Unit 1 Learning Guide Biology 12 PDF

Learning Guide Unit 1 1.1 Introduction to Cell Compounds We will begin this course with an introduction to the concept of Homeostasis, a theme that runs throughout biology 12. Most of earth's residence such as the euglena pictured here are unicellular or single celled. These single celled organism...

Learning Guide Unit 1 1.1 Introduction to Cell Compounds We will begin this course with an introduction to the concept of Homeostasis, a theme that runs throughout biology 12. Most of earth's residence such as the euglena pictured here are unicellular or single celled. These single celled organisms survive and reproduce as long as their environment is of a tolerable temperature and composition, and they are able to obtain nutrition. In contrast to single celled organisms humans are composed of trillions of cells surrounded by extracellular fluid that make up our internal organs and organ systems. Our cells interact in ways that keep this internal environment relatively constant, despite an ever-changing external environment. The body's maintenance of a stable internal environment is called homeostasis and is so important that it requires most of our metabolic energy. The body maintains homeostasis through a number of self-regulating control systems or homeostatic mechanisms. These mechanisms share the following four components: Change (stimuli) occur constantly in and around the cells of living systems. A change is anything that requires a cell to react, such as a change in temperature, pressure or chemical composition inside or surrounding the cell. Receptors, detect the change (stimuli) and alert the proper control center to counteract it, returning the cell and the overall system to a balanced state homeostasis. A control center, includes a set point which tells what a particular value should be (eg. body temperature at 37ºC). The control center receives impulses from its remote receptors and sends commands to the effect or the change in the environment. Effectors, are the physical change agents such as the muscles and glands -- the body the workhorses of homeostasis. Effectors act on the impulses from its specific command center, eliciting responses that counteract the change and returning the internal and external cell environment to a balanced state. Negative feedback controls many conditions in the body including body temperature, CO2 levels, blood sugar levels, blood pH levels osmoregulation etc. For this first example, we will consider one mechanism for blood pressure regulation. Blood pressure needs to remain high enough to pump blood to all parts of the body, but not so high as to cause damage while doing so. While the heart is pumping, baroreceptors detect the pressure of the blood going through the arteries. If the pressure is too high or too low, a chemical signal is sent to the pressure control center in the brain via the glossopharyngeal nerve. The brain then sends a chemical signal to the heart (effector) to adjust the rate of pumping: if blood pressure is low the heart rate increases, increasing the output of blood which in turn increases blood pressure. Once the set point is reached the stimulus for increased heart rate decreases. On the other hand, if blood pressure is high the heart rate decreases till the set point is reached. Instead of achieving normalcy, the adaptive response further stimulates the Regulatory Center causing the body to be in an increasingly unstable state. The only example of positive feedback you will need to know for this course is during childbirth. The positive feedback cycle is initiated when the head of the fetus comes in contact with the cervix. This contact initiates the release of a hormone called oxytocin that intensifies and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle goes on until the baby is born. The birth ends the release of oxytocin and ends the positive feedback mechanism. a) The normal range for blood glucose levels is 70-110 mg/dL. Does Patient X always remain within the normal range? Anywhere from the ranges of 80-110 so the answer would be yes b) Does Patient X have any apparent problems with glucose regulation? Why or why not? (2 marks) No, patient X seems to be in the normal range of blood glucose levels meaning that the body’s homeostatic is working correctly. c) Which type of feedback mechanism (positive or negative) is used to regulate blood glucose levels? Explain your reasoning. (2 marks) Negative feedback loop would be the normal rate of blood glucose such as 70-110 mg/dL, Positive feedback loop would be when someones blood glucose levels are pushing an extreme level such as 140-200mg/dL that would be diabetes aka hyperglycemia. a) Define homeostasis and describe how it relates to hyperthermia. (Use the following terms in your response: receptors, set point, and effectors). Homeostasis job is to keep the body’s condition in balance. Hyperthermia is related because when homeostasis cant maintain the body’s temperature due to high/extreme body external factors. When the set point is exceeded, receptors transmit signals to the regulatory center, which in turn communicates with the relevant effectors to restore the body to its set point. b) Explain why elderly individuals with poor circulation would have a greater risk of suffering heat exhaustion or heatstroke. Well when you are senior/older age person your skin is damaged and your blood circulation is most likely poor, that being said it makes older age people sweat a lot more and it makes it harder for them to do everyday life work just because their sweat glands aren’t working properly, this also means most people in there seniors years will have medical conditions. A good