Digestion Flashcards
What is the digestive tract also known as?
gastrointestinal tract (GI)
What is the main role of the digestive system?
metabolize food
What is the approximate length of the digestive tract in adults?
6-9 m
What is the process called that moves food through the digestive system?
peristalsis
How long does it take for food to pass through the digestive system?
1-3 days
What are the four steps of digestion?
- Ingestion
- Digestion
- Absorption
- Egestion
What is the first step in digestion?
Ingestion
What type of digestion involves chewing and stomach churning?
Mechanical
What enzyme in saliva breaks down complex carbohydrates?
amylase
What is the role of the epiglottis?
Covers the trachea during swallowing to prevent food from entering the lungs
What is the function of the esophagus?
Conveys the food bolus to the stomach via peristalsis
What is the stomach’s main role in digestion?
Storage of food, digestion, and transport of chyme to the small intestine
What is hydrochloric acid’s role in the stomach?
Kills bacteria and activates enzymes for digestion
What does pepsin do?
Breaks down long proteins into shorter chain polypeptides
What small amounts can be absorbed in the stomach?
- Water
- Medications
- Amino acids
- Some ethanol
What is the role of the small intestine?
Most absorption of nutrients occurs here
What are the three main sections of the small intestine?
- Duodenum
- Jejunum
- Ileum
What does the duodenum receive from the stomach?
Chyme, digestive enzymes from pancreas, and bile from gall bladder
Where does most nutrient absorption occur in the small intestine?
Jejunum
What is the role of the pancreas in digestion?
Releases digestive enzymes into the duodenum
What enzyme does the pancreas release for carbohydrate digestion?
amylase
What does bile help with in digestion?
Fat digestion
What stimulates the release of bile from the gall bladder?
Cholecystokinin (CCK)
What does the liver produce that assists in fat digestion?
Bile
What is the primary function of the large intestine?
Extracts water, minerals, and vitamins from waste
What are some digestive disorders to research?
- Acid Reflux
- Ulcers
- Gallstones
- Jaundice
- Cirrhosis
- Celiac disease
- Crohn disease
- Ulcerative colitis
- GERD
What are enzymes?
Enzymes are biological catalysts that speed up chemical reactions in the body.
Where are enzymes primarily found in the human body?
Enzymes are found in various locations including the digestive system, blood, and cells.
True or False: Enzymes can be used up in chemical reactions.
False: Enzymes are not consumed in the reactions they catalyze.
What is the optimal pH level for pepsin, an enzyme in the stomach?
The optimal pH level for pepsin is around 1.5 to 2.
Fill in the blank: Enzymes that work best in alkaline conditions are typically found in the _______.
small intestine.
What role do enzymes play in digestion?
Enzymes break down food into smaller molecules that can be absorbed by the body.
Which enzyme is responsible for breaking down carbohydrates?
Amylase.
What is the pH range of saliva, where amylase is active?
The pH range of saliva is typically around 6.5 to 7.5.
True or False: All enzymes have the same optimal pH.
False: Different enzymes have different optimal pH levels depending on their location and function.
What is the function of lipase?
Lipase is an enzyme that breaks down fats into fatty acids and glycerol.
Where is lipase primarily produced?
Lipase is primarily produced in the pancreas.
What is the effect of temperature on enzyme activity?
Increased temperature generally increases enzyme activity up to a certain point, beyond which the enzyme may denature.
Multiple Choice: Which enzyme is active in the acidic environment of the stomach? A) Amylase B) Pepsin C) Lipase
B) Pepsin.
What are the products of the enzyme lactase breaking down lactose?
The products are glucose and galactose.
Fill in the blank: Enzymes are proteins that can be denatured by extreme _______.
temperatures or pH levels.
What is the primary role of the human digestive system?
To exchange energy and matter with the environment.
What systems work together to maintain internal equilibrium in the human body?
Circulatory and defence systems.
How does the excretory system help maintain internal equilibrium?
Through the exchange of energy and matter with the environment.
What is the role of the motor system in the body?
To assist in the function of other body systems.
What are macromolecules?
Large, biologically important molecules obtained from food.
What are the four groups of macromolecules?
- Carbohydrates (sugars)
- Lipids (fats)
- Proteins
- Nucleic acids (DNA)
What is polymerization?
The creation of a polymer from monomers.
What reaction builds polymers from monomers?
Condensation/dehydration reactions.
What is hydrolysis?
The process of breaking down polymers into monomers.
What is metabolism composed of?
Anabolism and catabolism.
