Chapter 5 The human organism and the perpetuation of life.

1. Chapter 5The human organism and the perpetuation of life. Topics: The cell and its functions Cell division (mitosis & meiosis) Tissues, organs and systems The Reproductive System

2. About Cells • The cell is the basic unit of structure and function in living things • Cells are usually microscopic, but range from the size of a bacteria to the size of an unfertilized ostrich egg. • Living things contain one or more cells • Protozoans contain a single cell • Humans contain billions of cells

3. Three Main Parts of a Cell • A cell usually has three distinct areas or layers: • The membrane • The Cytoplasm & Organelles • The nucleus Membrane Cytoplasm Nucleus

4. Function of the Cell Membrane • The cell membrane is a flexible barrier that surrounds the cell and allows the cell to interact with its environment • Forms a protective barrier • Helps absorb nutrients and useful substances • Helps eliminate wastes and other materials produced inside cells

5. Drawing of a cell membrane Copy the “simplified diagram” from the blackboard

6. Part 2: The Cytoplasm & Organelles • Together, the cytosol and organelles are called the cytoplasm or protoplasm • The cytosol is the liquid portion of the cell. • It is a complex mixture of materials: water, gases, wastes, nutrients, raw materials • The Organelles • Suspended in the cytoplasm are many tiny structures called organelles. Each organelle has a specific function.

7. The Organelles • Mitochondria (sing. mitochondrion). • Endoplasmic reticulum • Rough • Smooth • Ribosomes • Golgi Apparatus • Lysosomes • Vacuoles

8. Mitochondria • The mitochondrion is the powerhouse of the cell. Here chemical energy is released by the break down of glucose, sugar units. • It is a bean-shaped organelle with an internal membrane folded into many “cristae” . I am very energetic! And cute as a bean too!

9. Endoplasmic Reticulum • The “ER” or Endoplasmic Reticulum is a network of tubes and membranes that runs through the cell. Its purpose is to transport materials quickly through the cell • Rough ER • Has ribosomes • Smooth ER • Has no ribosomes ER Transport system at your service! For when it absolutely, positively has to get to the ribosomes quick as possible.

10. Ribosomes • Very tiny, round organelles made from RNA in the nucleolus • They manufacture the cell’s proteins. We are very small, like beads. Sometimes we hang around the endoplasmic reticulum

11. GolgiApparatus(A.K.A. Golgi body or Golgi complex) • A network of membranes, similar in appearance to the ER • Its purpose is to modify and “package” proteins that will be secreted. • Also makes digestive enzymes I look like sort of like a stack of pancakes with blobs of syrup falling off!

12. Lysosomes & Vacuoles • These are storage areas within a cell • Lysosomes hold digestive enzymes that help the cell metabolize food. When a cell dies, the digestive enzymes help dissolve the dead cell • Vacuoles store food or water Let’s get together And have a feast! I’ve got the digestive enzymes And I’ve got the food

13. Part 3: The Nucleus • The nucleus consists of: • The nuclear membrane or envelope (with tiny nuclear pores in it) • The nucleoplasm • The chromatin (DNA) • AKA chromosomes • The nucleolus Hey! I am, like, in control, man! All the organelles get their instructions from me.

14. Typical Human Cell

15. Cell Membrane • Smooth ER • Cytoplasm • Mitochondrion • Ribosome • Nucleus • Golgi apparatus • Lysosome • Endocytosis / Exocytosis • Nucleoplasm or “matrix” (containing chromatin) • Nucleolus • Nuclear membrane “envelope” (with nuclear pores in it) • Rough ER

16. DNA a helix is a spiral shape, similar to a spring. DNA is a large reproductive molecule, shaped like a double helix, usually found inside the cell’s nucleus. • Facts about DNA • Genes are made of DNA • Genes stored in Chromosomes • 23 pairs of chromosomes make up the Human Genome. • Trivia: • DNA stands for DeoxyriboNucleic Acid. A Helix

17. Carbon atom (gray) Hydrogen atom (white) Phosphorus atom (orange) Oxygen atom (red) Nitrogen Atom (blue) DNA Molecule Model Simplified DNA Molecule

18. Some people compare the structure of DNA to a twisted ladder. • The sugar and phosphate form the sides, and the base pairs make the rungs or steps.

19. Assignments • Textbook: • Read pp. 125 to 127 • You may try questions 1 to 7 on p. 152 • Workbook • Do pages 67 to 70

20. Mitosis & Meiosis Topics: Mitosis Overview Meiosis Overview Mitosis vs. Meiosis

21. Cell Cycle The life of a cell: • Cell grows • Prepares for division (mitosis), • Divides to daughter cells, • Cycle begins again OR • Cell Dies

22. Overview of Mitosis(also see diagram page 134) Interphase Prophase Cytokinesis Metaphase Anaphase Telophase

23. 2 Main Events of the Cell Cycle • Interphase: Cell grows & prepares for Mitosis (see previous slide for diagram) • Prepares 2 ways • Replicates chromosomes • “Tools” for mitosis are produced • Mitosis: Cell divides to form two genetically identical cells • One copy of chromosomes goes into each new cell

24. Mitosis main points • Starts as diploid • two copies of each chromosome • Ends as diploid • One diploid parent cell makes two identical diploid copies of itself. • Very small portion of cell life spent in mitosis (6%) • All living and growing cells undergo mitosis

25. Meiosis

26. Meiosis main points • Meiosis Enables sexual reproduction • Starts with diploid cells • Two of each chromosome type • End products are haploid sperm or egg cells • One copy of each chromosome • Increased genetic diversity due to crossing over • Only cells in testes and ovaries undergo meiosis.

