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What are the building blocks of organic molecules?
Monomers, which are built into complex polymers
What are the four classes of organic molecules?
Amino acids, monosaccharides, fatty acids + glycogen, nucleotides
What is the macromolecule of an amino acid?
Polypeptide/protein
What is the macromolecule of a monosaccharide?
Carbohydrate
What is the macromolecule of a fatty acid + glycerol?
Lipid
What is the macromolecule of a nucleotide?
Nucleic acid
What are the functions of amino acids/polypeptides/proteins?
Structural component of cells
Perform chemical reactions (are enzymes)
What are the functions of monosaccharides/carbohydrates?
Primary energy source and short term energy storage for cells
What are the functions of fatty acids + glycogen/lipids?
Structural component of cell membranes
Long term energy storage for cells
What are the functions of nucleotides/nucleic acids?
Genetic material (DNA)
What are carbohydrates made of?
Carbon, hydrogen, oxygen
What is the function of carbohydrates in animals?
Serve as an important source of energy
What is the function of carbohydrates in plants?
Serve as an important source of energy, provide structure
What biochemical functions do carbohydrates serve? (Metabolism)
Monosaccharides are the fuel for cellular metabolism
What biochemical functions do carbohydrates serve? (Polysaccharides)
Monosaccharides may be converted into space-saving polysaccharides, providing short term energy for plants and animals
What biochemical functions do carbohydrates serve? (Structure)
They are used to form structural elements in plants and animals
What is the relationship between the monosaccharides?
They are all isomers of C6H12O6
What two monosaccharides make up sucrose?
Glucose and fructose
What two monosaccharides make up maltose?
Two glucose molecules
What two monosaccharides make up lactose?
Glucose and galactose
Starch, glycogen, and cellulose are made up of what subunit?
Glucose
What is the main function of lipids?
Used as long term storage molecules in animals and plants
Why are fats solid at room temperature?
Because all of its carbon bond spots are saturated, the fatty acids are straight and stack nicely
Why are oils liquid at room temperature?
Because of the double bond that makes it unsaturated, there is a kink/bend in the chain of fatty acids. As a result, the acids don’t stack nicely, creating space in between them
What is the main function of proteins?
Play a role in performing chemical reactions (biological catalysts/enzymes)
Why do amino acids have so many forms?
Every amino acid contains a set amino group and a carboxylic acid group, but they have interchangeable R groups
How do secondary protein structures form?
The sequence of amino acids in a primary protein structure are linked together by hydrogen bonds, forming a pleated sheet or an alpha helix
How do tertiary protein structures form?
Interactions between hydrophobic and hydrophilic R structures in the amino acids of alpha helixes and pleated sheets causes them to fold
Why does the primary structure of a protein remain intact after denaturation?
Denaturation is not strong enough to break peptide bonds
What is the relationship between denaturation and coagulation?
Denaturation is a prerequisite to coagulation, but denaturation doesn’t always lead to coagulation
What is the relationship between dehydration/condensation synthesis and hydrolysis reactions?
Hydrolysis reactions are the reverse of dehydration/condensation synthesis reactions
Can a reaction take place without an enzyme?
Yes, enzymes just speed up reactions and are not necessary to the reaction
What is the effect of enzymes on activation energy?
Enzymes lower activation energy
What are the factors that affect the rate of enzyme activity?
Temperature, pH, concentrations of substrate and enzymes
Why does temperature affect the rate of enzyme activity?
At low temperatures, enzymes are stiff and change shape (perform reactions) with difficulty; at high temperatures, enzymes become denatured, and because the function of the enzyme depends on its shape, enzyme function is greatly reduced
Why does pH affect the rate of enzyme activity?
The amino acids that make up an enzyme molecule contain many positive and negative regions, some of which are around the active site, and H+/OH- ions bond with these regions and prevent the substrate from reacting
Why do concentration of substrate and enzymes affect the rate of enzyme activity? (Set Enzyme Concentration)
If there is a set concentration of enzyme present in a reaction mixture, and the concentration of substrate increases, the rate of production of the products will increase because there is a greater chance of collisions between substrate and enzyme molecules
Why do concentration of substrate and enzymes affect the rate of enzyme activity? (Maximum Enzyme Rate)
If the concentration of a substrate increases to much, it will exceed the maximum rate at which an enzyme can work because at any one moment all the active sites are occupied by substrate molecules, and so adding more substrate has no further effect
How does non-competitive feedback inhibition happen?
The end product of a metabolic pathway binds to the allosteric site of an enzyme in that pathway, changing the shape of the enzyme and thus reducing its function
How does competitive feedback inhibition happen?
The inhibitor competes with a substrate for binding in the active site, and if an inhibitor occupies the active site then the substrate enzyme complex is unable to undergo an enzymatic reaction
Why are enzymes essential to digestion?
Enzymes are essential to speed up the rate of digestion so that it is fast enough to process nutrients to supply our needs
Why is the process of digestion essential?
