Cells Cell Transport Cell and Cell Transport Biology

Cells & Cell Transport Cell and Cell Transport Biology Ch. 6

The Cell Theory (ch 8) Is the result of work done by many scientists: Hooke (named cells) Leeuwenhoek (microscope) Schwann (animal cells) Schleiden (plant cells) Virchow (cell division) All living things are made up of cells The basic unit of structure and function for living things is the cell All cells come from other cells

Microscopes (ch 8) Three major types of microscopes: light microscope (LM) scanning electron microscope (SEM) transmission electron microscope (TEM) The type of microscope used depends on what you want to see A photo taken by a microscope is called a micrograph

Microscopes Magnification Pros Cons Light (LM) Uses light Magnification depends upon type of LM Color micrographs Magnification not always Living specimens enough Range of uses Affordable ($, time) Transmission (TEM) Uses e- traveling through specimen Very high mag Can see extremely Prep time small things Expense Specimens usually not alive Uses e- bouncing off surface of specimen Very high mag Can see extremely Prep time small things Expense Specimens usually not alive Scanning (SEM)

Electron Microscopes

Micrographs

Prokaryotes vs. Eukaryotes No nucleus (nuclear membrane) Smaller in size Circular DNA (plasmid) Simple in structure, small organelles, few organelles Usually have a cell wall and/or a capsid Often have flagella for motility Include both eubacteria & archaebacteria Has a nucleus (nuclear membrane) Larger in size Larger thread like DNA (chromatin/chromosomes) Larger, more specialized organelles, more organelles Mitochondria and Chloroplasts (plastids) can exist inside these cells Include all other organisms (plants, animals, fungus and protists)

Cell Membrane Cell membrane (plasma membrane): a phospholipid bilayer surrounding the cell Each phospholipid has a polar phosphate head and lipid tails

Cytoplasm AKA protoplasm The watery environment of the cell where all cell activity takes place Made up of mostly water, with ions, proteins, and other compounds

Cytoskeleton A network of fibers throughout the cytoplasm called microfilaments and microtubules They provide structure to the cell, points of attachment for organelles (MT), and are used in cell movement (MF)

Cytoplasmic Streaming Animation http: //www. youtube. com/watch? v=7 p. R 7 TN z. J_p. A

Nucleus Surrounded by a nuclear membrane AKA nuclear envelope which is a bilayer like the cell membrane Contains nuclear pores for transport in and out of the nucleus

Chromatin Made up of sections of DNA called genes Uncurled: chromatin Curled up for transport: chromosomes (these are stained & visible under a microscope) They do not leave the nucleus

Nucleolus Found inside the nucleus A mass of RNA, not an official membrane bound organelle like the rest described here ‘Disappears’ during cell division RNA can leave the nucleus for protein synthesis

Centrioles (AKA centrosomes) Lay just outside the nucleus, made up of microtubules Involved in cell division (although they are not present in plant cells) Replicate into two centrioles before cell division and migrate to opposite ends of nucleus

Endoplasmic Reticulum Can be rough (with ribosomes attached) or smooth (no ribosomes) Functions include: transportation (rough ER), toxin breakdown and phospholipid production (smooth ER)

Ribosome Can be free (in the cytoplasm) or bound (found on the rough ER) Made up of two subunits (large & small), equal parts protein & RNA The location of protein production (the site of protein synthesis)

Golgi Body AKA golgi apparatus Responsible for protein processing which includes: *marking proteins with their destination location *preparing proteins to become active and able to do their job (ex: enzyme folding)

Mitochondria Often called the ‘powerhouse’ of the cell, has a 2 nd inside membrane AKA the cristae It generates ATP from glucose molecules Contains its own DNA unlike every other organelle in the cell Is thought to have once lived on its own

Vacuole Used for storage for a variety of things including food, waste, and proteins to be transported out/around the cell A moving vacuole is called a vesicle Plants have a large central vacuole for water storage to keep the shape of the plant cell

Lysosome A vacuole containing digestive enzymes They fuse with vacuoles containing substances to be broken down (food, waste, invading bacteria) AKA suicide sacs because if they leak their enzymes, the cell can be damaged

