Download What is the active site of an enzyme?

Review for Module 7 quiz
1. What is an enzyme and how does it work? What is the active site of an enzyme?
What major nutrient form enzymes?
- An enzyme is a protein with a specific shape that lowers the Energy of
activation. The specific site to which the substrate attaches is known as the
active site. The enzyme and substrate join much like a ‘lock and key’
- It’s a Protien
2. Describe 3 ways enzymes are ‘turned off’ or their activity is slowed down.
- Temperature – anything away from optimum may cause denaturation or
coagulation
- pH
- substrate concentration – once saturation is reached reaction levels off
- Review: The effect of temperature and ph of enzyme activity
and what the purpose of an enzyme is:
3. Define monomers and polymers-
A monomer is the simplest unit a polymer is made up of numerous monomers
Eg. Starch is a polymer made of many glucose molecules
4. What is a lipid? Carbohydrate? Protein? What are their functions in the body?
Also give examples
Lipid – made of a glycerol backbone and 3 fatty acids and is known as a
triglyceride, functions as a part of cell membranes, some hormones, insulation,
and energy source
Carbohydrate (CH2O) – part of cell membranes and is our major Energy source
Protein – made up of amino acids (which contain N),of which there are 20 – 8 are
essential and must be obtained from the diet, functions as part of cell membranes,
enzymes, muscle tissue and energy source
5. Define, differentiate, give examples, and uses of monosaccharide, disaccharides,
and polysaccharides.
Monosaccharides – glucose, fructose and galactose – glucose major Energy
source in blood
Disaccharides – sucrose, lactose, and maltose – lactose is milk sugar
Polysaccharides – starch (stored form in plants),glycogen (stored form in animals)
and cellulose (structural carb in plants – fiber)
Know the structure of a lipid (What things make it up)
-All triglycerides (Lipids) have a glycerol backbone (that is always the same)
and 3 fatty acids attached. The fatty acids are what differ among
different types of triglycerides.
Know the structure of a protein (What things make it up)
- Proteins are formed from long chains of amino acids that are joined
together by peptide bonds.
- - The Enzyme Pepsin breaks proteins up into its amino acids
6. Give all the monomers of the three nutrients.
Carbohydrates – monosaccharides / Protein – amino acids / Lipids - triglycerides
7. Describe lab tests that are used to identify all three nutrients.
Benedicts – reducing sugar test – blue solutions turns orange upon heating
Biuret test – protein test – blue solution turns purple in presence of peptide
bonds
Iodine test – yellow iodine turns black/blue in presence of starches
Brown paper turns translucent in the presence of fats
Benedicts test:
Biuret test:
8. Define and differentiate between physical and chemical digestion
Physical – break into smaller pieces to increase surface are
Chemical – break bonds to break food into monomers for absorption
9. Trace the path of a piece of food from the time it enters the mouth until the waste
leaves the body. Give key features of each organ
Mouth – chewing – physical digestion/ saliva begins carb. digestion
Pharynx – throat links esophagus and trachea
Epiglottis – prevents food from entering trachea when swallowing
Esophagus – peristalsis pushes bolus towards stomach
Cardiac (esophageal) sphincter – controls the rate of food entering stomach
Stomach – physical digestion using HCl, chemical digestion of proteins
Pyloric sphincter – control rate of chyme entering duodenum
Duodenum – first part of the small intestine where most digestion occurs
Ileum – last part of the small intestine where most absorption occurs
Large intestine – absorption of water, and electrolytes and formation of digestive
wastes in the form of feces.
Be able to Identify all the different parts of the digestive system:
Know generally the role of each part of the digestive systems in food
digestion (the following picture might help).
