Bio 20 Units A, B, C, D1 Crash Course PDF

Bio 20 Units A, B, C, and D1 Crash Course  Earth’s Spheres The biosphere is the narrow zone around Earth that harbours life The biosphere extends from the bottom of the ocean all the way into the atmosphere  Biosphere Biotic Factors...

Bio 20 Units A, B, C, and D1 Crash Course  Earth’s Spheres The biosphere is the narrow zone around Earth that harbours life The biosphere extends from the bottom of the ocean all the way into the atmosphere  Biosphere Biotic Factors Abiotic Factors Living things Nonliving things Plants Rocks Animals Minerals Temperature Weather  Some More Terminology… A population is a group of individuals from the same species that live in the same area A community is all the populations in a given area (all the living things)  Some More Terminology… An ecosystem has both biotic and abiotic components ○ The community of organisms and its physical and chemical environment The Last of the Terminology (For Now)... Biodiversity is the number of species in an ecosystem  Food Chains A food chain is a sequence linking organisms that feed on each other Food chains start with producers that make their own food and continues with consumers who must eat producers or other consumers to survive ○ Organisms that feed on producers are called primary consumers ○ Organisms that feed on primary consumers are called secondary consumers ○ Organisms that feed on secondary consumers are called tertiary consumers  y Tertiar r me Consu r ry c o n d ary Produce Prima r Se mer Consu me Consu m po ser D e c o  Relationships in Food Chains Since organisms are connected to every other organism in an ecosystem, the increase in numbers or decrease in numbers of one species can have a cascading effect throughout an ecosystem  Food Webs Food webs are a representation of feeding relationships in an ecosystem that consist of multiple food chains ○ These are a more accurate representation of reality than food chains Terminology for Energy Transfer in Food Chains and Webs Trophic level is a category of living things defined by how it gets it energy ○ The first trophic level contains autotrophs ○ Each higher trophic level contains heterotrophs Autotrophs make their own food (producers) Heterotrophs cannot make their own food (consumers)  y Tertiar r on s u me C r ry c o n dary Produce Prima r S e s u mer o n su me C o n C Autotroph Heterotrophs First Second Third Fourth Trophic Trophic Trophic Trophic Level Level Level Level  2 Questions. Where does all of the energy on The Sun!!! Earth come from? How do autotrophs use the Sun Photosynthesis to make their own food?  Photosynthesis The process by which green plants (producers/autotrophs) use solar energy, carbon dioxide, and water to produce carbohydrates (glucose) This process provides energy for the entire ecosystem ○ More green plants = more energy in the ecosystem  Cellular Respiration The process by which cells break down glucose into carbon dioxide and water, releasing energy All organisms (including plants) undergo this process ○ ATP (Adenosine triphosphate) is the body's main fuel source  Chemosynthesis Not all food webs begin with photosynthetic organisms! In deep sea environments chemoautotrophs undergo chemosynthesis to make nutrients ○ Chemoautotrophs are organisms that undergo chemosynthesis. These are typically bacteria ○ Chemosynthesis is the process of converting inorganic chemicals to to organic compounds without solar energy A chemosynthetic reaction using sulfur is as follows:  Rule: Only about 10% of the energy at a given trophic level is passed onto the next trophic level Where does all this energy go? Lots of Energy Little Energy First Second Third Fourth Trophic Trophic Trophic Trophic Level Level Level Level  Rule: Only about 10% of the energy at a given trophic level is passed onto the next trophic level Where does all this energy go? Life Processes (metabolism, Lost as Heat movement, etc.)  A Quick Note on Thermodynamics Thermodynamics is the study of energy transformations The First Law of Thermodynamics Energy cannot be created or destroyed, it can only be transformed The Second Law of Thermodynamics During any energy transformation some of the energy is converted into thermal energy (heat) that cannot be passed on This explains why energy decreases as we move up trophic levels  Rule: Only about 10% of the energy at a given trophic level is passed onto the next trophic level 10,000 J 1J 1,000 J 100 J 10 J Lots of Energy Little Energy First Second Third Fourth Trophic Trophic Trophic Trophic Level Level Level Level  Condensation: Water vapour in the atmosphere condenses into clouds Evaporation: Liquid water from lakes/rivers/oceans turns into a gas Precipitation: Liquid water returning to the ground (rain, Transpiration: Liquid water from snow, hail, etc.) trees turns into a gas Runoff: Liquid water re-enters lakes and streams, eventually flowing into the ocean  Ground Water and Surface Water Percolation is the downward movement of water through soil As water moves downwards through soil, it carries dissolved organic matter and materials that are important for plant growth, this is called leaching  CO2 in the Atmosphere Diffusion Combustion Cellular Respiration Photosynthesis Dissolved Fossil CO2 in the Fuels Ocean action Decomposers Sedimentation Uplifting + Comp Weathering Organic Carbon in Carbon in Sediments Living Things Death Compaction The Composition of Earth’s Atmosphere  Why Should We Care About Nitrogen? Nitrogen is required for the formation of proteins and DNA Nitrogen is a critical nutrient for plant growth Nitrogen gas (N2) makes up about 79% of the Earth’s atmosphere  N2(g) n tio De xa nit Fi rif en icati on og itr N NO2-(aq) osition Decomp n tio ila Ammonia sim Nitrates As tion NH3(aq) Assimila NO3-(aq) Nitrification  Important Processes in the Nitrogen Cycle Nitrogen fixation turns unusable atmospheric nitrogen gas into ammonia ○ Performed by bacteria and lightning Nitrification turns ammonia into nitrates ○ Performed by bacteria Assimilation is the uptake of nutrients by plants ○ Primarily nitrates, but some ammonia as well Denitrification turns nitrates into nitrites and then to nitrogen gas ○ Performed by bacteria  Why Should We Care About Phosphorus? Like nitrogen, phosphorus is important in plant growth Phosphorus is a key element in cell membranes and the making of DNA Phosphorus is also a critical element in bone and teeth production in the form of calcium phosphate  The Phosphorus Cycle Black = Short Term Cycle Red = Long Term Cycle After weathering, Weathering of No cycling in phosphates are phosphates in the atmosphere absorbed by plants and rocks/fossils enter the food chain Phosphates are carried Animals use by rivers and runoff to phosphorus in bone the ocean formation Deposited as ocean Decomposers break sediments down waste from living Are uplifted over things and release the geological time and the phosphates back into process repeats the environment Geochemical Cycle Biological Cycle  Ecotones Ecosystems rarely have sharp, black-and-white boundaries, and organisms can move in between ecosystems Ecotones are the transition area between ecosystems. These are a grey area between ecosystems where organisms from both ecosystems interact  Question: Which area will have the highest biodiversity? The pond, the ecotone, or the field?  Ecological Niche An ecological niche is an organisms role in an ecosystem. This consists of… Its place in the food web Its habitat Its breeding area The time of day it is most active Everything it does to survive and reproduce  Ecological Niche Each species in an ecosystem tends to have a different niche. This helps avoid competition between species for the same territory and resources  Biomes A biome is a large geographical area with a specific climate, and the plants and animals that live in that area are adapted to that climate ○ Essentially, areas of similar climate  Biomes A biome is a large geographical area with a specific climate, and the plants and animals that live in that area are adapted to that climate ○ Essentially, areas of similar climate Canada has four major terrestrial ecosystems ○ Tundra ○ Taiga ○ Temperate Deciduous Forest ○ Grassland Alberta’s terrestrial ecosystems are found within the taiga and the grassland biomes  Taiga Ecosystem Also known as boreal forest, taiga ecosystems are dominated by conifers (cone-bearing trees that have needles) Conifers are very well adapted to warm, moist summers and cold, dry winters found in the taiga Question: What adaptations do conifers have that help them in winter? Needles provide less surface area for water loss and the trees pyramid shape helps shed snow  Taiga Ecosystem Taiga ecosystems are found in northern and central Alberta, and along the Rocky Mountains The soil in taiga ecosystems is slightly acidic and contains some water Precipitation is average, can range from 50-250 cm annually  Grassland Ecosystem The grassland ecosystems of south and central Alberta are characterized by their rich, fertile soil Grasslands have warmer temperatures than taiga or muskeg, but low precipitation Plants adapted to the grassland ecosystem includes rough fescue and wheat grass  Deciduous Forest Ecosystem In-between the grasslands and the taiga in central Alberta the ecosystem is dominated by large broad-leaf trees such as aspen, poplar, and birch (deciduous trees) Like grasslands, the soil is rich and fertile Temperatures are warm, but moderate Precipitation levels are also moderate  Tundra The most northern and coldest biome on Earth, the tundra contains little biodiversity compared to other biomes Precipitation is low There are no tall trees, and animals