Fundamentals of Zoology - ZOOLFUN Term 1 2024-2025 PDF

FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 THEMES OF BIOLOGY BIOLOGY EUKARYOTIC CELL & PROKARYOTIC CELL Is the scientific study of life. A eukaryotic cell has membrane-enclosed...

FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 THEMES OF BIOLOGY BIOLOGY EUKARYOTIC CELL & PROKARYOTIC CELL Is the scientific study of life. A eukaryotic cell has membrane-enclosed Is a subject of enormous scope. organelles, the largest of which is usually Has 5 unifying themes: the nucleus. ○ Organization By comparison, a prokaryotic cell is simpler ○ Information and usually smaller, and does not contain a ○ Energy and matter nucleus or other membrane-enclosed ○ Interactions organelles. ○ Evolution Has 7 characteristics: ○ Order ○ Energy processing ○ Growth and development ○ Response to the environment ○ Reproduction ○ Regulation ○ Evolutionary Biologists ask questions such as: How does a single cell develop into an organism? How does the human mind work? How do living things interact in GENETIC MATERIALS communities? CHROMOSOMES Within cells, structures called BIOLOGICAL ORGANIZATION chromosomes contain genetic material in Life can be studied at di erent levels, from the form of DNA (deoxyribonucleic acid).. molecules to the entire living planet. This range can be divided into di erent GENES levels of biological organization. Encode information for building the ○ Biosphere molecules synthesized within the cell. ○ Ecosystem Are the units of inheritance. ○ Community DNA controls the development and ○ Population maintenance of organisms. ○ Organism ○ Organ system Life's processes involve the expression and ○ Tissue transmission of genetic information. ○ Cell ○ Molecule ○ Atom GENOME Entire set of genetic instructions of an EMERGENT PROPERTIES organism. Result from the arrangement and interaction of parts within a system. GENOMICS Characterize nonbiological entities as well. Large-scale analysis of DNA sequences. ○ Example: a functioning bicycle Study of sets of genes within and between emerges only when all of the species. necessary parts connect in the correct way PROTEOMICS To explore emergent properties, biologists Study of whole sets of proteins encoded by use systems biology to analyze the the genome known as proteomes. interactions among parts of a biological system. LIFE REQUIRES THE TRANSFER AND TRANSFORMATION OF ENERGY AND MATTER STRUCTURE AND FUNCTION The energy from the sun and its At each level of the biological hierarchy, transformation from one form to another there is a correlation between structure and make life possible. function. Some energy is lost to the surroundings as heat during transformation. CELL As a result, energy flows through an An organism’s basic unit. ecosystem, usually entering as light and The lowest level of organization that can exiting as heat. perform all activities required for life. Enclosed by a membrane that regulates passage of materials. Between the cell and its environment. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 FROM ECOSYSTEMS TO MOLECULES, DOMAIN EUKARYA INTERACTIONS ARE IMPORTANT IN Includes all eukaryotic organisms. BIOLOGICAL SYSTEMS Domain Eukarya includes three Interactions between the components of the multicellular kingdoms system ensure smooth integration of all the ○ Plants parts. Which produce their own This holds true equally well for components food by photosynthesis. of an ecosystem and the molecules in a cell. ○ Fungi These interactions may be beneficial or Which absorb nutrients. harmful to one or both of the organisms. ○ Animals Which ingest their food. INTERACTIONS WITHIN ORGANISMS Other eukaryotic organisms were formerly Interactions between components (organs, grouped into the Protist kingdom. tissues, cells, and molecules) that make up living organisms are crucial to their smooth UNITY IN THE DIVERSITY OF LIFE operation. A striking unity underlies the diversity of Cells are able to coordinate various chemical life. pathways through a mechanism called Example feedback. ○ DNA is the universal genetic In feedback regulation, the output, or language common to all organisms. product of a process, regulates that very ○ Unity is evident in many features of process. cell structure. EVOLUTION ACCOUNTS FOR THE UNITY AND CHARLES DARWIN DIVERSITY OF LIFE Theory of Natural Selection Evolution makes logical sense of everything Published On the Origin of Species by we know about living organisms. Means of Natural Selection in 1859. The scientific explanation for both the unity Darwin’s theory explained the duality of and diversity of organisms is the concept unity and diversity. that living organisms are modified He observed that: descendants of common ancestors. ○ Individuals in a population vary in Fossils and other evidence document the their traits, which are heritable. evolution of life on Earth over billions of ○ More o spring are produced than years. survive, and competition is