(Accessory organs: Liver, Pancreas and Gall Bladder)
Know the following Accessory organs and there role in Digestion:
Accessory organs:
1) Pancreas
- a soft tubular gland that lies just behind the stomach, and is connected
to the duodenum by two ducts
- has both a exocrine (secretory) and endocrine (hormonal) function
- its exocrine functions are to secrete digestive enzymes and sodium
bicarbonate to neutralize the stomach acid and establish a pH of 7.1-8.2
which will not only neutralize the enzyme pepsin, but activate the
pancreatic enzymes
- enzymes:
- pancreatic amylase – digest carbohydrates  maltose
- trypsin – protein digestion: peptones  small polypeptides (activated
by enterokinase, secreted by the intestinal wall)
- chymotrypsin – protein digestion: small polypeptides  peptides
(activated by trypsin)
- carboxypeptidase – digests polypeptides  amino acids
- lipase – digests fats into fatty acids and glycerol
- ribonuclease – digests RNA to nucleotides
- deoxyribonuclease – digests DNA to nucleotides
2) Liver
- the liver has over 500 functions, three being fundamental:
- production of bile
- storage of glucose in the form of glycogen ( fat if glycogen limits
exceeded), conversion of galactose and fructose to glucose
- detoxification of the blood (makes enzymes to break down toxins; ex:
alcohol, caffeine, nicotine, barbiturates, poisons, excess hormones)
- deamination of amino acids – removing nitrogen, producing ammonia and
eventually urea (excreted by the kidneys)
- it receives two separate blood supplies
- via the portal vein – bringing freshly absorbed nutrients from the small
intestine
- via the hepatic artery – bringing oxygenated blood from the
lungs/heart
- bile
- each day, the liver secretes between 800 – 1000 mL of bile
- bile is stored in the gallbladder for release on demand into the small
intestine
- consists of water, bile salts, cholesterol and bile pigments (made from
bilirubin – yellow in colour)
- bile acts as an emulsifier, breaking large fat globules into small ones,
allowing lipase more surface area for digestion
Know the following organs and there role in Digestion:
Mouth
- the mouth is where mechanical and chemical digestion begins
- the food is moistened by saliva produced by the salivary glands(we
produce 1.7 L per day), which moistens the food to make it easier to
swallow, and also contains the first digestive enzymes:
- amylase (enzyme names end in ase) which begins the breakdown of
starch into maltose (a disaccharide) and dextrins (short glucose chains),
and maltase, which breaks maltose into glucose
Stomach
- the stomach holds up to 2L (4L) of food, and will hold food for from 3
to 6 hours while it is broken down
- There are three important chemicals in the stomach involved in digestion:
- HCl(aq) – secreted by the parietal cells of the stomach, lowers the pH
of the stomach to 2.0, allowing the activation of pepsin to pepsinogen
- Pepsin – secreted as an inactive precursor, pepsinogen (cannot be
active or it would digest cellular proteins) by the peptic (chief) cells.
It is activated by the lowered pH in the stomach (which changes the
shape of the enzyme)
- mucous – secreted by the mucous (goblet) cells, protects the stomach
endothelium from the acid and enzymes
- Two other secretions:
- gastrin – a hormone that stimulates gastric secretions (which is
stimulated by the presence of proteins in the stomach), and relaxes
the pyloric sphincter to allow stomach emptying
- rennin – found principally in children, it is involved in the digestion of
milk – slowing its emptying from the stomach
- physical digestion - the acid along with the peristaltic motions of the
stomach contents helps to break up tissues
- the pepsin will break up proteins into smaller polypeptides called peptones
(protein digestion will be completed in the small intestine)
- most materials are not absorbed in the stomach, but some drugs (notably
aspirin), some water, electrolytes, alcohol and some are absorbed in the
stomach
- the highly acidic stomach contents, called chyme is emptied into the small
intestine a bit at a time through the pyloric sphincter
Small Intestine
- measures up to 7m in length, but only 2.5 cm in diameter, divided into
three sections
- duodenum – 25 cm long, where most digestion occurs
- jejunum – 3 m long focusing on absorption
- ileum – 4 m long
- the majority of digestion and absorption (90%) takes place here – lipid
digestion, continuation of carbohydrate and protein digestion
- the accessory organs of digestion, the pancreas, gall bladder and the
liver secrete their juices into the duodenum to aid in digestion
- the small intestine, in order to better digest and absorb digested
materials is highly folded to increase surface area (by 600x); the folds
are called villi, which are covered in small cytoplasmic projections called
microvilli, the structure of the small intestine (from the outer surface in)
includes:
- villi/microvilli – surface (epithelial) cells designed for absorption
- lacteal – vessel projection of the lymphatic system, designed to
absorb fats
- capillaries – vessels of the circulatory system, for absorption of all
other nutrients for immediate transport to the liver for processing
- as the chyme enters the duodenum, its acidity and contents stimulates a
number of hormones’ release, which in turn stimulate the secretion of
digestive and protective chemicals from accessory organs and the
intestinal epthelium itself
Large Intestine
- about 1.5 m in length, a diameter of 6.5 cm.