example would be how many older people take supplements to maintain their body's normal functioning for everyday life. This could be due to insufficient nutrient intake from food or simply because their bodies require more support in their senior years. c) Explain why spraying water on the skin while sitting in front of a fan would lower body temperature. (Make sure to use and explain endothermic and evaporative cooling in your answer). The airflow from the fan increases the rate evaporation which makes evaporation cooling. Evaporation is an endothermic method, meaning water molecules need to start absorbing heat from there surroundings to create kinetic energy. Once the water that was on your skin evaporates, it basically takes away the heat from your body. d) When attempting to lower a person’s body temperature in response to hyperthermia one should avoid treatments that induce shivering or vasoconstriction. Why? Shivering is started by homeostasis which regulates body temperature meaning it controls your heat or raise your body temperature and generate enough heat. Vasoconstriction happens as a result of homeostasis because its going to get warm blood from the core of your body meaning its gonna lower heat around your whole body. Both of these occurrences may arise if hyperthermia treatment is overly intense, impeding the reduction of body temperature in both cases. 1.2 Water In the formation of chemical compounds, organic or inorganic, atoms must bond together to form stable structures. In order to do this, the electron configurations around the various nuclei in the compound must also be stable. This stability can be achieved through some degree of sharing electrons between the atoms. If the atoms share the electrons reasonably equally, their association is termed a covalent bond. The alternative is a very unequal sharing of electrons. This is called an Ionic Bond where it seems as though one atom actually gives away its electrons to another atom. Neutral atoms become positive ions when they lose electrons and negative ions when they gain electrons. In between these two extremes is what is termed polar covalent. Polar covalent molecules have dipoles (regions with slightly positive and negative natures). A water molecule is an example of this kind of molecule. There is an unequal sharing of electrons between the hydrogen and oxygen atoms within a water molecule. This unequal sharing of electrons results in a dipole. One end is the negative dipole (O) and the other is the positive dipole (H). Therefore a water molecule behaves as a mini-magnet with opposite charges attracting and like charges repelling one another. Bipolarity causes water to have some degree of structure that extends beyond the individual molecules and causes a community water effect. Due to its polar nature water molecules are loosely attracted to one another. The negative charge on the oxygen of one water molecule attracts the positively charged hydrogen of another water molecule some distance away to produce a weak bond called a hydrogen bond. Although hydrogen bonds are weak, the vast number of these bonds gives water its unique properties. Each water molecule can form hydrogen bonds with up to four neighbours. This is also why water is attracted to other surfaces. Remember opposite charges attract. The Properties of Water: 1) Water acts as a solvent and is able to dissolve many chemical substances, especially other polar molecules such as salt. Since blood is mainly water, the ability of water to dissolve and transport substances greatly aids in bringing about necessary chemical reactions in the body. Water is called the "universal solvent" because it dissolves more substances than any other liquid. This is important to every living thing on earth. A solution is a mixture of one or more soluble substances, called solutes, dissolved in a liquid called the solvent. A sugar cube in a glass of water will eventually dissolve to form a uniform mixture of sugar and water. The dissolving agent is the solvent (water) and the substance that is dissolved (sugar cube) is the solute. When you combine a solid and liquid to make a solution, it is relatively easy to identify which one is the solute (the solid substance) and which one is the solvent (the liquid substance). However, when you mix two liquids that are fully miscible (can be mixed) with each other, the labels of solvent or solute depend on their relative quantities to each other. For example, if 500.0 ml of water is mixed with 150.0 ml of ethanol then water is the solvent and ethanol the solute as there is more liquid water. However, if you have 500.0 ml of ethanol and mixed with 150.0 ml of water, the water is NOW the solute as it is present in a lesser quantity, and the ethanol is the solvent as there is more liquid ethanol. Thus, when combining two miscible liquids the relative quantity of each liquid determines their role in the solution created by this mixing. Can you identify the solvent and solute in each of the following solutions? Example 1: 15 g baking soda and 100 ml of water? Solvent: Water Solute: Baking Soda Example 2: Nail polish removed by acetone? Solvent: Acetone Solute: Nail Polish Example 3: 1.00L ethylene glycol and 875 mL water? Solvent: Ethylene Solute: Water Example 4: Chromium dissolved in hydrochloric acid? Solvent: Hydrochloric Acid Solute: Chromium 2) Moderates Climate (both internal and external climates). Water can absorb a great deal of heat while only rising in temperature a slight amount. Water also releases heat slowly. This property is referred to as a high heat of evaporation. As a liquid evaporates the most energetic molecules are carried away leaving the lower kinetic energy molecules