1. 3 - 1 Chapter 3 Cells: The Living Units

2. 3-1: The Study of Cells  Cell theory  Cells are building blocks of life  Cells are smallest unit of life  Cells are produced through division of other cells  Each cell maintains homeostasis  Study of cells—cytology 3 - 2

3. An Overview of Cell Anatomy  Cells contain:  Plasma (cell) membrane—surrounds cell  Cytoplasm—cell contents (organelles, etc.) 3 - 3

4. 3-1 Checkpoint 1. The cell theory was developed over many years. What are its four basic concepts? 2. The study of cells is called. 3 - 4

5. 3-2: The Plasma Membrane  Functions  Separates inside of cell from outside  Controls entry/exit of substances  Senses surrounding environment  Provides structure 3 - 5

6. Membrane Lipids  Phospholipids compose plasma membrane  Phospholipid bilayer  Hydrophilic heads on outside  Hydrophobic tails on inside  O 2 & CO 2 freely pass through; ions & other compounds do not 3 - 6

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8. Membrane Proteins  Plasma membrane proteins can either be transmembrane or partially embedded  Membrane proteins function as receptors, channels, carriers, enzymes, anchors, or identifiers 3 - 8

9. 3-2 Checkpoint 1. List the general functions of the plasma membrane. 2. Which component of the plasma membrane is primarily responsible for its ability to form a physical barrier between the cell’s internal and external environment? 3 - 9

10. 3-3: Diffusion & Filtration  Permeability—substances enter/leave cell membrane  Membrane is selectively permeable  Types of movement  Passive processes—don’t require energy  Active processes—require energy 3 - 10

11. Diffusion  Diffusion—movement of molecules from high concentration to low concentration  Difference in concentrations is the concentration gradient  O 2, CO 2 freely diffuse through body cells  Ions or large molecules cross the membrane through channel proteins

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13. Osmosis  Osmosis—diffusion of water across a membrane  Occurs until concentration of particles inside cell equals concentration outside cell  Water flows to higher particle concentration  “Water flows to where it’s low” 3 - 13

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15.  Isotonic solutions  Concentrations are equal, no water movement  Hypotonic solutions  Water moves into cell, cell swells  Hypertonic solutions Hypertonic  Water moves out of cell, cell shrinks 3 - 15

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17. Filtration  Pressure forces water across a membrane  Gases & nutrients filter through blood vessels; blood vessels in kidneys filter blood in the production of urine 3 - 17

18. 3-3 Checkpoint 1. What is meant by “selectively permeable?” 2. Define diffusion. 3. How would a decrease in the concentration of oxygen in the lungs affect the diffusion of oxygen into the blood? 4. Define osmosis.

19. 3-4: Carrier Transports Carrier-Mediated Transport  Membrane proteins carry substances across the membrane (glucose, etc.)  Can be passive (high  low conc.) or active (low  high conc.) 3 - 19

20.  Facilitated diffusion (no energy)  Molecule binds to receptor site on membrane protein  Protein changes shape & molecule moves into cell  Molecule moves from high  low concentration 3 - 20

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22.  Active transport (requires energy)  Ions/molecules moved against concentration gradient into or out of cell  ATP is needed to push molecules  Molecule moves from low  high concentration 3 - 22

23. Vesicular Transport  Endocytosis—materials packaged at cell surface for import into cell (requires energy)  Pinocytosis—brings in fluid  Phagocytosis—brings in solid objects  Exocytosis—vesicle fuses with cell membrane to expel substances out of cell (requires energy)

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26. 3-4 Checkpoint 1. What is the difference between active and passive transport processes? 2. When certain types of white blood cells encounter bacteria, they are able to engulf them and bring them into the cell. What is this process called?

