Mechanisms of Evolution: Overview and Cell Division Anthropology 101 Hybrid Course
Introduction to Genetics <ul><li>Genetics is the study of genes and the ways whereby they determine the traits of an organ...
Key Concepts in Evolution: Natural Selection <ul><li>Species : A group of life forms (plants and animals) that can reprodu...
Key Concepts in Evolutionary Thought: Mutation <ul><li>Heredity:  the transmission of all biological traits (inherited cha...
Structure of Cell: Diagram <ul><li>To understand how genetics works, we must start with the cell </li></ul><ul><li>The nex...
Cell Structure: Description <ul><li>Cell : Smallest unit of the organism considered to be alive </li></ul><ul><li>Nucleus ...
Cells: Other Parts <ul><li>Proteins:  The organic molecules that maintain the cells’ functions </li></ul><ul><li>Organelle...
Concepts  of Genetics <ul><li>Trait:  Any inborn feature of a living organism   </li></ul><ul><li>Each organism contains a...
Genes and Chromosomes <ul><li>In the cell nucleus is genetic material which determines our traits.  </li></ul><ul><li>Chro...
Genetic Composition: Genotype <ul><li>Genotype : Alleles of a gene possessed by an organism </li></ul><ul><li>Homozygous :...
Genetic Appearance: Phenotype <ul><li>Phenotype : Observable characteristics of an organism </li></ul><ul><li>Dominant : A...
Cell Division <ul><li>Cell division is a constant process in all living forms. </li></ul><ul><li>There are two types of ce...
Mitosis: First Phases <ul><li>In the  interphase , the cell is “at rest” between one division and the next </li></ul><ul><...
Mitosis: Middle Phases <ul><li>In the  prometaphase  the nucleus dissolves, the chromosomes line up in the center,  centri...
Mitosis: End Phases <ul><li>In the  anaphase,  the fibrils anchored by the centrioles pull the chromosomes toward the cent...
Meiosis: Introduction and Terms <ul><li>Meiosis  refers to cell division of a fertilized egg  in the reproductive process....
Meiosis: Fertilization of an Ovum <ul><li>First, the sperm has fertilizes an ovum (above left) </li></ul><ul><li>Three mil...
Meiosis I: Beginning Phases <ul><li>In the prophase stage, the doubled chromosomes cross over, so some of the genes on one...
Meiosis II: Early Middle Phases <ul><li>The first metaphase continues as mitosis; the chromosomes have been doubled and no...
Meiosis III: Late Middle Phases <ul><li>In the interphase 2, the chromosomes remain lined up and the nucleus has not forme...
Meiosis IV: Final Phases <ul><li>In telophase 2, a wall forms between each of the cells and the nuclei start to form </li>...
End of Meiosis; Beginning of Mitosis: Fertilization of an Ovum <ul><li>When the couple copulates, the sperm fertilizes the...
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Overview of ;Genetics and Cell Division

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Overview of Genetics. Key Concepts in Genetics. Cell Diviision

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Overview of ;Genetics and Cell Division

  1. 1. Mechanisms of Evolution: Overview and Cell Division Anthropology 101 Hybrid Course
  2. 2. Introduction to Genetics <ul><li>Genetics is the study of genes and the ways whereby they determine the traits of an organism </li></ul><ul><li>We cover the following concepts and principles of evolution based on genetics: </li></ul><ul><li>Biological Genetics </li></ul><ul><li>Chromosomes and Genes </li></ul><ul><li>Mitosis and Meiosis </li></ul><ul><li>Population Genetics </li></ul><ul><li>Molecular Biology </li></ul>
  3. 3. Key Concepts in Evolution: Natural Selection <ul><li>Species : A group of life forms (plants and animals) that can reproduce fertile offspring among themselves </li></ul><ul><li>Evolution : Change through time of biological species </li></ul><ul><li>Natural selection : Evolutionary change based on differential reproduction of the species within an environment </li></ul>
  4. 4. Key Concepts in Evolutionary Thought: Mutation <ul><li>Heredity: the transmission of all biological traits (inherited characteristic) from generation to generation </li></ul><ul><li>Chromosome : Body in the nucleus of the cell that contains the hereditary material: DNA and protein </li></ul><ul><li>Genes : A chromosomal segment with a specific function </li></ul><ul><li>Mutation : Alteration of genetic material giving rise to new life forms </li></ul>
