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Mit osis VS Mei osis

Mit osis VS Mei osis. Significance of cell reproduction. Unicellular Organisms : reproduce by a type of cell division called binary fission. Multicellular organisms- growth and repair upon cell division, also the production of sex cells. Chromosomes

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Mit osis VS Mei osis

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  1. Mitosis VS Meiosis

  2. Significance of cell reproduction Unicellular Organisms: reproduce by a type of cell division called binary fission.

  3. Multicellular organisms- growth and repair upon cell division, also the production of sex cells.

  4. Chromosomes -Carriers of genetic material found in nucleus -Made up of DNA -Information is copied and passed to future generations

  5. Usually exist as chromatin -long, winding strands which condense into chromosomes before dividing Humans have 46 chromosomes in body cells, 23 in sex cells

  6. Meiosis • Similar in many ways to mitosis • However there are several differences • Involves 2 cell divisions (mitosis only has one) • Results in 4 cells with 1/2 the normal genetic information that are not identical (mitosis results in 2 cells)

  7. Vocabulary • Diploid (2N) - Normal amount of genetic material • Haploid (N) - 1/2 the genetic material. • Meiosis results in the formation of haploid cells. • In Humans, these are the Ova (egg) and sperm. • Ova are produced in the ovaries in females • Process is called oogenesis • Sperm are produced in the testes of males. • Process is called spermatogenesis

  8. Comparison of Mitosis & Meiosis Page 276

  9. Meiosis Phases • There are 2 phases: Meiosis I, & Meiosis II. • Meiosis I. • Prior to division, amount of DNA doubles

  10. Crossing Over • During metaphase 1 homologous chromosomes line-up along the metaphase plate • Areas of homologous chromosomes connect at areas called chiasmata

  11. Crossing over contd. • Crossing Over of genes occurs now • Segments of homologous chromosomes break and reform at similar locations. • Results in new genetic combinations of offspring. • This is the main advantage of sexual reproduction

  12. Chromosome reduction • During anaphase 1, each homologous chromosome is pulled to opposite sides of the cell. Unlike mitosis, THE CENTROMERES DO NOT BREAK.

  13. Meiosis I continued • Nuclei may or may not reform following division. • Cytokenesis may or may not occur

  14. Meiosis II • DNA does not double • Chromosomes randomly line-up along metaphase plate like regular mitosis. • During anaphase 2, CENTROMERES BREAK and each chromosome is pulled to opposite sides of the cell. • Nuclei reform and cytokenesis usually occurs (although it is often unequal).

  15. Overview of Meiosis

  16. Introduction to Genetics Genetic variation within the White-cheeked Rosella

  17. Heredity & Genetics 1. Heredity: The passing of traits from parents to offspring2. Genetics: Study of heredity 3. Inherited characteristics are called traits

  18. Gregor Mendel was the first person to predict how traits are transferred.Austrian monk who studied garden peas

  19. -Mendel transferred pollen from plant to plant and then studied resulting peas-Studied only one trait at a time- Mendel is called the “father of genetics”

  20. Mendel used pea plants because - they reproduce sexually - have both male and female gametes in the same flower - fertilization could be controlled http://www2.edc.org/weblabs/WebLabDirectory1.html

  21. Figure 11-3 Mendel’s Seven F1 Crosses on Pea Plants Section 11-1 Seed Shape Seed Color Seed Coat Color Pod Shape Pod Color Flower Position Plant Height Gray Smooth Green Axial Tall Round Yellow Constricted Terminal Short Wrinkled Green White Yellow Round Yellow Gray Smooth Green Axial Tall Go to Section:

  22. Phenotypes & Genotypes Phenotype: appearance of an organism Example: short, tall, green, yellow Genotype: gene combination of an organism Example: tt, TT, Tt, gg, GG, Gg

  23. Heterozygous & Homozygous Heterozygous: the 2 alleles are differentExample: Tt -heterozygousHomozygous: the 2 alleles are the sameExample: TT means homozygous dominant, and tt means homozygous recessive Livestock: http://www.parkelivestock.com/semensales.htm http://www.mcrobertsgamefarm.com/buffalo/white_buffalo.htm

