1. 2012
How does it work?
James, Ross, Halen, Josh, Lance
Anatomy and Physiology
9/24/2012

2. Passive Transport- The movement of a chemical substance across a cell membrane without expenditure
of energy by the cell, as in diffusion. (7)
• Diffusion-The movement of atoms or molecules from an area of higher concentration to an area
of lower concentration. Atoms and small molecules can move across a cell membrane by
diffusion.(7)
• Dialysis-The separation of smaller molecules from larger molecules or of dissolved substances
from colloidal particles in a solution by selective diffusion through a semipermeable
membrane.(7)
• Osmosis-Diffusion of fluid through a semipermeable membrane from a solution with a low
solute concentration to a solution with a higher solute concentration until there is an equal
concentration of fluid on both sides of the membrane.(7)
• Facilitated Diffusion-a process whereby a substance passes through a membrane with a aid of
an intermediary or a facilitator. The facilitator is an integral membrane protein that spans the
width of the membrane. The force that drives the molecule from one side of the membrane to
the other is the force of diffusion. (6)
• Filtration-The act or process of filtering, especially the process of passing a liquid or gas, such as
air, through a filter in order to remove solid particles.(7)
Citation: Houghton, Mifflin. "The Free Dictionary by Farlex." The Free Dictionary. Farlex, n.d. Web. 24
Sep 2012. <http://www.thefreedictionary.com>.
Active Transport- This involves the use of proteins that not only facilitate the transport of substances,
but also require ATP to pump the substances in and out of the cells. Endocytosis is when the plasma
membrane extends outward and surrounds the food source while Exocytosis is the discharge of material
from vesicles at the cells surface.(8)
Examples: The gills of marine fish have cells that can remove salt from the body by pumping it into salt
water, the uptake of glucose in the intestines, and the uptake in mineral ions in root hair cells of plants.
Citation: Frank, George. "Active Transport." VBS. VBS, 01/04/2001. Web. 20 Sep 2012.
<http://staff.jccc.net/pdecell/cells/activet.html>.
Cell Metabolism- The chemical processes occurring within a living cell or organism that are necessary for
the maintenance of life. In metabolism some substances are broken down to yield energy for vital
processes while other substances, necessary for life, are synthesized.(9)
Catabolism- The metabolic breakdown of complex molecules into simpler ones, often resulting in a
release of energy
Anabolism- The phase of metabolism in which simple substances are synthesized into the complex
materials of living tissue.

3. Enzymes- Any of numerous proteins or conjugated proteins produced by living organisms and
functioning as biochemical catalysts.
Mifflin, Houghton, ed. "thefreedictionary." thefreedictionary. Houghton Mifflin Company, 2009. Web. 21
Sep 2009. <http://www.thefreedictionary.com/Enzymes>.
Protein Synthesis-Protein synthesis is a 2 part process that involves a second type of nucleic acid along
with DNA. This second type of nucleic acid is RNA, ribonucleic acid. RNA differs from DNA in two
respects. First, the sugar units in RNA are ribose as compared to DNA's deoxyribose. Because of this
difference, RNA does not bind to the nucleotide base Thymine, instead, RNA contains the nucleotide
base Uracil (U) in place of T (RNA also contains the other three bases: A, C and G).(10)
• Transcription: In the first step of protein synthesis, the 2 DNA strands in a gene that codes for a
protein unzip from each other. Similar to the way DNA replicates itself, a single strand of
messenger RNA (mRNA) is then made by pairing up mRNA bases with the exposed DNA
nucleotide bases. The top column in the table below shows 6 bases in a DNA sequence. Click on
each DNA base to see the complementary mRNA base in the bottom column.
• Translation: After the mRNA is manufactured, it leaves the cell nucleus and travels to a cellular
organelle called the ribosome (we will learn about the cell, nucleus and ribosome in the next
lesson). In the ribosome, the mRNA code is translated into a transfer RNA (tRNA) code which, in
turn, is transfered into a protein sequence. In this process, each set of 3 mRNA bases (the
mRNA base triplet is called a codon) will pair with a complimentary tRNA base triplet (called
an anticodon). Each tRNA is specific to an amino acid, as tRNA's are added to the sequence,
amino acids are linked together by peptide bonds, eventually forming a protein that is later
released by the tRNA. Using the mRNA strand we obtained above, you can generate the
complimentary tRNA/amino acid sequence by clicking on the mRNA codons in the table below.
Citation: Copyright © 1998-1999, All Rights Reserved, Anthony Carpi
The DNA double helix gif copyright Lisa Graf at MCAT
The DNA movie and CHIME molecule copyright A. Parrill & J. Gerway
"DNA Replicating Itself" copyright Access Excellence
Cell growth- Cell growth is one of the two phases of the cell life cycle.
Newly formed cells grow to maturity by synthesizing new molecules and organelles g1 and g2 phases.
Including the replication of an extra set of DNA molecules in anticipation of reproduction s phase.
Cell reproduction- The 2nd phase of cell life is cell reproduction, cells reproduce by splitting themselves
into two separate cells. One parent cell becomes two daughter cells. Splitting the plasma membrane and
cytoplasm is called cytokenesis. Each cell gets a complete set of the dna from the mother cell.