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Name ____________________________________________________________________ Test Date______________ UNIT 5 - THE WORKING CELL I. CELL TRANSPORT A cell is defined as the smallest ____________________ unit of life. In order to maintain ______________________, _____________________ must be moved into the cell and ______________________ must be transported out of the cell. In addition, some cells produce _______________ and other materials designated for export. All materials moving in and out of the cell must pass through the ____________________________________, a ________________________ ____________________________ boundary found in _________ cells. There are two basic mechanisms for transport of materials into and out of the cell: A. Passive Transport (pgs. 183 – 187) Does not require ________________. Movement of substances from a __________________ concentration to ____________. There are three types of passive transport: 1. Diffusion – Due to the random movement of molecules in a ____________________ or ________. Many substances move across the ___________________________ by diffusion, for example, ___________________. 2. Facilitated Diffusion – Diffusion of ____________________________________________ through a _______________________________. Protein channels provide larger openings for larger molecules like _________________. In addition, due to the ________________ fatty acid tails that make up most of the phospholipid bilayer, __________________ molecules and _________________ utilize protein channels. This includes _________________, which utilizes specialized protein channels known as ________________________. 3. Osmosis – Diffusion of water from a _____________ water concentration to a __________ water concentration through a ______________________________ membrane. There are comparative terms used to describe the water versus solute concentration on either side of a membrane: Hypertonic = _________________ solute; ___________________ water Hypotonic = __________________ solute; ___________________ water o Water always moves from ___________________ → _________________________ Isotonic = Relative concentrations of __________________ and _________________ are ___________ o There will be ________ net movement of water if two solutions are isotonic Cells must have a mechanism for counteracting the pressure osmosis can create, otherwise a cell could swell & burst or explode when it is placed in a _________________________ environment. Cell Wall - Rigid boundary found in ________________, ______________, and _______________ cells Contractile Vacuole - Actively ___________ water out of cell in single-celled organisms without _________________________________ Blood/Extracellular Fluid – Designed to be _______________ with cells B. Active Transport – Requires energy in the form of ___________ (pgs. 188 – 189) 1. Protein Pumps – Energy-requiring process during which membrane proteins pump molecules across a membrane against a concentration gradient from a _________ concentration to a ___________ concentration. An example is the sodium-potassium pump. Its purpose is to establish an ____________________________ gradient in cells by pumping _______ sodium ions (______) into the cell for every ______ potassium ions (_____) pumped out of the cell. This slight ____ charge inside the cell relative to the outside is very important for ______________________ ____________________________ and _______________________________. 2. Endocytosis – “________________________”. Larger substances are moved into the cell from the exterior by extending ______________________, forming a ________________ around the substance. Examples include macrophages, amoeba, etc. 3. Exocytosis – “______________________”. Export of molecules from the inside of the cell to the exterior of the cell by a ________________ fusing with the cell membrane. Mechanism used to release _______________________ from cells II. METABOLISM There are countless numbers of chemical reactions occurring in every cell all the time. Virtually all of these reactions require the action of _____________________, catalytic ______________________. A catalyst ______________ a chemical reaction without being _____________________________________. An enzyme works by lowering the activation energy, that is the energy required to ___________________________________________________. Enzymes share four common features: A. Enzymes work best within a narrow _______ and _________________ range. This is because of the importance of the ________________ or ________________________ of the enzyme. When the pH or temperature is altered, the _________________________ and interactions are also changed, changing the shape of the enzyme. B. Enzymes do not make a reaction happen that couldn’t happen on its own; they simply make the reaction occur much ________________________. C. Enzymes are not _____________________________________. The same enzyme may be used over and over again. D. Enzymes are _____________________________. The substrate is the ________________________. The substrate fits into a portion of the enzyme called the _______________________. As the substrate fills the active site, this leads to a phenomenon known as _____________________________, almost like a ___________. It is this induced fit that is responsible for lowering the __________________________________________ of the reaction. III. CHEMICAL ENERGY AND LIFE (pp. 201, 202) A. Energy and Life Energy is the _____________________________. Cells require energy for _________________ reactions, _____________________ transport, cell ____________________, and maintaining __________________. We obtain energy from _______________, but most energy originally comes from the ________. Plants are able to capture the sun’s energy and use it to produce glucose, ____________. This process, known as _________________, occurs in the ___________________ of plant cells. The reaction for photosynthesis is: ______________________________________________________________________________________________ Plants and other organisms that can make their own food are known as ________________________. Humans and other organisms that have to obtain food are known as _____________________________. Although glucose is the preferred energy molecule for the cell, other _________________________, ___________, and __________ can also be broken down for energy. B. Chemical Energy The chemical energy in food (and all molecules) is stored in the ____________________________. This is ___________________________ energy. When the bonds are broken and the ___________________ are released, some energy is lost as ___________, but a percentage of the potential energy can be converted to useable energy in the form of ____________. Food molecules cannot be used as a direct energy source for the cell because food contains too much energy ... if it were released all at once, it would be _______________ and ___________________. C. ATP __________________________________ is a ________________________ that is composed of: ___________________ - nitrogen base ___________________ - _______ carbon sugar ______________________ Energy is stored in ______________________________________. These “rechargeable batteries” are mostly present in the cell in two forms: ATP - ____________________________________. Has ___ phosphate groups. ADP - ____________________________________. Has ____ phosphate groups. ________ has the most phosphate bonds, and therefore contains the most _______________ or stored energy. Cells are able to use and recycle ATP by breaking off or adding a ________________ group. 