27. 3-5: Organelles  Cytosol—intracellular fluid that contains nutrients, ions, proteins & wastes Organelles  Internal structures that perform specific functions 3 - 27

28. Cytoskeleton  Gives the cell strength & flexibility  Microfilaments attach plasma membrane to cytoplasm  Microtubules give cell strength & rigidity  Microvilli project from cell & absorb materials

30. Centrioles, Cilia & Flagella  Centrioles help cell divide  Cilia extend from surface, move fluids & secretions  Flagella extend from surface, propel cell

31. Organelles  Ribosomes make proteins  Can be free or fixed on RER  Smooth endoplasmic reticulum (SER) makes lipids, carbs, hormones  Rough endoplasmic reticulum (RER) makes proteins, delivers to Golgi

32.  Golgi apparatus modifies & packages proteins, repairs plasma membrane  RER sends vesicles to Golgi; Golgi sends to cell surface  Lysosomes use enzymes to clean up cell, defend against disease  Peroxisomes break down fatty acids

33.  Mitochondria provide energy for the cell  Have a double membrane & cristae (folds)  Break down glucose to form ATP  Cells requiring more energy have more mitochondria

35. 3-5 Checkpoint 1. Cells lining the small intestine have numerous fingerlike projections. What are these structures and what is their function? 2. How does the absence of centrioles affect a cell? 3. What does the presence of many mitochondria imply about a cell’s energy requirements?

36. 3-6: The Nucleus  Nucleus—control center for cellular operations, determines functions Nuclear Structure & Contents  Nuclear envelope surrounds nucleus  Nuclear pores allow substances in/out of nucleus 3 - 36

37.  Nucleoli—in nucleus; make rRNA  Nucleus stores DNA in chromosomes surrounds nucleus  Unwind in nucleus as chromatin 3 - 37

38. Information Stored in the Nucleus  Nucleus stores genetic code for amino acids  Stored in triplet sequences of A, T, G, C  Gene—unit of heredity; contains triplet sequences to make proteins

39. 3-6 Checkpoint 1. Describe the contents and structure of the nucleus. 2. What is a gene?

40. 3-7: Protein Synthesis Transcription  Strand of mRNA made from DNA  DNA strand unzipped, nucleotides form mRNA on open DNA strand  G – C, A – U  Codon—3 nucleotides (AUG, CGC, etc.) 3 - 40

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42. Translation  Protein made from mRNA strand  Sequence of codons determines what protein is made  mRNA binds with tRNA in a ribosome  tRNA contains anticodon to mRNA codon  Has amino acid attached also 3 - 42

43.  Translation process:  “Start” codon on mRNA (AUG) begins process  tRNA anticodon (UAC) binds to mRNA  Second tRNA arrives with next anticodon  First tRNA leaves its amino acid on 2 nd tRNA  Process continues until “stop” codon is reached 3 - 43

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45. 3-7 Checkpoint 1. How does the nucleus control the cell’s activities? 2. During the process of transcription, a nucleotide was deleted from an mRNA sequence for a protein. What effect would this deletion have on the amino acid sequence of the protein?

46. 3-8: Cell Life Cycle  Cells increase in number through cell division  Mitosis occurs during the division of somatic cells (body cells)  Meiosis occurs in sex cells (ova/sperm) 3 - 46

47. Interphase  Most of cell’s life cycle  Phases  G 1 phase: growth  S phase: DNA copied through DNA replication  G 2 phase: protein synthesis 3 - 47

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49. Mitosis  Divides cell into two identical cells  Phases: prophase, metaphase, anaphase, telophase  Prophase  Chromosomes visible as pair of chromatids  Nucleus disappears 3 - 49

50.  Metaphase  Chromatid pair move to center of cell  Anaphase  Chromatids separate as daughter chromosomes; move to opposite cell ends  Telophase  Nucleus reforms & chromosome DNA unwinds 3 - 50

51. Cytokinesis  Cytoplasm pinches in along middle of the cell (cleavage furrow)  Two daughter cells with identical chromosomes are formed 3 - 51

52. 3-8 Checkpoint 1. Describe interphase, and identify its stages. 2. Define mitosis and list its four stages. 3. What would happen if the spindle fibers that help divide the cell failed to form during mitosis?

53. 3-9: Tumors & Cancer  Tumor—mass or swelling from excess cell growth & division  Benign tumor—seldom dangerous  Malignant tumor—spread to other tissues  Metastasis—malignant cells spread to other tissues & organs  Cancer happens due to malignant tumors  Cancer cells compete with healthy cells

54. 3-9 Checkpoint 1. An illness characterized by mutations that disrupt normal control mechanisms and produce potentially malignant cells is termed. 2. Define metasasis.