- at the junction of the small and large intestine, the ileum exists the
appendix, which has no real function given our diet
- the large intestine has three main functions:
- absorption of water and electrolytes
- production of feces – consisting of water, inorganic salts, cells from
the GI tract, bacteria, bacterial decomposition and undigested food
- housing bacteria, that will use remaining unabsorbed nutrients or
undigested carbohydrates to make vitamin K and B vitamins for us to
absorb (as well as methane gas)
10. Why are salivary glands important?
Moistens food forming the bolus and contains salivary amylase starting
carbohydrate digestion
11. Identify all of the enzymes found in the stomach. What do they digest? How are
these enzymes activated? What does the mucous lining do?
Pepsinogen activated by HCl forms pepsin which breaks proteins down into
polypeptides. Mucous lining prevents the stomach walls form being digested.
12. Identify all of the enzymes found in the small intestine. What do they digest?
What do they produce? How are they activated?
- Pancreatic amylase breaks down carbs
- Carbohydrases break down disaccharides into monosaccharides
- Pancreatic proteases (trypsin) breaks down polypeptides into dipeptides
- Pancreatic lipase breaks down fats into fatty acids
- These enzymes are all activated by the secretion of bicarbonate from the
pancreas - result in a pH of 8
13. Discuss the role of the pancreas in digestion. Why doesn’t the pancreas digest
itself? What is the role of bicarbonate ions?
- Pancreas secretes various digestive enzymes
- Enzymes are secreted in inactive form
- Bicarbonate reduces acidity of the duodenum activating enzymes.
14. Discuss the role of the liver and gall bladder in digestion.
- Liver produces bile which is stored in the gall bladder – physically breaks
down fats by emulsification
15. How is the surface area of the small intestine increased? Why is this important?
- The lining of the gut is folded into villi and microvilli greatly increasing SA –
allows us to absorb large quantities of nutrients
16. What is peristalsis? Identify two places it occurs.
- Rhythmic contraction of smooth muscle – esophagus and small intestine
17. Why is chewing important in digestion?
Increases surface area of food molecules making digestion more efficient
18. How and where are all the monomers of lipids, proteins, and carbohydrates
absorbed? What happens to the nutrients after they are absorbed?
- Amino acids and monosaccharides are absorbed from the villi into blood
- Fatty acids absorbed from villi into lymph (lacteal)
- Once absorbed these nutrients are used for life processes
19. Why is the diet of a person whose gall bladder has been removed restricted in fat
intake?
- Less bile
20. What is the role of the large intestine?
Absorption of water, electrolytes and elimination of digestive waste in the form of
feces.
