UNIT 1 MICROSCOPES THEIR PARTS Cells were invisible

UNIT 1

MICROSCOPES & THEIR PARTS

Cells were invisible to the naked eye until microscopes were invented in the 1600’s. � Robert Hooke (1665) � First to identify and name cells Anton van Leeuwenhoek (1674) First to describe living cells by looking at pond water � Schleiden & Schwann (1838 -1839) First to note that both plants and animals are made of cells

The lens through which you look into a microscope

Part by which the microscope is carried

The movable surface on which slides are placed

Used for general focusing of microscope

Used for fine detailed focusing of a microscope

Part on which the microscope rests. Also held when carrying the microscope from place to place.

Source of light found near the base of the microscope. The light source makes the specimen easier to view.

Controls the amount of light that enters through the stage

Holds the slides in place

Composed of a low power, medium power, high power, and oil immersion lens. Used to view specimens at different magnifications.

Revolving circular structure containing objective lenses.

3. 1 CELL THEORY & PROKARYOTIC VS. EUKARYOTIC CELLS

� All living things are made of one or more cells � Cells are the basic units of structure and function in all organisms � All cells come from preexisting cells

� “Pro” = before � Contains “Karyote” = nucleus no nucleus � DNA is found in the cytoplasm � Contains no membrane bound organelles � All are single celled

� “Eu” = true � Contains “Karyote” = nucleus a nucleus where DNA is found � Contains membrane bound organelles � May be single celled or multicellular

3. 2 CELL ORGANELLES & FUNCTION

• Cell Membrane • Golgi Apparatus • Cytoplasm • Vesicle • Cell Nucleus & Nucleolus • Vacuole • Ribosome • Mitochondria • Endoplasmic Reticulum Plant Cell • Animal Cell

� Structure § 2 rows of lipids and protein molecules � Location § Outside perimeter of cell � Function § Regulates movement of substances in and out of the cell

� Structure § Jelly-like matrix interior containing molecular building blocks � Location § Enclosed inside the cell membrane in which all organelles are found � Function § Maintains the shape of the cell and “provides a home” for all organelles

� Structure § Nucleus: Membrane bound organelle containing pores. Also carries genetic information known as DNA. § � Nucleolus: Non-membrane bound structure Location § Nucleus: Found within the cytoplasm § Nucleolus: Found within the nucleus ** Only found in Eukaryotic Cells** � Function § Nucleus: Protects the DNA “blueprint codes” and regulates cellular activities § Nucleolus: Responsible for ultimately producing ribosomes

INTERESTING FACT! If the nucleus were the size of a penny then the rest of the cell would be the size of a football field!

� Structure § Composed of a large and small subunits made of proteins and nucleic acids � Location § Found loose in the cytoplasm or attached to the Rough Endoplasmic Reticulum (RER) � Function § Make proteins from all amino acids once attached to RER

� Structure § Rough ER: twisted, flattened tube network studded by ribosomes § Smooth ER: branching, rounded tube network not studded with ribosomes � Location § Rough ER: at or around the nucleus § Smooth ER: towards the outside of the rough ER � Function § Rough ER: site of protein synthesis § Smooth ER: detoxifies harmful substances and produces lipids

� Structure § Series of flattened, slightly curved membrane sacs � Location § Near the nucleus and ER � Function § “Shipping Center”. Packages and sorts proteins and lipids into vesicles for transport in and out of the cell.