It breaks food molecules into small molecules, and only small molecules can enter cells and be used in the body
What happens in the mouth during digestion?
Food is broken into small pieces by the jaws and teeth and is mixed with saliva containing salivary amylase, which begins the chemical digestion of any starch the food contains into maltose
What is the pH of the mouth?
7
What happens in the esophagus during digestion?
The food, now a bolus, is passed down the esophagus to the stomach by peristalsis
What happens in the stomach during digestion?
The digestion of proteins begins, as glands on the wall of the stomach secrete pepsinogen that is activated by HCl into pepsin (a protein digesting enzyme)
What is the pH of the stomach and what is it maintained by?
1.5-2.0, HCl
Why does the HCl in the stomach not cause harm to it?
Cells in the stomach lining secrete mucus to protect the interior of the stomach from the acid and enzymes
What are the three distinct regions of the small intestine?
Duodenum, jejunum, ilium
What is the pH of the small intestine?
Around 8
What is the role of the pancreas in digestion? (Bicarbonate)
It produces bicarbonate ions to neutralize chyme from the stomach that enters the duodenum to protect the small intestine from developing ulcers and allow pancreatic enzymes to work at their optimum pH
What is the role of the pancreas in digestion? (Enzymes)
Releases a number of enzymes, which completes the digestion of polymers into monomers that can be absorbed into the bloodstream
What is the role of the liver in digestion?
Bile is produced in the liver from the breakdown of red blood cells, which helps to digest lipids
What is the role of the gallbladder in digestion?
Stores bile and releases it into chyme to help digest lipids
Why do lipids present a problem for digestion in the intestine?
In the intestine, where the medium is aqueous and lipase is water soluble, while lipids are insoluble
How are lipids digested?
Lipase can only hydrolyze the outer lipid molecules, so the internal areas of the droplet remain undigested. Bile salts emulsify large fat droplets, producing many small fat droplets, making them water soluble
How are proteins digested?
Small polypeptides from the stomach are further broken down in the duodenum by pancreatic enzymes called proteases, and digestion of proteins is completed by peptidases from the pancreas to produce amino acids that can be absorbed into the bloodstream
How are carbohydrates digested?
Simple sugars and other complex carbohydrates enter the duodenum, where they are further broken down by a number of enzymes. Carbohydrases released by the membrane of the duodenum converts disaccharides to monosaccharides, which can be absorbed
How are nutrients absorbed in the small intestine?
The epithelial cells of the villi transport amino acids and carbohydrates from the lumen of the intestine into capillaries of the bloodstream and lipids into lacteals of the lymphatic system, taking place mostly in the jejunum and occasionally in the duodenum and ilium
How are glucose and amino acids absorbed?
Come into contact with jejunum wall and are absorbed by active transport into the epithelial cells of the villi, then diffused into the blood following their concentration gradient
How are lipids (glycerol and fatty acids) absorbed?
Come into contact with jejunum wall and are absorbed by diffusion into the epithelial cells of the villi, reassembled into triglycerides and gain a protein coat to increase solubility, are actively transported to the lymphatic system via vesicles
How is the small intestine folded to increase efficiency?
What increases absorption in the small intestine?
Villi/micro villi that increase surface area, thin epithelium to increase diffusion, long length
What is the main role of the large intestine?
Reabsorbing water and mineral ions such as sodium (Na+) and chloride (Cl−)
Where does additional water in our gut contents come from?
Hydrolysis occurs during digestion, which is where the additional water added to the intestine in digestive juices comes from
Why can’t humans/mammals digest cellulose?
Cellulose is a complex carbohydrate requiring the enzyme cellulase to catalyze its digestion, which humans and other mammals are unable to produce
What is the role of gastrin in regulating the digestive system?
Stimulates the release of HCl when food enters the stomach and touches the stomach lining
What is the role of enterogastrone in regulating the digestive system?
Decreases the production of digestive juices in the small intestine when fatty meals are detected to slow down digestion and give time for fat emulsification and digestion
What is the role of CCK in regulating the digestive system?
Stimulates the release of bile salts when fatty chyme is released into the duodenum
What is the role of secretin in regulating the digestive system?
Stimulates the release of pancreatic enzymes and bicarbonate as acidic chyme enters the duodenum
Why is negative feedback important in regulating processes and substances in the body?
It results in homeostasis
How is gastrin/acid secretion regulated in the body?
Food in the stomach causes cell walls to start release gastrin, which stimulates stomach glands to release HCl. Once the stomach reaches a pH of 1.5, the cells on the stomach wall stop releasing gastrin
Which reagent reacts with simple/reducing sugars? What does a positive test look like?
Benedict, blue → orange/red
Which reagent reacts with protein? What does a positive test look like?
Biuret, blue → purple
Which reagent reacts with starch? What does a positive test look like?
Iodine, orange → black
Which reagent reacts with lipids? What does a positive test look like?
Paper, non-translucent → translucent
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