  5. 5. Structure of Cell: Diagram <ul><li>To understand how genetics works, we must start with the cell </li></ul><ul><li>The next discussion follows this diagram of a cell and its components </li></ul>
  6. 6. Cell Structure: Description <ul><li>Cell : Smallest unit of the organism considered to be alive </li></ul><ul><li>Nucleus : Center of the cell, which contains genetic material (chromosomes, comprising the genes) </li></ul><ul><li>Nuclear Membrane : Membrane enclosing the nucleus </li></ul><ul><li>Cytoplasm : Jellylike material that make up the rest of the cell </li></ul><ul><li>Plasma Membrane : The membrane that keeps the cell in shape and allows entry and exit of certain material. </li></ul><ul><li>The diagram to the left show other specialized parts: nerve cell, white blood cell, sperm </li></ul>
  7. 7. Cells: Other Parts <ul><li>Proteins: The organic molecules that maintain the cells’ functions </li></ul><ul><li>Organelles: functional parts within cytoplasm </li></ul><ul><li>Ribosomes : organelles important to protein synthesis, as we will see </li></ul><ul><li>Mitochondria: organelles responsible for energy production; They have their own DNA whose regular mutations enable relative dating within a species, human in this case </li></ul>
  8. 8. Concepts of Genetics <ul><li>Trait: Any inborn feature of a living organism </li></ul><ul><li>Each organism contains a pair of genes for each trait </li></ul><ul><li>Each gene may have two or more alleles (variants) </li></ul><ul><li>Monogenic Trait: a trait coded by one gene for each trait (e.g., phenylthiocarbamide [PTC] taster vs. nontaster of the bitterness of Brussels sprouts); </li></ul><ul><li>Mendelian Trait: This is a synonym for Monogenic trait </li></ul><ul><li>Polygenic: a trait coded by more than one gene (e.g. skin color, eye color) </li></ul>
  9. 9. Genes and Chromosomes <ul><li>In the cell nucleus is genetic material which determines our traits. </li></ul><ul><li>Chromosomes are long strands of molecules and protein; they come in pairs </li></ul><ul><li>Humans have 23 pairs of chromosomes, or 46 in all </li></ul><ul><li>Genes are units within chromosomes </li></ul><ul><li>Also in pairs, they occur in specific location, or loci , of the chromosomes </li></ul><ul><li>Each variant of a trait is determined by an allele of a gene </li></ul>
  10. 10. Genetic Composition: Genotype <ul><li>Genotype : Alleles of a gene possessed by an organism </li></ul><ul><li>Homozygous : Having two of the same allele in a gene pair </li></ul><ul><li>Heterozygous : Having two different alleles in a gene pair </li></ul>
  11. 11. Genetic Appearance: Phenotype <ul><li>Phenotype : Observable characteristics of an organism </li></ul><ul><li>Dominant : Allele of a pair that is expressed in the phenotype (e.g. PTC taster) </li></ul><ul><li>Recessive : Allele of a pair that is expressed only when homozygous (e.g. PTC nontaster, Blood Type O) </li></ul><ul><li>Codominant : Both alleles of a pair are expressed in the phenotype (e.g., Blood Type A and B) </li></ul><ul><li>Or four o’clock flowers: red, white—and pink </li></ul>
  12. 12. Cell Division <ul><li>Cell division is a constant process in all living forms. </li></ul><ul><li>There are two types of cell division: </li></ul><ul><li>Mitosis: The division of somatic or body cells </li></ul><ul><li>Meiosis: The division of gametes or sex cells: sperm in the males of any species and ovum (plural ova ) or egg in the females of any species </li></ul><ul><li>The next sections explain how these two types of cells divide. Refer to the diagram in the next panel </li></ul>
  13. 13. Mitosis: First Phases <ul><li>In the interphase , the cell is “at rest” between one division and the next </li></ul><ul><li>In the prophase , the chromosome double, from 46 (23 pairs) chromosomes to 92 (46 pairs) </li></ul><ul><li>They appear to “thicken” as each chromosome replicates itself. </li></ul><ul><li>The chromosomes are attached to each other at the center, forming an x; these are known as centromeres </li></ul>
