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A cell is the basic unit of all living things.
Explain Eukaryotic cells
Complex cells with a nucleus and subcellular structures. (organelles)
Eu-: true; -karyon: nucleus
All fungi, plants, and animals (including humans) are eukaryotes
Explain Prokaryotic cells
Simple cells (Pro-: before, -karyon: nucleus
Most are unicellular organisms (bacteria, Archae)
How does prokaryotes differ from eukaryotes?
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.
What is an organelle
they are tiny organs that carry out essential cell functions.
Why are eukaryotes more difficult to diable or kill
because those pathogens (disease-causing organisms) are similar to our cells, with similar genes and metabolic
Eukaryotic cells have three parts, what are they?
What is the plasma membrane?
a covering that regulates what comes into or leaves from the cell.
What is cytoplasm (cytosol)?
a mixture of water, salt, and proteins in which the organelles float.
What is the nucleus?
the control center of the cell. DNA and RNA are made in the nucleus.
What is the function of plasma membrane?
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.
What is the function of cytoplasm?
Gives the cell its shape.
Contains structural (cytoskeletal) proteins
Organells except the nucleus.
What do scientists believe about mitochondria?
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.
What is thought of as our "blueprints" for the cells body?
Deoxyribonucleic acid DNA
Where is RNA made and the function?
RNA is made in the nucleus and exported into the cytoplasm, where it carries our its work: making proteins.
What are the components of the plasma membrane, as defined by fluid-mosaic model?
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
Compare peripheral and integral (transmembrane) membrane proteins.
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.
What is differential permeability
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)
What can pass through the cell membrane?
- Small uncharged molecules
- lipid-soluble substances (fat-soluble)
What can't pass through the cell membrane?
- charged ions
- water-soluble molecules
Name the six functional classes of membrane proteins.
- ion channels
- cell identity markers
Ion Channels (integral)
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.
Enzyme (integral and peripheral)
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.
Linker (integral and peripheral)
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.
Cell Identity Markers (glycoprotein)
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.