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Biology 12: Unit 4
Unit 4 of Bio
| Question | Answer |
|---|---|
| What is Metabolism? | the totality of an organisms chemical reactions. It is needed for survivaly and is a combination of the bichemical reactions & pathways that occur w/in the cells. |
| What are Metabolic Pathways | the orderly step-wise series of chemical reactions from the initial reactants to the final products. One reaction leads to the next. Highly structured and controlled by enzymes |
| What is required at each step of a Metabolic Pathway? | a specific enzyme |
| Why do metabolic pathways exist? | it is not possible inbiological syystems to have a single reaction that could produce complex molecules from simple reactants |
| What are Catabolic Pathways? | breakdown pathways that release energy by breaking down complex molecules to simple compounds ->ex. Cellular respiration - glucose breaks down to CO2 and water |
| What are Anabolic Pathways? | consume energy to build complicated molecules from simple ones ->ex. Amino acids synhesized from simple molecules and proteins synthesized from amino acids |
| What are enzymes? | proteins that can speed up a chemical reacion without being consumed -->they act as a caalyst |
| Why do metabolic pathways need enzymes? | without enzymes, metabolic pathways would be congested because reactions would take too long |
| Why are enzymes highly specific? | each enzyme speeds up only one reaction. |
| What is a substrate? | the reactant in an enzymes reaction |
| What is an enzyme-substrate complex? | when an enzyme binds to its substrate -->chemical reaction occurs when ES complex exists |
| What is an active site? | the place where the substrates actually bind on the enzyme |
| What occurs when E + S are joined? | catalyic action of enzyme converts the substrate o the product |
| What is the lock and key theory? | E + S meet during the reaction and fit perfectly like a lock and key |
| What is the Induced Fit theory? | the enzyme changes shape slightly when it binds to the substrates in order to get a tighter grip on the reactants. |
| What does the Induced Fit do? | 1)brings chemical groups of active sites into positions that enhance their ability to catalyze the chemical reactions -->after reaction enzyme re-assumes its original shape |
| What are ways enzymes speed up reactions? | 1)provides template where S can gather in proper place, 2)as E holds S it can stretch molecules towards transition-state form, stressing & bending critical bonds that must be broken, 3)active site might have best PH, 4)direct participation of active site |
| How does an enzyme work? | Lowers activation energy by brining the substrate molecules together and holding them long enough for reaction to take place |
| what is activation energy? | the energy that must be supplied to cause molecules to react with one another |
| What are factors that affect enzyme activity? | 1) PH, 2)Temperature, 3)Concentration, 4)Inhibitors, 5)Cofactors |
| Explain how PH affects enzyme activity | most enzymes optimal pH is around 6-8 (exceptions pepsin=3, trypsin=8) --> if pH is too low or too high, enzyme denatures |
| Explain how temperature affects enzyme activity | the lower the temperature, the lower the rate of reaction --> up to a point, rate of reation increase w/ temp. BUT above optimal temp, enzyme denatures -->optimal temp is about 37 |
| Explain how concentration of substrates affects enzyme activity | if con'c of substrate increase, amount of product increase --. after a certain concentration, rate won't increase anymore because E are saturated with substrates and can't work any faster |
| Explain how concentration of enzymes affects enzyme activity | This is what limits the overall rate of reaction. More enzyme = more product. This rate only levels off if you run out of substrate, which is usually not the case |
| Explain how the presence of inhibitors affects enzyme activity | inhibitors are molecules that bind to the enzyme in some way o prevent or reduce the rate of substrate binding to enzyme |
| What is competitive inhibition? | a molecule that looks like the substrate can compete for space at the active site. -->will SLOW DOWN reaction rate. -->can be reversible or irreversible |
| What is non-competitive inhibition? | inhibitor binds to another place on E (not the active site) causing the E to change shape at the active site. AKA allosteric inhibition |
| Explain how the presence of cofactors affects enzyme activity | nonprotein helpers for catalyic activity, may be bound permanenly or loosely & reversibly along with S |
| What are organic Cofactors called? What do the do? example. | called Coenzymes (ex. vitamins, NAD in the NAD cycle) -> Helps the reaction - may participate by accepting or donating atoms |
| What is a good use of reversable inhibition | used as a way of slowing down the metabolic pathway |
| Examples of inhibitors | HCN, Lead (Pb) and other heavy metals like mercury (Hg) |
| What are enzymes made out of? | 1) a protein part called an Apoenzyme --.gives its specificity, 2)a non-protein group called Coenzyme (may helps reaction by accepting or donating atoms) |