  14. 14. Mitosis: Middle Phases <ul><li>In the prometaphase the nucleus dissolves, the chromosomes line up in the center, centrioles form at the opposite end of the cells, and spindle fibers (fibrils or microtubules) form between the centromeres of the chromosomes and the centrioles (top diagram) </li></ul><ul><li>In the metaphase, the chromosomes are lined up and the centrioles prepare to pull each new pair of chromosomes toward them using the spindle fibers) </li></ul>
  15. 15. Mitosis: End Phases <ul><li>In the anaphase, the fibrils anchored by the centrioles pull the chromosomes toward the center of each new cell </li></ul><ul><li>In the telophase, the fibrils and the centrioles dissolve and the wall forms between the two new cells </li></ul><ul><li>In cytokinesis , the walls are completely formed and the two new cells are in interphase. </li></ul>
  16. 16. Meiosis: Introduction and Terms <ul><li>Meiosis refers to cell division of a fertilized egg in the reproductive process. </li></ul><ul><li>Gametes : sex cells </li></ul><ul><li>Sperm : male sex cells </li></ul><ul><li>Ovum : female sex cells </li></ul><ul><li>Each gamete (sex cell) </li></ul><ul><li>Contains half the normal number of chromosomes in cells </li></ul><ul><li>Contains 23 chromosomes in humans </li></ul>
  17. 17. Meiosis: Fertilization of an Ovum <ul><li>First, the sperm has fertilizes an ovum (above left) </li></ul><ul><li>Three million sperms enter the vagina; only one ultimately enters the ovum, roughly a third of the way down the Fallopian tube </li></ul><ul><li>The fertilized ovum (now a zygote ) is then implanted in the uterus </li></ul><ul><li>The rapid process of meiosis begins there </li></ul><ul><li>Of course, some couples don’t get it quite right (below left) </li></ul>
  18. 18. Meiosis I: Beginning Phases <ul><li>In the prophase stage, the doubled chromosomes cross over, so some of the genes on one chromosome moves over to the other chromosome—and vice versa </li></ul><ul><li>Otherwise, the process is the same as mitosis </li></ul><ul><li>The prometaphase follow the same process as in mitosis: the chromosomes line up and the spindle fibers and centrioles are now in position. </li></ul>
  19. 19. Meiosis II: Early Middle Phases <ul><li>The first metaphase continues as mitosis; the chromosomes have been doubled and now line up. </li></ul><ul><li>The anaphase continues as in mitosis; the chromosomes are pulled apart by the spindle fibers and the centrioles </li></ul><ul><li>The telophase continues as in mitosis; the chromosomes are centered in the daughter cells and a new wall forms. </li></ul>
  20. 20. Meiosis III: Late Middle Phases <ul><li>In the interphase 2, the chromosomes remain lined up and the nucleus has not formed </li></ul><ul><li>In metaphase 2, there is only a pair of chromosomes in each cell; they remain lined up and the spindle fibers and the centrioles go into position </li></ul><ul><li>In anaphase 2, the chromosomes (now numbering 23 as haploids ) are pulled apart. </li></ul>
  21. 21. Meiosis IV: Final Phases <ul><li>In telophase 2, a wall forms between each of the cells and the nuclei start to form </li></ul><ul><li>In cytokinesis or interphase, the daughter cells remain with one pair of chromosomes. </li></ul><ul><li>On fertilization, the sperm will contribute half the chromosomes and the ovum contributes half to the offspring </li></ul>
  22. 22. End of Meiosis; Beginning of Mitosis: Fertilization of an Ovum <ul><li>When the couple copulates, the sperm fertilizes the egg (upper left) </li></ul><ul><li>In so doing, each parent contributes exactly half of the chromosomes of the offspring cell </li></ul><ul><li>Three million sperms enter the vagina; only one ultimately enters the ovum, roughly a third of the way down the Fallopian tube </li></ul><ul><li>The fertilized ovum (now a zygote ) is then implanted in the uterus </li></ul><ul><li>The rapid process of mitosis of the zygote begins there </li></ul><ul><li>Of course, some couples don’t get it quite right (lower left) </li></ul>

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