inevitable. DIVERSITY OF LIFE ○ Species generally suit their Approximately 1.8 million species have been environment. identified to date, and thousands more are identified each year. NATURAL SELECTION Estimates of the total number of species He inferred that the environment “selects” that actually exist range from 10 million to for the propagation of beneficial traits. over 100 million. ○ He called this process natural selection. TAXONOMY Natural selection results in the adaptation of organisms to their environment. Branch of biology that names and classifies ○ Bat wings are an example of species into groups of increasing breadth. adaptation. TREE OF LIFE Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species. Evolutionary relationships are often illustrated with treelike diagrams that show ancestors and their descendants. THREE DOMAINS OF LIFE Organisms are divided into three domains, named Bacteria, Archaea, and Eukarya. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 CHEMISTRY OF LIFE CARBON CHOLESTEROL Backbone of life. Crucial molecule in animals, especially in Living organisms consist mostly of cell membranes. carbon-based compounds. Carbon is unparalleled in its ability to form PROTEINS large, complex, and varied molecules. Include a diversity of structures, resulting Carbohydrates, Proteins, DNA, and other in a wide range of functions. molecules that distinguish living matter are all composed of carbon compounds. AMINO ACID Basic unit of proteins. CARBOHYDRATES There are 20 types of amino acids. Serve as fuel and building material. POLYPEPTIDES MONOSACCHARIDES Are amino acid polymers. Is the basic unit of Carbohydrates. e.g. sugar STRUCTURES OF PROTEIN PRIMARY STRUCTURE DISACCHARIDES Is the linear chain of amino acids. Consists of two monosaccharides joined by a glycosidic linkage. SECONDARY STRUCTURE Are regions stabilized by hydrogen bonds POLYSACCHARIDES between atoms of polypeptide backbone. Are macromolecules, polymers with a few hundred to a few thousand TERTIARY STRUCTURE monosaccharides joined by glycosidic Are 3-dimensional shape stabilized by linkages. interactions between side chains. LIPIDS QUATERNARY STRUCTURE Diverse group of hydrophobic molecules. Is the association of 2 or more polypeptides. FATS Consist of glycerol and fatty acids. Sickle-Cell Disease is the change in primary structure of a red blood cell in which the fibers of SATURATED FATS abnormal hemoglobin deforms the red blood cell into a sickle shape. At room temperature, the molecules are packed closely together such as fat in butter. NUCLEIC ACID UNSATURATED FATS Store, transmit, and help express hereditary At room temperature, the molecules cannot information pack together closely enough to solidify because of the kinks in some of their fatty DEOXYRIBONUCLEIC ACID acid hydrocarbon chains. The molecule is usually a double helix. Example is olive oil. RIBONUCLEIC ACID PHOSPHOLIPIDS The tRNA molecule has roughly an Essential for cells. L-shaped structure. Made up of 2 fatty acids (hydrophobic end) and glycerol (hydrophilic end). STEROIDS Lipids that are characterized by a carbon skeleton consisting of four fused rings. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 THE CELL TWO TYPES OF CELLS NUCLEUS Contains most of the cell’s genes and is usually the most conspicuous organelle. NUCLEAR ENVELOPE Encloses the nucleus, separating it from the cytoplasm. NUCLEAR PORES Regulate the entry and exit of molecules from the nucleus. NUCLEAR LAMINA Lines the nuclear size of the envelope. Composed of proteins and maintains the shape of the nucleus. CHROMOSOMES Discrete units where the DNA is organized in the nucleus. ANIMAL CELL STRUCTURE CHROMATIN The DNA and proteins of chromosomes are together called chromatin. NUCLEOLUS Located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis. ENDOMEMBRANE SYSTEM Collection of membrane-based organelles that work together to create, modify, and export cell products such as proteins and lipids. Consists of the nuclear envelope, the rough and smooth endoplasmic reticulum, the Golgi apparatus, and several types of vesicles. Can be modified slightly to meet the specific needs of each cell. RIBOSOMES Complexes made of ribosomal RNA and protein. For example, a muscle cell usually has more Carry out protein synthesis in two locations: rough ER because of its need for protein, while a ○ Cytosol (free ribosomes) liver cell usually contains more smooth ER ○ Outside of endoplasmic reticulum or because of its role in detoxification. the nuclear envelope (bound ribosomes) PLASMA MEMBRANE Is a selective barrier that allows su cient passage of oxygen, nutrients, and waste to service the volume of every cell. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 ENDOPLASMIC RETICULUM LYSOSOME Accounts for more than half of the total Membranous sac of hydrolytic enzymes that membrane in many eukaryotic cells. can digest macromolecules. Continuous with the nuclear envelope. Lysosomal enzymes work best in an acidic There are two types of endoplasmic environment inside the lysosome. reticulum, rough and smooth. Hydrolytic enzymes and lysosomal membranes are made by rough ER and then ROUGH ENDOPLASMIC RETICULUM transferred to the Golgi apparatus for Studded with ribosomes, specifically bound further processing. ribosomes. Fuses with another vesicle coming in from Membrane factory of the cell. the plasma membrane. Bound Ribosomes Its digestive enzymes then break down the ○ Give the rough ER its rough contents of the vesicle, releasing nutrients appearance. for the cell. ○ Responsible for producing glycoproteins, which are packaged into transport vesicles and carried to the Golgi apparatus. SMOOTH ENDOPLASMIC RETICULUM Lacks ribosomes on its surface. Other cell materials leaving the Golgi apparatus Mainly responsible for the detoxification of are for secretion from the cell. Some are harmful chemicals such as drugs and hormones that help with body regulation, while poisons. others are proteins that become part of the Responsible for the production of lipids, material surrounding the cell. Before these which are also packaged into transport products can be exported from the cell, they vesicles and sent to the Golgi apparatus. must first be packaged into a secretory vesicle. Metabolizes carbohydrates. Stores calcium ions. SECRETORY VESICLE Merges with the plasma membrane, releasing its contents into the external environment. PHAGOCYTOSIS Some types of cell can engulf another cell by phagocytosis; this forms a food vacuole. A lysosome fuses with the food vacuole and digests the molecules. Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy. GOLGI APPARATUS MITOCHONDRIA Made of a series of flattened sacs called Are in nearly all eukaryotic cells. cisternae that look a little like pancakes. They have a smooth outer membrane and Packages and distributes cell products for a an inner membrane folded into cristae. specific location within the cell, such as the The inner membrane creates two plasma membrane or for secretion from the compartments: cell. ○ Intermembrane space Some of the proteins from the rough ER are ○ Mitochondrial matrix modified by the Golgi Apparatus to become Some metabolic steps of cellular digestive enzymes, which are packaged into respiration are catalyzed in the a special type of vesicle, called a lysosome. mitochondrial matrix. Cristae present a large surface area for enzymes that synthesize ATP. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 PEROXISOME CENTROSOME Are specialized metabolic compartments In animal cells, microtubules grow out bounded by a single membrane. from a centrosome near the nucleus Produce hydrogen peroxide and convert it The centrosome has a pair of centrioles, to water. each with nine triplets of microtubules Perform reactions with many di erent arranged in a ring. functions. CYTOSKELETON Network of fibers that organizes structures MICROTUBULES and activities in the cell. Control the beating of flagella and cilia, It is a network of fibers extending microtubule-containing extensions that throughout the cytoplasm. project from some cells. It is composed of three types of molecular Cilia and flagella di er in their beating structures. patterns. Helps to support the cell and maintain its shape. CILIA AND FLAGELLA It interacts with motor proteins to produce Share a common structure. motility. ○ A core of microtubules sheathed by Inside the cell, vesicles can travel along the plasma membrane. tracks provided by the cytoskeleton. ○ A basal body that anchors the cilium or flagellum. ○ A motor protein called dynein, which drives the bending movements of a cilium or flagellum. DYNEIN Dynein arms alternately grab, move, and release the outer microtubules. Protein cross-links limit sliding. Forces exerted by dynein arms cause doublets to curve, bending the cilium or flagellum. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 MICROFILAMENTS TIGHT JUNCTIONS Microfilaments that function in cellular Membranes of neighboring cells are pressed motility contain the protein myosin in together, preventing leakage of addition to actin. extracellular fluid. In muscle cells, thousands of actin filaments are arranged parallel to one DESMOSOMES another. Also known as anchoring junctions. Thicker filaments composed of myosin Fasten cells together into strong sheets. interdigitate with the thinner actin fibers. GAP JUNCTIONS Also known as communicating junctions. Provide cytoplasmic channels between adjacent cells. EXTRACELLULAR MATRIX Extracellular components and connections between cells help coordinate cellular activities Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM). The ECM is made up of glycoproteins such as collagen, proteoglycans, and fibronectin. ECM proteins bind to receptor proteins in the plasma membrane called integrins. Has an influential role in the lives of cells. ECM can regulate a cell’s behavior by communicating with a cell through integrins. The