The Cell
Antoni  van  Leeuwenhoek <ul><ul><li>(1632-1723), Dutch, maker of first  single  lens  microscope </li></ul></ul><ul><ul><...
Types  of  Microscopes <ul><ul><ul><li>1.  COMPOUND/LIGHT MICROSCOPE </li></ul></ul></ul><ul><ul><ul><li>Principle: sunlig...
 
 
Image under Compound  microscope Scanning  EM Transmission  EM
CELL <ul><li>Robert  Hooke   (1665)  =  studied the cork & other plant materials    many small partitions separating </li...
Cell Diversity <ul><li>Cells that connect body parts </li></ul><ul><li>Cells that cover and line body organs </li></ul><ul...
3 Main Parts <ul><li>1. PLASMA MEMBRANE </li></ul><ul><li>2. CYTOPLASM </li></ul><ul><li>3. NUCLEUS </li></ul>
1. Plasma Membrane <ul><li>syn:  plasmalemma, cell membrane </li></ul><ul><li>- outer covering of the cell </li></ul><ul><...
Plasma Membrane <ul><li>some, cholesterol and glycolipids </li></ul><ul><li>LIPID BILAYER + integral and peripheral protei...
Plasma Membrane <ul><li>Impermeable to: ions, glucose, a.a. </li></ul><ul><li>transport assisted by: ion channels, transpo...
Plasma Membrane
rane
Definition of Terms <ul><li>Intracellular fluid (ICF)  – inside body cells i.e. fluid in cytoplasm, 2/3 of body fluid  </l...
Definition of Terms <ul><li>Solute – any material dissolved in a fluid </li></ul><ul><li>Solvent – fluid in w/c the solute...
Definition of Terms <ul><li>CONCENTRATION  – the amount of a solute in a solution </li></ul><ul><li>CONCENTRATION GRADIENT...
Substances move across cellular membranes by: <ul><li>PASSIVE PROCESSES  – substance moves down its concentration gradient...
Passive Processes <ul><li>DIFFUSION  – a substance moves from one place to another due to the substance's kinetic energy  ...
Diffusion
2 Types of Diffusion <ul><li>1. SIMPLE DIFFUSION  </li></ul><ul><ul><li>lipid-soluble substances diffuse through the lipid...
Simple Diffusion
2 Types of Diffusion <ul><li>1. SIMPLE DIFFUSION  </li></ul><ul><ul><li>Ion channels – allow a specific type of ion to mov...
 
2 Types of Diffusion <ul><li>2. FACILITATED DIFFUSION  </li></ul><ul><ul><li>an integral membrane protein assists a specif...
 
Passive Processes 2.  OSMOSIS  = net movement of water through a selectively permeable membrane - water moves from an area...
Osmosis
EFFECT  of  OSMOSIS  in  CELLS ISOTONIC   = any solution in w/c cells maintain their normal shape and volume, concentratio...
Effects of Osmosis
Passive Processes 3. FILTRATION  = process by w/c H2O and solutes are forced through a membrane (or capillary wall) by  fl...
Active Processes 1.  ACTIVE TRANSPORT   - cellular energy is used to transport substances across the membrane against a co...
Active Transport
Active Processes 2.  TRANSPORT IN VESICLES  - VESICLE   –  small round sac formed by budding off from an existing membrane...
2 Types of Transport in Vesicles 1. ENDOCYTOSIS –   materials move into a cell in a vesicle formed from the plasma membran...
<ul><li>1. PHAGOCYTOSIS –   large solid particles (e.g. bacteria, viruses, aged or dead cells), are taken in by the cell  ...
<ul><li>2. BULK-PHASE ENDOCYTOSIS (PINOCYTOSIS) –   cells take up tiny droplets of ECF  </li></ul><ul><li>- fuses with a l...
2 Types of Transport in Vesicles 2. EXOCYTOSIS   – results in secretion (release of materials from a cell) a. SECRETORY CE...
Exocytosis
Table. 3.2
Specializations of the Plasma Membrane <ul><li>Microvilli </li></ul><ul><li>Membrane junctions </li></ul>
Membrane Junctions <ul><li>1. TIGHT JUNCTIONS  = formed from fusion of adjacent cell membrane --> impermeable or leak-proo...
2. Cytoplasm <ul><li>consists of all cellular contents bet. the cell membrane and nucleus </li></ul><ul><li>Includes:   </...
1. Cytoskeleton <ul><li>network of 3 different types of protein filaments </li></ul><ul><li>1. MICROFILAMENTS  – thinnest,...
1. Cytoskeleton 2. INTERMEDIATE FILAMENTS   – found in parts of cells subject to tension (stretching), hold organelles in ...
 
