The sum of all chemical reactions that occur in the body it can be broken down into catatonic and anabolic reactions.
Catatonic reactions are
Reactions where large chemicals are broken down and energy is released.
Anabolic Reactions are
Reactions where large chemicals are built and energy is used.
What is ingestion?
The acquisition of food and other raw materials.
What is digestion?
The process of converting food into a usable form so that it can pass through the membranes in the digestive tract and enter the body
What is absorption?
The passage of nutrient molecules through the lining of the digestive tract into the body proper. They are absorbed through the cells lining the digestive tract through active transport or diffusion.
What is transport?
The circulation of essential compounds required to nourish the tissues and the removal of waste products from the tissues.
What is Assimilation?
The building of new tissues from digested food materials.
What is Respiration?
The consumption of oxygen by the body.
What is Excretion?
The removal of waste produced during metabolic processes like respiration and assimilation.
What is synthesis?
The creation of complex molecules from simple ones (anabolism)
What is regulation?
The control of physiological activities.
What is homeostasis?
The body's metabolism fxns to maintain its internal environment in a changing external environment. This is regulated by hormones and the nervous system.
What is irritability?
The ability to respond to stimulus and is a part of regulation.
What is growth?
An increase in size causes by a synthesis of new materials
What is reproduction?
The generation of additional individuals of a species.
What are enzymes?
Enzymes are organic catalysts.
What are catalysts?
Any substance that affects the rate of a chemical reaction without being changed itself.
How do enzymes work?
Then regulate metabolism by slowing down or speeding up certain chemical reactions. They affect the reaction rate by lowering the activation energy.
What is activation energy?
the minimum quantity of energy that the reacting species must possess in order to undergo a specified reaction.
What does 'enzymes are selective' mean?
Enzymes may catalyze only one reaction or lone specific class of closely related reactions.
What is a substrate?
The molecule upon which an enzyme acts.
What is an active site?
The active site is a spot on an enzyme that the substrate binds to.
What are the 3 rules of an enzyme?
1. Enzymes do NOT alter the equilibrium constant.
2. Enzymes are NOT consumed in the reaction. They will be in both the products and reactants.
3. Enzymes are pH and temperature sensitive, with optimal activity at specific pH ranges and temps
What is the lock and key theory?
This theory states that the spatial structure of the enzymes active site is exactly complementary to the spatial structure of its substrate. This theory has been largely discounted.
What is the induced fit theory?
This theory suggests that the activation site has flexibility. When the appropriate substrate comes in contact with the active site, the confirmation of the active site changes to fit the substrate.
Are most enzyme reactions reversible?
Yes the product synthesized by an enzyme can be decomposed by the same enzyme.
What affects the rate of an enzymatic reaction?
Temperature, pH and the concentration of enzyme and substrate.
How does temperature effect enzyme activity?
As temperature increases enzymatic activity increases until it reaches an optimal temperature. After this point additional heat alters the activation site until the enzyme is deactivated leading to a rapid decline in activity.
How does pH affect enzyme activity?
For each enzyme there is an optimal pH, above and below that enzymatic activity declines (think bell curve)
What is the typical optimal pH for enzymes in the human body?
What is an example of an enzyme that works in a highly acidic condition and where can it be found?
Pepsin works at a pH of 2, and is found in the stomach.
Where are enzymes found that function in basic conditions and what is their typical optimal pH?
Pancreatic enzymes found in the small intestines and their optimal pH is 8.5.
What happens when you increase the substrate concentration?
Increasing the concentration rate will increase the reaction rate until all the active site are filled. After this point further increases in substrate concentration will have no effect on the reaction rate.
Explain competitive inhibition.
If a molecule similar to and has comparable concentration relative to the substrate they will compete for the active site on the enzyme. The enzyme activity is thus for inhibited by the inactive substrate or competitor.
What is noncompetitive inhibition?
When a substance forms strong covalent bonds with the enzyme and can not be displaced by the addition of excess substrate. It is irreversible. The inhibitor can be bound at, near or remote from the activation site.
In noncompetitive reactions, what is it called when the inhibitor binds to a place other than the activation site?
Allosteric inhibition (allosteric meaning "other site" or "other structure") This changes the structure of the enzyme and also the structure of the activation site.
What are hydrolysis reactions?
Digest larger molecules into smaller components.
What is a lactase reaction?
When lactase hydrolyzes lactose into it's monosaccharides glucose and galactose.
What does protease do?
Breaks down proteins into amino acids.
What does lipase do?
Breaks down lipids to fatty acids and glycerol.
What are synthesis reaction?
When small molecules are combined to make big molecules.
Why are synthesis reactions necessary?
Growth, repair, regulation, protection, and production of food reserves such as fat and glycogen.
What are cofactors?
A nonprotein molecule the many enzymes require to become active. They can be metal cations such as Zn2+ or Fe2+ or small organic groups called coenzymes.
What is a prosthetic group on an enzyme?
A cofactor that binds to the enzyme by strong covalent bonds.
What are the 5 parts of cell theory?