like polar bears, arctic fox, and caribou call the tundra home  Tropical Rainforest (Jungle) Found near the equator, the tropical forest is the most productive ecosystem on the planet and has the highest biodiversity Temperatures and rainfall are high Animals like jaguars, toucans, and monkeys call the tropical rainforest home  Forestry Practices Slash and Burn The complete clearing of a forest by felling and burning of trees Commonly used in tropical areas to clear forests for agriculture  Forestry Practices Clear Cutting The removal of all trees in an area Commonly used to harvest timber Followed by a replanting of the dominant species Pros and cons? Forestry Practices  Forestry Practices Selective Cutting The harvesting or selected trees in an area One More Important Graph Rule: Temperature and the solubility of oxygen are inversely proportional to each other What does this mean? Warm water holds less dissolved oxygen than cool water This could become an issue in a hot spell during the summer. A lake may lose so much oxygen that some species would die  2 Types of Lakes Oligotrophic Lakes Eutrophic Lakes Deep, cold, low nutrient levels Shallow, warm, high nutrient levels Water is usually clear Water is usually murky The Evolution of Lakes - Eutrophication In general, oligotrophic lakes gradually become eutrophic over time Eutrophic lakes become increasingly shallow, eventually filling in and becoming dry land  c lusive t In Taxonomy Mos Taxonomy is the science of classifying organisms Our current classification system has 8** levels of taxa (categories) ○ Domain ○ Kingdom ○ Phylum ○ Class ○ Order ○ Family ○ Genus ○ Species ific s t S pec Mo Where does the name Homo sapiens come from? Genus: Homo Species: sapiens  Binomial Nomenclature A method of naming organisms coined by Carl Linnaeus that consists of using both the genus and species name to name an organism Scientific names are italicized The genus is capitalized, while the species is lowercase Homo sapiens What can we say about the relationships of these organisms? American Black Bear Grizzly Bear Polar Bear Ursus americanus Ursus arctos Ursus maritimus Koala Bear Panda Bear Phascolarctos cinereus Ailuropoda melanoleuca Evolution Evolution is a scientific theory that explains how organisms change over time and the diversity of species on Earth A theory is an explanation of the natural world that accounts for all the known scientific evidence This Lesson Next Lesson Evidence of Evolution #1: Fossils Paleontology is the study of fossils and this discipline plays a crucial role in the study of evolution Scientists have uncovered approximately 250 000 fossil species, but this is estimated to be a tiny fraction of all the species that have lived on Earth as most organisms leave no trace of their existence Evidence of Evolution #2: Biogeography Biogeography is the study of the geographic distribution of life on Earth Earth’s landmasses have undergone significant changes by the process of continental drift 225 mya Earth’s landmasses formed the supercontinent Pangea As a result, fossils of species that are more than 150 million years old can be found on different continents today Evidence of Evolution #2: Biogeography  Evidence of Evolution #3: Anatomy Homologous Features Analogous Features Vestigial Features Similar structure, different Similar in appearance and Structures with no apparent function function use Evolutionary origin No evolutionary origin Evolutionary origin Evidence of Evolution #4: Embryology In the early weeks of development, humans possess a tail and gill slits ○ The tail becomes the tailbone (vestigial structure) ○ Gills become modified and form the bones of the inner ear Evidence of Evolution #5: Artificial Selection Since the beginning of agriculture, humans have used artificial selection to alter the appearance, behaviour, and chemical makeup of plants and animals Artificial selection is the process of humans selecting and breeding individuals with desired traits This provides compelling evidence that similar and even more dramatic changes can occur in nature over millions of years Evidence of Evolution #6: Biochemistry DNA is the molecule that makes up genetic material A gene is a segment of DNA that codes for a particular protein While humans share about 60% of our genes with fruit flies, we share 96% of our genes with chimpanzees Geneticists have also found large numbers of homologous and vestigial genes that indicate evolutionary relationships Gene sequencing and genetics is a very new field Lamarckism - Inheritance of Acquired Characteristics Lamarckism was the first evolutionary theory Lamarck reasoned that characteristics that were acquired throughout an organism's lifetime would be passed onto its offspring While he was incorrect that acquired traits can be inherited, he was the first person to acknowledge