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The Living Cell

The Living Cell. Lecture 11 UNIV301 – Great Ideas of Science. Great Idea: Life is based on chemistry, and chemistry takes place in cells. Cells. All living things are made of cells, which are like chemical factories Every cell has an “ inside ” and an outside, separated by a cell membrane

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The Living Cell

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  1. The Living Cell Lecture 11 UNIV301 – Great Ideas of Science Great Idea: Life is based on chemistry, and chemistry takes place in cells

  2. Cells • All living things are made of cells, which are like chemical factories • Every cell has an “inside” and an outside, separated by a cell membrane • Every cell uses raw materials and energy to produce new chemicals • Every cell must contain information on how to operate and how to make new cells

  3. Observing Cells: The Microscope

  4. Observing Cells: The Microscope

  5. The Cell Theory • Robert Hooke (1635-1702) Cells are like small compartments • Matthais Scheiden – plants, 1838 • Theodor Schwann – animals, 1839

  6. The Cell Theory, 1839 • All living things are composed of cells • The cell is the fundamental unit of life • All cells arise from previous cells

  7. Two Kinds of Cells • Prokaryotes (“before nucleus”) • Eukaryotes (“true nucleus”)

  8. Cellular Architecture • Organelle: Any specialized cell structure • Cell membrane (cell wall in plants) • Nucleus • Mitochondria and chloroplasts (power plants)

  9. Plant Cells

  10. Animal Cells

  11. Lipids

  12. Cell Membranes • Cell Membranes • Isolate the cell • Separate cell parts • Transport • Individual molecules • Channels for specific materials • Receptors • Bind molecules • Encapsulate • Cell Wall (plants)

  13. The Nucleus Nucleus • Nucleus • Contains DNA • Prokaryotes • No nucleus • Eukaryotes • Nucleus • The nucleus has a double membrane. Why?

  14. Cytoskeleton • Cytoskeleton • Gives cell shape • Anchors • Allows movement • Transport system within cell • Structure • Strong filaments • Complex web

  15. How Is Energy Obtained? Plants – make sugar in the presence of the Sun by the process of photosynthesis Energy (light) + CO2 + H2O  Glucose + O2

  16. Carbohydrates (sugars) Carbon Hydrogen Oxygen

  17. Cellulose and Starch

  18. How Is Energy Obtained? Plants and animals convert sugar into small energy-rich molecules by the process of glycolysis. Glucose  2 Pyruvic Acids + ATP ATP  ADP + PO4 + energy

  19. ATP: The Cell’s Energy Currency • Adenosine triphosphate (ATP) • Provides energy • Structure • 3 phosphate groups • Sugar molecule: ribose • adenine • Function • Removal of phosphate group provides energy

  20. How Is Energy Obtained? Some animals obtain energy by the process of respiration: Glucose + O2 Energy + CO2 + H2O

  21. The Final Stages of Respiration • Glucose is broken down • CO2 is produced • ATP is produced to serve as energy-carrying molecules • Result: 36-38 ATP

  22. How Is Energy Obtained? Many organisms obtain additional energy from pyruvic acid by the process of fermentation: Pyruvic Acid  small molecules + ATP Vinegar, alcohol, carbonic acid

  23. The Energy Organelles: Chloroplasts and Mitochondria • Chloroplasts • Plant cells only • Energy transformation • chlorophyll • Double membrane • Mitochondria • Plants and Animals • Produces the cell’s ATP • Double membrane • Has its own DNA

  24. Mitochondria Where ATP is manufactured Mitochondria (mtDNA) = maternally inherited Unaltered from your mother Genetic material from common ancestor Genetic anthropology

  25. Genetics: The Genetic Code • KEY IDEA: All living things share the same genetic code • Classical genetics – the observation of organisms • Cellular genetics – the observation of cell division and chromosomes • Molecular genetics – the study of DNA and RNA