| In terms of metabolism, what does thyroxin do? | partially governs the rate of metabolism |
| How does thyroxin help the rate of metabolism? | thyroxin attaches to receptor sites on the surface of body cells where it increase the rate that cells consume oxygen --> promotes ATP production by cellular respiration, thus increasing rate of cell metabolism |
| What is homeostasis? | the maintenance of a relatively constan set of internal body conditions that results from enzymatic reactions |
| What is a endothermic reaction? | overall reaction requires a net input of energy |
| What is a exothermic reaction? | it releases energy -->energy is available o be capture in the form of ATP or given off as heat |
| What is negative feedback? | occurs when con'c of the product of one step increase high enough to begin to inhibit the first step hat is dedicated to its own production |
| What is NAD? what does it do? | derived from niacin, one of B vitams -->transports hydrogen to or from a reaction (called a hydrogen carrier) |
| What are the 4 Stafes of Food processing? | Ingestion, Digestion, Absorbtion, Elimination |
| What is ingestion? | eating or feeding |
| What is digestion? | food being broken down into molecules small enough for body to absorb ->there is mechanical and chemical |
| what is mechanical digestion? | breaks down food into small pieces, increasing surface are available for body to absorb |
| What is chemical digetion? | large molecules are broken down into their components --> breaks bonds with addition of water -->splitting is called enzymatic hydrolisis |
| What is absorbtion? | cells absorb small molecules like amino acids and simple sugars |
| What is elimiation | undigested maerial passes out the digestive system |
| How many pathways does food take to get from mouth to anus (LOL so gross actually) | One way path from mouth to esophagus to stomach to small intestine to large intestine to anus |
| In mammals, what does digestive system consist of? | alimentary canal and various accessory glands that secrete digestive juices through ducts ino the canal |
| What are the accesory glands? | 3 pairs of slicary glands, the pancreas, the live and the gallbaldder |
| What happens to proteins during digestion? | broken down to amino acids |
| What happens to carbohydrates during digestion? | broken down into glucose |
| What happens to fat during digestion? | breaks down into fatty acids and glycerol |
| what happens to nucleic acids during digestion? | the are broken down into nucleotides |
| How is food pushed along the digestive system? | by Peristals --> alternating waves of contraciong and relaxation in the smooth muscles lining the alimentary canal |
| How is digestion achieved? | through the cooperation of a number of body parts and organ systems and its coordination depends on key hormones |
| What do sphincters do? | they close off the alimentary canal to regulate the passage of material btwn compartments |
| Where does digestion begin? | the mouth |
| Wha does the mouth do? | it recieves food, chews it up, moistens it, starts to digest and startch |
| What is the structure of the mouth? | anterior hard palate (several bones) and a posterior soft palate composed of muscle tissue) |
| What is the uvula | the end of the soft palae |
| Why do we get the sense of hunger? | due to the combined sensations of smelling and tasting food |
| What reminds you that you are hungry? | your taste buds and olfactory (scent) receptors in the nose |
| What is the purpose of teeth? how many do we have? | normal adult has 32, Purpose is to chew food into pieces that can easily be swallowed |
| What are the different types of teeth? | 8 incisors for biing, 4 canines for tearing, 8 flat premolars for grinding, 12 molars for crushing |
| What does a tooth look like? | it is shrouded by a tough layer of enamel, dentine and an inner layer of nerves and blood vessels called pulp |
| What are cavities cause by? | bacteria in the mouth feeding on foods (like sugars) and giving off acids hat corrode the tooth |
| What is plaque? | the living and dead bodies of millions of bacteria |
| What does flouride do? | it makes tooth enamel stronger and more resistan to decay |
| What does gingivitis do? | If it spreads to the periodontal membrane (the lining of the tooth socket), it can cause bone loss in the socket and loosening of the teeth (= peridontitis) |
| How many sets of Salivary glands are they? What do they produce? | 3 sets; produce saliva |
| What are the three sets of salivary glands | 1) parotid (below ears), 2) sublingual (below tongue), 3) submandibular (under lower jaw) |
| What does saliva contain? | water, mucus, salivary amylase |
| Wha is salivary amylase | a hydrolic enzyme that breaks down startch in the presence of water |
| What is startch broken down into? | into maltose (later broken down to glucose in the intesine |
| What does saliva do to food when we chew it? | it moistens and lubricates it |
| What does mucus in saliva do? | i protects the lining of the mouth from abrasian and lubricates foord |
