Chapter 4 Flashcards
The idea that all organisms are composed of cells is called _______
Cell theory
Nothing smaller than a cell is considered ______
Alive
Describing cell size increase. Cell volume grows much more rapidly than surface area.
Surface to volume ratio
All cells are surrounded by a delicate membrane called _____ that controls the permeability of the cell to water and dissolvable substances.
Plasma membrane
A semifluid matrix called ______ fills the interior of the cell.
Cytoplasm
When to use a light microscope.
When studying living cells, bacteria and basic structure
When to use a Electron Microscope (SEM)
Looking at surface details of tiny objects (viruses or nano particles)
When to use a Transmission Electron Microscope (TEM)
When examining internal structures of cells and molecules.
The minimum distance two points can be apart and still be distinguished as two separated points.
Resolution
Microscope’s that magnify in stages using several lenses are called _______ they can resolve structures that are separated by more than 200 nm
Compound
Encasing all living cells is a delicate sheet of molecules called the
Plasma membrane
All plasma membranes have the same basic structure of proteins embedded in a sheet of lipids called the
Fluid mosaic model
The lipid layer that forms the foundation of a plasma membrane is composed of modified fat molecules called
Phospholipids
What makes a phospholipid
A polar head(water soluble) with two non polar tails (fatty acid chains)
What happens when a collection of phospholipid molecules is placed in water ______
Lipid bilayer
A multi ringed molecule that affects the fluid nature of the membrane and is a non polar lipid molecule.
Cholesterol
The second major component of every biological membrane is a collection of __________ that float within the lipid bilayer. They function as transporters, receptors and cell surface markers.
Membrane proteins
Many membrane proteins project up from the surface of the plasma membrane like buoys often with carbohydrate chains or lipids attached to their tip like flags. They act as markers to identify particular types of cells or as beacons to bind specific hormones or proteins to the cell.
Cell surface proteins
Proteins that extend all the way across the bilayer can provide passage ways for ions and polar molecules like water so they can pass into and out of the cell.
Transmembrane proteins
How do transmembrane proteins manage to span the membrane?
The helical spiral is held within the lipid interior of the bilayer anchored there by the strong tencency of water to avoid contact with these Nonpolar amino acids