<ul><li>found near the nucleus </li></ul><ul><li>Includes: </li></ul><ul><li>1. Centrioles (paired) – composed of microtub...
3. Cilia and Flagella <ul><li>CILIA  – short, hairlike projections extending from the surface of the cell </li></ul><ul><u...
4. Ribosomes <ul><li>Tiny, round, dark bodies </li></ul><ul><li>Actual site of protein production </li></ul><ul><li>high r...
5. Endoplasmic Reticulum (ER) <ul><li>network of folded membranes  </li></ul><ul><li>2 Types </li></ul><ul><li>Rough ER   ...
5. Endoplasmic Reticulum (ER)
6. Golgi Complex <ul><li>Stack of flattened membranous sacs </li></ul><ul><li>Modify and package proteins </li></ul><ul><u...
 
7. Lysosomes <ul><li>membrane-encosed vesicles, >/= 60 digestive enzymes </li></ul><ul><li>digestion, recycling </li></ul>...
 
8. Peroxisomes <ul><li>Sacs containing oxidase enzymes </li></ul><ul><li>Use oxygen to detoxify harmful or poisonous subst...
9. Proteasomes <ul><li>continuous destruction of unneeded , damaged or faulty proteins  </li></ul><ul><li>contain protease...
10. Mitochondria <ul><li>powerhouse of the cell (site of ATP production) </li></ul><ul><li>increased in: muscles, liver, k...
3. Nucleus <ul><li>most prominent feature of a cell </li></ul><ul><li>NUCLEAR ENVELOPE – separates the nucleus from the cy...
3. Nucleus <ul><li>GENES  – hereditary units </li></ul><ul><ul><li>direct cellular activities  </li></ul></ul><ul><ul><li>...
 
 
 
Protein Synthesis <ul><li>DNA found in genes gives instructions for making proteins </li></ul><ul><li>1. Transcription – D...
Transcription <ul><li>occurs in the nucleus </li></ul><ul><li>genetic info in DNA  base triplets  is copied into complemen...
3 Kinds of RNA <ul><li>1.  Messenger RNA  (mRNA )  – directs synthesis of a protein </li></ul><ul><li>2.  Ribosomal RNA  (...
Base pairing
Translation <ul><li>mRNA attaches to ribosomes and directs protein synthesis by converting sequence of nucleotides (CODON)...
 
Somatic Cell Division <ul><li>process by which damaged, diseased or worn out cells are replaced </li></ul><ul><li>process ...
2 Types of Cell Division <ul><li>1. REPRODUCTIVE CELL DIVISION (MEIOSIS) </li></ul><ul><li>- the process that produces gam...
Prerequisite of somatic cell division: DNA Replication  <ul><li>DNA – building blocks  “nucleotides” </li></ul><ul><ul><li...
<ul><li>duplication of the DNA sequences that make up the genes and chromosomes --> daughter cells w/ same genes and same ...
DNA Replication
Cell Cycle <ul><li>sequence of changes that a cell undergoes from the time it forms until it duplicates its contents and d...
<ul><li>DNA replication occurs </li></ul><ul><li>manufactures organelles and cytosolic components </li></ul><ul><li>increa...
Mitotic Phase <ul><li>consists of: </li></ul><ul><li>MITOSIS  – nuclear division </li></ul><ul><li>CYTOKINESIS  – cytoplas...
<ul><li>PROPHASE   =  chromatin coil and shorten   chromosomes,  bar-like bodies </li></ul><ul><ul><li>Chromosome = 2 str...
<ul><li>Mitosis </li></ul><ul><li>STAGES : </li></ul><ul><li>METAPHASE  – chromosomes cluster and align  at the center (me...
<ul><li>Mitosis </li></ul><ul><li>STAGES: </li></ul><ul><li>ANAPHASE   –  movement of chromosomes toward    opposite ends ...
<ul><li>Mitosis </li></ul><ul><li>STAGES: </li></ul><ul><li>TELOPHASE   –  chromosomes uncoil and become  chromatin again,...
Cytokinesis <ul><li>division of a cell's cytoplasm and organelles </li></ul><ul><li>formation of cleavage furrow that exte...
 
