Bell work 11/14 What type of microscope would you use to view a sample of live microorganisms in pond water? Nothing to do with Microscopes… I’m Just adorable.

Cell theory 1665- Robert Hooke used an early compound microscope to look at a thin slice of cork Cork seemed to be made of thousands of tiny, empty chambers Hooke called these chambers “cells”

Cell Structure and Function Unit 3

Cell theory Anton van Leeuwenhoek Used a single lens microscope to observe pond water and other things Saw a tiny world of living things

Cell theory 1838- Matthias Schleidan concluded that all plants were made of cells 1839- Theodore Schwann stated that all animals were made of cells

Cell theory 1855- Rudolf Virchow concluded that new cells could be produced only from the division of existing cells

Cell theory All living things are composed of cells Cells are the basic unit of structure and function in living things New cells are produced from existing cells

Diversity Cells come in a variety of shapes and sizes Typical cell ranges from 5-50 micrometers Tiniest- .2 micrometers Largest- 1000 micrometers Common characteristics: Surrounded by a cell membrane Contain DNA at some point in their lives

Eukaryotes Cells that contain a nucleus Nucleus- a large membrane- closed structure that contains the cell’s genetic material in the form of DNA Usually larger and more complex Ex: Plants, animals, fungi, and protists

Prokaryotes Do NOT have a nucleus Generally smaller and less complex than Eukaryotes Still carry out all of the characteristics of life

What are the characteristics of life?? Prokaryotes Do NOT have a nucleus Generally smaller and less complex than Eukaryotes Still carry out all of the characteristics of life What are the characteristics of life??

Cell boundaries Cell membrane- The thin, flexible barrier surrounding a cell Cell wall- A strong, supporting layer outside the cell membrane Provides support and protection for the cell Made from fibers of carbohydrates (cellulose) and protein

What is the function of the lipid bilayer? A flexible structure that forms a strong barrier between the cell and its surrounding What is the function of the lipid bilayer?

Lipid bilayer Regulates what enters and leaves the cell A flexible structure that forms a strong barrier between the cell and its surrounding Regulates what enters and leaves the cell Provides support and protection

Why is the cell membrane often called the fluid mosaic model?

Mosaic Model Other membranes embedded in the lipid bilayer Proteins Carbohydrates

Diffusion What is diffusion?

Bell work 11/15 What is diffusion?

Diffusion Particles tend to move from an area of HIGH concentration to an area of LOW concentration Equilibrium- when the concentration of the solute is the same throughout a system

Measuring concentration The cytoplasm of cells contains a solution of many different substances in water Concentration- mass of solute/volume of solution Review What is solute and solution?

Measuring concentration Example: Pairs of 2 If you dissolved 12 grams of salt in 3 liters of water, what is the concentration of salt in the solution? Suppose you added 12 more grams of salt to the solution, what would be the resulting concentration? What then if you added another 3L of water to that solution? Which solution of the ones discussed would be called the most concentrated?

Facilitated Diffusion Facilitated Diffusion- molecules that cannot diffuse across the cell membrane’s lipid bilayer on their own move through protein channels instead to help. Example: Glucose Moves from a HIGHER concentration to a lower concentration Does NOT require energy!

Facilitated Diffusion

Active transport Active transport- cells move AGAINST the concentration gradient Requires ENERGY! Active transport of small molecules is generally carried out by transport proteins or “pumps”

NA+/ K- Pump

Endo/Exocytosis Large molecules can be actively transported across the membrane by endocytosis and exocytosis. Endocytosis- the process of taking material INTO the cell by means of infoldings, or pockets, of the cell membrane. Exocytosis- the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents OUT of the cell.

Endo/Exocytosis

Phagocytosis Phagocytosis or “cell eating”- extensions of cytoplasm surround a particle and package it within a food vacuole

Pinocytosis Pinocytosis- tiny pockets form along the cell membrane, fill with liquid, and pinch off to form vacuoles within the cell

Selective permeability Most biological membranes are selectively permeable What does this mean?

Selective permeability Some substances are too large or too strongly charged to cross the lipid bilayer If a substance IS able to cross the membrane, it is said to be permeable to it.

What is happening here?

What is the difference between phagocytosis and pinocytosis? Bell work 11/16 What is the difference between phagocytosis and pinocytosis?

Osmosis Osmosis- The diffusion of WATER through a selectively permeable membrane. Water tends to move across the membrane until equilibrium is reached

Osmosis Isotonic- The concentration of solutes is the SAME inside and outside the cell Hypertonic- Solution has a higher solute concentration than the cell Hypotonic- Solution has a lower solute concentration than the cell

Describe isotonic, hypertonic, and hypotonic solutions. Bell work 10/12 Describe isotonic, hypertonic, and hypotonic solutions.

Osmosis

Osmotic pressure The cell is filled with salts, sugars, and proteins. Will the water move into or out of the cell when in fresh water?

Osmotic pressure The cell is filled with salts, sugars, and proteins. Will the water move into or out of the cell when in fresh water? INTO!

Demonstration http://www.youtube.com/watch?v=OYoaLzobQmk

Osmotic Pressure Organisms must have a way to balance the intake and loss of water Osmotic pressure should produce a net movement of water into the cell, causing it to swell and eventually burst Fortunately, most cells in organisms do not come into contact with fresh water. Bathed in blood (isotonic)

Osmotic pressure What structure protects plant and bacterial cells from potential danger resulting from osmotic pressure?

Osmotic pressure Cell wall! What structure protects plant and bacterial cells from potential danger resulting from osmotic pressure? Cell wall! Other cells, such a bacteria and plant cells, that do come into contact with fresh water are protected by a cell wall

Osmotic pressure A homeowner contracts a lawn company to add fertilizer to the lawn in order to make the grass grow better. This process is normally done by spraying a mixture of fertilizers and water onto the lawn. Questions What would happen if too much fertilizer and too little water were sprayed onto the lawn? Suggest what happened to the cells of the grass. In that case, was the fertilizer-water mixture hypotonic or hypertonic compared to the grass cells?