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Genetics & Heredity

Genetics & Heredity. Who was Gregor Mendel?. Who was Gregor Mendel?. Austrian monk who studied mathematics and science As a boy he experimented with pea plants

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Genetics & Heredity

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  1. Genetics& Heredity

  2. Who was Gregor Mendel?

  3. Who was Gregor Mendel? • Austrian monk who studied mathematics and science • As a boy he experimented with pea plants • Made careful use of scientific methods, which resulted in the first recorded study of how traits pass from one generation to the next.

  4. What is GENETICS?

  5. What is GENETICS? The study of how traits are inherited through the interactions of genes.

  6. Genetic Material • The nucleus of a cell contains genetic material • DNA • Chromosomes • Genes www.kent.edu/projects/cell/page7.htm

  7. Genes • Genes are short sections of chromosomes • Genes come in pairs and offspring inherit one copy of each gene from each parent http://www.accessexcellence.org

  8. Genes come in pairs • Since chromosomes come in pairs (one from mom, one from dad) Genes come in pairs http://anthro.palomar.edu/biobasis/images/karyotype_male.gif

  9. Define the following terms: • Heredity • Allele • Trait

  10. Define HEREDITY The passing of traits from parent to offspring

  11. Allele • Alleles are different versions of a gene • Every gene has two or more alternatives http://library.thinkquest.org

  12. Define TRAIT • Characteristic or a way of looking, thinking, or being • Traits that are genetic are passed down through the genes from parents to offspring

  13. Describe RECESSIVE

  14. Describe RECESSIVE • A trait that is covered over, or dominated, by another form of that trait and seems to disappear • Shown with a lower-case letter • Example: c, d

  15. What is HOMOZYGOUS?

  16. What is HOMOZYGOUS? • Both alleles [forms of the gene] are the same • When offspring inherit two dominant genes, (one dominant gene from each parent) they are said to be homozygous dominant (BB) • When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive (bb)

  17. What is HETEROZYGOUS?

  18. What is HETEROZYGOUS? • When alleles occur in different forms • When offspring inherit one dominant gene and one recessive gene, they are said to be heterozygous (Bb) • Since the dominant gene will be expressed, they are said to be heterozygous dominant

  19. Describe DOMINANT

  20. Describe DOMINANT • A trait that covers over, or dominates, another form of that trait • Trait that always shows up, even when only one of the two alleles is in the dominant form • Shown by a capital letter

  21. Define GENOTYPE

  22. Define GENOTYPE An organism's genetic makeup Or the letters Example: Bb, bb, BB

  23. Define PHENOTYPE

  24. Define PHENOTYPE Outward physical appearance and behavior of an organism Example: black hair

  25. What is a PUNNETT SQUARE?

  26. What is a PUNNETT SQUARE? • A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine • A way to show phenotype & genotype • A chart that shows all the possible combinations of alleles that can result when genes are crossed

  27. What is a PUNNETT SQUARE? • Letters stand for dominant and recessive alleles • An uppercase letter stands for a dominant allele • Lowercase letters stand for recessive alleles

  28. Read More About Punnett Squares Here: http://www.borg.com/~lubehawk/psquare.htm

  29. List the 3 Principles of Heredity

  30. List the 3 Principles of Heredity • Traits are controlled by alleles on chromosomes • An allele’s effect is dominant or recessive • When a pair of chromosomes separate during meiosis the different alleles for a trait move into separate sex cells

  31. What is meant by MULTIPLE ALLELES?

  32. What is meant by MULTIPLE ALLELES? • A trait that is controlled by more than two alleles is said to be controlled by multiple alleles • Traits controlled by multiple alleles produce more than three phenotypes of that trait

  33. What is meant by MULTIPLE ALLELES? For Example: The alleles for blood types in humans are called A, B, and O The O allele is recessive to both the A and B alleles

  34. What is meant by MULTIPLE ALLELES? When a person inherits one A allele and one B allele for blood type, both alleles are expressed The person has the blood phenotype AB

  35. What is meant by MULTIPLE ALLELES? A person with phenotype A blood inherited an A and an O allele (AO) ~OR~ an A and an A allele (AA)

  36. What is meant by MULTIPLE ALLELES? Someone with phenotype B blood has the genotype BB or BO This person inherited either a B and an O allele ~OR~ Two B alleles

  37. What is meant by MULTIPLE ALLELES? A person with phenotype O blood has the genotype OO

  38. What is POLYGENIC INHERITANCE?

  39. What is POLYGENIC INHERITANCE? • Occurs when a group of gene pairs acts together to produce a trait • The effects of many alleles produces a wide variety of phenotypes

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