behind which cool the surface of the liquid that remains - evaporative cooling. Internal example - Body systems are mainly water, therefore, bodies tend to stay at relatively constant temperatures despite external conditions. External example - Oceans keep surrounding land masses cool in summer and warmer in winter Density of Water 3) Liquid water is unusual because it is denser than ice (very rare for compounds). Most materials contract as they solidify. Water expands. Therefore, ice forms on top of water insulating lower levels. This oddity has important consequences for life. If ice sank, eventually all ponds, lakes, and even oceans would freeze solid. During the summer, only the upper few inches of the ocean would thaw. Instead, the surface layer of ice insulates liquid water below, preventing it from freezing and allowing life to exist under the frozen surface. 4) Light penetrates well into bodies of water to the organisms below. This is important for all organisms that undergo photosynthesis. Water is Both Cohesive and Adhesive 5) Water molecules stick to each other and to other surfaces. This keeps surfaces moist and lubricated. Diffusion of gases occurs much more efficiently across moist surfaces. Cohesion (sticking to each other) among water molecules plays a key role in the transport of water against gravity in plants. Surface tension is a measure of the force necessary to stretch or break the surface of a liquid and is related to cohesion. Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface. Water behaves as if covered by an invisible film. Some animals can stand, walk, or run on water without breaking the surface. Adhesion (clinging of one substance to another) contributes too, as water adheres to the walls of the blood vessels. **** Note: Focus on the properties of water that apply to the human body.**** What are four important functions of water in the human body? Example 1: Dissolves many substances to be transported throughout the body Example 2: Helps to regulate the body’s internal temperature (homeostasis) Example 3: Helps to lubricate for ease of movement. Examples joints, esophagus etc. Example 4: Required for hydrolytic reactions in the body U2 Water 1. Sketch a ball and stick diagram of a water molecule. Label the atoms and indicate the partial charges that exist in a water Answer: 2. What type of bonds are found between hydrogen and oxygen atoms within a single water molecule? Covalent bond 3. What type of bonds form between two or more water molecules? Hydrogen bond 4. Use a diagram with 5 water molecules to illustrate hydrogen bonding between water molecules (start with one molecule in the middle). How many water molecules can hydrogen bond with a single water molecule? Answer: 5. List 3 everyday examples of the cohesive and/or adhesive properties of water - Raindrops sticking to windows - Rain gathers into puddles - water bugs “standing” on water 6. Water is a polar molecule. Water dissolves many substances (especially other polar molecules). This property makes water an excellent solvent. 7. Use several examples each to explain how water is essential to the human body with respect to the following properties: a) Water acts as a Solvent - It dissolves charged and polar molecules like salts, allowing them to be transported throughout the body. - It dissolves molecules like salts, enabling them to react with each other and form new compounds. b) Water acts as a Temperature Moderator - The human body is 70% water meaning our body results in consistent body temperature, when we absorb water our body releases heat slowly. - Hydrogen bonding and polarity of water results in high heat, meaning the body will start evaporating and continue to be a cooling on your skin. c) Water acts as a Lubricant and Transportation Facilitator - The polarity and hydrogen bonding of water confer cohesion and adhesion properties, allowing it to easily fill and flow through vessels, making it an efficient transport medium. - The liquid in body stay as water at body temperature contrary to a gas making it a really good transport medium - The inherent polarity of water enables it to adhere to various surfaces, facilitating lubrication essential for the smooth movement of joints, the blinking of eyes, and other physiological functions requiring surface interaction. 8. Please indicate whether the statements below are true or false. Please correct any false statements. a) Water molecules can attract other water molecules by hydrogen bonding. Answer True b) Hydrogen bonds are stronger than ionic or covalent bonds. Answer False c) The majority of our cellular reactions occur in water. Answer True d) Large lakes and oceans tend to moderate local temperatures. Answer True e) Water is an organic molecule. Answer False 1.3 pH Organisms are sensitive to changes in pH (pH refers to the potential Hydrogen Ion (H+) concentration of a solution). An acid is a substance that increases the hydrogen ion concentration in a solution. For example when hydrochloric acid is added to water, hydrochloric acid dissociates to form hydrogen ions and chloride ions: HCl —> H+ + Cl- The addition of H+ makes a solution more acidic. A base is a substance that increases the hydroxide ion concentration in a solution. For example, when sodium hydroxide is added to water, sodium hydroxide dissociates to form sodium ions and hydroxide ions: NaOH —> Na+ + OH- Solution with more OH- than H+ are basic solutions. The pH scale is used to describe how acidic or basic (the opposite of acidic) a solution is. When the concentration of H+ is higher than OH-, the solution is acidic and has pH less than 7 [H+] > [OH-] When the concentration of H+ is less than OH-, the solution is basic