| What does the tounge do? | it evaluates the ingested material and enables its further passage --> tounge shapes food into a ball of food |
| What is a ball of food called? | a bolus |
| After swallowing food, where does it enter? | the pharynx |
| What is the pharynx | the region between mouth and esophagus |
| What are the two passageways of the pharynx? | he esophogus (leads to the stomach) and the trachea (leads to lungs) |
| What does the epiglottis do when swallowing? | it covers the glottis, thus blocking the entrance to the larynx |
| What is happening when we swallow? | 1)Soft palate moves back (covers openings to nose)m 2) Trachea moves up under epiglottis blocking its opening, 3)Opening to Larynx (the glottis) is covered |
| What is the esophagus | a long musculare tube that extens from pharynx to stomach. -->contains both striated muscles and smooth muscle |
| What is striated muscle and smooth muscle | striated muscle is at he op and is active during swallowing; smooth muscles function in peristalsis to move the bolus |
| What is the inner surface of the esophagus lined with? | mucus membranes attached by connective tissue to the layer of smooth muscles that contain both circular and lonitudunal muscle |
| What is the cardiac sphincter | the sphincter that is connected to the esophagus and stomach |
| What is the function of the cardiac sphincter? | prevents food from moving up out of the stomach -->but when we vomit, revers peristaltic waves causes the sphincter to relax and the contents of the stomach are prepelled outwards |
| What is the stomach? | a thick-walled, J-shaped organ the lies on the left side of the body, beneath the diaphram, has accordian like folds and a very elastic wall |
| What does the stomach do? | it stores food and begins the digestion of proeins |
| How many layers of muscle are there in the stomach? what is its function? | three layers --> contract to churn and mix its contents |
| What does the mucus lining of the stomach contain? | Gastric glands which produce gastric juice |
| What does gastric juice contain? | pepsinogen and HCl --> when they combine, pepsinogen forms Pepsin |
| what is pepsin? | a hydrolytic enzyme that breaks down proteins into smaller chaines of amino acids (called peptides) |
| What happens when gastric juice mixes with food? | it makes Chyme |
| What does HCl do to the stomach? | gives it a pH of 3 (highly corrosive) --> this kills bacteria in food and helps break it down |
| Why doesn't the stomach digest itself? | Because the inner wall is protected by a thick layer of MUCUS, that is secreated by mucosal cells |
| What happens if HCl does pentrae? | pepsin starts to digest the stomach lining, thus forming an ulcer |
| What causes gastirc ulcers? | 1) too much gastric juice, 2) too much nervous stimulation (stress), 3) bacterial infections that impair the ability of cells to produce mucus |
| How often does the stomach mix its contents? | muscle contraction and relazation mixes the contents about every 20 seconds |
| How long does it take for contents of stomach to pass through the small intestine? | 2-6 hours |
| What causes heart burn? | The cardiac spincter opening and allowing chyme in the lower end of the esophagus |
| What does the Pyloric Sphincter do? | it conrolls the emptying of acid chyme into the first part of he small intestine (the duodenum) |
| Where does most of the digestion and absorbtion occur? | in the small intestine |
| What are the three zones of the small intesting | the duodenum, jejunum, ilium |
| What is the first 25cm of the small intestine called? | the duodenum |
| What occurs in the duodenum? | acid chyme mixes with digestive juices from the pancreas, liver, gallbladder and gland cells |
| What do the secreations from the liver and pancreas do? | breakdown fat and peptides |
| What do secreations from the duodenum do? | the breakdown other nutriets |
| What does the liver do? How is it sent to the duodenum? | it produces bile; sent via duct from the Gall bladder (where bile is stored) |
| What is bile? What does it contain | a thick green liquid (colour comes from byproducts of hemoglobin breakdown) --> what does it contain? emulsifying agents called bile salts which break fat into fat droplets |
| What does the pancreas send to the duodenum? | sends pancreatic juice that contains enzymes and sodium bicarbonate |
| what does sodium bicarbonate do? | it neutralizes the acidity of the chyme and makes the small intestine pH basic |
| What are the enzymes that are in the pancreas? | the hydrolytic enzymes are: pancreatic amylase (startch to maltose), trypsin(protein to peptide), lipase(fat droplets to glycerol and fatty acids), nucleases |
| What is the pancreas' endocrine function? | produces Insulin and glucagen |
| what is insulin? | a hormone that causes glucose in the blood to be taken up by cells (lowers blood sugar) |
| What happens to people who don't produce insulin or not enough insulin? | they suffer from diabetes |
| How does Glucagon work? | raises the blood glucose concentration |