END <ul><li>QUIZ NEXT MEETING! </li></ul>
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Cell

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Cell

  1. 1. The Cell
  2. 2. Antoni van Leeuwenhoek <ul><ul><li>(1632-1723), Dutch, maker of first single lens microscope </li></ul></ul><ul><ul><li>The first to document the structure of RBC & the nature of the circulatory system </li></ul></ul><ul><ul><li>protozoans & bacteria, life cycles of many species of insects. </li></ul></ul><ul><ul><li>MICROMETER ( µ m) = 1/1000 </li></ul></ul>
  3. 3. Types of Microscopes <ul><ul><ul><li>1. COMPOUND/LIGHT MICROSCOPE </li></ul></ul></ul><ul><ul><ul><li>Principle: sunlight (light source) </li></ul></ul></ul><ul><ul><ul><li>2. ELECTRON MICROSCOPE </li></ul></ul></ul><ul><ul><ul><li>Principle: beam of electrons </li></ul></ul></ul><ul><ul><li>a. Transmission (magnification: >/=1Mx) </li></ul></ul><ul><ul><li>b. Scanning – 3D image <250,000x </li></ul></ul><ul><ul><li>Magnification = extent to which an image is enlarged </li></ul></ul>
  4. 6. Image under Compound microscope Scanning EM Transmission EM
  5. 7. CELL <ul><li>Robert Hooke (1665) = studied the cork & other plant materials  many small partitions separating </li></ul><ul><li>cavities  cells. </li></ul><ul><li>Basic structural and functional units of an organism </li></ul><ul><li>Carry out all chemical activities </li></ul><ul><li>needed to sustain life </li></ul>
  6. 8. Cell Diversity <ul><li>Cells that connect body parts </li></ul><ul><li>Cells that cover and line body organs </li></ul><ul><li>Cells that move organs and body parts </li></ul><ul><li>Cell that stores nutrients </li></ul><ul><li>Cell that fights disease </li></ul><ul><li>Cell that gathers information and controls body functions </li></ul><ul><li>Cells of reproduction </li></ul>
  7. 9. 3 Main Parts <ul><li>1. PLASMA MEMBRANE </li></ul><ul><li>2. CYTOPLASM </li></ul><ul><li>3. NUCLEUS </li></ul>
  8. 10. 1. Plasma Membrane <ul><li>syn: plasmalemma, cell membrane </li></ul><ul><li>- outer covering of the cell </li></ul><ul><li>- surrounds each cell  separate its contents from external environment </li></ul><ul><li>- regulates what enters & leaves the cell </li></ul><ul><li>- allows communication </li></ul>
  9. 11. Plasma Membrane <ul><li>some, cholesterol and glycolipids </li></ul><ul><li>LIPID BILAYER + integral and peripheral proteins </li></ul><ul><li>SELECTIVE PERMEABILITY </li></ul><ul><ul><li>- water & nonpolar (lipid-soluble) molecules e.g. FA, fat-soluble vit., steroids, O2, CO2 </li></ul></ul><ul><li>mainly made up of phospholipids and proteins (latter, mainly glycoproteins) </li></ul>
  10. 12. Plasma Membrane <ul><li>Impermeable to: ions, glucose, a.a. </li></ul><ul><li>transport assisted by: ion channels, transporters </li></ul><ul><li>Integral proteins act as: receptors, enzymes, cell identity markers </li></ul>
  11. 13. Plasma Membrane
  12. 14. rane
  13. 15. Definition of Terms <ul><li>Intracellular fluid (ICF) – inside body cells i.e. fluid in cytoplasm, 2/3 of body fluid </li></ul><ul><li>Extracellular fluid (ECF) – fluid outside body cells </li></ul><ul><li>Interstitial fluid – the ECF between cells </li></ul><ul><ul><li>e.g. plasma (in blood vessels), lymph (in lymphatic vessels) </li></ul></ul><ul><ul><li>** materials dissolved in body fluids: gases, nutrients, ions, etc. </li></ul></ul>
  14. 16. Definition of Terms <ul><li>Solute – any material dissolved in a fluid </li></ul><ul><li>Solvent – fluid in w/c the solute is dissolved e.g. water </li></ul><ul><li>Solution – homogenous mixture of 2 or more components (e.g. air, seawater, alcohol) </li></ul>