and has a pH greater than 7 [H+] < [OH-] The pH scale, ranging from 1-14, compresses the range of concentrations by employing logarithms. In other words every number on the pH scale is a multiple of 10. pH = -log [H+] or [H+] = 10 -pH A pH of 7 is a neutral pH where the concentration of hydrogen ions = concentration of hydroxide ions. [H+] = [OH-] A pH that ranges between 7 and 14 has more hydroxide ions than hydrogen ions making it a basic solution. A pH that ranges between 1 and 7 has more hydrogen ions than hydroxide ions making it an acidic solution. We can calculate the difference in hydrogen ion concentrations at different pH levels by multiplying or dividing by 10. For example a pH 6 has 10 times more H+ than at pH 7. A pH of 3 has 100 times more H+ than pH 5 and so on. Example 1: pH of 14 has 100x less H+ than a pH of 12 Example 2: pH of 6 has 100,000x more H+ than a pH of 11 The pH scale is just a comparison between the [H+] and [OH-]. Buffers Most enzymes that are made of protein and control the chemical reactions in your body can only operate at certain pH levels. If pH levels change too drastically these biochemicals will denature (lose their shape) and no longer function properly. Example: Blood must be at a pH close to 7.4 or else we may become ill. At the wrong pH the blood cannot transport O2 + CO2 as efficiently. As you can see then the chemical processes in the cell can be disrupted by changes to the H+ and OH- concentrations away from their normal or optimum pH values. To maintain cellular pH values at a constant level, biological fluids have chemicals called buffers. The function of Buffers is to "resist changes" to the pH of a solution when H+ or OH- is added to the solution. Buffers are chemicals or combinations of chemicals that are able to keep pH levels constant. Buffers help prevent changes in pH by combining with excess OH- or H+ in a solution to help maintain homeostasis. Recall that changes in pH can cause proteins to denature. If the pH is not buffered, denaturing can occur and vital chemical reactions and cellular structures in the body would be negatively affected. Buffers accept hydrogen ions from the solution when they are in excess and donate hydrogen ions when they have been depleted. Note: The buffer keeps pH constant despite adding more acid. Acids are molecules that dissociate to release hydrogen ions. In this respect, water acts as a weak acid. HCI on the other hand is a strong acid because it dissociates to a much greater extent. Systems with HCI in them have a lot of free H+ floating around. Bases are molecules that release OH- ions. Molecules like NaOH are bases. Bases have a neutralizing effect on acids because the H+ in an acidic environment will combine with OH- from a base and form water and salt. Note: The first graph shows pH change without a buffer, while the second graph shows pH change with a buffer. U3: pH, ACIDS AND BASES 1. Define the following terms a) Acid: An acid is a substance that, when dissolved in water, increases the concentration of hydrogen ions (H+), resulting in a lower pH value. This property gives acids their characteristic sour taste and ability to react with bases to form salts and water. b) Base: A base is a compound that, when dissolved in water, increases the concentration of hydroxide ions (OH-), resulting in a higher pH value. This property gives bases their characteristic bitter taste and slippery texture, and they can also neutralize acids to form salts and water. c) pH: It refers to the acidity or basically of a solution, measured on a negative logarithmic scale based on the concentration of hydrogen ions (H+) present in the solution. d) Buffer: a substance that resists changes in pH despite the addition of an acid or base 2. Indicate whether the following pH values represent an acidic, basic or neutral solution a) pH 0: Acid b) pH 12: Base c) pH 7: Neutral d) pH 3: Acid 3. Hydrochloric acid (HCl), a strong acid, is added to a beaker of pure water: a) What is the pH of the pure water in the beaker before the acid is added? The pH of pure water is 7 which is neutral b) How does the hydrogen ion concentration change after the acid is added? The acids increase the hydrogen ion concentration of a solution c) What happens to the pH of the solution in the beaker as the acid is added? PH decreases 4. How much has the hydrogen ion concentration changed in a solution if its pH value goes from 6 to 4? Remember to indicate whether this change represents an increase or decrease in hydrogen ion concentration. The pH decreasing from 6 to 4 signifies a decrease in pH, indicating an increase in hydrogen ion concentration. Given that pH operates on a logarithmic scale, each unit change in pH corresponds to a tenfold alteration in hydrogen ion concentration. Consequently, a change of 2 pH units translates to a hundredfold change in hydrogen ion concentration. 