Lab 3: Cellular Structure and Function
What is the basic unit of life? The simplest form of life is the cell! All living things are either: unicellular (only one cell) multicellular (many cells make one organism) We never think about it, but we are made of probably trillions of cells!
Inner Life of a Cell 3 minute version 8 minute version
Review from Lab 2 Last week we mentioned a few key terms: Plasma membrane a double membrane, outer barrier of a cell, it controls what goes in or out Cytosol liquid-like substance that fills the cytoplasm Organelles term for membrane-bound structures in cell We also mentioned one common organelle: Nucleus membrane-enclosed storage area and processing center for genetic information (e.g.: DNA)
The 2 main types of cells All living cells can be split into two groups: Prokaryotic ( Pro = before, karyon = kernel) Eukaryotic ( Eu = true) One main difference between the two is whether or not they have a nucleus!
Prokaryotic vs. Eukaryotic Cells PROKARYOTIC EUKARYOTIC Genetic information is found in Nucleoid region Nucleus Does it have membrane-bound organelles? NO YES Ribosomes? Chromosomes? YES YES
Which cells are Prokaryotic? Which are Eukaryotic? PROKARYOTIC Bacteria Archae EUKARYOTIC Animal cells Plant cells Fungi Protists (like Euglena)
Parts of the eukaryotic cell Nucleus Nucleolus: area of concentrated chromatin, RNA and proteins. Produces ribosome components. Nuclear envelope: encloses nucleus in double membrane with nuclear pores and is attached to Endoplasmic Reticulum.
Nuclear Envelope and ER attached
Parts of the eukaryotic cell Endoplasmic Reticulum (ER) Channels and canals that create and modify proteins and lipids. It also makes vesicles for transport. Rough ER Smooth ER Ribosome: Protein factory, seen both bound to Rough ER and free in the cytosol.
Types of Endoplasmic Reticulum Rough ER Attached to nuclear envelope Ribosomes attached Makes proteins Smooth ER Makes lipids: oils, phospholipids, and steroids (hormones) Detoxification Helps flush out drugs and poisons.
Parts of the eukaryotic cell Mitochondrion: power plants that carry out cellular respiration and produce ATP (energy).
Parts of the eukaryotic cell Golgi apparatus: The Post Office Processing center that accepts lipids and proteins from ER. Modifies, re-packages and distributes lipids/proteins in vesicles cannibalized from its own membrane.
Parts of the eukaryotic cell Vacuoles and vesicles: storage containers Lysosomes: Recycling centers, vesicle containing hydrolytic enzymes that break down proteins, nucleic acids, lipids, and carbohydrates. Release their enzymes by fusing with vesicles /organelles.
Parts of the eukaryotic cell Cytoskeleton: Maintain cell shape and can act like highways to assist internal movement of cell parts. Microtubules Intermediate Filaments Actin Filaments Cilia and Flagella: On surface of the cell, help the cell move in its environment
Animal vs. Plant Cells Since both are eukaryotic = both have organelles But some organelles and cell structures are specific to animals or plants: Cell wall (plant) Chloroplast (plant) Centrioles (animal) Size of vacuole
Animal Cells Centrioles: A pair are found in the centrosome of animal cells and made of microtubules. However its function is unknown.
Plant Cells Cell wall: rigid outer layer that maintains shape of the plant cell and protects from damage. Made of cellulose. Large central vacuole: used for storage & to breakdown waste molecules Chloroplast: turns sunlight to sugar molecules for energy (photosynthesis).
Diffusion The movement of molecules from high to low concentration until reaching equilibrium. See Figure 3.6 on page 29 Equilibrium: state in which molecules are moving back & forth in equal amounts & speed. Net change = 0
Osmosis The same concept of diffusion! However it specifically means diffusion of water across the plasma membrane.
Tonicity Compare the relative concentration of solute (particles) and solvent (water) outside of the cell to inside of the cell. A solution is either: Isotonic: Conc. outside & inside are the same Hypertonic: Less water (more solute) outside cell Hypotonic: More water outside the cell
Tonicity
Experimental Procedure: Diffusion across Plasma Membrane Dialysis bag: semi-permeable membrane Benedict s reagent: detects reducing sugars (monosaccharide/disaccharides). If it is heated and a red/yellow precipitate forms then glucose is present. Iodine: detects starch & turns dark (blue/black)
Experimental Procedure: Diffusion across Plasma Membrane Iodine Blue: Starch Red: Glucose