APHY 101: CH 3 - Overview

what are the smallest units that possess the characteristics of life?

cells

example of cells moving independently

blood cells in blood plasma

example of cells being a part of a larger structure

cells of the liver

cells are measured in …

micrometers

what is a differentiated cell?

one that has developed specialized characteristics

what are the three major parts of a cell?

nucleus, cytoplasm, and cell membrane

nuclear membrane

the thin membrane that encloses the nucleus

nucleus

contains genetic material (DNA) which directs the cell’ functions

cytoplasm

includes specialized structures called cytoplasmic organelles that are suspended in a liquid called cytosol

organelles

any of the structures in cells that has a specialized function

cytosol

fluid portion of the cytoplasm

which major part is missing in an erythrocyte?

nucleus

cell membrane

the outermost limit of a cell that separates the two major fluid compartments; intracellular and intracellular fluid

intracellular fluid (ICF)

or cytosol

within a cell

extracellular fluid (ECF)

outside a cell

selectively permeable

membrane that allows some types of molecules through but not others

signal transduction

series of biochemical reactions that allows cells to receive and respond to messages reaching the cell membrane

what molecules are permeable and can easily pass through the phospholipid bilayer?

molecules soluble in lipids

ex: oxygen, carbon dioxide, and steroid hormones

what molecules are impermeable and can not easily pass through the phospholipid bilayer?

molecules soluble in water

ex: amino acids, sugars, proteins, nucleic acids, and various ions

receptors

respond to extracellular signals

pores, channels, carriers

transport small molecules and ions; transduce signals

enzymes

catalyze chemical reactions

cell surface proteins

establish self

cellular adhesion molecules

enable cells to stick to each other

integral protein

extends into the lipid bilayer and may protrude from one or both sides

transmembrane protein

an integral protein that extends through both sides of the lipid bilayer

has a hydrophilic (polar) region that faces the fluid on both sides

has a hydrophobic (nonpolar) region in the middle

peripheral protein

associate with one side of the bilayer rather than being embedded within it

often attached to a transmembrane protein and to the cytoskeleton

aquaporins

pores that admit water into the cell

channels

highly selective membrane proteins that are specific to only particular types of ions

ex: nerve/muscle cells have selective channels in their cell membrane that control movements of Na+ and K+

carrier proteins

bind solutes and bring them into cells

ex: glucose molecules