5. pH balance is very important to biological systems. a) why? As numerous cellular processes rely on enzymes, which are proteins with three-dimensional structures and functions that hinge on specific pH conditions, alterations in pH can disrupt their structure and impede their enzymatic functions. Consequently, this disruption inhibits cellular activities. b) What prevents rapid or large changes in pH in biological systems? Buffer prevent rapid or large changes in pH in biological systems. c) Give an example of where pH balance is important and regulated in a living organism. - In the stomach, with a pH around 2, the environment ensures the activation of digestive enzymes like pepsin, while simultaneously initiating the denaturation (unfolding) of ingested proteins. This process is regulated by parietal cells, which secrete hydrochloric acid. 1.4 Introduction to Biological Molecules Carbon is the basic element of life. It is a non-metal that must bond with other non-metals to become stable. When two non-metals bond together they form covalent bonds. Covalent bonds are formed when a pair of atoms share electrons (Covalent bonds are strong bonds). Atoms will share electrons in order to complete the complement of electrons in their outermost electron shell. Carbon can share electrons with as many as 4 other atoms to form chains or rings. Drawing each bond in a molecule as two dots gets old very fast. To save time chemists usually depict a bond as a line drawn from one atomic symbol to another. Such representations are called Lewis structures rather than Lewis electron dot structures. Rings can also form: Carbon rings or chains act as the skeleton for the unit molecules, which make up the life compounds. Examples: of life compounds are Proteins, Carbohydrates, Fats (Lipids), and Nucleic Acids. Below is a carbon ring that is classified as a carbohydrate. Unit molecules join together to form larger molecules called Polymers. Proteins, carbohydrates, fats, and nucleic acids are all polymers. To join the unit molecules (or building blocks) together, a molecule of water must be removed. H+ is taken from 1 molecule and OH- from the other molecule. This process is called Dehydration synthesis and energy is required. To help remember this chemical reaction, think of what is happening to you as you lose water - you dehydrate. The word synthesis means to make. So we are making something by taking water away. What if instead of making larger molecules (polymers) from smaller units (monomers) our body needs to break down a polymer into its monomers? To do this a molecule of water must be added. This process is called Hydrolsis and energy is required. Sometimes breaking words down will help you understand them. Hydro - refers to water and lysis means to break apart. U4: INTRODUCTION 1. List the 4 major classes of carbon-containing life molecules that will be studied in this unit and throughout the course? a) Proteins b) Carbohydrates c) Lipids d) Nucleic Acids 2. Define the following terms: a) momomer: Its a molecule that can be bonded with other identical molecules to build a polymer. b) polymer: A streak made of bunch of momomers that are bonded together. c) dehydration synthesis: Its a chemical reaction where two smaller molecules join together to make a bigger molecule while removing H+ and OH- to create water. d) hydrolysis: Breakdown reaction to tears apart polymers by adding water. 1.5 Carbohydrates Carbohydrates: are sugars. We will look at 3 groups of carbohydrates; the monosaccharides (mono - meaning one), the disaccharides (di-meaning two), and the polysaccharides (poly - meaning many). The elements in all carbohydrates are: Carbon, hydrogen, and oxygen. The ratio of hydrogen atoms to oxygen atoms is always 2:1 and the empirical formula for carbohydrates is CH2O Sugars: Provide us with short term energy. We will start by looking at the monosaccharides of which there are two groups. There are 5 carbon sugars (pentoses) and the 6 carbon sugars (hexose). For the purpose of this unit we are only concerned with the hexose monosaccharides, but below are some examples of the pentose sugars. Note the 5 carbon rings. a) Monosaccharides: 5 or 6 carbon sugars (simple sugars) i) Pentoses: 5 carbon sugars Examples: Ribose, Deoxyribose (1 less oxygen than ribose) ii) Hexose = 6 carbon sugars: Note the six carbon rings (below) 3 examples that you need to know for this course are: glucose, fructose, and galactose All have the formula C6H12O6, however if you examine their structural formulas, you will find the difference in the organization of their atoms. Looking at the 3 diagrams you will see that all 3 monosaccarides is the way these atoms are arranged. They are called isomers. There Are Three Ways To Represent the Structure of Glucose (draw them in below) For the purpose of this course there are 3 monosaccharides that you will need to know: 1. Glucose - you will hear a lot about glucose in later units as it is the main form of sugar in the blood. 2. Fructose - the sweetest monosaccharide found in fruits. 3. Galactose - one of the building blocks of lactose (the sugar found in milk and milk products). b) Disaccharides: are Double sugars (two simple sugars bonded together) They have the common formula C11H22O11 3 Common Disaccharides along with their building blocks that you will need to know for this course are: i) Maltose: 2 molecules of glucose ii) Sucrose: 1 glucose and 1 fructose iii) Lactose: 1 glucose and 1 galactose c) Polysaccharides: The 3 common polysaccarides that you need to know for this course are: Starches, cellulose and glycogen (be sure that you can recognize a diagram of their structure and know the function of each of these) - the polysaccarides are long chains of glucose molecules bonded together (simple sugars) - the basic formula for these polymers is (C6H10O5)n. n = dozens to thousands of glucose units i) Starch: -Is the basic storage form of food of plants -starch is made up of many glucose molecules bonded together in long chains with a few side chains ii) Glycogen: Is the "animal starch" (in other words excess glucose in animals is stored as glycogen) in liver and muscle tissue. In other words, the basic storage forms of food in animals. - like starch Glycogen is also made up of long chains of glucose molecules, however it has many side chains instead of just a few - Between meals - as [glucose] in blood decrease, the glycogen that is stored in the liver and muscle tissue is broken down into glucose to raise blood [sugar] to 0.1%. - After meals - [glucose] in