21. What does the epiglottis do?
Prevents liquids/solids from entering the trachea
Respiration, Ch 7
1. Describe the path of a molecule of oxygen as it moves from the air to a blood cell.
Give key features of each part of this respiratory tract
Nose – warms and moistens air
Pharynx – hallway between digestive and respiratory systems
Trachea – mucus traps debris and cilia sweep it away
- has cartilage rings to prevent collapse
Bronchi – one leading to each lung, mucus and cilia – trap and sweep and divide
Bronchioles – smaller tubes throughout the lungs leading to
Alveoli – microscopic air sacs where oxygen diffuses to blood
2. What does the nasal cavity do to the air that is inhaled?
Moisten and warms the air
3. How do bronchioles differ from the trachea?
They are smaller and do NOT have cartilage rings
4. Where does gas exchange with blood occur in the respiratory tract? Why does it
occur in this location?
The alveoli walls are very thin and are surrounded by capillaries
•Carbon dioxide and oxygen transfer between the alveoli and capillaries
through diffusion
•You have about 150 million alveoli, whose total combined surface area could
cover a tennis court!
Between the blood capillaries and the alveoli – this location has a large surface
area, is moist, and the walls are thin enough to allow diffusion
5. Why must the internal surface of the lungs be kept moist?
Facilitates diffusion
6. Why are there tiny hairs (cilia) and mucus in the respiratory tract?
Trap and sweep debris
7. What is the role of the cartilage rings (C-rings) that line the trachea and bronchi?
Prevent collapse of these tubes
8. Describe the movement of your ribs, intercostal muscles and diaphragm as you
breathe in and out.
Inhalation – active process – diaphragm moves down and ribs up and out
lowering air pressure
Exhalation – passive process – diaphragm moves up and ribs drop back down
raising air pressure
9. Explain why a pressure gradient must be made to allow proper inhaling and
exhaling
Air always moves from high pressure to low pressure
10. Define the following terms: tidal volume, inspiratory reserve volume, expiratory
reserve volume, vital capacity. What device takes these measurements?
Spirometer readings:
11. Why must the respiratory system and the circulatory system work together?
Oxygen gained through respiration and delivered via circulation
12. List and describe 3 respiratory disorders.
Pneumonia, Emphysema, Lung Cancer
13. Describe the structure and function of hemoglobin. What blood cell contains
hemoglobin? Explain how hemoglobin picks up oxygen
Hb contains 4 Heme (Fe2+) which binds to oxygen and the globin part binds to
carbon dioxide
14. How is carbon dioxide transported in the blood? What is carbonic anhydrase
needed for in the blood?
- HbCO2
- Dissolved in the blood plasma
- H20 + CO2 forms H2CO3 which dissociates into H+ and HCO3
- Transport of Gases in the Blood
- •oxygen is only slightly soluble in the blood (0.3mL / 100 mL), so it
must be bound to hemoglobin to be transported in the blood. As
oxyhemoglobin, the blood can carry 20 mL/100 mL of oxygen. The
amount of oxygen that combines with hemoglobin depends on the
partial pressures of oxygen in the blood and in the tissues. About
97% of all oxygen is carried by oxyhemoglobin, and the other 3% is
carried in the plasma of the blood.
- •About 9% of the carbon dioxide is carried in the plasma and 27%
is carried as carbaminohemoglobin (HbCO2), and 64% is carried as
carbonic acid or bicarbonate. This reaction is catalyzed by the
enzyme carbonic anhydrase. The reaction decreases the amount
of carbon dioxide in the plasma, thus increasing the rate of
diffusion of carbon dioxide from the cells to the blood. Once the
blood is returned back to the lungs, the concentration of carbonic
acid becomes very high, encouraging the diffusion of carbon
dioxide out of the blood into the lungs.
15. If the blood has lots of carbon dioxide in it, what would its pH be? Explain
Acid due to the build – up of H+ ions
16. What are chemoreceptors? How do they control breathing rate?
Measure pH and regulate breathing
•Breathing is an autonomic function that is controlled by nerves from the
medulla oblongata in the brain. Chemoreceptors detect the levels of carbon
dioxide (acid) and oxygen in the blood and signal the brain to speed up or
slow down breathing.
17. Describe all the ways smoking destroys your respiratory tract.
- Damages cilia
- Damages mucus producing cells
- Destroys lung tissue