Ch. 6 - Enzymes/Digestion Flashcards
What do you need to start a reaction?
Activation energy—begins the reaction, then most reactions can produce enough energy to keep going.
What is a way to produce activation energy?
- Heat the reactants
- Use a catalyst
What is a catalyst? How does it work?
- A chemical that can regulate a reaction by lowering the activation energy required to start it, or by providing an alternate pathway for the reaction.
- A catalyst speeds up the rate of reaction but is not used up or changed during the reaction.
What is an enzyme?
A catalyst in a living system (globular (3D) proteins) that helps cells perform reactions at body temperatures. Provides alternate pathways so reactions can be controlled.
The “lock/key” needs to be different for every substrate.
How are enzymes named?
Often the name of the substrate is shortened with the ending “-ase”.
Ex:
lipid -> lipase
sucrose -> sucrase
protein -> protease
What is a substrate?
The molecule that the enzyme works on.
- Each substrate molecule combines with a specific enzyme, and the substrate is changed during the reaction, creating a new product.
- Each enzyme has a specific shape and can only combine with its specific substrate
- Part of the enzyme that binds to the substrate is called the ACTIVE SITE
How do enzymes work?
They bring the probability of reactions occuring, by bringing substrate molecules together. They bind temporarily to the active site of the enzyme.
Lock/key analogy + hydrolysis
What do enzymes sometimes need to help them work correctly?
Cofactors and co-enzymes; if this is needed, the enzyme won’t work without it.
What is a cofactor?
An inorganic substance.
Ex: Zn, Fe
What is a co-enzyme?
An organic molecule usually made from vitamins.
What will happen if there is damage to an enzyme?
It will become denatured (temporary) or coagulated (permanent)—-the protein part.
This will make the enzyme impossible to work correctly, potentially stopping important metabolic reactions in the organism.
What are the roles of vitamins and minerals for?
These are compounds that an organism needs to function.
What is a vitamin?
Organic compounds that an organism needs to function. Not an energy source, but co-enzymes.
What are minerals?
Inorganic substances that an organism needs to function. Not an energy source, but cofactors.
What are the factors that affect enzyme controlled reactions?
- Temperature
- pH
- Substrate Concentration
- Inhibitors
How does temperature affect enzyme controlled reactions?
As temperature increrase, the rate of reaction increases.
However, there is a limit, as excess heat will denature or coagulate the proteins. For most enzymes, it’s around 37, the human body temperature.
How does pH affect enzyme controlled reactions?
Each metabolic reaction has an optimum range of pH that is best for that reaction.
Ex: Pepsin has a pH of 2 in stomach
How does substrate concentration affect enzyme controlled reactions?
Greater concentration means a higher rate of do for enzyme
How do inhibitors affect enzyme controlled reactions?
Molecules that attach to enzymes can reduce their ability to bind to the substrate.
What are the two types of inhibitors?
Competitive and Non-Competitive
What is a competitive inhibitor?
It attaches to the active site of the enzyme that blocks the substrate from binding. Like a bad key inside.
Ex: CO
Bind on the active site
What is a non-competitive inhibitor?
It attaches elsewhere on the enzyme which changes its 3D shape that makes it unable to bind with the substrate.
Bind elsewhere, to the allestoric site.
How are enzymes regulated by feedback pathways?
- Negative Feedback
- Feedback Inhibition
What are the steps to digestion?
Food goes down the mouth, into the esophagus, through the cardiac sphincter, into stomach, through the pyloric sphincter into the duodenum of the small intestine where stuff from the pancreas (pancreatic duct), liver, and gall bladder (common bile duct) also come. Through ileocal valve, then goes to large intestine, into the rectum, and out.
What is digestion?
To break food down into smaller piecces.
Both physical and chemical digestion, for the purposes of absorption
What is physical digestion?
(No chemical bonds/reaction broken)
Used to make food smaller, and to create a larger surface area on which enzymes can work.