the blood increase as food is digested. The excess glucose is converted into glycogen and stored in the liver and muscle tissues for later use. iii) Cellulose: Is probably the most abundant organic compound found on Earth. Cellulose is formed in the cell walls of plants and gives pants their structure. Cellulose is made of long chains of glucose with alternating linkages and no side chains. There is a different type of linkage between the sugars found in cellulose as compared to starch or glycogen. Our digestive system is unable to digest this linkage. Cellulose passes through our system as fiber or roughage. It may be important for good health and prevention of colon cancer. Functions of Carbohydrates a) Source of short-term energy for all organisms. (all carbohydrates) -Energy is released as the carbohydrates are broken down by hydrolysis b) Structural molecules in plants. (cellulose) c) Storage form of food in both plants and animals. (starch/glycogen) U5: CARBOHYDRATES 1. What is the empirical formula for carbohydrates? CH2O 2. Define the following terms and give two examples of each. a) Monosaccharide: Sugar = saccharide, containing a singular ring structure such as glucose, fructose, and galactose. b) Disaccharide: Sugar that contains two bonded ring structures for example, lactose = glucose + galactose or sucrose = glucose = fructose or lastly maltose = glucose + glucose. c) Polysaccharide: sugar containing many momomers bonded for example starch, cellulose, and glycogen. 3. Name the three disaccharides that you need to know for this course Maltose, sucrose, lactose 4. Identify the building blocks or monomers that come together to form each of the disaccharides that you listed above. Lactose = glucose + galactose, sucrose = glucose + fructose, maltose = glucose + glucose. 5. Name the three polysaccharides that you need to know for this course. Starch, cellulose, glycogen 6. Describe how you can distinguish the structures of each of these polysaccharides. Look at the examples closely and come up with a way to memorize which is which and then explain it (do not just simply draw each structure). Starch = few side branches cellulose = no side branches with alternating bonds (because plant cell walls are carbon atom and glucose molecule) glycogen = has many side branches 7. State the functions of each of these polysaccharides. Starch is the storage of glucose in plants cellulose is the structural component of plant cell walls glycogen is the storage of glucose in animals 8. Why is cellulose considered "roughage" in our diets? Humans don't possess the enzyme required to break down the bonds in cellulose, which is crucial for maintaining a healthy digestive system as roughage. Cellulose lacks any nutritional value. 1.6 Lipids 2. Lipids: Fats, oils, waxes, phospholipids, soaps, steroids We eat lipids as part of our food group. Our bodies are capable of producing them as well as metabolizing them. The three lipids you need to know for this course are the neutral fats, phospholipids and steroids. Elements: Carbon, hydrogen, and oxygen but the H:O ratio is greater than 2:1. Fatty acids are one of the two building blocks of neutral fats and are non-polar chains of carbon and hydrogen with a carboxylic acid end. A tremendous number of variations exist between fatty acids.(be sure that you can recognize a diagram of both saturated and unsaturated fatty acids) Saturated fatty acids those compounds without double bonds between the carbon atoms. In other words these molecules are holding all the hydrogen atoms that they can. Other fatty acids are unsaturated (compound with double bonds between carbon atoms). Natural Fats: 1 molecule of glycerol in combination with 1, 2 or 3 molecules of fatty acids. Next to glucose, fats are the second most important energy molecules for us. Unfortunately, we store the excess in adipose (fat) cells. They function as a long term energy source, insulation, and padding. In the diagram above X = glycerol and Y = fatty acids. Monoglyceride - one fatty acid attached to a glycerol. Diglyceride - two fatty acids attached to a glycerol. Triglycerisde - three fatty acids attached to a glycerol. Phospholipids Phospholipids are a variation of a triglyceride where one of the 3 fatty acids is replaced with a phosphate and a nitrogen-containing group. (Note the glycerol backbone, 2 fatty acids and the phosphate group as the three building blocks or monomers of phospholipids). This creates a polar region and consequently phospholipids can mix with both polar (likes water) and non-polar (dislikes water) materials. Phospholipids are very important in cells as they form much of the cell membrane. The Heads of phospholipids are polar and are said to be water loving. (Hydrophilic) The Tails of the phospholipids are non polar and are said to be water hating. (Hydrophobic) Because they have water soluble heads and water insoluble tails they tend to form a thin film on water with their tails in the air like above. Sterols: Compounds such as sex hormones, cholesterol, and some of the ingredients of bile. Instead of a straight chain of carbon, sterioids are non-polar ring structures. They are insoluble in water therefore considered a lipid. Example: Cholesterol - important part of cell membrane and the protective cover around nerve fibers. Note: Cholesterol is important, but too much results in fatty deposits inside arteries. This narrows the pathway for blood so the heart has to pump harder to push the blood through the body. ie. Increase blood pressure. Steroids such as Testosterone are able to pass through cell membranes and combine with receptors in the cell. The steroid receptor complex activates certain genes leading to protein synthesis. Increase protein synthesis is better for the athlete for muscle development. U6: LIPIDS 1. What are the three major types of lipids that you need to know for this course? Neutral fats such as triglyceride, phospholipids, steroids. 