Active transport uses energy to move substances against a concentration gradient using pumps or endocytosis/exocytosis. Cell metabolism includes catabolic pathways that break down molecules and anabolic pathways that build molecules, facilitated by enzyme catalysts. Cell growth requires production of new structures and DNA replication, while cell reproduction occurs through mitosis or meiosis to form daughter cells.

1. Anatomy and Physiology
How Does It Work? Menu
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Active Transport
o “pumps”
o Endocytosis
o Exocytosis
Cell Metabolism
o Catabolism
o Anabolism
o Enzymes
Growth
o Cell growth
o Cell reproduction

2. Active Transport
Calcium Pump
Allows the cells to force nearly all the of the intra-
cellular calcium ions (Ca++) into special compart-
Active transport is when a sub-
ments or out of the cell entirely. A muscle cell can-
stance moves from an area of low
not operate properly unless the intracellular Ca++
concentration to an area of high
levels are low. concentration.
Sodium-Potassium Pump
Transports sodium ions out of cells and potassium
ions into cells. The sodium –potassium pump maintains lower
sodium concentration in intracellular fluid than surrounding
extracellular fluid. It maintains higher potassium concen-
tration in the intracellular fluid than surrounding extra-
cellular fluid.
Endocytosis
The plasma membrane traps some extracellular material
and brings it into the cell. Phagocytosis: microorganisms
are engulfed by the plasma membrane and enter the cells in
in vesicles that have been pinched off from the membrane.
Pinocytosis: “condition of the cell drinking” is a similar pro-
cess in which fluid and the substances dissolved in it enter the
cell.
Exocytosis
Is the process by which large molecules can leave the cell
even though they are too large to move out through the plas-
ma membrane.
(1)(page 9-98)

3. Cell Metabolism
Metabolic Pathway
Cell metabolism involves many different chemicals reactions that usually happen in a sequence of reac-
tions. This can be described as Catabolic- Catabolism is the kind of metabolism that breaks down mole-
cules, usually nutrient molecules, and thus releases energy rom the broken molecules. (require net out-
put energy)
Some metabolic pathways build larger molecules from smaller ones and are called anabolic pathways–
anabolism is where pathways build large, complex molecules from smaller ones. (require net input en-
ergy)
Enzymes
Are classified as functional proteins. Chemical reactions that make up the metabolic pathway can’t hap-
pen on their own. the activation energy needed to start a chemical reaction is too great for a significant
number of chemicals to react by themselves. What is needed to make a reaction happen is a catalyst. A
catalyst is a chemical that reduces the amount of activation energy needed to start a chemical reaction.
They participate in chemical reactions but are not they are not changed by the reaction. This is how en-
zymes contribute to cell metabolism.
Coenzymes
Usually enzyme molecules contain a non-protein part called cofactor which can be made up of inorganic
ions or vitamins may make up part of a cofactor. A coenzyme is a cofactor that is an organic non-protein
molecule.
Active site
This is a part of the enzyme molecule that chemically “fits” the substrate molecules. A substrate is the
molecules acted on by an enzyme molecule.
Classification and Naming of Enzymes
Oxidation– reduction enzymes: these are known as oxidases, hydrogenates, and dehydrogenases. Ener-
gy release for muscular contraction and all physiological work depends on these enzymes.
Hydrolyzing, or hydrolases: Digestive enzymes belong to this group. The hydrolyzing enzymes are
named after the substrate acted on, for example, lipase, sucrose, and maltase.
Phosphorylating: these add or remove phosphate groups and are known as phosphorylates or phospha-
tase.
Enzymes that add or remove carbon dioxide: These are known as carboxylases or decarboxylases.
Enzymes that rearrange atoms within a molecule: These are known as mutates or isomerizes.
Hydrases: These add water to a molecule without splitting it, as do hydrolases.

4. General Functions of Enzymes
Allosteric Effector: A molecule or other agent that alters enzyme function by changing its
shape.
End– product inhibition: A chemical product at the end of a metabolic pathway binds to the
allosteric site of one or more enzymes along the pathway that produced it and thereby in-
hibits synthesis of more product. This type of negative feedback mechanism in the cell that
prevents the accumulation of an extreme amount of a metabolic product.
Proenzymes: Substances that convert proenzymes to active enzymes are often called kinas-
es. They usually do their job of activating enzymes by means of allosteric effect.
Catabolism
Cellular respiration is a process in which the cell breaks down glucose (C6H12O6), or a nutri-
ent that has been converted to glucose or on of its simpler products, into carbon dioxide
(CO2) and water. Potential energy is released as the molecules break down.
3 smaller pathways that are chemically linked together to form larger catabolic pathway
(cellular respiration) are shown below:
1. Glycolysis
2. Citric acid cycle
3. Electron Transport System
Anabolism
Many anabolic or “building” pathways occur in human cells. The process of protein synthe-
sis is very important because it begins with reading the genetic “master code” in the cell’s
DNA. This influences all cell structures and functions.
Obligatory base– pairing: Adenine pairs with thymine and Guanine pairs with cytosine (or
vise versa).
Process of transcription and translation is shown below:
(1)(pages 98-107)

5. Growth
Cell Growth
Growth depends on using genetic information in DNA to make
structural functional proteins needed for cell survival. During
this phase of growth newly formed cells produce new
molecules in addition to cell membrane, fibers, and other
structures necessary in the development process. The
production of cytoplasm and plasma membrane is produced
as protein synthesis. Also DNA replication , the process in
which nucleic acid (RNA) is directly synthesized on the DNA
molecule to help enzymes. The replication of the entire set of
DNA molecule will prepare it for cell reproduction.
Cell Reproduction
Reproduction of the cells is the splitting of two separate cells.
One the parent cell, which becomes a split into the now
daughter cell. The genetic information is needed of each cell
to run them properly. Cell division also known as mitosis, the process
in which cell are organized to replication of DNA into two identical sets
that will then make one complete daughter cell. Mitosis has four
phases which include Prophase, Metaphase, Anaphase, and Telophase.
Meiosis the type of cell division that occurs only in primitive sex cells
during the becoming of mature sex cells. The primitive sex cells
become mature sex cells called gametes. Each cell receives 23
chromosomes from each parent cell making 46 total for the offspring.
(1) (pages 109-114)