  26. Two great mysteries of life • Like begets like • You begin life as a single cell

  27. Three Stages of Genetics Research 1. Classical Genetics 2. Cellular Genetics 3. Molecular Genetics

  28. Gregor Mendel (1822-1884) • Pea plant – breeding experiments • Two-characteristic variations • Established pure-breeding stocks • Studied cross breeding • Offspring’s traits are derived from parents

  29. Classical Genetics • Gregor Mendel’s Laws • Pea plant experiments • Purebred • Hybrid • Results • First generation all hybrid tall

  30. If you cross a pure bred tall pea plant with a pure bred short pea plant, all offspring are tall. T T t tT tT t tT tT

  31. Classical Genetics • Gregor Mendel’s Laws • Pea plant experiments • Purebred • Hybrid • Results • First generation all hybrid tall. • Cross breed those hybrids. • Second generation is ¾ tall and ¼ short!

  32. If you cross two hybrid pea plants, ¾ will be tall and ¼ will be short. T t T TT Tt t tT tt

  33. Classical Genetics Mendel Laws • Genes exist (“atoms of inheritance”) • Each parent contributes half. • Some are dominant and some are recessive.

  34. If you cross a pure bred tall pea plant with a hybrid pea plant, what would the first generation of offspring look like? T T T TT TT t tT tT

  35. Gregor Mendel’s Three Laws of Heredity • There exist “atoms of inheritance” or genes • Each parent contributes half • Some genes are dominant, others are recessive • Genes are expressed independently of each other (WRONG)

  36. Cellular Genetics • Use microscope to observe cells dividing • Chromosomes – elongated colored objects

  37. Cellular Genetics • Use microscope to observe cells dividing • Chromosomes – elongated colored object • Mitosis (one cell becomes two) • Most cellular division in your body • Humans 23 pairs (before division 46 pairs) • 2 daughter cells same as parent • Meiosis (one becomes 4 gametes) • Crossing-Over (reshuffle = end of meiosis) • Recombination yields different mix of genes

  38. Mitosis • Mitosis is cell division (Not sexual reproduction) • Observe chromosomes • Multi-step Process 1. Copy chromosomes 2. Spindle fibers 3. Migration of chromosomes 4. Nuclear membrane reforms

  39. Mitosis

  40. Meiosis Meiosis is sexual reproduction 1 cell forms 4 gametes Gametes are genetically unique Multi-step process 1. Copy chromosomes 2. Crossing over

  41. Meiosis Meiosis is sexual reproduction 1 cell forms 4 gametes Gametes are genetically unique Multi-step process 1. Copy chromosomes 2. Crossing over 3. Segregation 4. Segregation again Result: 4 daughter cells, each with ½ normal number of chromosomes. Each chromosome is unique!

  42. Molecular Genetics • What chemical carries the genetic message? • How is that molecular message translated into the chemicals of life?

  43. The Discovery of DNA Oswald Avery (1877-1955) DNA is composed of deoxyribose (5-carbon sugar), phosphate, and one of four bases (ATGC). A = T; G = C Sugar=Phosphate=Base (1:1:1 ratio)

  44. Nucleotides: The Building Blocks of Nucleic Acids Nucleotides are made of three molecules 1. Sugar DNA: deoxyribose RNA: ribose 2. Phosphate ion 3. Base Adenine (A) Guanine (G) Cytosine (C) Thymine (T)

  45. DNA’s Double Helix Nucleotide: Building blocks in nucleic acids (A phosphate linked to a sugar linked to a base)

  46. DNA Structure • Join nucleotides by alternating phosphate and sugar • DNA • 2 strands of nucleotides • Joined by base pairs • Bonding pattern • Adenine:Thymine • Cytosine:Guanine

  47. DNA Base Pairing Adenine:Thymine Cytosine:Guanine

  48. The Replication of DNA DNA replication occurs before mitosis & meiosis Process 1. DNA double helix splits 2. New bases bond to exposed bases 3. Results in two identical DNA strands

  49. Proteins – Enzymes

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