| What are in the walls of the duodenum and small intestine? | it is lined with millions of interstitial glands --> produce juices containing enzymes that finish he digestion of protein and startch |
| What do the secretions from the interstitial glands contain | digestive enzymes: peptidases (digest peptides to amino acids), maltase (digests maltose to glucose), others digest other disaccharides |
| What is the structure of the Small intestine like? | long convulted walls consisting of millions of finger like projects called villi --> each villi has a microvilli (where nutrients are absorbed) |
| What does each villi contain? | blood vessels and lymphth vessls |
| What is needed in order for nutrients to reach body tissues? | it must cross the lining ot the alimentary canal |
| Where does absorbtion take place? | across the wall of each villus -->can be passive or active --> after this, nutrient can now enter the blood or lymphatic system |
| What happens to fatty acids and glycerol during absorbtion? | once absorbed they are recombined into fat molecules in the epitelial cells of the villus -->fats then move into the laceal of each villus and enter the lymphatic system -> then coated with phospholipids, cholestrol and proteins formin chylomicrons |
| What happens o sugars and amino acids after absorbitio | they ener the blood through the capillary netwrok --> blood vessels from the villi in the small intestine merge to form he Hepatic Portal vein which leads to the liver --> allows liver to remove toxic substances |
| What happens to chylomicrons? | first transported from epithelial cell into a lacteal, a vessel a core of each villus --> can enter lymphatic system and eventually large veins |
| What are the functions of the Liver? | 1)keeps blood con'c constant, 2)Interconversions of nutrients, 3)detoxifies, 4)destroys old red blood cells, 5)production of urea, 6)manufacture of plasma proteins & cholesterol, 7)storage of iron & vitamins, 8)in embryos, makes red blood cells |
| What are examples of disorders of the liver? | jaundice, gallstones, viral hepatitis, cirrhosis |
| What is jaundice | gives a yellowish tint -> tint is due to buildup of bilirubin --> due to lives damage or blockage of bile duct (latter is called obstructive jaundice) |
| What causes Gallstones? What does it do? | obstructive jaundice causes it; gallstons can block bile ducts |
| What is Cirrhosis | usually caused by chronic over-consumption of alcohol |
| What does the large intestine consist of? | colon, cecum and rectum |
| What is the opening of the rectum called? | the anus |
| how does the large intestine connect to the small intestine? | connected at a T-shapped junction -->one arm of the T is the colon, which leads to rectum --> other end is a pouch called the cecum |
| What does the cecum do? | fermts ingested material (especially animals that eat a lot of plants) |
| What is the appendix? | extension of the cecum |
| What are he main functions of the colon? | reabsorbtion of water (from feces), absortion of certain vitamins |
| What does feces contain? | bile pigments, heavy metals and E.coli |
| What does E.coli do? | break down some indigestible food and in the process, produce vitamins, amino acids and other growth factors that are in turn absorbed by the colon |
| What is diarrhea? what causes it? | too much water is expelled in the feces. Caused by infection or stress. Symptom is actually a body defense against pathogens |
| What is constipation? what causes it? | feces are dry, hard, difficult to expel. Leading cause is dietary fiber |
| What is Appendicitis? | a vestigial strucure located at the bottomm of cecum with no know function. Can get infected and burst -> can be deadly as it would fill the abdominal cavity with bacteria |
| what is Colostomy? | removal of rectum and anal canal --> intestine atached to abdominal wall, feces collect in plasttic bag |
| what does the presence of food in the digestive system trigger? | triggers digestive glands to secrete their enzymes |
| What do hormones do? | control secretion of specific juices |
| What are the 4 hormones? | gastrin, secretin, CCK and GIP |
| what is the spincter between the small intestine and large intestine? | ileo-caecal valve |
| What do sensory cells detect when food is eaten? | detects the presence of peptides, others will detect that the stomach is stretching ->causes other stomach cells to release gastrin |
| Gastrin: Released/Acts/Purpose | released by upper part of stomach/in response to protein in the stomach; acts on Gastric juice secreting cells at top of stomach; causes secretion of gastirc juices |
| Secretin: Released/Acts/Purpose | released by S.I/in response to chyme; acts on pancreas; causes pancreas to release sodium bicarbonate and pancreatic juices |
| CCK: Released/Acts/Purpose | released by S.I/response to acid chyme; acts on pancreas and gall bladder; causes liver to secrete bile and panrease to secrete pancreatic juice |
| GIP: Released/Acts/Purpose | released by S.I/in response to acide chyme rich in fats enter duodenum; acts on stomach; inhibits stomach peristalsis and acid secretion |
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