1. All living things are composed of cells.
2. The cell is the basic functional unit of life.
3. The chemical reactions of life take place inside the cell.
4. Cell arise only from pre-existing cells.
5. Cells carry genetic information in the form of DNA. The genetic material is passed from parent cell to daughter cell.
What is the cell membrane?
A selectively permeable barrier that encloses the cell, regulating what materials pass in and out of the cell.
What does the fluid mosaic model describe?
The phospholipid bilayer with proteins embedded through out the lipids and proteins can move freely within the membrane.
How is the phosopholipid bilayer structured?
Hydorphobic "fatty" chains of carbon and hydrogen face each other; with the phosphorus-containing, polar, hydrophilic heads facing outward.
What the different types of molecules that can pass through the cell membrane and how?
The membrane is readily permeable to small nonpolar hydrophobic molecules like oxygen and small polar molecules like water. Small charged particles can usually cross through protein channels. Charged ions and larger charged molecules cross the membrane with the assistance of carrier proteins.
What is the nucleus and what is its function?
The nucleus controls the activities of the cell. it is surrounded by a nuclear membrane and contains the DNA. It also contains the nucleolus.
How is the DNA contained in the nucleus?
The DNA is held together by proteins called histones to form chormosomes.
What is the function of the nucleolus and where is it located?
It is located in the nucleus of the cells and is the site of ribosomal RNA (rRNA) synthesis.
What is a Ribosome?
Ribosomes are the site of protein synthesis. They can be found in the cell cytoplasm or attached to the endoplasmic reticulum.
What is the Endoplasmic Reticulum?
The ER is a network of membrane-enclosed spaces involved in the transport of materials throughout the cell, mostly those to be secreted by the cell.
What is the Golgi Apparatus?
The golgi receives vesicles and their contents from the smooth ER, modifies them, repackages them then send them to the cell surface via exocytosis.
What is the mitochondria?
Mitochondria are the site of aerobi respiration within the cell and the supppliers of energy. They have a double membrane.
What is the cytoplasm of the cell?
This is where most of the cells metabolic activity occurs. Transport within the cytoplasm is called cyclosis.
What are vacuoles and vesicles?
These are membrane-bound sacs involved in the transport and storage of material ingested,secreted, processed or digested by the cell. Vacuoles are larger and vesicles are more likely to be found in plant than in animal cells.
What are centrioles?
These are involved in spindle formation during cell division. Animal cells usually have a pair located in the centrosome. Plant cells do not have centrioles.
What are lysosomes?
Vesicles involved in breaking down molecules for digestion using hydrolytic enzymes.
What is autolysis?
When an injured or dyint tissue "commits suicide" by rupturing the lysosome membrane and releasing it's hyrdolytic enzymes.
What is the cytoskeleton?
It supports the cell, maintains it's shape and fxns in cell motility, It is composed of microtubules, microfilaments, and intermediate filaments.
What are microtubules?
Hollow rods made up of polymerized tubulin that radiate throughout the cell and provide it with support. The provide the framework for organelles to move around.
What other structures are made up of microtubules?
Centrioles. Also flagella and cilia which are involved with cell movement and cytoplasmic movement they are extended from certain cells.
What are microfilaments?
Solid rods of actin. They are important in cell movement and support. They move stuff across the plasma membrane.
What is simple diffusion?
The movement of dissolved particle down their concentration gradient, requires no external energy.
What is osmosis?
The simple diffusion of water from a region of lower solute concentration to a region of higher solute concentration.
When the cytoplasm of a cell has a lower solute concentration than the extracellular medium it is hypertonic, the water will flow out of the cell causing it to shrivel and is called plasmolysis.
When the outer region is less concentrated than the inside of the cell causing water to enter the cell, causing the cell to swell and lyse.
What is facilitated diffusion?
The net movement of dissolved particles down their concentration gradient through special channels or carrier proteins in the cell membrane, does not require energy.
What is active transport?
Movement of molecules up their concentration gradient with the help of transport proteins, requires energy.
What are several carrier molecules involved in active transport? (4)
1.Energy independent carriers-facilitate the movement of compounds along a concentration gradient
2.Symporters-move two or more ions or molecules
3.Antiporters-exchange one or more ions(or molecules) for another ion or molecule
4, Pumps-energy dependent carriers (require ATP) e.g. NA-K pump
What is endocytosis?
Whe the cell membrane invaginates, forming a vesicle that contains extracellular medium.
What are two types of endocytosis?
Pinocytosis the ingestion of fluids or small particles. Phagocytosis the engulfing of larger particles.
What is exocytosis?
When a vesicle fuses with the cell membrane releasing its contents outside of the cell. May play an important role in cell growth and.or intercellular signalling.
3 types of intracellular circulation, GO
1. Brownian Movement-keinetic energy spreads small suspended particles throughout the cytoplasm of the cell
2. Cyclosis or streaming- The circular movement of cytoplasm around the cell transport molecules
3. ER- This provides channels throughout the cytoplasm and provides a direct continuing passageway from the plasma membrane to the nuclear membrane.