Digestion Quiz Flashcards
Nutrient
Anything a cell needs ( gas, food, water, minerals, vitamins)
Food
An organic chemical which can be broken down in respiration to get ATP
Dehydration Synthesis
Making a larger molecule by taking out water
Hydrolysis
Using water to spilt a larger molecule into smaller parts
Carbohydrates
Make up 1% of protoplasm
Produced by photosynthesis & mainly used up in respiration for ATP.
Converted into needed body chemicals & fatty acids & non-essential amino acids
Can be identified by the formula (Carbon: Hydrogen: Oxygen)
Classes of Organic Compounds
Carbon, hydrogen and oxygen
Classes of carbohydrates
Monosaccharides, Disaccharides and Polysaccharides
Monosaccharides
One sugar units
Basic units of carbohydrates
5-carbon ring structure
(Ex. glucose, frctuose, galactose)
Disaccharides
2 sugar units
Two monosaccharides joined together with loss of water (Dehydration synthesis)
Glucose + Glucose =
Maltose [malt sugar] + water
Glucose + Fructose =
Sucrose [table sugar] + water
Glucose + Galactose
Lactose [milk sugar] + water
Polysaccharides
Many sugar units (Ex. Glygcogen, starch, cellulose)
Cellulose
Insoluble solid found in plant cell walls and is called plant fibre
We don’t have enzymes to digest it
-Joined by bonding about 3000 glucose together
- Forms layers not coils
- Ex. Celery & grass
Starch
Storage form of carbs in plants
Formed by bonding about 1100 glucose together as a helix or coils Animals convert it into glucose
Amylose and amylopectin are two forms
Glycogen:
Storage form of carbs in animals
- Formed by bonding 700 glucose together
- Stored in cells of the muscles, brain and liver cells
Benedict’s Solution
For reducing sugars (ex. all monosaccharides)
Turns blue colour to red/ brown
Lipids
C, H, O compounds
Oils, fats, waxes and steroids (non-polar)
Function:
- Used in the structure of membranes.
- The storage form of energy- stores 2.25 times more energy per gram than other biological molecules.
The structure of some food
Iodine
Starch (Polysaccharides)
Turns yellow/ red liquid to black/blue
Saturated Fats
Lots of hydrogen
Usually solid @ room temperature
Most animal fats
Only have C -C single bonds
Fats
Sometimes called triglycerides
Formed by dehydration synthesis with enzymes
Structure: 3 fatty acids & 1 glycerol
Unsaturated Fats
Usually liquid @ room temperates
Most are found in plants as oils
C = C double bonds or triple bonds
Sudan IV
A test of lipid
Turns pink to red in the presence of lipid
It is a carcinogenic
Cholesterol
Formed by the bonding of one glycerol to a complex 4 ring, carbon structure
Most common steroid and is converted to vitamin D and hormones like testorone or estrogen
Animal Fats
Solid
Carries cholesterol
Long saturated fatty acids
Waxes
Semi-solids that are made by the bonding of 3 fatty acids to a long chain of alcohol instead of glycerol
Plant Fats
Liquid
No cholesterol
Short unsaturated fatty acids
Unglazed Brown Paper
Becomes translucent (see-through) in the presence of lipids
Peptide Bonds
Amino acids are connected together by peptide bonds
Proteins
Makeup structures such as hormones, enzymes, membranes
Energy is NOT the main function
The most abundant organic molecule
Synthesized at the ribosome
Made up of amino acids and amino acids bonded together on strands that form protein
Polypeptide
A chain of amino acids
Types of Protein
Primary
Secondary
Tertiary
Quaternary
Primary
Amino acids are in a linear sequence
Secondary
Hydrogen bonds between amino acids made alpha helix and beta sheets
Tertiary
3-D, R groups interaction alters helix
Quaternary
Globular proteins (Ex. enzymes)
Examples of Protein
Adrenalin, Insulin, Collagen [skin], Keratin [hair], Actin & Myosin [Muscle]
Denaturation
A slight change to the structure by breaking hydrogen bonds
Can be REVERSED
Coagulation
Breaking of bonds by extreme heat, acid or base
Can NOT be reversed
(Ex. frying an egg, high fever, stomach acid, base)
Biuret’s Reagent
Tests for peptide bonds
NOT individual amino acids
If it turns BLUE- Negative (No protein), turns PINK [+] turns VIOLET [++], turns PURPLE [+++]
Nucleic Acids
DNA & RNA
Structure: Sugar + phosphate + nitrogenous base
Genetic material that directs cell’s activity
Ways to increase the rate of chemical reactions
Increasing the concentration of a reactant in solution
Increasing the surface area of a solid reactant,
Increasing the temperature of the reaction system
Is increasing the temperature good for your body?
