Anatomy & Physiology I Unit Five

1. Anatomy & Physiology I Unit Five

2. The Characteristics and Functions of Meiosis Production of gametes Assures correct chromosome numbers in offspring Creates new combinations of genes Begins with a diploid sex cell & ends with non-identical haploid gametes

3. Meiosis Meiosis is the cell division process by which gametes are produced It occurs only in sex cells that are found in the gonads

4. Meiosis The process goes through two meiotic divisions – meiosis I and meiosis II

5. Meiosis Homologous chromosomes

6. Meiosis

7. Meiosis

8. Meiosis

9. Meiosis vs. Mitosis

10. Genetics Genetics – the study of heredity Heredity – the passing of traits from one generation to the next Trait – a physical or physiological characteristic coded for by a gene Gene – a portion of a chromosome that codes for a particular protein Allele – a form of a gene

11. Genetics Dominant allele – an allele that masks the effects of the other Recessive allele – an allele that can be masked by a dominant allele Locus – the position of a gene on a chromosome

12. Genetics Homologous chromosomes – a pair of chromosomes, one each from the female & male parent, that have identical structure and gene loci

13. Genetics Mom (female) Dad (male) Recessive allele Dominant allele Homologous chromosomes

14. Genetics Genotype – the set of genes an organism has Homozygous – alleles are the same type Heterozygous – alleles are different

15. Genetics Phenotype – the expression of the genotype Purebred – having a homozygous genotype Hybrid – having a heterozygous genotype

16. Genetics Codominance – the two alleles at a locus are equally expressed Karyotype – a chart of the chromosomes of an organism, arranged in order by size and structure

17. Genetics

18. D D d d D d

19. D D d d Punnett Square

20. D D d d D d D d D D d d

21. D d D d Complete Dominance Monohybrid Cross Genotypic Ratio – 1:2:1 Phenotypic Ratio – 3:1

22. Complete Dominance

23. D d d d Complete Dominance Monohybrid Cross Genotypic Ratio – 2:2 Phenotypic Ratio – 2:2

24. A O B O Codominance Genotypic Ratio – 1:1:1:1 Phenotypic Ratio – 1:1:1:1

25. Autosomal vs. Sex Linked Autosomes – all chromosomes except for the ones that determine sex Sex chromosomes – chromosomes that determine sex Sex linked traits – traits controlled by genes on the sex chromosomes

27. XB Xb Xb Y Sex Linked Cross

29. Human Sex Chromosomes ♀ ♂ X Y X X

30. Human Sex Chromosomes ♀ ♂

31. Mutations A mutation is any change in the DNA of an organism Mutations occur due to: - pathogen infection - exposure to radiation - introduction of chemicals - nondisjunction

32. Mutations Mutations involve: - base pair substitutions - base pair insertions or deletions - DNA segments

33. Mutations

34. Genes, Genetic Code & Genetic Disease Remember, genes are portions of DNA that code for a particular protein In order for the protein to be functional, the DNA nitrogen base sequence must be correct

35. Genes, Genetic Code & Genetic Disease Any variance of that sequence can cause the wrong amino acid to be inserted into the polypeptide which could result in: - a non-functioning protein - a protein that changes the outcome of a process

36. Nondisjunction Nondisjunction is the failure of chromosomes to separate during anaphase I of meiosis The normal separation, disjunction, produces daughter cells with 23 chromosomes each

37. Nondisjunction Nondisjunction results in one daughter cell with 24 chromosomes and the other with 22 chromosomes

38. Nondisjunction Monosomy is the result of the fertilization of a normal gamete and one that has only 22 chromosomes Trisomy is the product of the fertilization of a normal gamete and one that has 24 chromosomes

39. Disjunction Nondisjunction

40. Genetic Disorders Several genetic disorders are sex linked and found predominantly in men, but can also be present in women The shorter Y chromosome means there is only one allele that determines these traits

41. Genetic Disorders Male pattern baldness and color blindness are two examples that are inconvenient, but non-life threatening Hemophilia, a condition in which the blood does not clot correctly, can be deadly

42. Genetic Disorders Remember: Any variance of the DNA base sequence can cause the wrong amino acid to be inserted into the polypeptide which could result in: - a non-functioning protein - a protein that changes the outcome of a process

43. Genetic Disorders These mutations can lead to a number of human health disorders Some of these abnormalities are inconvenient, while others can be lethal

44. Genetic Disorders Albinism is a condition in which the body does not produce the pigment melanin The phenotypic results are white hair, pale skin and pink colored eyes

45. Genetic Disorders Albinism is the result of a homozygous recessive genotype that produces a nonfunctional tyrosinase enzyme Melanin is synthesized from tyrosine by way of the enzyme tyrosinase

46. Genetic Disorders Sickle cell disease is a condition in which red blood cells are deformed due to the substitution of one amino acid in a hemoglobin chain

47. Genetic Disorders The deformation of the RBCs inhibits the binding of oxygen, causing anemia The deformation also causes the sickled RBCs to be sticky and agglutinate

48. Genetic Disorders Without treatment a child will usually die before age two Even with treatment most affected people die before the age of fifty

49. Genetic Disorders The substitution of one amino acid is caused by a recessive allele Sickle cell is the result of a homozygous recessive genotype that produces the malformed hemoglobin

50. Genetic Disorders Approximately 8.5% of people of central and southern African descent are carriers of the allele