ECM around a cell can influence the activity of gene in the nucleus. Mechanical signaling may occur through cytoskeletal changes, that trigger chemical signals in the cell. CELL JUNCTIONS Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 MEMBRANE STRUCTURE AND FUNCTION PLASMA MEMBRANE ROLE OF MEMBRANE CARBOHYDRATES Boundary that separates the living cells CELLS from its surroundings. Recognize each other by binding to Exhibits selective permeability, allowing molecules often containing carbohydrates, some substances to cross it more easily than on the extracellular surface of the plasma others. membrane. ○ It regulates the cell’s molecular tra c. MEMBRANE CARBOHYDRATES May be covalently bonded to lipids (forming SELECTIVE PERMEABILITY glycolipids) or more commonly to proteins Cells must exchange materials with its (forming glycoproteins) surroundings, a process controlled by the plasma membrane. CARBOHYDRATES On the external side of the plasma PHOSPHOLIPIDS membrane vary among species, individuals, Most abundant lipid in the plasma and even cell types in an individual membrane. Amphipathic molecules, containing SYNTHESIS & SIDENESS MEMBRANES hydrophobic and hydrophilic regions. Membranes have a distance inside and outside faces. FLUID MOSAIC MODEL The asymmetrical distribution of proteins, “A membrane is a fluid structure with a lipids, and associated carbohydrates in the ‘mosaic’ of various proteins embedded in plasma membrane is determined when the it.” membrane is built by the ER and Golgi Apparatus. PROTEINS Are not randomly distributed in the THE PERMEABILITY OF THE LIPID BILAYER membrane. HYDROPHOBIC Determines most of the membrane’s Nonpolar molecules such as hydrocarbons specific functions. can dissolve in the lipid bilayer and pass through the membrane rapidly. THE FLUIDITY OF MEMBRANES Phospholipids in the plasma membrane can HYDROPHILIC move within the bilayer. Molecules including ions and polar Most of the lipids, and some proteins drift molecules do not cross the membrane laterally. easily. Rarely, a lipid may flip-flop transversely across the membrane. PASSIVE TRANSPORT Is a di usion of a substance across a MEMBRANE PROTEINS membrane with no energy investment. PERIPHERAL PROTEINS Bound to the surface of the membrane. DIFFUSION Is the tendency for molecules to spread out INTEGRAL PROTEINS evenly into the available space Penetrate the hydrophobic core. Transmembrane proteins ○ Integral proteins that span the Although each molecule moves randomly, membrane. di usion of a population of molecules may be The hydrophobic region of an integral directional. protein consists of one or more stretches of nonpolar amino acids, often coiled into DYNAMIC EQUILIBRIUM alpha helices. Equal amount of molecules cross the membrane in both directions. SIX MAJOR FUNCTIONS OF MEMBRANE PROTEIN 1. Transport OSMOSIS 2. Enzymatic Activity Di usion of water across a selectively 3. Signal Transduction permeable membrane. 4. Cell-Cell Recognition Water di uses across a membrane from the 5. Intercellular Joining region of lower solute concentration to the 6. Attachment to the Cytoskeleton and ECM region of a higher solute concentration until the solute concentration is equal on both sides Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 SELECTIVE PERMEABILITY SODIUM-POTASSIUM PUMP Type of active transport system. TERM DEFINITION MEMBRANE POTENTIAL Tonicity Ability of a surrounding solution to Is the voltage di erence across a cause a cell to gain or lose water. membrane. Isotonic Solute concentration is the same as VOLTAGE Solution that inside the cell. No net Created by di erences in the distribution of movement across the plasma positive and negative ions across a membrane. membrane. Hypertonic Solute concentration is greater ELECTROCHEMICAL GRADIENT Solution than that inside the cell; the cell Two combined forces that drive the loses water. di usion of ions across a membrane Chemical Force Hypotonic Solute concentration is less than ○ The ion’s concentration gradient. Solution that inside the cell; the cell gains Electrical Force water. ○ The e ect of the membrane potential on the ion’s movement. Hypertonic or hypotonic environments create ELECTROGENIC PUMP osmotic problems for organisms. Transport protein that generates voltage across a membrane. OSMOREGULATION Sodium-Potassium Pump The control of solute concentrations and ○ Major electrogenic pump of animal water balance. cells. Is a necessary adaptation for life in such Proton Pump environments. ○ Main electrogenic pump of plants, fungi, and bacteria. The protist Paramecium, which is hypertonic to COTRANSPORT its pond water environment, has a contractile Occurs when active transport of a solute vacuole that acts as a pump. indirectly drives transport of other substances. TRANSPORT PROTEIN Speeds up the passive movement of Small molecules and water enter or leave the molecules across the plasma membrane. cell through the lipid bilayer or transport proteins. Large