Ch. 6 - Enzymes/Digestion Flashcards
1
Q
What do you need to start a reaction?
A
Activation energy—begins the reaction, then most reactions can produce enough energy to keep going.
2
Q
What is a way to produce activation energy?
A
- Heat the reactants
- Use a catalyst
3
Q
What is a catalyst? How does it work?
A
- 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.
4
Q
What is an enzyme?
A
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.
5
Q
How are enzymes named?
A
Often the name of the substrate is shortened with the ending “-ase”.
Ex:
lipid -> lipase
sucrose -> sucrase
protein -> protease
6
Q
What is a substrate?
A
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
7
Q
How do enzymes work?
A
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
8
Q
What do enzymes sometimes need to help them work correctly?
A
Cofactors and co-enzymes; if this is needed, the enzyme won’t work without it.
9
Q
What is a cofactor?
A
An inorganic substance.
Ex: Zn, Fe
10
Q
What is a co-enzyme?
A
An organic molecule usually made from vitamins.
11
Q
What will happen if there is damage to an enzyme?
A
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.
12
Q
What are the roles of vitamins and minerals for?
A
These are compounds that an organism needs to function.
13
Q
What is a vitamin?
A
Organic compounds that an organism needs to function. Not an energy source, but co-enzymes.
14
Q
What are minerals?
A
Inorganic substances that an organism needs to function. Not an energy source, but cofactors.
15
Q
What are the factors that affect enzyme controlled reactions?
A
- Temperature
- pH
- Substrate Concentration
- Inhibitors
16
Q
How does temperature affect enzyme controlled reactions?
A
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.
17
Q
How does pH affect enzyme controlled reactions?
A
Each metabolic reaction has an optimum range of pH that is best for that reaction.
Ex: Pepsin has a pH of 2 in stomach
18
Q
How does substrate concentration affect enzyme controlled reactions?
A
Greater concentration means a higher rate of do for enzyme
19
Q
How do inhibitors affect enzyme controlled reactions?
A
Molecules that attach to enzymes can reduce their ability to bind to the substrate.
20
Q
What are the two types of inhibitors?
A
Competitive and Non-Competitive
21
Q
What is a competitive inhibitor?
A
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
22
Q
What is a non-competitive inhibitor?
A
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.
23
Q
How are enzymes regulated by feedback pathways?
A
- Negative Feedback
- Feedback Inhibition
24
Q
What are the steps to digestion?
A
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.
25
What is digestion?
To break food down into smaller piecces.
Both physical and chemical digestion, for the purposes of **absorption**
26
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.
27
What is chemical digestion?
Enzymes break down chemical structure of food.
Chemical digestion = hydrolysis
28
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
29
What is diffusion?
[High] > [Low]
30
What is osmosis?
Water [High] > [Low]
31
What is active transport?
[Low] > [High] w/ATP
32
What is facilitated diffusion?
[High] > [Low] w/Transport Protein
33
What is egestion?
Removing wastes of undigested materials from the intestinal tract.
i.e. pooping
34
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.
35
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).
36
Where does the digestive process start? Is this physical or chemical digestion?
The mouth and includes both physical and chemical digestion.
37
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**.
38
What do salivary glands do?
Chemical digestion that secrestes necessary saliva to begin digestion.
Saliva contains digestive enzymes, such as amylase.
39
What does saliva do?
Lubricates the inside of the mouth to assist in swallowing.
Also contains digestive enzymes.
40
What does amylase do?
Chemical digestion.
Begins the digestion of starches, breaking them into disaccharide sugar maltose.
41
What does the esophagus do?
Is a muscular tude that directs food from the mouth into the stomach.
42
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.
43
What is reverse peristalsis?
A defense mechanism used to remove unwanted material from the stomach and esophagus (vomiting).
44
What does food go after the mouth "process" is done?
Stomach
45
What does the stomach do in digestion?
Physical and chemical digestion.
Layers of muscle -> contract to mix food along gastric juice.
46
Where is the stomach determined by?
Determined by the cardiac (heart) sphincter (a ring of msucles at the end of the esophagus)
47
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**
48
What is gastric juice made of?
