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The Living Cell

Discover the fascinating world of cells and their chemical processes. Learn about cell structure, the role of organelles, energy production, and genetics. Explore the microscopic world and unravel the mysteries of life.

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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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