  15. 17. Definition of Terms <ul><li>CONCENTRATION – the amount of a solute in a solution </li></ul><ul><li>CONCENTRATION GRADIENT – difference in concentration between 2 different areas </li></ul><ul><ul><li>moving down vs. moving up </li></ul></ul>
  16. 18. Substances move across cellular membranes by: <ul><li>PASSIVE PROCESSES – substance moves down its concentration gradient using only its own energy of motion (kinetic energy) </li></ul><ul><ul><li>SIMPLE DIFFUSION, OSMOSIS </li></ul></ul><ul><li>ACTIVE PROCESSES – cellular energy (e.g. ATP) is used to push the substance through the membrane against its concentration gradient </li></ul><ul><ul><li>ACTIVE TRANSPORT, VESICLES </li></ul></ul>
  17. 19. Passive Processes <ul><li>DIFFUSION – a substance moves from one place to another due to the substance's kinetic energy </li></ul><ul><ul><ul><li>particles move from a region of higher to lower concentration </li></ul></ul></ul><ul><ul><ul><li>endpoint: EQUILIBRIUM – substance is evenly distributed throughout the solution and the concentration gradient disappears </li></ul></ul></ul><ul><ul><ul><li>may or may not involve a membrane </li></ul></ul></ul>
  18. 20. Diffusion
  19. 21. 2 Types of Diffusion <ul><li>1. SIMPLE DIFFUSION </li></ul><ul><ul><li>lipid-soluble substances diffuse through the lipid bilayer e.g. O2, CO2, N, f.a., steroids, vit. ADEK, H2O, urea </li></ul></ul><ul><ul><li>used in: exchange of gases, absorption of nutrients, release of wastes </li></ul></ul>
  20. 22. Simple Diffusion
  21. 23. 2 Types of Diffusion <ul><li>1. SIMPLE DIFFUSION </li></ul><ul><ul><li>Ion channels – allow a specific type of ion to move across the membrane through the channel's pore </li></ul></ul><ul><ul><li>e.g. K, Cl, Na, Ca </li></ul></ul>
  22. 25. 2 Types of Diffusion <ul><li>2. FACILITATED DIFFUSION </li></ul><ul><ul><li>an integral membrane protein assists a specific substance across the membrane </li></ul></ul><ul><ul><li>substance binds to a specific TRANSPORTER on one side of the membrane --> released on the other side after the transporter undergoes a change in shape </li></ul></ul><ul><ul><li>movement along a conc. gradient, NO ATP needed </li></ul></ul><ul><ul><li>e.g. glucose, fructose, galactose </li></ul></ul>
  23. 27. Passive Processes 2. OSMOSIS = net movement of water through a selectively permeable membrane - water moves from an area of higher water to an area of lower water concentration - or, from an area of lower solute concentration to an area of higher solute concentration OSMOTIC PRESSURE – depends on the concentration of its solute particles - the higher the solute conc., the higher the osmotic pressure
  24. 28. Osmosis
  25. 29. EFFECT of OSMOSIS in CELLS ISOTONIC = any solution in w/c cells maintain their normal shape and volume, concentrations of solutes are same on both sides = tissue fluids, blood plasma, 0.9% NSS, 5% dextrose (glucose) HYPOTONIC = lower concentration of solutes (higher conc. of H2O) than the cytosol inside the cell = cell swells --> ruptures HYPERTONIC = higher concentration of solutes (lower conc. of water) than the cytosol inside the cell = cell shrinks
  26. 30. Effects of Osmosis
  27. 31. Passive Processes 3. FILTRATION = process by w/c H2O and solutes are forced through a membrane (or capillary wall) by fluid or hydrostatic pressure (pressure gradient) e.g. filtering capacity of the kidney (e.g. in urine formation)