- Pepsininogen (and therefore, pepsin)
- Hydrochloric acid
- Rennin
- Mucus
49
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).
50
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.
51
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
52
What suffix refers to an enzyme or chemical that's inactive?
A "-ogen" suffix.
53
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**
54
What does rennin do? Is it chemical or physical digestion?
(Not really digestion at all)
- Clotting (more just brings it together) agent for milk and blood
- Clumps and concentrates the above for easier job for enzymes
But still leaves enough room for the surface area.
55
What does mucus do? Is it chemical or physical digestion?
- Lines of stomach to protect stomach walls from HCl and pepsin
- Therefore, not really digestion at all either.
56
What is gastric juice secreted in response to? Two things.
- The hormone, **gastrin**
This is released by the stomach in response to food in the stomach. Releases HCl.
- The **vagus nerve**
Stimulates production of gastric juice when food is discussed, viewed, or thought
57
The stomach mixes and grinds food into a liquid called __ (very __).
Chyme, acidic
58
What must the chyme pass through to enter the small intestine?
**Pyloric Sphincter**
59
The role of the stomach is largely __ because...
Physical digestion.
Lots are not absorbed because there is insufficient breakdown, meaning not much is chemically absorbed.
60
What does the gall bladder do? How does it secrete this thing? What does it look like?
It **stores** bile made by the liver. Very small organ.
It secretes bile through the common bile duct, into the duodenum of the small intestine.
61
What does bile do?
Bile emulsifies lipids in the small intestine so that enzymes can break them down. It contains this emulsifier.
A form of **physical digestion**.
62
What is emulsification?
- Fats are insoluble and enter the small intestine as small drops
- They act like detergents to disperse large fat molecules into fine suspensions
- This results in a large surface area, allowing it to be digested quickly by lipases
63
What is the role of the pancreas? Is this physical or chemical digestion? Via what?
A gland that secretes **pancreatic juice** (chemicals) into the small intestine's duodenum, via the **pancreatic duct.**
**Chemical digestion**
64
What are the pancreas's exocrine and endocrine functions?
The production of pancreatic juice is an exocrine function.
But BOTH: Other cells in the pancreas produce insulin and glucagon which are released directly into the blood, which is endocrine.
65
What are the enzymes of the pancreas?
PLANTS
Peptidase
Lipase
Amylase
Nuclease
Trypsinogen
Sodium Bicarbonate (NaHCO3)
66
What does peptidase do in the pancreas?
Breaks down short chains of amino acids (peptides).
Into smaller polypeptides or single amino acids
Can be secreted in active form (pepsin, protease) because it will only work on partially broken proteins.
67
What does lipase do in the pancreas?
Digestive enzymes for lipids -> fatty acids.
68
What does amylase do in the pancreas?
Breaks down carbohydrates (polysacc. -> simpler sugars).
69
What does nuclease do?
Breaks down nucleic acids.
70
What does sodium bicarbonate do?
Base to neutralize stomach acid, as it has a pH of 7-8.
Without it, the stomach would burn a hole in the duodenum.
71
Difference between polypeptides and proteins?
Polypeptide: chains, not organized
Proteins: chains, organized
72
What does trypsinogen do?
An inactive enzyme that, when active as trypsin, breaks down proteins/peptides into small chains of amino acids in the duodenum of the small intestine.
73
What does the small intestine do?
**Chemical digestion and absorption.**
74
What is the duodenum? Exocrine or endocrine.
Part of the small intestine that secretes enzymes (exocrine), and hormones (endocrine), from small "pits" in its wall.
75
What enzymes does the duodenum secrete?
SMELLE
Sucrase
Maltase
Erepsin
Lipase
Lactase
Enterokinase
76
What does lipase do in the duodenum?
Digests lipids.
77
What does maltase do in the duodenum?
Breaks maltose.
78
What does sucrase do in the duodenum?
Breaks sucrose.
79
What does lactase do in the duodenum?
Breaks lactose.
80
What does erepsin do in the duodenum?
Digests peptides into amino acids.
81
What does enterokinase do in the duodenum?
Activates trypsinogen (secreted in the pancreas) -> forms trypsin -> protease.