that the environment played a role in evolution  **Probably the most important slide of this unit The Theory of Evolution by Natural Selection Three Key Points 1. Individuals of the same species are in a constant struggle for survival 2. Individuals with more favourable variations are more likely to survive and pass these variations on. Survival is not random. This is natural selection 3. Since individuals with more favourable variations contribute proportionately more offspring to succeeding generations, their favourable inherited variations will become more common. This is evolution  i s s in g … p i ec e w e are m e i s on e Ther How does variation arise????? This is a question that Darwin himself never answered. It wasn’t until the 1930’s that we answered this question Source of Variation #1: Mutations In most cases, DNA (heredity material) will remain the same throughout its life Mutations are random changes in DNA and can be caused by environmental factors or by errors when cells copy DNA While mutations are rare, the number of mutations in large populations that reproduce over several generations is substantial Source of Variation #1: Mutations Fitness is an organism's reproductive success Harmful mutations reduce an individual's fitness Neutral mutations have no effect on fitness Beneficial mutations enhance an individual's fitness Harmful mutations are more common than beneficial mutations, but harmful mutations are selected against, and do not accumulate over the generations Beneficial mutations are rare, but they accumulate over generations because they are selected for Source of Variation #2: Sexual Reproduction Sexual reproduction is the production of offspring by the union of sex cells from two different parents; the offspring inherit a combination of genes from both parents How does this cause variation? ○ Sexually reproducing species had two copies of each gene. Offspring inherit one copy from their mother and one copy from their father, giving offspring distinct combinations ○ The assortment of genes that offspring receive are random (eye colour, height) ○ Sexually reproducing species choose different mates. In a small population of 1000 males and 1000 females, there are 1 million possible mating pairs Allopatric Speciation Most new species are thought to arise by allopatric speciation (speciation by reproductive isolation) Allopatric speciation has 3 distinct steps: 1. A physical barrier separates a single interbreeding population into two or more groups that are isolated from one another 2. Natural selection works on each group independently 3. In time, accumulated physical or behavioural differences between the populations become so pronounced that even if the groups were reunited, they would no longer be sexually compatible with one another Allopatric Speciation  The Rate of Speciation and Evolution Gradualism - speciation occurs at a Punctuated Equilibrium - species slow, steady pace evolve rapidly (in quick bursts), followed by a time period of little to no change Supported by the fossil record  What is Photosynthesis? This process is only performed by Photosynthesis is the process of plants and other producers trapping energy from the sun and converting it into chemical energy Photosynthesis is an anabolic in the form of glucose pathway (builds molecules) 6CO2(g) + 6H2O(l) + Light → C6H12O6(s) + 6O2(g) Carbon dioxide + Water + Light → Glucose + Oxygen Photosynthesis occurs in chloroplasts  Some Important Molecules… Glucose stores energy for cells  Some Important Molecules… ATP (adenosine triphosphate) is the cells usable form of energy ATP is formed by the addition of an inorganic phosphate group (Pi) to the lower-energy molecule ADP (adenosine diphosphate) This energy can be released by the opposite reaction  The Light-Dependent Reactions The light-dependent rxns occur inside thylakoids and across the thylakoid membrane within chloroplasts The light-dependent rxns generate ATP and high energy electron carriers to provide fuel for the light-independent rxns The inputs are sunlight and water (also NADP+ and ADP + Pi ) The outputs are ATP, NADPH, and O2 LDR Step 1a: Photoexcitation Solar energy strikes chlorophyll in photosystem II, exciting an electron The excited electron leaves the photosystem and into the electron transport chain LDR Step 1b: Photolysis The electron that leaves PSII must be replaced The replacement electron comes from the photolysis of water ○ Photolysis is the breaking down of a compound by light H2O → 2H+ + e- + ½O2 Water is absorbed by the roots of a plant and transported to chloroplasts through the xylem LDR Step 2: Electron Transport Chain Excited electrons in PSII are passed through the electron transport chain (ETC) The ETC is a series of electron acceptors that acts like a staircase and allows energy to be released in usable