meiosis? Meiosis Meiosis produces new cells with _______the usual number of chromosomes. This process creates ___________cells. The chromosomes are copied/duplicated only__________ & nucleus divides ________________.