82
What are the two hormones formed in the small intestine? Is this an exocrine or endocrine function?
Endocrine.
Secretin
Cholecystokinin (CCK)
83
What does secretin do, the hormone released by the small intestine?
Causes the pancreas to secrete sodium bicarbonate to neutralize HCl
84
What does cholecystokinin (CCK) do, the hormone released by the small intestine?
Goes to the liver and gall bladder, and causes it to release bile.
85
What processes contribute to absorption by the small intestine?
- Diffusion
- Active transport
- Endocytosis
86
How are carbohydrates transported into the bloodstream.
Active transport
87
What are villi?
Tiny finger-like projections from the inside wall of the small intestine.
88
What does the villi contain?
Exocrine glands that secret enzymes to finish digestion by converting maltose to glucose and polypeptides to amino acids. Thus, the villi absorbs glucose, amino acids, and vitamins.
89
How do villi work?
Increase the rate of diffusion from the small intestine to the blood by increasing surface area.
90
What moves through the villi and into the bloodstream?
All sugars, amino acids, minerals, water-soluble vitamins, and small amounts of fatty acids and glycerol.
91
What are lacteals?
Tiny lymphastic vessels that pick up and transport fat soluble substances, and fatty acids. Part of the lymphastic system.
92
Where does all the blood and nutrients from the small intestine go (aside from the fat products)?
The liver via the hepatic portal vein.
93
What does the villi look like?
1.3 cm in height.
Fuzzy.
94
What does the liver do?
**Makes** bile and filters blood---regulating nutrients in the blood.
It is the largest internal organ.
95
What does the liver produce?
Bile. It does this by breaking down red blood cells, which prevents clots and recycles hemoglobin.
96
What is hemoglobin?
Hemoglobin is a protein in red blood cells that carries oxygen.
97
What does the liver store?
Minerals like iron, vitamin A, vitamin B, vitamin D, and glucose, in the form of glycogen.
98
What substances does the liver convert? What type?
Organic susbtances from one form to another.
Glucose -> Glycogen
Fatty acids -> Glucose
Amino Acids -> Glucose, which requires deamination of Nitrogen, producing toxic urea.
99
What is the large instestine?
"Package for way out."
Absorption of water and some physical digestion.
100
Where does the large intestine start?
The end of the small intestine: located at the ileocaecal valve.
101
What does the large intestine do?
NO DIGESTION.
Reabsorbs some salts, but as much water as possible back into the body.
Physically breaks down some undigested food, NOT TO DIGEST, TO EGEST.
102
What does the large intestine contain?
Bacteria, breaking down undigested foods not for digestion but for egestion.
103
What does the large intestine break down?
Undigested food, such as cellulose.
104
What does the large intestine produce?
Vitamins B and K.
105
What is the importance of fiber to the large intestine?
Needed to keep materials moving through large intestine to prevent buildup of toxic materials.
106
Where is the colon?
The longest part of the large intestine.
107
What is the function of the rectum? Where?
Stores undigested food until enough is accumulated to release undigested food and dead bacteria.
Final 20m of large intestine.
108
What is the function of the anus? How?
Regulates release of feces.
Controlled by two sphincters, one regulated by nervous (automatic), other controlled by us.
109
What are ten digestive disorders?
- Ulcers
- Hepatitis
- Inflammatory Bowel Disease, Chrohn
- Inflammatory Bowel Disease, Colitis
- Anorexia Nervosa
- Gallstones
- Cirrhosis
- Obesity
- Appendicitis
- Type 1 Diabetes
110
What are ulcers?
- Thick layer of mucus in stomach erodes
- Allows acid to eat away stomach wall
- Most caused by bacteria Heliobactor pylori, which attached to stomach wall, preventing mucus protection.
- Treat with antibiotics, change in lifestyle, surgery, allowing the reduction of acidity or strengthened mucus
Because of smoking, caffeine, alcohol, stress
111
What is hepatitis?
- Inflammation of liver
- Hep. A: drinking contaminated water
- Hep. B: spread through sexual contact, and is more contagious than HIV
- Hep. C: usually transmitted through contact with infected blood.