amounts for the formation of ATP LDR Step 2: Electron Transport Chain Excited electrons in PSII are passed through the electron transport chain (ETC) The ETC is a series of electron acceptors that acts like a staircase and allows energy to be releases in usable amounts for the formation of ATP LDR Step 2: Electron Transport Chain As e- move down the ETC they are also carried across the thylakoid membrane towards the thylakoid lumen As e- pass through the thylakoid membrane, they pump hydrogen ions into the thylakoid lumen (see Step 3) Electrons eventually end up in photosystem I (see Step 4) LDR Step 3: Chemiosmosis As hydrogen ions are pumped into the thylakoid lumen an electrochemical gradient is produced LDR Step 3: Chemiosmosis H+ ions escape through ATP synthase complexes which use this energy to combine ADP with a Pi to create ATP ATP produced can then be used in the light-independent reactions The process of synthesizing ATP using the energy of an electrochemical gradient and an ATP synthase enzyme is chemosynthesis LDR Step 4: Reduction of NADP+ The electrons that end up in photosystem I from the ETC are excited by light once again These excited electrons are used to reduce NADP+ to NADPH NADPH can then be used in the light-independent reactions Light-Dependent Reactions Recap Photoexcitation: excitation Photolysis: water is split by of e- in PSII by sunlight, e- is light, replacing e- and transferred to ETC producing O2 as a byproduct Electron Transport Chain: e- move towards thylakoid lumen, ending at PSI and pumping H+ ions into the lumen Chemosynthesis: ATP is Reduction of NADP+: produced by electrochemical NADP+ is reduced to NADPH gradient of H+ ions in lumen by excited e- in PSI  The Light Independent Reactions (Calvin Cycle) The light-independent rxns occur in the stroma of chloroplasts The light-independent rxns use the energy of ATP and the reducing power of NADPH to reduce carbon dioxide and make glucose The inputs are NADPH, ATP, and CO2 The outputs are G3P (glucose), NADP+, and ADP + Pi  The Light Independent Reactions (Calvin Cycle) NADPH and ATP are used to reduce CO2 to G3P (a sugar that is used to make glucose)  Summary of Photosynthesis 6CO2(g) + 6H2O(l) + Light → C6H12O6(s) + 6O2(g) Location Inputs Outputs Sunlight ATP Light-Dependent H2O Thylakoids NADPH Rxns ADP + Pi O2 NADP+ ATP G3P (Glucose) Light-Independent Stroma NADPH ADP + Pi Rxns CO2 NADP+  What is Cellular Respiration? This process is performed by both Cellular respiration is the plants and animals process of breaking down the chemical energy of glucose into Cellular respiration is an catabolic usable energy (ATP) pathway (breaks down molecules) C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l) + Energy Glucose + Oxygen → Carbon dioxide + Water + ATP Cellular respiration primarily* occurs in the mitochondria  Why Convert Glucose to ATP? (The Vending Machine Analogy) To use a vending machine, you need change (for this analogy we are going to assume that the vending machine only accepts loonies) In cells, loonies are analogous to ATP molecules All processes conducted by cells use ATP molecules, and ONLY ATP molecules as their energy source  Roles of ATP in the Cell ATP is constantly being used and reformed by cells to do all kinds of work, including: Active transport across membranes Contraction of muscle fibres Building DNA Switching enzymes on/off Bioluminescence  The Two Types of Cellular Respiration Aerobic Cellular Respiration Anaerobic Cellular Respiration Produces 36 ATP, 6 CO2 and 6 H2O Produces 2 ATP and either ethanol or lactic acid (there are two types) Involves 4 Stages: Involves 2 Stages: 1. Glycolysis 2. Pyruvate Oxidation 1. Glycolysis 3. Kreb’s Cycle 2. Fermentation 4. ETC + Chemiosmosis Both types of cellular respiration begin with glycolysis  Glycolysis Glycolysis is the process in which one glucose molecule is split into two pyruvate molecules This occurs in the cytoplasm of the cell Takes place without oxygen (anaerobic)  Aerobic Cellular Respiration Glycolysis Pyruvate Oxidation Krebs Cycle ETC + Chemiosmosis  The Mitochondria The mitochondria is the site of aerobic cellular respiration Bound by an inner and an outer membrane The matrix is the fluid filled innermost section Cristae are folds in the inner membrane to increase surface area ATP Counter 2 Pyruvate Oxidation Pyruvate oxidation connects glycolysis in the cytoplasm with the Krebs Cycle in the mitochondrial matrix The following 3 changes occur to pyruvate in this stage: 1. CO2 is removed from each pyruvate 2. The remaining 2-carbon molecules are oxidized by NAD+, producing NADH and the remaining 2-carbon molecule becomes an acetyl acid group 3. Coenzyme A (CoA) attaches to the acetyl acid to form acetyl-CoA which enters the Krebs Cycle **Note: This occurs twice because glycolysis produced two pyruvates ATP Counter 