No, it is not good for your body as it will denature proteins in the body.
Catalyst
Another way to SPEED UP the reaction rate
It’s a chemical that speeds up a chemical reaction but isn’t used up in the reaction.
Can be recovered unchanged when the reaction is finished
Functions by lowering the amount of energy needed to start a reaction
Enzyme
A protein molecule that acts as a catalyst to increase the rate of reactions.
Each enzyme has a very specific shape that allows it to attach to a specific substance molecule called the REACTANT
When the substrate binds to the active site, its bonds become less stable and thus more likely to be altered and to form new bonds
They are a quaternary proteins
Active Site
The spot where the substrate binds to the enzyme
Substrate/ reactant
Is the substance that could fit into the enzymes
Factors Affecting Enzyme Action
Temperature
pH
Inhibitors
Inhibitors
Molecules that attach to the enzyme and reduce its ability to bind to the substrate
Non-Competitive Inhibitors
Attach somewhere else on the enzyme (NOT on the active site)
Changes the shape of the enzyme, making so the substrate no longer fits properly.
Competitive Inhibitors
Attach to the enzyme in its active site
Compete with the substrate to occupy the active site space
In biological systems, this is often the end product of enzymatic reactions as a form of negative feedback.
Ingestion
The taking in of nutrients
Digestion
The breakdown of complex organic molecules into smaller parts by enzymes
Absorption
The transport of digested nutrients to the cells of the body
Egestion
The removal of food waste from the body
Salivary Amylase
An enzyme that breaks down complex carbs (starch) into simple carbs
Salivary Glands
Produces saliva & salivary amylase
Teeth
Important for physical digestion
Grinds food into smaller pieces
Esophagus
Food moves from the mouth to the stomach through the esophagus
Peristalsis
Rhythmic, wave-like contractions of muscles that move food along the gastrointestinal tract
Stomach
Site of food storage and initial protein digestion.
Involved in the physical & chemical digestion that mixes food with the gastric fluids
Enzyme Pepsin starts protein digestion in the stomach
Digestive fluids in the stomach include hydrochloric acid (HCl), pepsinogens and mucus.
Mucus
Protects the stomach from HCl & Pepsin
Small Intestine
Completes digestion of macromolecules & absorbs their component sub-units
Most chemical digestion & absorption takes place here
Secretes digestive enzymes and moves its content along by peristalsis
Pancreas
Delivers pancreatic fluids to the duodenum and used for digestion in the small intestine
Storage for bicarbonate ions that neutralize stomach acid in the small intestine
Enzymes: Trypsin, chymotrypsin, pancreatic amylase, lipase are all found in pancreatic fluids
Liver
Secretion of the bile salts
Continually makes bile and blood proteins
Removes the highly toxic nitrogen group from amino acids forming urea
Converts the toxic part of hemoglobin
Converts glucose to glycogen and vice versa to maintain a constant blood sugar level
Stores glycogen, vitamins A, B12 and D
Converts harmful compounds to LESS harmful products (Ex. alcohol)
Gallbladder
Stores bile
Large Intestine
Reabsorbs water and salt from undigested food in the colon
Houses bacteria like E-Coli which are essential to life
Uses waste materials to make vitamins
Digestion DOES NOT occur here
Shorter but thicker than the small intestine
Digestion & Absorption in the Small Intestine
Most chemical digestion in the small intestine occurs in the duodenum
Lipase
Produced by the pancreas
Breaks down fats to glycerol & fatty acids
Fats + H2O = glycerol + fatty acids
Trypsinogen
Produced by the pancreas
Once activated to TRYPSIN by an enzyme called enterokinase it converts long-chain peptides into short-chain peptides
Protein Digestion
Protein digestion starts in the stomach with the enzyme pepsin.
In the small intestine, proteins are further broken down by trypsin and chymotrypsin, enzymes secreted by the pancreas.
Trypsin and chymotrypsin break peptide bonds between specific amino acids, forming shorter peptide chains.
Additional enzymes continue breaking down these short peptides, separating single amino acids from the ends.
