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Whose got Genes?

Whose got Genes?. Genes, Heredity, & DNA. What are genes? . Genes are a segment of DNA on a chromosome that controls a particular trait. Genes are located on the chromosomes in the nuclei. Each organims has a fixed number of chromosomes. Humans have 23 pairs (46) chromosomes.

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Whose got Genes?

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  1. Whose got Genes? Genes, Heredity, & DNA Baker 2003/2004

  2. What are genes? • Genes are a segment of DNA on a chromosome that controls a particular trait. • Genes are located on the chromosomes in the nuclei. Each organims has a fixed number of chromosomes. • Humans have 23 pairs (46) chromosomes. • Genetics is the study of how traits are passed on from one generation to another Baker 2003/2004

  3. So what is DNA? • DNA is a complex molecule (polymer) found in all living things. • The primary function of DNA is to store and transmit genetic information that tells cells which proteins to make and when to make them. Baker 2003/2004

  4. DNA TRIVIA • An idea about size: • An average cell nucleus is about 6 micrometers in diameter. • The total length of the DNA in the human genome is 1.8 meters. • There must be several levels of coiling and super coiling in DNA Baker 2003/2004

  5. Who was Gregor Mendel? Baker 2003/2004

  6. Who was Gregor Mendel? • Austrian monk who studied mathematics and science • As a boy he could predict the possible types of flowers and fruits that would result from crossbreeding two plants in his father’s garden Baker 2003/2004

  7. Who was Gregor Mendel? • Curiosity about the connection between the color of a pea flower and the type of seed that same plant produced inspired him to begin experimenting with garden peas in 1856. • Made careful use of scientific methods, which resulted in the first recorded study of how traits pass from one generation to the next. Baker 2003/2004

  8. What is GENETICS? Baker 2003/2004

  9. What is GENETICS? The study of how traits are inherited through the interactions of genes. Baker 2003/2004

  10. What is a GENE? Baker 2003/2004

  11. What is a GENE? • The material that controls which traits are expressed in an organism • Genes come in pairs and offspring inherit one copy of each gene from each parent Baker 2003/2004

  12. Define the following terms: • Heredity • Allele • Trait Baker 2003/2004

  13. Define HEREDITY The passing of traits from parent to offspring Baker 2003/2004

  14. Define ALLELE • The different forms of a trait that a gene may have • One form of a gene Baker 2003/2004

  15. Define TRAIT • Ways of looking, thinking, or being • Traits that are genetic are passed down through the genes from parents to offspring Baker 2003/2004

  16. Describe RECESSIVE Baker 2003/2004

  17. Describe RECESSIVE • A trait that is covered over, or dominated, by another form of that trait and seems to disappear • Hidden when the other copy of the gene contains the dominant allele. • A recessive allele shows up only when there is no dominant allele present • Shown with a lower-case letter Baker 2003/2004

  18. What is HOMOZYGOUS? Baker 2003/2004

  19. 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 • When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive Baker 2003/2004

  20. What is HETEROZYGOUS? Baker 2003/2004

  21. 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 • Since the dominant gene will be expressed, they are said to be heterozygous dominant Baker 2003/2004

  22. Describe DOMINANT Baker 2003/2004

  23. 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 Baker 2003/2004

  24. Define GENOTYPE Baker 2003/2004

  25. Define GENOTYPE An organism's genetic makeup Baker 2003/2004

  26. Define PHENOTYPE Baker 2003/2004

  27. Define PHENOTYPE Outward physical appearance and behavior of an organism Baker 2003/2004

  28. 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 Baker 2003/2004

  29. 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 Baker 2003/2004

  30. Introduction to Punnett Squares: • A Punnett Square is a chart drawn to determine the probable results of a genetic cross. To be able to draw a Punnett Square, you must know the genotype of both parents. Baker 2003/2004

  31. Punnett Squares • Sample Problem 1.   In roses, red flowers are dominant over white flowers. What are the possible offspring when a homozygous red rose is crossed with a homozygous white rose. Baker 2003/2004

  32. Generation 1 homozygous red rose = RR homozygous white rose = ww Baker 2003/2004

  33. Generation 2 homozygous red rose = RR heterozygous red rose = Rw homozygous white rose = ww Baker 2003/2004

  34. Generation 3 homozygous red rose = RR heterozygous red rose = Rw homozygous white rose = ww Baker 2003/2004

  35. List the 3 Principles of Heredity Baker 2003/2004

  36. 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 Baker 2003/2004

  37. References • Slideshow adapted from http://www.science-class.net/PowerPoints/Genetics.htm Baker 2003/2004

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