2 Krebs Cycle The main purpose of the Krebs Cycle is to produce more NADH and FADH2 for use in the ETC Occurs in the mitochondrial matrix Also referred to as the citric acid cycle ATP Counter 4 ETC + Chemiosmosis The final step of aerobic cellular respiration uses NADH and FADH2 produced in the other steps to transfer electrons to the electron transport chain. The electrochemical gradient produced by the ETC powers chemosynthesis. Together, these processes are known as oxidative phosphorylation ATP Counter 4 ETC + Chemiosmosis Events in oxidative phosphorylation: 1. Electrons from NADH and FADH2 are transferred to the ETC 2. As the electrons are passed along carrier molecules the energy released is used to pump H+ ions into the intermembrane space, creating an electrochemical gradient between the matrix and intermembrane space ATP Counter 4 ETC + Chemiosmosis Events in oxidative phosphorylation: 3. Electrons are accepted by oxygen at the end of the ETC and water is produced as a by-product 4. The excess hydrogen ions in the intermembrane space diffuse through channels in the ATP synthase enzyme, providing energy for the phosphorylation of 32 ADP to 32 ATP per glucose molecule ATP Counter 4 ETC + Chemiosmosis Some notes on Oxidative Phosphorylation: Oxygen is required for this step, it acts as the final electron acceptor. If oxygen is not present, this step will not occur Electrons from NADH and FADH2 produce different amounts of ATP ○ 3 e- are produced per 1 NADH ○ 2 e- are produced per 1 FADH2  Aerobic Cellular Respiration p l asm Cyt o Glucose splits into 2 pyruvates, also Glycolysis produces 2 ATP ix Pyruvate Oxidation Matr Pyruvates are converted to acetyl-CoA and travel into the mitochondria ix Krebs Cycle Matr Energy in acetyl-CoA is transferred to NADH and FADH2, produces 2 ATP r Electrons from NADH and FADH2 ETC + Chemiosmosis Inne rane are used to pump H+ ions across b Mem membrane for chemiosmosis, produces 32 ATP  An Overview of Anaerobic Cellular Respiration If O2 is not present, the ETC cannot operate. Anaerobic cellular respiration is a way of recycling NAD+ to allow glycolysis to continue Occurs entirely in the cytoplasm Much quicker source of energy than aerobic cellular respiration Only generates 2 ATP per glucose molecule 36 2 Classes of Anaerobic Cellular Respiration Bacteria (Yeast) Animals Glycolysis Glycolysis Alcohol Lactic Acid Fermentation Fermentation Produces ethanol Produces lactic acid  What are Enzymes? Catalysts are chemicals that increase the rate of a chemical reaction without being altered itself (decrease the activation energy) Enzymes are protein catalysts in the human body The molecules on which enzymes work are called substrates Important!! Enzymes remain unchanged by chemical reactions and are re-used over and over by the cell Enzymes typically end in the suffix -ase  What are Enzymes? Some enzymes require cofactors or coenzymes to help them bind to substrates ○ Cofactors are inorganic ions ○ Coenzymes are organic molecules  What are Enzymes? Competitive inhibitors are molecules that resemble the shape of the target substrate ○ These compete with the target substrate for access to the active site and blocks chemical reactions ○ They “steal the substrates identity”  Factors Affecting Enzyme Reactions Enzymes are quite particular about the conditions that they work in Factors that affect enzyme reactions include: ○ Temperature ○ pH ○ Substrate molecule concentration ○ Feedback inhibition Factors Affecting Enzyme Reactions Factor #1: Temperature As temperature increases, reaction rates increase until they hit a peak and then severely drop off Question: Why does this occur?? As temperature increases, molecules gain more kinetic energy and collide together more often, increasing the number of reactions Once temperature gets to high, the enzyme becomes denatured Factors Affecting Enzyme Reactions Factor #1: Temperature Enzymes in human bodies are adapted to a constant temperature of 37°C Enzymes in heat-resistant bacteria are adapted to function at temperatures around 80°C Factors Affecting Enzyme Reactions Factor #2: pH Like with temperature, certain enzymes function best in certain pH ranges otherwise they will become denatured ○ Pepsin is found in the stomach, where the pH is low ○ Trypsin is found in the small intestine, where the pH is typically around 9 Factors Affecting Enzyme Reactions Factor #3: Substrate Molecule Concentration As the number of substrate molecules increases, the number of collisions increases, and therefore the reaction rate increases This occurs until a point because there is a limit to the amount of enzyme available Factors Affecting Enzyme Reactions Factor #4: Feedback Inhibition Feedback inhibition is the turning off of an enzyme by the final product in a metabolic pathway The final product binds to the regulatory site