1. Energy can be used when a ___________ bond is _______________________. __________________________________________________________________ 2. Energy is stored; that is, ATP is “recharged” by ____________ a phosphate group to ___________. __________________________________________________________________ *Under normal conditions, both of these processes are occurring at the _____________ and ______________ in a cell* IV. CELLULAR RESPIRATION - ____________________________ ENERGY PRODUCTION (pp. 221-223, 226-229) Cellular respiration is the breakdown of _______________________ in the presence of _________________ to “make” ___________. The oxygen required for cellular respiration is ___________ into the _________, __________ into the ____________, and is delivered to the __________________ of the body cells by ________________. The glucose needed is obtained through ____________________. The glucose is transported in the blood and enters the body cells via ___________________________________. There are two major parts to cellular respiration: A. Glycolysis – Means __________________________. Occurs in the ____________________ of the cell. Glycolysis does not require ___________________. The splitting of glucose, or glycolysis, occurs very quickly with the aid of _____________________, producing two _______-C molecules known as _________________________. In addition, when the bonds of glucose are broken, the high energy electrons that are released are caught by ____________, a molecule that acts as an electron carrier. This electron energy will be converted to ATP later in the process. Glycolysis requires __________ ATP to occur, but results in the formation of _________ ATP, for a net ________________ of ________ ATP. Reaction: ______________________________________________________________________ Net Energy Gain = _____________________ B. Oxidative Respiration – Glycolysis releases less than ¼ of the chemical energy stored in glucose. Most of its potential energy remains bound in the _________________ formed from glycolysis. In aerobic conditions, meaning ____ is available, the pyruvic acid formed from the breakdown of ___________________ during ______________________ enters the _______________________________________ of the cell where the __________________ of oxidative respiration complete the breakdown of glucose to produce ________________, _________, and _______________. Reaction: _________________________________________________________________ Oxidative respiration is a 2-part process: 1. Krebs Cycle – Series of reactions that occur in the _______________________, in which the energy stored in ______________________ is released in the form of high-energy ________________ when bonds are broken and pyruvic acid is completely broken down to ____________. There are only ______ additional ATP produced in the Krebs Cycle; most of the energy released is captured in the form of electron energy, producing additional __________. In addition, a second type of electron carrier is utilized, producing 2 “filled” ____________. Net Energy Gain = _________________________________________________________________ 2. Electron Transport Chain – In this step, the electron carriers, ___________ and ______________ “dump” their electrons. These electrons are passed along a series of molecules embedded in the inner membrane of the ___________________ of ___________________ cells. This same process occurs in the ____________________ of __________________ cells. As the electrons “fall” down the ETC, the energy they release is used to power an enzyme known as ___________________________, which attaches phosphate groups to _________ to produce _________. This process is known as _____________________________________________ because _______________ must be present. It is the __________________________ of oxygen that “pulls” the electrons down the ETC. As the electrons are collected by oxygen, ___________ is produced. Net Energy Gain = ____________________ *Combined Reactions of Glycolysis + Oxidative Respiration (Krebs &ETC) = Cellular Respiration* _____________________________________________________________________________ *Total ATP Yield Per Molecule of Glucose:* Glycolysis = Krebs Cycle = ETC = _________ ATP _________ ATP _________ ATP V. FERMENTATION - _______________________ ENERGY PRODUCTION (pp. 223, 224) Glycolysis is constantly occurring in the _____________ of every cell under _________________ conditions, meaning ___________________ is not required. The reaction for glycolysis is: _______________________________________________________________________________________________ Glycolysis is the first step for all cellular energy production. If oxygen is available, _________________________________ follows glycolysis. Pyruvic acid is broken down to __________________________________ and _______ ATP are produced. If oxygen is not available, some types of cells have a back-up mechanism for glucose metabolism called ______________________. If a cell cannot switch to fermentation, it cannot survive without oxygen. o Cells that can carry out cellular respiration and fermentation are known as _______________________ ______________________. o Cells that cannot switch to fermentation are known as ______________________________________. A. General Description In fermentation, the pyruvic acid formed during glycolysis does not enter the _______________________, instead, the entire pathway takes place in the ________________. Fermentation does not produce any additional _____________, but the removal of ______________________ from the cytosol allows the process of glycolysis and the net gain of _______ ATP to continue. B. Types of Fermentation - The 2 most common fermentation pathways used by cells are: 1. Lactic Acid Fermentation – Pyruvic acid is converted to __________________. May be utilized by: Human Muscle Cells – Occurs when demand on muscles exceeds supply of oxygen. As lactic acid builds up in the muscle cells, it is felt as ______________________. This is referred to as ________________. As activity slows, and oxygen is re-supplied, the muscle cells switch back to _______________________ and the lactic acid is sent to the _______________________ to be broken down. Bacteria & Fungi – There are some types of bacteria & fungi that carry out lactic acid fermentation in _______________________ conditions. This is utilized by the dairy industry to produce ___________ and ________________________. ______________________________________________________________________________ 2. Alcoholic Fermentation – Pyruvic acid is converted to ___________________ and _________. When oxygen supplies are depleted, ____________ and many bacteria switch to alcoholic fermentation. This process is used commercially for ____________________________________ ______________________________________________________________________________ **TOTAL ATP GAIN IN FERMENTATION = ________ ATP **