Finally, peptidases from the pancreas and small intestine split the remaining peptide chains into individual amino acids, completing digestion.
Summary:
Digestion Starts: Stomach
Digestion Ends: Small Intestine
Carbohydrates Digestion
Starch digestion starts in the mouth with salivary amylase.
In the stomach, starch isn’t digested because the acidic pH (around 2) inactivates salivary amylase, which works best at pH 7.
Digestion resumes in the small intestine, where the pH is about 8.
Pancreatic amylase breaks down starch into disaccharides, and other enzymes convert these into monosaccharides like glucose, galactose, and fructose.
Digestion Starts in the MOUTH & ends in the SMALL INTESTINE
Carbohydrates absorption
Monosaccharides are absorbed into the cells of the intestinal villi by active transport.
From the intestinal lining, they enter the bloodstream and are carried directly to the liver.
The liver converts monosaccharides like galactose and fructose into glucose.
Glucose is then released back into the bloodstream and transported to body cells for energy.
Any excess glucose is converted into glycogen by the liver and stored in the liver and muscles for later use. When needed, glycogen is converted back into glucose to fuel the cells.
Absorption Pathway:
Small intestine → Bloodstream → Liver → Bloodstream → Body cells
Protein Absorption
Amino acids are absorbed into the villi of the small intestine through active transport.
They then diffuse into blood capillaries and are transported to the liver via the bloodstream.
In the liver, amino acids undergo various reactions before being sent back into the bloodstream to be used by cells that need them.
Absorption Pathway:
Small Intestine (Villi) → Bloodstream → Liver → Bloodstream → Body Cells
Fat Absorption
Glycerol and fatty acids are absorbed into the cells of the villi in the small intestine by simple diffusion.
Inside these cells, they are reassembled into triglycerides and coated with proteins to make them soluble.
The coated triglycerides enter the lymph vessels in the villi and are transported to the chest region, where they join the bloodstream.
Once in the bloodstream, the protein coating is removed by lipase in the blood vessel lining.
Lipase then breaks down the triglycerides again, making fatty acids and glycerol available for use by the body.
Absorption: Small Intestine [Villi] —> Lymph Vessels —> Bloodstreams
Fat Digestion
When fats enter the duodenum (the first part of the small intestine), they trigger the release of bile from the liver and gallbladder.
Bile emulsifies large fat droplets into smaller ones, increasing their surface area. (This is a physical process, not chemical digestion.)
Lipase, an enzyme secreted by the pancreas into the duodenum, chemically breaks down fats into glycerol and fatty acids through hydrolysis.
Digestion Starts & Ends: Small Intestine
Blood Capillaries
Absorption through active transport of amino acids & monosaccharides
Absorbs glucose & amino acids
Nucleic Acid Digestion & Absorption
Nucleic acids (DNA and RNA) are broken down in the small intestine by enzymes called nucleases, producing nucleotides.
Nucleosidases further hydrolyze nucleotides into their individual components: nitrogenous bases, sugars, and phosphates.
These components are then absorbed into the bloodstream via active transport.
Lacteals
Absorption through passive transport of fatty acids & glycerols (Tiny lymphatic vessels)
Sphincter
Control the passage of food from one area to another by use of a circular band of muscles
- Cardiac Esophageal Sphincter:
Between the esophagus & stomach
Pyloric Sphincter:
Between stomach & small intestine
Ileocecal Sphincter:
Between the small intestine & large intestine
Rectal Sphincter
Below the rectum
Salivary Amylase
Secreted by the salivary glands
Starts the breakdown of polysaccharides to monosaccharides
Hydrochloric Acid (HCl)
Kills pathogens
Helps convert PEPSINOGEN to PEPSIN
Secreted by the stomach
Pepsinogen
When converted to pepsin by HCl it initiates the digestion of PROTEINS
Pancreatic amylase
Secreted by the pancreas and continues to breakdown of carbs into disaccharides
Starch + Water = maltose
Bicarbonate Ions
Secreted in the pancreas and neutralizes HCl from the stomach
Erepsin
Secreted in the small intestine and the pancreas it completes the breakdown of proteins
Turns short-chain peptides –> Individual amino acids
Peptides + water = amino acids
Maltase
Disaccharides secreted by the small intestine
Breaks down disaccharides to monosaccharides
maltose + water = glucose
Bile
Produced by the liver and stored by the gallbladder till it is delivered to the small intestine
Bile emulsifiers fat