  28. 32. Active Processes 1. ACTIVE TRANSPORT - cellular energy is used to transport substances across the membrane against a concentration gradient (from an area of low to an area of high concentration), needs ATP - splitting of ATP changes the shape of a transporter protein (PUMP) --> moves a substance across the membrane against its conc. gradient - Na, K, H, Ca, I, Cl
  29. 33. Active Transport
  30. 34. Active Processes 2. TRANSPORT IN VESICLES - VESICLE – small round sac formed by budding off from an existing membrane - transport substances, take in and release substances - requires energy (ATP)
  31. 35. 2 Types of Transport in Vesicles 1. ENDOCYTOSIS – materials move into a cell in a vesicle formed from the plasma membrane - substances are surrounded by a piece of the plasma membrane w/c buds off inside the cell to form a vesicle containing the ingested substances.
  32. 36. <ul><li>1. PHAGOCYTOSIS – large solid particles (e.g. bacteria, viruses, aged or dead cells), are taken in by the cell </li></ul><ul><li>- fuses w/ a lysosome --> break down of material </li></ul><ul><li>- e.g. WBCs, macrophages </li></ul>2 Types of Endocytosis
  33. 37. <ul><li>2. BULK-PHASE ENDOCYTOSIS (PINOCYTOSIS) – cells take up tiny droplets of ECF </li></ul><ul><li>- fuses with a lysosome --> enzymatic breakdown of engulfed solutes </li></ul>2 Types of Endocytosis
  34. 38. 2 Types of Transport in Vesicles 2. EXOCYTOSIS – results in secretion (release of materials from a cell) a. SECRETORY CELLS – release digestive enzymes, hormones, mucus, etc. b. NERVE CELLS – during release of neurotransmitters * membrane-enclosed secretory vesicles form inside the cell, fuse w/ the cell membrane, and release contents into the ECF
  35. 39. Exocytosis
  36. 40. Table. 3.2
  37. 41. Specializations of the Plasma Membrane <ul><li>Microvilli </li></ul><ul><li>Membrane junctions </li></ul>
  38. 42. Membrane Junctions <ul><li>1. TIGHT JUNCTIONS = formed from fusion of adjacent cell membrane --> impermeable or leak-proof sheets </li></ul><ul><ul><li>= keep digestive juices & harmful substances from damaging the organs or getting into the bloodstream </li></ul></ul><ul><li>2. DESMOSOMES = anchoring junctions (button-like thickenings), prevent cells under mechanical stress from being pulled apart e.g. skin </li></ul><ul><li>3. GAP JUNCTIONS = allows communication e.g. heart, nervous system </li></ul>
  39. 43. 2. Cytoplasm <ul><li>consists of all cellular contents bet. the cell membrane and nucleus </li></ul><ul><li>Includes: </li></ul><ul><ul><li>CYTOSOL (ICF) – fluid portion of the cytoplasm, 55% of total cell volume, 75-90% H2O, site of chemical reactions </li></ul></ul><ul><ul><li>ORGANELLES – specialized structures inside cells w/ specific functions </li></ul></ul>
  40. 44. 1. Cytoskeleton <ul><li>network of 3 different types of protein filaments </li></ul><ul><li>1. MICROFILAMENTS – thinnest, concentrated at the periphery --> strength and shape </li></ul><ul><li>- provides mechanical support and generates movement </li></ul><ul><li>- anchor cytoskeleton to integral proteins </li></ul><ul><li>- support for microvilli </li></ul><ul><li>- intercellular attachment </li></ul>
  41. 45. 1. Cytoskeleton 2. INTERMEDIATE FILAMENTS – found in parts of cells subject to tension (stretching), hold organelles in place, intercellular attachment 3. MICROTUBULES – long, hollow tubes, determines cell shape, movement of organelles w/in the cell, migration of chromosomes during cell division, movement of cilia and flagella
