Cells are the basic unit of life Cells Tissues Organ systems Organs Organisms
CELL THEORY 1665 – Robert Hook - Looked at cork, gave the little chambers the name “cells”
CELL THEORY 1674 – Anton Van Leeuwenhoek - first to look at living cells - saw “animalcules” or little animals
CELL THEORY 1838 – Schleiden - All plants are made of these Cells 1839 – Schwann - All animals are made of these cells 1855 – Virchow –Noticed that Cells make more of themselves.
FINAL CELL THEORY All living things are made up of one or more cells Cells are the basic unit of structure and function in living things Cells come from previously existing cells – NO spontaneous generation!
Prokaryotes Vs. Eukaryotes Prokaryotes: - literally means “before nucleus” - primitive single celled life, the first! - example: bacteria - still has DNA just not enclosed in a nucleus
Prokaryotes Vs. Eukaryotes Eukaryotes: - literally means “true nucleus” - DNA enclosed by the nuclear membrane - Can be single celled like protists (amoebas, paramecium) - Or can be part of a multicellular organism like: plants, animals or fungi
Prokaryotes Vs. Eukaryotes Eukaryotes: - significantly larger than prokaryotic cells - have many more organelles than prokaryotic cells
Electron microscopy Pros: –Significantly greater mag/res Cons: –Specimen Prep is much more involved –Specimen prep will kill specimen, no live observations
Electron microscopy *Color is added, EM’s Only see produce black And white images
All cells must perform the same few functions to stay alive BUT, since they have different organelles, they might go about it differently
I. All cells must control what enters and exits a cell II. All cells must convert the energy in nutrients to into energy it can use III. All cells must make, modify and ship proteins to where they need to go
IV. All cells must be able to store nutrients, digest large molecules and recycle damaged organelles V. All cells must grow and divide VI. All cells have a particular shape and can move IF THEY NEED TO
Why proteins? Proteins increase contact with water and act as channels through which certain molecules can pass
Why cholesterol? Cholesterol keeps the membrane fluid and flexible; prevents solidification Why Carbs? Carbohydrate chains act as cell “ID” tags.
Fluid Mosaic Model: theory that describes the composition of the membrane - Fluid because it is flexible; p-lipids and proteins can shift position - Mosaic because it is made of many small molecules that work together as a whole
Membrane acts as a semi-permeable barrier (think bouncer!) some stuff passes right through the phospholipids: - small, hydrophobic, uncharged
some stuff can’t: - ions (Na+, Cl-, K+, Ca++) - polar molecules (Sugars, Amino Acids) - large nonpolar But don’t we need these?!?! We’re getting there….
There are two general categories of transport: Passive transport: The easy way; no energy required; molecules just flow naturally across Active Transport: the hard way; energy required; molecules need to be pushed or carried across
Passive Processes: No energy needed Diffusion: Movement of solutes from areas of high concentration to areas of low concentration until concentrations are equal. Concentration Gradient = differences in Concentration
Facilitated Diffusion – movement of solute from high concentration to low concentration BUT requires transport protein to move molecule that are too big or polar to get through the bilayer on their own Glucose is too big to fit through phospholipids and will be diffused through a transport protein to get into the cell
Active Transport Cell must use energy to force molecules to move across the membrane from a low concentration to a high concentration. Usually used to move ion and since ions can not go through the phospholipids requires a transport protein
Vesicle Transport Vesicle transport is different from Diffusion, Osmosis, facilitate diffusion and active transport in that we are moving large quantities (many molecules) rather than individual molecules. The cell must package the material in a vesicle and bring it in or out of the cell depending on the goal.
Making a vesicle requires the cell to exert energy in the form of ATP, but we don’t have to concern ourselves with concentration differences. The two types of vesicle transport depend on direction - Moving materials into a cell in a vesicle is called endocytosis. Moving materials out of a cell is called exocytosis.
Bulk transport into cell Endocytosis Phagocytosis Pinocytosis (SOLIDS) (LIQUIDS)
Phagocytosis: “cell eating” large proteins, dead cells, bacteria substances WAY too big for even a protein; Making/moving a vesicle requires energy ATP
Pinocytosis: Cell drinking; bulk ingestion of liquids Particularly important in kidney and intestinal cells
Exocytosis Exocytosis – Bulk Transport out of cell Way of releasing large quantities of stuff from the cell including : Hormones, mucus and cell wastes NEEDS ATP