� Structure § Small, membrane bound sacs � Location § Anywhere, but usually near the golgi body � Function § Temporary storage of cell material for transport in and out of the cell

� Structure § Fluid filled sac � Location § In animal cells: small size & random placement § In plant cells: one LARGE central vacuole � Function § In plant & animal cells: temporary storage of food, water, minerals, and wastes § In plant cells only: serves as structural support for the cell

� Structure § Kidney bean shaped with two membranes. § Outer membrane is smooth § Inner membrane that is made up of curves and folds **Contains its own DNA codes inside that are maternal** � Location § Randomly located inside of cytoplasm � Function § Provides energy for the cell. Usually referred to as the “Power House”. § Inner membrane (cristae) converts glucose into ATP

§ Lysosomes § Centrioles Animal Cell

� Structure § � � Membrane bound organelles that contain enzymes Location § Randomly located throughout the cytoplasm Function § Contains enzymes that destroy foreign particles in the cell § § Digests worn-out organelles, food molecules, viruses, and bacteria Cells “Garbage Disposal System”

� Structure § � � Cylinder shaped organelles, made of microtubules arranged in a circle Location § Found near the nucleus, but only seen when cell is undergoing division Function § Aids in cell division

§ Cell Wall § Chloroplast

� Structure § � � Thick layers of cellulose fibers which form a rigid shape Location § Outside the cell membrane Function § Helps give the cell shape, support, protection, AND connects them to neighboring cells

� Structure § Highly compartmentalized. Composed of an outer and inner membrane & disc shaped sacs ** Contains its own DNA codes within plants ** � Location § Random in cytoplasm but usually closer to cell membrane Function § Responsible for photosynthesis § Converts light energy to chemical energy § Contains chlorophyll which is responsible for plant pigment �

3. 3 CELL MEMBRANE

� Made of a phospholipid bilayer: two parallel rows of phospholipids • The heads face outward • The tails face inward � Polar head is “Hydrophyllic” = “Water loving” � Fatty Acid Tail is “Hydrophobic” = “Water fearing”

� Definition: § Allows some substances to pass across the cell membrane, but not all. � Our cell membranes are selectively permeable

3. 4 DIFFUSION AND OSMOSIS

� Definition: The mass of a solute in a given amount of solution, or mass/volume. (Example: 12 g of sugar per 3 L of water = 4 g/L concentration) � �Example: Which picture below has the greatest concentration of red dye?

� Definition: � The movement of gas or liquid molecules across a membrane from high to low concentration. � How diffusion works: � Lipids diffuse easily across the membrane (like dissolves like) � Small particles with NO charge like O 2, CO 2, and H 2 O diffuse easily across the membrane � Process continues until an equilibrium is achieved [inside cell] = [outside cell]

� Definition: § The diffusion of WATER across a selectively permeable membrane � Water flow across a cell membrane depends on the solute concentration of the surrounding liquid 1) H 20 moves from: high water concentration low water concentration 2) “Salt Sucks”: H O is attracted toward the high concentration of solutes 2

1) Isotonic Solution 2) Hypotonic Solution 3) Hypertonic Solution

�Refers to two solutions having the same concentration. � � A cell in an isotonic solution will have the same amount of water going in and coming out. No net gain or loss of water.

� Refers to a less concentrated solutions � Hypotonic solutions have less solute and more water. �Therefore cells bathed in hypotonic solutions gain water and increase in size.

� � Refers to a more concentrated solution. Hypertonic solutions have more solute and less water. �Therefore cells bathed in hypertonic solutions lose water and shrink in size.

Why could drinking too much sea water be dangerous?

Based on the basic principles of diffusion and osmosis! As the salt water solution enters your body, the cells near the solution release water in order to reach equilibrium with the surrounding fluid. The cells then shrink and may die out. This is a condition called dehydration!

� Which cell is in a Hypertonic solution? � Which cell is in an Isotonic solution?

3. 4 ACTIVE & PASSIVE TRANSPORT, FACILITATED DIFFUSION, ENDOCYTOSIS, EXOCYTOSIS

� Molecules can freely move across the cell membrane at any time from High to Low concentration � Moves by concentration gradient = NO ATP needed

� Molecules are “FORCED” across the cell membrane from Low to High concentration � AGAINST the concentration gradient = ATP energy needed

� The diffusion of molecules across the cell membrane using the help of transport proteins

� Process of taking liquids or fairly large molecules into a cell by engulfing them in a membrane (comes from a piece of the cell membrane)

� Release of substances out of a cell by the fusion of a vesicle with the cell membrane