  24. Traits can be dominant or recessiveDominant traits: exhibited trait, written with 1 or 2 capital letters Example: TT, TtRecessive traits: inhibited trait (not expressed unless homozygous), written with lowercase letters Example: tt

  25. Monohybrid Crosses Crosses that differ by a single trait Example: Tall pea plant x short pea plant The first generation produced offspring resembling only one parent Example: all tall pea plants

  26. Principles of Dominance Section 11-1 P Generation F1 Generation F2 Generation Tall Tall Tall Short Tall Short Tall Tall Go to Section:

  27. Principles of Dominance Section 11-1 P Generation F1 Generation F2 Generation Tall Short Tall Tall Tall Tall Tall Short Go to Section:

  28. The second generation produced: 3/4 of peas were tall 1/4 of peas were short Mendel concluded that each trait has 2 factors -Factors are now called alleles - Organisms inherit one allele from mother and one allele from father

  29. Principles of Dominance Section 11-1 P Generation F1 Generation F2 Generation Tall Short Tall Tall Tall Tall Tall Short Go to Section:

  30. Tt X Tt Cross Section 11-2 Go to Section:

  31. Tt X Tt Cross Section 11-2 Go to Section:

  32. Probability:the chance or percentage of chance of a trait being exhibited Now you know that the probability of a heads-up landing when you flip a coin is 1/2. What is the probability of getting tails if you flip it again? - It is still 1/2. The two events do not affect each other. They are independent!

  33. Mendel Revisited • Quick Review • Genotype: genetic code for traits TT Tt tt • Phenotype: physical appearance • Homozygous, heterozygous, dominant, recessive • Punnett Square: • TT x tt • Tt x Tt

  34. Law of Dominance • In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. • Offspring that are hybrid for a trait will have only the dominant trait in the phenotype. • TT (tall) x tt (short) all Tall

  35. Law of Segregation • During the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other. Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring. • Tt (tall) x Tt (tall)75% Tall, 25% short • alleles act independently

  36. Incomplete dominance Incomplete dominance-neither allele is Dominant or recessive Example- white flowers X red flowers= pink flowers-a mixture or blend of the parent colors

  37. Codominanceoffspring shows phenotype of neither parent both alleles are dominantExample- bay horse x white horsed= roan horse- both hair colors are present

  38. Multiple alleles: more than 2 alleles control a traitExample-blood type in humans a. blood type is determined by presence or absence of proteins on the surface of red blood cellsExamples- A, B, AB, & O

  39. GenotypePhenotypeAA, Ao A bloodBB, Bo B bloodOO O blood

  40. To determine the blood types of possible offspringParents = A blood, O bloodGenotypes AA, AO OO

  41. Calico Cats • Calico is not a breed of cat, but an unusual coloring occurring across many breeds • Virtually all calico cats are female • a male calico is a genetic anomaly and usually sterile • Producing calico kittens through selective breeding also is nearly impossible due to unpredictable actions of genes and chromosomes when cells multiply in a feline fetus

  42. Sex linked alleles: controlled by genes located on sex chromosomes -usually carried on the X chromosomes -Females XX, males XY -If trait is X-linked, males pass the trait on to all their daughters, but none to their sons -mothers have 50/50 chance of passing it to all their childrenExamples-colorblindness

  43. Colorblindness,Hemophilia, MD • Colorblindness – recessive disorder where a person can’t distinguish between certain colors. • Hemophilia – blood clotting disorder • Muscular Dystrophy – deterioration of the skeletal muscle. Children rarely live past early adulthood.

  44. Colorblindness test • http://www.geocities.com/Heartland/8833/coloreye.html

  45. Aneuploidy • Abnormal # of chromosomes • Trisomy – aneuploidy of the 1st 22 pairs of chromosomes • Autosomes – 1st 22 pairs of chromosomes. • Turners Syndrome – XO 1/2000. Females that lack ovaries, shorter, and live normal lives. • Klienfelters syndrome – 1/500 males XXY taller than avg., longer limbs, sterile

  46. Karyotype • A chart of all 23 pairs of chromosomes • Tell the sex of the child • Aneuploidy yes/no

  47. Pedigree Analysis

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