Module 4

A cell is the basic unit of all living things.

Complex cells with a nucleus and subcellular structures. (organelles)

Eu-: true; -karyon: nucleus

All fungi, plants, and animals (including humans) are eukaryotes

Simple cells (Pro-: before, -karyon: nucleus

Most are unicellular organisms (bacteria, Archae)

Prokaryotes don't have a true nucleus.

Their DNA is spread out through the cell and is not collected into packed structures.

They differ in some metabolic pathways from eukaryotes.

Subcellular structures. 

they are tiny organs that carry out essential cell functions.

Example: mitochondrion

because those pathogens (disease-causing organisms) are similar to our cells, with similar genes and metabolic

Plasma Membrane

Cytoplasm

Nucleus

a covering that regulates what comes into or leaves from the cell.

a mixture of water, salt, and proteins in which the organelles float.

the control center of the cell. DNA and RNA are made in the nucleus.

Covers and protects the cell.

Controls what goes in and out.

Links to other cells.

Flies a flag to identify the tissue or organ that the cell comes from, as well as the individual that the cell belongs to.

Gives the cell its shape.

Contains structural (cytoskeletal) proteins

Organells except the nucleus.

mitochondria are primitive prokaryotic cells that were "enslaved" by our eukaryotic ancestors and forced to create energy for the cell.

Mitochondria have their own DNA, which means that they can be used to determine maternal lineage.

Deoxyribonucleic acid  DNA

RNA is made in the nucleus and exported into the cytoplasm, where it carries our its work: making proteins.

Lipid "sea" with protein "icebergs" floating in it.

Proteins are integral or peripheral.

Integral: embedded in bilayer, go from one side to the other (transmembrane protein)

• Peripheral: associated with inside or outside of cell
•                inside: link cytoskeleton to membrane
•                outside: links cell to connective-tissue or
•                              to other cells

Peripheral proteins are loosely associated with the cell membrane and lie either completely on the outside or completely on the inside of the cell.

Integral proteins span the cell membrane from outside to inside the cell.

tells how easily a substance can cross the plasma membrane.

is what defines a cell.

• -the cell lets some things pass
• (water and cell nutrients must be allowed into the cell)

• -the cell does not let other things pass
• (guts of the cell should not leak out)
• (toxic substances should not leak in)

• Small uncharged molecules
• lipid-soluble substances (fat-soluble)
• gases

• charged ions
• water-soluble molecules

• ion channels
• carriers
• receptors
• enzymes
• linkers
• cell identity markers

Allows specific ion (O) to move through water-filled pore.  Most plasma membrane include specific chennels for several common ions.

Transports specific substances (O) across membrane by changing shape.  For example, amino acids, needed to synthesize new proteins, enter body cells via carriers.  Carrier proteins are also known as transporters.

Recognizes specific ligand and alters cell's function in some way.  For example, antiduretic hormone binds to receptors in the kidneys and changes the water permeability of certain plasma membranes.

Catalyzes reaction inside or outside cell (depending on which direction the active site faces).  For example, lactase protruding from epithelial cells lining your small intestine splits the disaccharide lactose in the milk you drink.

Anchors filiments insid and outside the plasma membrane, providing structural stability and shape for the cell.  May also participate in movement of the cell or link cells together.

Dinstinguishes your cells from anyone els's (unless you are an identical twin).  An important class of such markers are the major histocompatibility (MHC) proteins.