2. Fill in the lipid summary table found below. Lipid Neutral fats Chemical structure Biological Function - Long term energy - Padding - Insulation phospholipid - Forms a phospholipid - bilayer of the cell - membrane Steriods - A biological messenger capable of traveling through the bloodstream, examples include estrogen and testosterone. 3. How do the bonds differ in a saturated versus unsaturated fatty acid tail? Saturated fatty acids are saturated with hydrogen atoms, featuring single bonds between carbon atoms. On the other hand, unsaturated fatty acids contain one or more double bonds between carbon atoms. 4. The diagram to the right represents an important type of lipid: a) What type of lipid does the diagram represent? Phospholipid b) What cell structure is this lipid primarily responsible for forming? A cell c) Please place a circle/oval ( ) around the glycerol backbone, a rectangle ( ) around the fatty acid tails and a cloud ( ) around the phosphate/nitrogen group. d) Identify/label which portion of the molecule is hydrophobic and which portion is hydrophilic. e) Define hydrophobic and hydrophilic. Answer to (c) (d) (e) Are in my diagram 5. Steroids have a very different structure than the other types of lipids: a) Describe the characteristic structure of a steroid. Its bonded to a carbon ring that can be up to 1-5 rings b) Explain why steroids are classified with other lipids. Steroids are classified with other lipids because they share similar chemical properties and functions, such as being insoluble in water and playing roles in cell structure and hormone regulation. c) Identify two important steroids in the human body and briefly explain their functions. You have testosterone which regulates from sperm production, this is very important of second hand to sex learning. Second important function is estrogen this is basically the females production hormone, this regulates the females cholesterol body cycle. 1.7 Proteins 3. Proteins Made of the elements: Carbon, hydrogen, oxygen and nitrogen. Sulfur is often present and phosphorus and iron are sometimes included. The Basic structure of all proteins are: long Chains of amino acids (or what is called a polypeptide) Amino acids - there are about 21 different amino acids with the general structure like the one below Be sure that you can identify the different parts of an amino acid. Note the amine group, the carboxylic acid, the central carbon bonded to hydrogen and finally the radical group. R = A variety of other atoms that distinguish one amino acid from another. There are 21 different amino acids so there 21 different R groups. Dehydration synthesis of amino acids will result in the bonding of amino acids together and the release of water molecules. If we consider the amino acids glycine and alanine, they will bond together and produce the dipeptide "glyala". A.A are joined by a peptide bond. A dipeptide has one peptide bond where a Tripeptide has two peptide bonds holding three amino acids together and so on. The order and combination of these A.A determines the type of protein that is produced. The term Polypeptide means numerous peptide bonds that join many amino acids together. Dehydration synthesis refers to the way in which a protein molecule is assembled and the factors that cause its specific three dimensional shape. There are four levels to protein structure of which you need to know the first 3 including the bonds that hold them in these shapes. Remember that chains of amino acids (the subunits or building blocks) which make up a protein are called monomers. The first, or primary structure as it is called, is simply a straight sequence of amino acids. Note the peptide bonds that bind these amino acids together. Because there are twenty-one different amino acids, it is easy to realize that there are literally millions of different variations of amino acid sequences - each with many (some with hundreds of) amino acids. Consequently, there are millions of proteins. As the chains of amino acids get longer they begin to twist into a spiral (called an alpha helix). This is a result of the stress on the bond angle. Hydrogen bonds form between the Hydrogen of one amino acid and an Oxygen further down the chain. An alpha helix contains 3.6 amino acids per spiral. There are other secondary structures, but the alpha helix is the most common and the one you will need to know for this course. The third level is described as the bending and folding of the alpha helix into a globular molecule. As the helix gets longer there are some amino acids that cannot fit the configuration and therefore cause kinks. New bonds can form to hold it into a three-dimensional shape. The types of bonds are iconic, covalent and/or hydrogen and sometimes sulfur. Tertiary structures occur in some protein systems, particularly enzymes, where different three- dimensional configurations are associated with function and with each other. Hemoglobin is a well- known protein that is actually made up of the association of four 3 dimensional shapes around a central heme (iron containing) component. (This would be considered a quarternary structure which you do not need to know for the purpose of this course) The weaker hydrogen and ionic bonds of the tertiary structure are easily broken. They are very sensitive to things like pH changes, the presence of heavy metal ions, or extreme temperature changes. If a protein's normal shape is destroyed because of such environmental conditions, it is said to be denatured (it will not work). Without the enzymes normal shape, the enzyme is unable to combine efficiently with its substrate and therefore no chemical reaction will occur. Examples we can see: - This is what happens when milk spoils. The protein in milk, Caesin, denatures and becomes insoluble, forming floating lumps. - Egg white is protein. Excess heat denatures the protein. (fried or poached) - Cooking Liver. Be sure you understand these 4 important points: 1. The enzyme loses its normal three dimensional shape, changing the shape of its active site. 2. Due to the change in the shape of the enzyme's active site the enzyme can no longer bind to its substrate. 