27. Mitosis in Detail • Remember: • Mitosis is normal cell division • It is part of the cell cycle The Rest of the CELL CYCLE Cell Division (MITOSIS)

28. Phases in the Cell Cycle I P M A T Remember: I = INTERPHASE Preparing for Mitosis P Where’s my Pee MAT? = PROPHASE M Undergoing Mitosis = METAPHASE A = ANAPHASE T = TELOPHASE (and cytokinesis)

29. Interphase: The Cell grows and the DNA replicates. The cell prepares to divide. The Cell Cycle G1 S G2 M1 M2 M3 M4 Prophase: The nuclear envelope disappears as chromosomes appear and the centrioles migrate to opposite poles Metaphase: The chromosomes line up near the middle of the cell (equatorial plane) and spindle fibres attach to them . Anaphase: The chromosomes split into new chromatids, and the new chromatids migrate to opposite poles Telophase: The chromatids reach the poles, new nuclei begin to form, the cell prepares to split. Cytokinesis:The cell splits into two new cells

30. Interphase • Interphase: Cell prep for mitosis (G1, S, G2) • Cell spends ~94% of life in interphase

31. Photograph of Interphase

32. Stages of Mitosis Prophase: (Prep Phase) • Chromosomes coil and become visible • Nuclear membrane breaks down • Spindle fibers assemble

33. Photo: Early Prophase Chromosomes

34. Stages of Mitosis • Metaphase (Middle) • Chromosomes line up in the middle of cell • Spindle fibers bind to the centromere

35. Photo: Metaphase Spindle (fibers) Centrosome Chromosomes Equatorial Plane

36. Stages of Mitosis • Anaphase (Apart) • Spindle fibers pull chromatids (daughter chromosomes) to opposite sides of the cell

37. Photo: Anaphase Centrosome Chromosomes Equatorial Plane

38. Stages of Mitosis • Telophase (Two) • Cell begins to split into two cells • Nuclear membranes reform

39. Photo: Telophase & Cytokinesis Cleavage furrow Nucleus forming Cells Divide

40. Stages of Mitosis • Cytokenisis • Cytoplasm is split in half • Each cell has identical chromosomes

41. During your lifetime, mitosis has created the billions of cells of cells that make up your body. • Mitosis is simple and nearly flawless (errors in mitosis are extremely rare) • Mitosis gives each cell its own copy of all your genetic information (your DNA) • Simple organisms (like the amoeba) can even reproduce by mitosis.

42. If mitosis works so well, why do we need meiosis? • Sexual reproduction helps a species survive. • It allows traits from two individuals to be mixed, giving greater diversity. • Greater diversity gives a species a better chance of surviving hard times.

43. In order to have sexual reproduction, there must be a way of reducing chromosome numbers. • You have 46 chromosome, your spouse has 46 chromosomes • If meiosis did not occur, your children would have 92 chromosomes • Your grandchildren would have 184 chromosomes • Your great-grandchildren 368, and so on… • This would soon lead to genetic problems like birth defects or bad mutations.

44. Meiosis • Two divisions occur, producing four cells • Strips away half of the chromosomes • In humans this produces haploid gametes (ova and spermatozoa) with only 23 (instead of 46) • Fertilization restores the chromosomes • When a human ovum is fertilized, the diploid zygote gets 23 from the mother and 23 from the father, restoring the normal 46

45. Assignments on Cell Division • Textbook: • Read pages • Try questions 8 to 15 on page 153 • Workbook: • Do pages 71 to 74

46. Cell Specialization • As your cells divide they also become different from each other. They specialize. • Some cells become blood cells, some become muscles, some become bone cells, and some become brain cells. • A group of similar cells, with a common function, is called a tissue:

47. Levels of Organization Strings?  make up  Quarks  make up  Subatomic Particles  make up  Protons, Neutrons  including  Atoms  make up  Molecules  make up  Macromolecules (like DNA)  make up  Cell Parts  make up  Cellsmake up  Tissues  make up  Organs  make up Systems  Which make up the  Organisms  make up  Biosphereof our Planet in our Solar System in our  Galaxy in the Local Galactic Group  in the  Virgo Supercluster in theUniverse

48. 4 Main Tissue Groups • Epithelial Tissues cover and protect your body and its organs; also used for absorption, secretion and filtration. (tissues lining organs) • Connective Tissues bind and support the organs and the body. They also transport oxygen and nutrients. • Nerve Tissues control and guide the body, and communicate using electrochemical impulses between body parts. • Muscle Tissues make body movement possible

49. Epithelial Tissues many places for epithelial tissue: • Skin • Stomach lining • Intestinal lining • Arteries, veins capillaries • Kidney tubules

50. Connective Tissues • There are also many connective tissues, such as: • Bone tissue • Cartilage • Tendons & Ligaments • Fatty tissues • Blood