  42. 47. <ul><li>found near the nucleus </li></ul><ul><li>Includes: </li></ul><ul><li>1. Centrioles (paired) – composed of microtubules </li></ul><ul><li>2. Pericentriolar material – composed of tubulins, organizing centers for growth of the mitotic spindle (role in cell division) </li></ul>2 . Centrosome
  43. 48. 3. Cilia and Flagella <ul><li>CILIA – short, hairlike projections extending from the surface of the cell </li></ul><ul><ul><li>propel fluids across surfaces of cells </li></ul></ul><ul><li>FLAGELLA - move an entire cell </li></ul>
  44. 49. 4. Ribosomes <ul><li>Tiny, round, dark bodies </li></ul><ul><li>Actual site of protein production </li></ul><ul><li>high rRNA content </li></ul><ul><ul><li>Free ribosomes </li></ul></ul><ul><ul><li>attached to RER </li></ul></ul>
  45. 50. 5. Endoplasmic Reticulum (ER) <ul><li>network of folded membranes </li></ul><ul><li>2 Types </li></ul><ul><li>Rough ER – extends from the nuclear envelope, studded w/ ribosomes, synthesis of secretory proteins and membrane molecules </li></ul><ul><li>Smooth ER – extends from the RER --> network of membranous tubules, lacks ribosomes, f.a. & steroids (e.g. estrogen, testosterone) are produced, detoxification (e.g. alc, pesticides, carcinogens) </li></ul>
  46. 51. 5. Endoplasmic Reticulum (ER)
  47. 52. 6. Golgi Complex <ul><li>Stack of flattened membranous sacs </li></ul><ul><li>Modify and package proteins </li></ul><ul><ul><li>secretory vesicles </li></ul></ul><ul><ul><li>carries proteins and phospholipids to become part of cell membrane </li></ul></ul><ul><ul><li>incorporated in lysosomes </li></ul></ul>
  48. 54. 7. Lysosomes <ul><li>membrane-encosed vesicles, >/= 60 digestive enzymes </li></ul><ul><li>digestion, recycling </li></ul><ul><li>autophagy, autolysis </li></ul>
  49. 56. 8. Peroxisomes <ul><li>Sacs containing oxidase enzymes </li></ul><ul><li>Use oxygen to detoxify harmful or poisonous substances (e.g. alcohol, formaldehyde) </li></ul><ul><li>Disarm “free radicals” </li></ul><ul><ul><li>FR -> H2O2->H2O </li></ul></ul><ul><ul><li>liver and kidney cells </li></ul></ul>
  50. 57. 9. Proteasomes <ul><li>continuous destruction of unneeded , damaged or faulty proteins </li></ul><ul><li>contain proteases </li></ul>
  51. 58. 10. Mitochondria <ul><li>powerhouse of the cell (site of ATP production) </li></ul><ul><li>increased in: muscles, liver, kidneys </li></ul>
  52. 59. 3. Nucleus <ul><li>most prominent feature of a cell </li></ul><ul><li>NUCLEAR ENVELOPE – separates the nucleus from the cytoplasm </li></ul><ul><li>NUCLEAR PORES – control movement of substances </li></ul><ul><li>NUCLEOLI – sites of assembly of ribosomes </li></ul>
  53. 60. 3. Nucleus <ul><li>GENES – hereditary units </li></ul><ul><ul><li>direct cellular activities </li></ul></ul><ul><ul><li>arranged along chromosomes </li></ul></ul><ul><ul><ul><li>46 chromosomes (23/parent) </li></ul></ul></ul><ul><ul><ul><li>in a nondividing cell, chromosomes appear as diffuse granular mass --> CHROMATIN </li></ul></ul></ul><ul><li>GENOME – total genetic information carried in a cell or organism </li></ul>
  54. 64. Protein Synthesis <ul><li>DNA found in genes gives instructions for making proteins </li></ul><ul><li>1. Transcription – DNA is copied --> RNA </li></ul><ul><li>2. Translation – information in RNA (attached to a ribosome) is translated into a sequence of a.a. --> protein molecule </li></ul>
  55. 65. Transcription <ul><li>occurs in the nucleus </li></ul><ul><li>genetic info in DNA base triplets is copied into complementary sequence of CODONS in a strand of RNA (helped by RNA polymerase) </li></ul><ul><li>PROMOTER – sequence of nucleotides in DNA where RNA polymerase attaches to </li></ul><ul><li>TERMINATOR – sequence of nucleotides in DNA where transcription ends </li></ul>