What is chemical digestion?
Enzymes break down chemical structure of food.
Chemical digestion = hydrolysis
What is absorption? What process make up it?
Moving materials from the intestine to the blood.
Includes processes of:
- Diffusion
- Osmosis
- Active Trasnport
- Facilitated Diffusion
What is diffusion?
[High] > [Low]
What is osmosis?
Water [High] > [Low]
What is active transport?
[Low] > [High] w/ATP
What is facilitated diffusion?
[High] > [Low] w/Transport Protein
What is egestion?
Removing wastes of undigested materials from the intestinal tract.
i.e. pooping
What is an exocrine function?
Gland that secretes chemicals into a cavity or onto a surface. DIRECT. Secretes substances directly into ducts that lead to the target organs or tissues.
Examples: sweat glands, salivary glands, and digestive glands like the pancreas and liver.
What is an endocrine function?
This system comprises glands that secrete hormones directly into the bloodstream. These hormones travel through the bloodstream to target cells or organs, where they regulate various physiological processes.
Glands of the endocrine system include the pituitary gland, thyroid gland, adrenal glands, and pancreas (which has both endocrine and exocrine functions).
Where does the digestive process start? Is this physical or chemical digestion?
The mouth and includes both physical and chemical digestion.
What does the teeth do? What is their process called? What is the food called after the mouth?
Part of the mouth.
- Physical digestion that is used to break down large particles into smaller ones: mastication.
- As its chewed, tounge rolls food into a smooth, lump-like mass into the back of mouth to swallow: bolus.
What do salivary glands do?
Chemical digestion that secrestes necessary saliva to begin digestion.
Saliva contains digestive enzymes, such as amylase.
What does saliva do?
Lubricates the inside of the mouth to assist in swallowing.
Also contains digestive enzymes.
What does amylase do?
Chemical digestion.
Begins the digestion of starches, breaking them into disaccharide sugar maltose.
What does the esophagus do?
Is a muscular tude that directs food from the mouth into the stomach.
What does peristalsis do?
Wave-like contractions of the muscles in an organ used to move materials. Push down = peristalsis.
It can also go in reverse.
What is reverse peristalsis?
A defense mechanism used to remove unwanted material from the stomach and esophagus (vomiting).
What does food go after the mouth “process” is done?
Stomach
What does the stomach do in digestion?
Physical and chemical digestion.
Layers of muscle -> contract to mix food along gastric juice.
Where is the stomach determined by?
Determined by the cardiac (heart) sphincter (a ring of msucles at the end of the esophagus)
What is the stomach’s composition? Use the terms mucus, rugae, and gastric pits/juice.
- Lined with mucus (to prevent acid/enzyme damage).
- Covered with ridges (called rugae) to expand easier.
- Gastric pits, which contain endocrine and exocrine glands, which produce gastric juice
What is gastric juice made of?
- Pepsininogen (and therefore, pepsin)
- Hydrochloric acid
- Rennin
- Mucus
What does pepsinogen do? Is it chemical or physical digestion?
Is an inactive enzyme to digest protein.
Requires HCl to become active into pepsin (a chemical digestive process).
What is pepsin? Why is it not secreted in this active form?
Pepsinogen + HCl = Pepsin, a protease, which digests proteins (chemical digestion). Turns proteins into short chains of amino acids.
It would digest the cells that are making it.
ONLY ACTIVATED w/HCl.
What is a protease?
Proteases are a large group of enzymes that catalyze the hydrolysis of peptide bonds in proteins and polypeptides.
Into smaller polypeptides or single amino acids
What suffix refers to an enzyme or chemical that’s inactive?
A “-ogen” suffix.
What does hydrochloric acid do? Is it chemical or physical digestion?
- Acid that causes the pH of stomach to be 1-2
- Disinegrates food, so is PHYSICAL DIGESTION
Not chemical digestion