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Cytology

Cytology. Cytology = The study of cells Cell = the structural and functional unit of all living things. Cell Organelles. Organelles = “tiny organ” = carry out the life processes of the cell. * each organelle has a specific function. Cell Organelles (cont’d). Nucleus

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Cytology

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  1. Cytology Cytology = The study of cells Cell = the structural and functional unit of all living things.

  2. Cell Organelles Organelles = “tiny organ” = carry out the life processes of the cell. * each organelle has a specific function.

  3. Cell Organelles (cont’d) • Nucleus - surrounded by the nuclear envelope - double membrane, with pores = controls what enters/exits the nucleus - contains the genetic material

  4. DNA DNA = deoxyribonucleic acid - model of DNA was discovered by 2 scientists = Watson and Crick - found to be a double stranded helix - each strand is made up of alternating sugars and phosphate groups. - attached to the sugars are base pairs that fit together like pieces of a puzzle

  5. DNA (cont’d) • Base pairs: - A = T - C = G • 1 strand reads: A other strand? C C G T

  6. Organelles (cont’d) • in the cell, DNA is located on the chromosomes = 46 chromosomes in the average human cell = 23 in the gametes = sex cells

  7. Organelles (cont’d) • Nucleolus - dark area of nucleus - contains rRNA (ribosomal) = makes RIBOSOMES

  8. Organelles (cont’d) • Ribosomes - passes through nuclear envelope into cytoplasm ( ) - site of protein synthesis - strings amino acids together to form proteins - can be free-floating or attached to another organelle.

  9. Organelles (cont’d) • Endoplasmic Reticulum (ER) - 2 types; 1. RER = Rough ER - has ribosomes attached - helps make proteins 2. SER = Smooth ER - no ribosomes attached - sends proteins out from ER

  10. Organelles (cont’d) • Golgi Apparatus - flattened stacks of membranes in the cell - modifies, packages, then ships proteins out of the cell in a vesicle

  11. Organelles (cont’d) • Mitochondria - “power house” of the cell - supplies energy to the cell (ATP) - breaks down food to form ATP in a process called Cellular Respiration

  12. Organelles (cont’d) • Lysosomes - digests/break-down wastes in the cell. • Centrioles - aid in cell reproduction • Cytoskeleton - gives support/shape to the cell

  13. Organelles (cont’d) • Plasma Membrane - protective barrier around the cell. - double layer made up of phosphates and lipids - controls what enters and exits the cell

  14. Plant Organelles • Plastids - produce sugar in plants 3 types: 1. Chloroplasts - contain chlorophyll = green pigment that captures sunlight as energy for plants

  15. Plant Organelles (cont’d) 2. Chromoplasts - contain red, orange, yellow pigments that give flowers and fruits their color. 3. Leucoplasts - colorless plastid - convert sugar to starch - better energy storage form

  16. Plant Organelles (cont’d) b. Vacuoles - store materials c. Cell Wall - in plants and fungi (NOT in animals!) - outside plasma membrane - protects and supports the cell. - made up of cellulose (rigid/hard)

  17. Movement of material in a cell Molecules are in constant motion – This energy of motion is called: KINETIC ENERGY - molecules move in a straight line, until it strikes another molecule - decrease area = increase collisions - molecules move until they all have an = amount of space.

  18. Passive Transport Passive Transport - movement of molecules WITHOUT using any energy from the cell. - the cell membrane is SELECTIVELY PERMEABLE to some molecules. = allows certain molecules to pass through. (water, oxygen, CO2, etc)

  19. Passive Transport Permeability of an object depends on: 1. Size – (sugar/starch) 2. Charge – (+) or (-) 3. Solubility – ability to be dissolved in water

  20. Passive Transport • Diffusion = movement of MOLECULES from an area of high concentration to an area of low concentration. ex; - sugar in tea - kool-aid - tea bags - odors

  21. Passive Transport • Osmosis = the movement of WATER from an area of high concentration to an area of low concentration. - causes osmotic pressure in cells = pressure change as result of water moving in or out of the cell.

  22. Passive Transport (cont’d) • Facilitated Diffusion - increase the rate of diffusion by using carrier proteins in the cell membrane.

  23. Passive Transport • Molecules will continue to move in and out until equilibrium is reached. = rate of molecules leaving the cell is = to the rate of molecules entering the cell.

  24. Solution types 3 types of solutions are possible when compared to the cell. • Isotonic Solution = number of solutes in fluid is = to the number of solutes in cell

  25. Solutions (cont’d) • Hypertonic Solution = solution contains a higher number of solutes than the cell - solutes move into cell, water moves out - results in cell shriveling

  26. Solutions (cont’d) • Hypotonic Solutions = solution contains a lower number of solutes than the cell - solutes move out of the cell, water moves into the cell. - results in cell swelling/expanding.

  27. Active Transport Active Transport - movement of molecules into or out of the cell using cellular energy (ATP) 3 types: 1. Carrier Mediated Active Transport - use of carrier proteins (like FD) - movement from low concentration to high, and uses energy.

  28. Active Transport • Endocytosis - transporting substances into the cell a. Pinocytosis - membrane surrounds molecule, forms vesicle and pinches off into cell. b. Phagocytosis - for larger particles - cell surrounds and engulfs molecule

  29. Plant Cells • plant cells are surrounded by a rigid cell wall. - Osmotic pressure in plant cell causes cell to swell against the cell wall, but not burst = Turgor Pressure - gives plants, stems and leaves their rigid, upright form.

  30. Plant Cells Plasmolysis = loss of turgor pressure in plants - cell shrinks from cell wall - less rigid = WILTING

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