of the enzyme, altering the active site and preventing the union of enzyme and substrate This prevents the build up of too much product  The Human Digestive System Digestive Tract (where food travels through) Mouth, pharynx (throat), esophagus, stomach, small intestine, large intestine, rectum, anus Accessory Organs (aid in digestion but do not physically handle food) Salivary glands, liver, gallbladder, pancreas Pg. 259  The Mouth, Salivary Glands, and Teeth The digestive process begins with the ingestion of food via the mouth Chewing of food by the teeth begins mechanical digestion (a.k.a. physical digestion) ○ Mechanical digestion is the breaking of food into smaller pieces, increasing the surface area for chemical digestion ○ Chemical digestion is the breakdown of molecules into their nutrients  The Mouth, Salivary Glands, and Teeth Salivary glands flanking the mouth produce saliva that contains amylase Saliva serves to dissolve food particles so that we can taste then and to lubricate food for swallowing The amylase in saliva breaks down starches into simpler carbohydrates (chemical digestion)  The Esophagus After swallowing, food travels from the mouth to the stomach by way of the esophagus The bolus is pushed through the esophagus by peristalsis ○ Peristalsis is the involuntary contractions of muscle that moves food along the digestive tract  The Esophagus After swallowing, food travels from the mouth to the stomach by way of the esophagus The bolus is pushed through the esophagus by peristalsis ○ Peristalsis is the involuntary contractions of muscle that moves food along the digestive tract  The Stomach Physical Digestion in the Stomach The stomach contains three layers of muscle designed to churn food around and break it up  The Stomach Chemical Digestion in the Stomach Cells of the inner wall secrete the following gastric fluids into the stomach: ○ Hydrochloric acid: kills harmful substances that are ingested with food, also converts pepsinogen to its active form ○ Mucus: a protective, lubricating substance that lines the walls of the stomach, protecting it from the other gastric juices ○ Pepsinogen: the inactive form of pepsin Pepsin: protein digesting enzyme  The Stomach pH of the Stomach The stomach typically has a pH ranging from 2.0 to 3.0 but can approach pH 1.0 as well This is highly acidic (pH 2.0 is acidic enough to dissolve fibers in a rug) Without a thick layer of mucus, the stomach would digest itself In places where the mucus breaks down, peptic ulcers occur ○ Peptic ulcers are lesions on the lining of the stomach caused by exposure to HCl and pepsin  The Small Intestine The small intestine is responsible for most of the bodies digestion and absorption Most of the digestion and absorption occurs in the first segment called the duodenum The jejunum and ileum are the other two segments of the small intestine  The Small Intestine Absorption in the Small Intestine The small intestine is lined with small, fingerlike projections called villi that increase surface area for absorption Each villus has microvilli that are microscoping fingerlike projections of the cell membrane to further increase surface area  The Small Intestine Absorption in the Small Intestine Each villus is supplied with a capillary network (where monosaccharides and amino acids are absorbed) and lymph vessels called lacteals (where fats are absorbed) ○ Lacteals are part of the lymphatic system (L10)  The Small Intestine Digestion in the Small Intestine Digestion in the small intestine is aided by digestive enzymes secreted from the pancreas, liver, and gallbladder  Teamwork of the Pancreas and the Small Intestine Pancreatic juices consist of: 1. Bicarbonate ions that neutralize the HCl from the stomach ○ This neutralization protects the lining of the duodenum  Teamwork of the Pancreas and the Small Intestine Pancreatic juices consist of: 2. Trypsinogen ○ Upon entering the small intestine, enterokinase converts trypsinogen into its active form: trypsin ○ Trypsin breaks down long chain polypeptides into shorter chain peptides  Teamwork of the Pancreas and the Small Intestine Pancreatic juices consist of: 3. Erepsin that completes the digestion of proteins by converting short chain peptides into single amino acids ○ Erepsin is also secreted by the small intestine  Teamwork of the Pancreas and the Small Intestine Pancreatic juices consist of: 4. Pancreatic amylase which continues the digestion of carbohydrates started by salivary amylase by further breaking down starch into disaccharides ○ The small intestine releases disaccharidases that complete the digestion of carbohydrates  Teamwork of the Pancreas and the Small Intestine Pancreatic juices consist of: 5. Lipases that break down lipids into fatty acids Teamwork of the Pancreas and the Small Intestine Teamwork of the Liver, Gallbladder and the Small