What is the main monosaccharide needed for cellular respiration?
Glucose.
What is the formula for monosaccharides?
C_nH_{2n}O_n.
What are disaccharides?
Carbohydrates formed from two monosaccharides.
What are the main types of disaccharides?
- Sucrose
- Maltose
- Lactose
What is a polysaccharide?
A complex carbohydrate formed from many monosaccharides.
What is the test for reducing sugars?
Benedict’s test.
What color does Benedict’s reagent turn in the presence of reducing sugars?
From blue to orange/red.
What is the test for starch?
Iodine test.
What color change indicates the presence of starch?
Blue-black.
What are lipids primarily used for?
Energy storage and cell membranes.
What are the two main components of lipids?
- Glycerol
- Fatty acids
What is the difference between saturated and unsaturated fatty acids?
- Saturated: single bonds, solid at room temperature
- Unsaturated: one or more double bonds, liquid at room temperature
What is the test for lipids?
Translucence test and Sudan IV test.
What does the Biuret test detect?
Proteins.
What color change indicates the presence of proteins in the Biuret test?
Blue to purple.
What are vitamins and minerals essential for?
The structure and function of all cells.
What are vitamins classified as?
Organic compounds.
What are minerals classified as?
Inorganic compounds.
What is the role of carbon in biological molecules?
Used to build carbohydrates, proteins, lipids, and nucleic acids.
What is the primary structure of a protein?
The sequence of amino acids.
What does the tertiary structure of a protein refer to?
The folding of a polypeptide into a larger globular structure.
What is protein denaturation?
The breakdown of hydrogen bonds due to excessive heat, radiation, or pH changes.
What are the two types of cholesterol?
- Low density lipoproteins (LDLs)
- High density lipoproteins (HDLs)
True or False: Lipids are water soluble.
False.
Fill in the blank: The process of joining monomers to form polymers is called _______.
polymerization.
What biological molecules are built using carbon?
Carbohydrates, proteins, lipids, nucleic acids
Carbon is essential for storage compounds and cell formation in all organisms.
What is nitrogen used for in organisms?
Building proteins and nucleic acids
What is phosphorus used for in organisms?
Building nucleic acids and certain lipids
What are the primary components of a typical bag of fertilizer?
Nitrogen, phosphorus, potassium, magnesium, calcium
What is a catalyst?
A substance that increases the rate of a chemical reaction without being consumed
How do enzymes affect activation energy?
They reduce the activation energy by lowering the energy of the transition state
What are transition states in enzymatic reactions?
Unstable states at the top of the energy hill during a reaction
What is the active site of an enzyme?
The region where the substrate binds to the enzyme
What is the induced fit model?
The concept that enzymes change shape slightly upon substrate binding for a tighter fit
What pH range do blood enzymes function best at?
7.2-7.4
What pH do stomach enzymes function best at?
About 1.0
What happens to enzymes if the pH is too low or too high?
They may denature
What effect does substrate concentration have on enzyme activity?
Higher substrate concentrations usually produce greater enzyme activity until all active sites are occupied
How does temperature affect enzyme activity?
Increased temperatures increase enzyme activity until denaturation occurs
What are competitive inhibitors?
Molecules that resemble the substrate and bind to the active site, preventing the desired reaction
What is feedback inhibition?
The inhibition of an enzyme by the final product in a metabolic pathway
What are co-factors?
Inorganic ions that help enzymes combine with substrate molecules
What are co-enzymes?
Organic molecules that assist enzymes in substrate binding
What is allosteric activity?
The change in an enzyme caused by the binding of a molecule, which may promote or prevent activity
What does the enzyme’s active site do in a reaction?
It binds to and stabilizes the reactant or transition state, decreasing activation energy
What is the importance of the shape and charge of substrates?
They must be compatible with the active site of the enzyme for specificity
What is the role of amylase?
Catalyzes the conversion of starch to simple sugars
What color change indicates amylase activity in an iodine solution?
From dark blue (presence of starch) to light brown (absence of starch)
Why is a control test tube important in enzyme experiments?
It shows the color change that occurs in the absence of enzyme activity
What effect does increasing substrate concentration have on competitive inhibition?
Competitive inhibition will decrease as more active sites are occupied by substrate
What is the effect of increasing the concentration of substrate (ethyl alcohol) on ADH activity?
There will be an increase in formaldehyde because ADH activity increases
How does alanine inhibit pyruvate kinase activity?
It binds to an allosteric site, changing the shape of the enzyme’s active site
During which time interval is the reaction rate lowest?
0-1 minute