- There are vaccines for Hep. A and B, NOT C
112
What is Inflammatory Bowel Disease, Chrohn (Iletis Enteritis)?
- Usually of the ileum of the small intestine
- Inflammed tissue = intestine empty lots and lots of rectal bleeding
- Painful, hard to diagnose
- Autoimmune, no cure
- Medications heals tissue/surgery
- Affects entire thickness
113
What is Inflammatory Bowel Disease, Colitis?
- Inflammation/ulceration of colon
- Restricted to innermost lining
- Pain/Inflammed tissue = intestine empty lots and lots of rectal bleeding (similar to IBD, Chrohn)
- Medications heals tissue
- Last resort is to remove rectum/bowel, which requires waste from an external opening
114
What is anorexia nervosa?
In order to lose weight and be more attractive, depriving oneself of basic nutrients.
- Eating disorder, morbid of gaining weight
Leads to: starvation, less than 85% of normal body weigjt, a distorted self-image
Symtomps of starvation:
- low blood pressure
- irregular heartbeat
- constipation
- dry skin
- odd menstrual cyclle
End: digestive/organs shut down = death
115
What are gallstones?
- Bile can sometimes crystalize in gall bladder, which form small, hard, sharp gallstones
- Factors include obesity, alcohol, and heredity
- Treated with medications or UV to disintegrate, passing them through urine
Last resort: remove gall bladder
116
What is cirrhosis?
- A chronic disease where scar tissue replaces normal tissue in the liver, preventing proper function. Fatty liver.
- Chronic alcoholism and hepatitis C are the most common causes
117
What is obesity?
- Body mass of +20% above ideal height
- Over 1/2 of Canadians are considered "obese" (by the BMI)
- Caused by a combo of hormonal, genetics, lifestyle, and social factors
- Combated with a balanced, moderated diet, and increased physical activity
118
What is the BMI? Why is it kinda flawed?
A measure of the best body weight to height ratio.
Kinda flawed cause some athletes are mostly muscle, but are considered "obese".
119
What is appendicitis?
- Inflammation of the appendix
- Can rupture, which causes bacteria to enter the abdomonal cavity
- Usually results in removal of appendix, which recently discovered to have beneficial bacteria for gut (intestines)
120
What is type 1 diabetes?
- Pancreas does not produce insulin, which helps glucose regulation.
- Blood glucose tends to rise and fall dramatically with diet.
- Requires insulin shots, no cure
121
What does nucleosidases do?
Converts nucleotides to nitrogen bases, sugars, and phosphates.
122
How are substances transported to the blood?
Simple diffusion
123
How are substances absorbed?
Active transport
124
Define accessory organ.
An organ that helps with digestion but is not part of the digestive tract, where food passes through.
Ex: Liver, gall bladder, pancreas
125
Define digestive tract.
The organs that food and liquids travel through when they are swallowed, digested, absorbed, and leave the body as feces. These organs include the mouth, pharynx (throat), esophagus, stomach, small intestine, large intestine, rectum, and anus.
126
What is jaundice?
Yellowish cast to skin that indicates liver dysfunction.
127
What is allosteric activity?
Change in an enzyme shape caused by the binding of a molecule.
May prevent or promote enzyme activity: allosteric inhibition and allosteric activation.
128
What is negative feedback?
(Self-regulating, most of human systems)
Build up of metabolic products interferes with some step in the pathway that created it. If any step in the process fails, the whole process fails.
Example: a product inhibits one of the enzymes in the pathway, decreasing production
Example 2: buildup of metabolic products blocks the production of those very products.
129
What is feedback inhibition?
Inhibition of an enzyme by the final product in the metabolic pathway.
The mechanism by which the reaction's end product inhibits or controls the enzyme's function that helped make it.
130
How can lipids be digested?
If they are coated in a protein.
131
Are proteins soluble?
They vary. So with carbs.
132
What is a peptone?
Peptone is any water-soluble mixture of polypeptides and amino acids
133
What is insulin and glucagon?
Hormones made by the pancreas, that are endocrine functions.
134
What is the allorestic site?
Where the inhibitor acts on the enzyme, which changes the shape.
(In non-competitive inhibition, where it binds elsewhere other than the active site)