Intestine The liver continually produces bile that contains bile salts ○ Bile salts help break down globules of fat (mechanical digestion) Bile is stored in the gallbladder Teamwork of the Liver, Gallbladder and the Small Intestine Bile salts break down fat globules into smaller droplets so that there is an increase in surface area for lipases to go to work ○ Emulsifying by bile salts is physical digestion as it does not break any chemical bonds, only breaks down to fats into smaller pieces Summary of Macronutrient Digestion/Absorption Carbohydrates Physical: chewing, churning of stomach Chemical: Salivary amylase in the mouth begins the breakdown of polysaccharides Pancreatic amylase from the pancreas continues the breakdown of carbs into disaccharides in the small intestine Disaccharidases in the small intestine digest disaccharides into monosaccharides Absorption: capillary Summary of Macronutrient Digestion/Absorption Lipids Physical: chewing, churning of stomach, emulsifying by bile salts from the liver/gallbladder in the small intestine Chemical: Lipase from the pancreas breaks down fats in the small intestine Absorption: lacteal Summary of Macronutrient Digestion/Absorption Proteins Physical: chewing, churning of stomach Chemical: Pepsin in the stomach begins protein digestion Trypsin from the pancreas breaks long chain polypeptides into short chain peptides in the small intestine Erepsin from the pancreas and small intestine breaks down short chain peptides into amino acids in the small intestine Absorption: capillary The Respiratory System Pt 1 Unit D Lesson 5 9.1  Parts of the Respiratory System Nasal and Oral Cavity (Nose and Mouth) Where air enters the respiratory system The nasal cavity is lined with hair and mucus which filters and traps foreign particles The nasal cavity also warms and moistens the air Pg. 283  Parts of the Respiratory System Pharynx (Throat) Air-filled channel at the back of the mouth that branches into two openings: the esophagus and the trachea (windpipe) Pg. 283  Parts of the Respiratory System Epiglottis A flap of cartilage that covers the opening of the trachea (glottis) when food is swallowed Pg. 283  Parts of the Respiratory System Trachea Carries air to the lungs, supported by cartilage Pg. 283  Parts of the Respiratory System Larynx The vocal cords, located at the top of the trachea Pg. 283  Parts of the Respiratory System Bronchi Passages of the trachea into the left and right lung, supported by cartilage Bronchioles Branches of the bronchi, smallest pathways of the respiratory tract Not supported by cartilage Pg. 283  Parts of the Respiratory System Alveoli Tiny sacs at the end of bronchioles The site of gas exchange ○ Made up of a single layer of cells and surrounded by capillaries Pg. 283  Parts of the Respiratory System Diaphragm Sheet of muscle that separates the thoracic cavity (lungs) from the abdominal cavity (stomach and liver) Works with the intercostal muscles to move air in and out of the lungs Pg. 283  Parts of the Respiratory System Intercostal Muscles Muscles that move the rib cage up and down Works with the diaphragm to move air in and out of the lungs *Not on the diagram Pg. 283  Breathing Movements Inspiration (Inhalation) Intercostal muscles contract, rib cage moves ↑ The diaphragm contracts and moves ↓ Together, these muscle contractions expand the thoracic cavity Expiration (Exhalation) Intercostal muscles relax, rib cage moves ↓ The diaphragm relaxes and moves ↑ Together, these muscle relaxations contract the thoracic cavity  Respiratory Disorders Bronchitis An inflammation of the bronchial tubes that leads to a narrowing of air passages Leads to excess mucus production Main symptoms are cough and difficulty breathing  Respiratory Disorders Asthma The narrowing of bronchial passages in response to an allergic reaction or an environmental factor  Respiratory Disorders Pneumonia An infection of the lung by a virus or bacteria that causes the alveoli to fill with liquid or pus This results in less surface area for oxygen exchange and can even be fatal  Respiratory Disorders Emphysema The inflammation of the walls of the alveoli Over time, this destroys the air sacs, causing them to lose their elasticity and rupture Individuals with emphysema have less surface area for oxygen exchange, resulting in an increased breathing rate and extra work for the circulatory system Most common cause is smoking  3 Muscle Types Cardiac Muscle Smooth Muscle Skeletal Muscle Makes the heart Lines organs Attached to bones beat (stomach, blood Voluntary control Involuntary control vessels, etc.) Striated Involuntary control appearance  Skeletal Muscle Skeletal muscle is the muscle that allows us to move Attached to bones by tendons 80% of the energy used in skeletal muscle contraction is lost as heat ○ This is why we shiver when we are cold!