Definitions
A~B~C~D~E~F~G~H~I~J~K~L~M~N~O~P~Q~R~S~T~U~V~W~X~Y~Z
ACID
~ A molecule that can contributes a proton
(H+) to a solution.
ACTIVE
TRANSPORT ~ Movement of a molecule across
a membrane that requires a protein and cell energy from ATP.
AMINO
ACIDS ~ One of the twenty small molecules
with both an amine (NH2)
group and an acid (COOH) group that are the building blocks of proteins.
ATP SYNTHASE
~ An enzyme in mitochondria that leads to
making ATP (cell energy).
CELL
MEMBRANE ~ An organelle that is a bilayer
of phospholipid molecules with inserted proteins. It acts as a gateway
and a barrier for the cell. The cell membrane keeps certain molecules
out and lets certain molecules in.
CYTOPLASM
~ The gel-like salt water solution inside
the cell membrane in which the cell's organelles are suspended.
DIFFUSION
~ Movement from a high concentration to a
low concentration across a membrane. Diffusion of some molecules
occurs across the lipid bilayer and diffusion of other molecules occurs
with the help of a special protein. Diffusion does not need energy
from the cell.
DNA~(deoxyribonucleic
acid) Nucleotides that store genetic information and are found in the nucleus.
ENDOPLASMIC
RETICULUM ~ (E.R.) An organelle that is the
site of the synthesis of certain molecules and is part of the cell's highway
system.
GOLGI
APPARATUS ~ An organelle composed of hollow
curved sacs that modifies proteins and packages them into vesicles for
the cell's highway system.
IONS
~ Atoms with positive or negative charges. Often part of a salt (like
Na+ or Cl- from NaCl.)
LYSOSOMES
~ Small spherical organelles that contain
digestive enzymes to break down many molecules (similar to the digestive
system in the body).
MITOCHONDRIA
~ The organelles where ATP (cell energy) is
made (the cell's powerhouse).
NUCLEOLUS
~ Contains genes that direct synthesis of
ribosomal RNA.
NUCLEUS
~ The control center of the cell that contains
DNA that directs all functions of the cell.
ORGANELLES
~ Assorted structures that each do one or more of the cell's functions.
OSMOSIS
~ The movement of water from a high concentration
of water to a low concentration of water across a membrane.
PHOSPHOLIPIDS
~ Make up the fat portion of cell membranes.
PROTEIN
SYNTHESIS ~ Assembling a protein from amino
acids.
PROTEIN
TRAFFICKING ~ Moving proteins around in the
cell (the cell's highway system).
RED
BLOOD CELL GHOSTS ~ Small pieces of broken
red blood cell membranes.
RIBOSOME
~ Granules of RNA and protein that assemble
amino acids into proteins.
RNA ~
(ribonucleic acid) Nucleotides that read the genetic information stored
in DNA and use it to direct protein synthesis.
SELECTIVELY
PERMEABLE ~ Some molecules can go through
while others cannot.
VESICLES
~ Small membrane-bound bodies that carry molecules and water around inside
the cell or to the outside of the cell (part of the cell's highway system).
Other Pages:
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~ PAGE DIRECTORY
HOT TOPIC ~ EMAIL
~ GUEST BOOK ~ QUIZ 
This page was
created by Patrick Ireland.
It was last
updated January 3, 2000
The American
Physiological Society, Education Office
9650 Rockville Pike, Bethesda, MD 20814-3991
Phone: 301-634-7132 - Fax: 301-634-7098 - Email: education@the-aps.org