3. Because the protein (or enzyme) can no longer bind to its substrate the enzyme cannot perform its normal function. 4. Therefore, there is no enzyme activity. When enzymes in the human body denature, the biochemical pathway they work in no longer functions and the result is disease or possibly even death. 1. FUNCTIONAL Enzymes can cause reactions (that would otherwise take 7 hours) to take only a fraction of a second. 1. Maltase - an enzyme that digests maltose to 2 glucose molecules 2. Carbonic Anhydrase - aids in the conversion of carbon dioxide to carbonic acid and the bicarbonate ions. Transport - Hemoglobin in red blood cells transports CO2, O2, and H+. Infection fighting - Antibodies help stop intruders from harming the body STRUCTURAL – Used to maintain connective tissues Keratin - forms protective layer in skin Collagen - major component of connective tissue Actin/myosin - involved in muscle contraction for movement U7: PROTEINS 1. Identify the basic building block (monomer) of all proteins. Amino Acids 2. Draw the generic structure of the basic building block of proteins and clearly labeling its 4 key parts. 3. A dipeptide is: a. formed by what type of reaction? Dehydration synthesis b. held together by what type of bond? Peptide bonds 4. Describe the following levels of protein structure including the types of bonds that are involved: a. Primary A linear sequence of amino acids linked by peptide bonds. b. Secondary In secondary structures, alpha helices are formed by hydrogen bonds between amino and carboxyl groups within a protein chain. c. Tertiary and Quaternary Tertiary is a 3 dimensional structure of protein holding ionic, covalent, hydrogen and sometimes sulfer. Quaternary is a structure that holds four subunits of hemoglobin. 5. Describe what is meant when we say a protein/enzyme is denatured. Elevated temperatures or drastic pH alterations lead to the enzyme losing its tertiary structure, resulting in the unraveling of the enzyme and the disruption of its active site. Consequently, the enzyme can no longer bind to its substrate, preventing any chemical reaction from occurring. 6. Identify at least three factors that can denature proteins/enzymes. Temperature going up extremely fast, severe PH change, lastly heavy metals. 7. Define enzyme and give two examples of enzymes and their functions in the human body. Enzymes are small biological helpers that speed up the chemical reactions in living organisms without being consumed in the process. Example one would be protease which is made in your pancreas it basically breaks down proteins, Example two is lipase which is also made in the pancreas its job is to break down fats. 8. Describe what is meant by a structural protein and provide two examples in the human body. keratin for hair and nails, collagen for connective tissues, and actin/myosin for muscle tissue, I gave three instead. 1.8 Nucleic Acids 4. Nucleic Acids are made up of polymers of nucleotides. A nucleotide has 3 components to it, a sugar, a phosphate group, and a nitrogenous base. Be sure that you can label it and recognize its structure. There are three types of nucleic acids. DNA and RNA are the genetic material and are involved in the functioning of chromosomes and protein synthesis. We will study these in more detail in a later unit. Adenosine Triphosphate (ATP) One particularly important nucleic acid is the modified nucleotide known as ATP. TP is quite simply an RNA nucleotide with an adenine base (adenine + ribose = adenosine) with three phosphate groups attached to it. Note the ~ line in between the phosphate groups used to indicate high energy bonds. Phosphate bonds are unique in that they are very rich in energy. Cells store energy as Chemical energy in this way. In order to release the energy, an enzyme, ATPase, breaks one of the bonds, thus producing ADP (adenosine diphosphate) and energy. ADP can be recycled. We can add a phosphate group back to the ADP with a small input of energy and we get an ATP molecule back. In this way, ATP is often called the energy currency of a cell (because cells make and "spend" ATP) FAT ------ GLYCOGEN ------ GLUCOSE ------ ATP Savings Bond -- Bank Account -- Piggy Bank -- Pocket Cash ATP ADP + P + Energy (7 Kcal per mole) ATP molecules can be moved all over the body. When energy is needed, the 3rd phosphate group is broken off. This results in Adenosine Diphosphate (ADP) and the release of heat energy. The heat energy runs metabolic reactions. U8: NUCLEIC ACIDS 1. Identify the basic building block (monomer) of nucleic acids. Nucleotides 2. Draw the generic structure of the basic building block of nucleic acids and label its three key parts. 3. ATP is a key nucleotide in the human body: a. What does "ATP" stand for? Adenosine triphosphate b. What is ATP's primary function? Energy molecule of the cell c. Does ATP release energy when it is being formed (dehydration synthesis) or broken down (hydrolysis)? Energy is liberated when a phosphate is released by breaking its bond in a hydrolysis reaction.