Cell Wall Found in bacteria, fungus, plant, and some protists Made up of cellulose in plant cells Adds extra security/protection and/or provides structure (shape) for cells

Flagella and Cilia Used for movement in some protist and animal cells, made of microtubules Flagella are whip like tails (one or more) for movement much like a tail is used for swimming by fish Cilia are hair like extensions (circular movement is like that of a bullet) Video comparing flagella and cilia movement: http: //www. youtube. co m/watch? v=QGAm 6 h Mys. TA

Chloroplasts Contain chlorophyll (green, yellow, red color) Only found in cells that do photosynthesis (plants, some protists, some bacteria) Like mitochondria, they contain their own DNA and are thought to have lived as single celled organisms at one time

Plant vs. Animal Cells No centrioles for cell division A large central vacuole Cell wall of cellulose to help maintain square shape Chloroplasts containing chlorophyll for photosynthesis Use centrioles for cell division No central vacuole No cell wall No chloroplasts, no chlorophyll, no photosynthesis

The Cell Membrane in Detail

Fluid Mosaic Model The cell membrane used to be thought of as a solid layer Now it is known as the fluid mosaic model: it can move (fluid) and it has many parts (a mosaic) including proteins, carbohydrates, & lipids The cell membrane is semi-permeable (aka selectively permeable) http: //www. youtube. co m/watch? v=LKN 5 sq 5 dt W 4

Components of the Cell Membrane Structure Function Phospholipids Make up bulk of membrane Mainly hydrophobic (nonpolar) Protein channels Protein carriers (pumps) Facilitated diffusion of hydrophilic (polar) substances Active transport of substances against their concentration gradient Cholesterol (lipid) Cell membrane fluidity/rigidity Oligosaccharides (carbohydrates) Attached to proteins for cell signaling (cell communication)

Two Types of Transport Passive Transport Does not require energy to be used by the cell Typically involves small particles moving down the concentration gradient (high to low concentration) Active Transport Requires energy to be used by the cell to move the substance This is due to either the very large size of the item OR that the cell is moving it against (up) its concentration gradient (low to high)

Solutions Solution: a well mixed mixture Solute: what is mixed into the solution Solvent: what the solute is mixed into

Passive Transport Diffusion The movement of a substance from HIGH concentration to LOW concentration Facilitated diffusion: diffusion through a protein channel

Passive Transport Osmosis: the diffusion of water across a semi-permeable membrane

Tonicity Hypertonic: when one solution has more solute than the other Hypotonic: when one solution has less solute than the other Isotonic: when both solutions have the same amount of solute Dynamic Equilibrium: all solution pairs attempt to reach an isotonic state of equilibrium, particles are constantly moving

Tonicity

Tonicity 80% water 20% Na. Cl 90% water 10% Na. Cl Which way will the salt move…in or out of the cell? Which way will the water move…in or out of the cell?

Tonicity 92% water 8% Na. Cl 90% water 10% Na. Cl Which way will the salt move…in or out of the cell? Which way will the water move…in or out of the cell?

Tonicity 82% water 18% Na. Cl Which way will the salt move…in or out of the cell? Which way will the water move…in or out of the cell? What do we call these two solutions?

Tonicity A cell in a hypotonic solution could take in so much water that it bursts This is known as lysis (cell dies) A cell in a hypertonic solution could lose so much water that it significantly shrinks This is called plasmolysis and can lead to cell death

Tonicity

Active Transport Endo/exocytosis p. 122 Aka phago (solids) & pinocytosis (liquids) The movement of very large substances with the use of microfilaments under the cell membrane and vacuoles/vesicles Protein carriers Aka protein pumps Carries substances up (against) their concentration gradient (from LOW concentration to HIGH concentration)

Endocytosis A form of active transport Substance is too large to go through normal cell membrane channels Microfilaments help cell to move around the substance and engulf it Phagocytosis vs. Pinocytosis Amoeba eating using endocytosis: http: //www. youtube. co m/watch? v=W 6 rnhi. Mx t. KU