  56. 66. 3 Kinds of RNA <ul><li>1. Messenger RNA (mRNA ) – directs synthesis of a protein </li></ul><ul><li>2. Ribosomal RNA (rRNA) – joins w/ ribosomal proteins to make ribosomes </li></ul><ul><li>3. Transfer RNA (tRNA) – binds to an a.a. and holds it in place on a ribosome until it becomes part of a protein during translation </li></ul>
  57. 67. Base pairing
  58. 68. Translation <ul><li>mRNA attaches to ribosomes and directs protein synthesis by converting sequence of nucleotides (CODON) into a specific sequence of a.a. --> PROTEIN </li></ul><ul><li>tRNA contains the triplet of nucleotides called ANTICODON </li></ul><ul><li>Protein synthesis ends when ribosome reaches a STOP CODON </li></ul><ul><li>15 a.a./second </li></ul>
  59. 70. Somatic Cell Division <ul><li>process by which damaged, diseased or worn out cells are replaced </li></ul><ul><li>process by which cells reproduce themselves </li></ul>
  60. 71. 2 Types of Cell Division <ul><li>1. REPRODUCTIVE CELL DIVISION (MEIOSIS) </li></ul><ul><li>- the process that produces gametes (sperm & oocytes) </li></ul><ul><li>2. SOMATIC CELL DIVISION </li></ul><ul><li>- division of all body cells (except gametes) --> two identical cells </li></ul>
  61. 72. Prerequisite of somatic cell division: DNA Replication <ul><li>DNA – building blocks “nucleotides” </li></ul><ul><ul><li>Deoxyribose sugar </li></ul></ul><ul><ul><li>Phosphate group </li></ul></ul><ul><ul><li>Nitrogen-containing base </li></ul></ul>
  62. 73. <ul><li>duplication of the DNA sequences that make up the genes and chromosomes --> daughter cells w/ same genes and same number of chromosomes </li></ul>Prerequisite of somatic cell division: DNA Replication
  63. 74. DNA Replication
  64. 75. Cell Cycle <ul><li>sequence of changes that a cell undergoes from the time it forms until it duplicates its contents and divides into two cells </li></ul><ul><li>2 MAJOR PERIODS </li></ul><ul><li>1. INTERPHASE – cell is not dividing </li></ul><ul><li>2. MITOTIC PHASE – cell is dividing </li></ul>
  65. 76. <ul><li>DNA replication occurs </li></ul><ul><li>manufactures organelles and cytosolic components </li></ul><ul><li>increased metabolic activity </li></ul><ul><li>cell is growing </li></ul>Interphase
  66. 77. Mitotic Phase <ul><li>consists of: </li></ul><ul><li>MITOSIS – nuclear division </li></ul><ul><li>CYTOKINESIS – cytoplasmic division into 2 cells </li></ul>
  67. 78. <ul><li>PROPHASE = chromatin coil and shorten  chromosomes, bar-like bodies </li></ul><ul><ul><li>Chromosome = 2 strands of chromatids , held together by a buttonlike body, centromere </li></ul></ul>Mitosis
  68. 79. <ul><li>Mitosis </li></ul><ul><li>STAGES : </li></ul><ul><li>METAPHASE – chromosomes cluster and align at the center (metaphase plate) </li></ul>
  69. 80. <ul><li>Mitosis </li></ul><ul><li>STAGES: </li></ul><ul><li>ANAPHASE – movement of chromosomes toward opposite ends of the cell </li></ul>
  70. 81. <ul><li>Mitosis </li></ul><ul><li>STAGES: </li></ul><ul><li>TELOPHASE – chromosomes uncoil and become chromatin again, nuclear envelope forms around each chromatin mass </li></ul>
  71. 82. Cytokinesis <ul><li>division of a cell's cytoplasm and organelles </li></ul><ul><li>formation of cleavage furrow that extends around the center of the cell </li></ul><ul><li>endpoint: 2 new and separate cells </li></ul>
  72. 84. END <ul><li>QUIZ NEXT MEETING! </li></ul>

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