molecules such as CHANNEL PROTEIN polysaccharides and proteins cross the Provide corridors that allow a specific membrane in bulk via vesicles. Bulk transport molecule or ion to cross the membrane. requires energy. AQUAPORINS EXOCYTOSIS Facilitate the di usion of water. Transport vesicles migrate to the membrane, fuse with it, and release their ION CHANNELS contents outside the cell. Facilitate the di usion of ions. Many secretory cells use exocytosis to Gated channels export their products. ○ Some ion channels that open or close in response to a stimulus. ENDOCYTOSIS Cell takes in macromolecules by forming CARRIER PROTEIN vesicles from the plasma membrane. Undergo a subtle change in shape that translocates the solute-binding site across TYPES OF ENDOCYTOSIS the membrane. PHAGOCYTOSIS ACTIVE TRANSPORT Taking in large food particles. Cell eating. Moves substances against their PINOCYTOSIS concentration gradients. Requires energy, usually in the form of ATP. Taking in large liquid particles. Cell Performed by specific proteins embedded in drinking. the membranes. Allows cells to maintain concentration RECEPTOR-MEDIATED ENDOCYTOSIS gradients that di er from their Uses special receptor proteins to help carry surroundings. large particles across the cell membrane. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 METABOLISM AND CELLULAR RESPIRATION THE ENERGY OF LIFE Exists in various forms, some of which can The living cell is a miniature chemical perform work. factory where thousands of reactions occur. Can be converted from one form to another. Cell extracts energy and applies energy to perform work. TYPES OF ENERGY Some organisms convert energy to light or bioluminescence. TYPE DEFINITION METABOLISM Kinetic Associated with motion. Totality of an organism’s chemical Energy reactions. Emergent property of life that arises from Thermal Associated with random movement interactions between molecules within the Energy of atoms or molecules. cell. Potential Energy that matter possesses METABOLIC PATHWAY Energy because of its location or structure. Begins with a specific molecule and ends with a product. Chemical Potential energy available for release Each step is catalysed by a specific enzyme. Energy in a chemical reaction. CATABOLISM Set of metabolic pathways that breaks down A diver has more potential energy on the molecules into smaller units that are either platform than in water. Diving converts oxidised to release energy or used in other potential energy to kinetic energy. a diver has anabolic reactions. less potential energy in water than on the platform. Climbing up converts the kinetic CATABOLIC PATHWAY energy of muscle movement into potential Release energy by breaking down complex energy. molecules into simpler compounds. Cellular Respiration THERMODYNAMICS ○ Breakdown of glucose in the presence of oxygen. Study of energy transformation. ○ Example of catabolism pathway. ISOLATED SYSTEM ANABOLISM Such as that approximated by liquid in a thermos is isolated from its surroundings. Set of metabolic pathways that construct molecules from smaller units. OPEN SYSTEM These reactions require energy, known as an endergonic process. Energy and matter can be transferred An example would be the synthesis of between the system and its surroundings. protein from amino acids. Organisms are open systems. ANABOLIC PATHWAY LAWS OF THERMODYNAMICS Consume energy to build complex FIRST LAW OF THERMODYNAMICS molecules from simpler ones. According to the first law, the energy of the universe is constant. BIOENERGETICS ○ Energy can be transferred and Study of how organisms manage their transformed, but it cannot be created energy resources. or destroyed. It is also called the principle of conservation of energy. REDOX REACTION Transfer of electrons during chemical SECOND LAW OF THERMODYNAMICS reactions releases energy stored in organic During every energy transfer or molecules. transformation, some energy is unusable, Released energy is used to synthesize ATP. and is often lost as heat. Every energy transfer or transformation OXIDATION & REDUCTION increases the entropy (disorder) of the OXIDATION universe. A substance loses electrons or is oxidized. FREE-ENERGY CHANGE, ΔG REDUCTION A living system’s free energy is energy that A substance gains electrons or is reduced. can do work when temperature and The amount of positive charge is reduced. pressure are uniform or as a living cell. ENERGY Capability to cause change. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 CHEMISTRY OF LIFE’S PROCESSES Glucose - form the digestive system EXERGONIC REACTION Oxygen - from the respiratory system Proceeds with a net release of free energy Carbon Dioxide - waste product exhaled and is spontaneous. Water - waste product exhaled Energy - useful ENDERGONIC REACTION Absorbs free energy from its surroundings and is nonspontaneous. MAIN PLAYERS IN CELLULAR RESPIRATION ADENOSINE TRIPHOSPHATE (ATP) Energy source for all cells. EQUILIBRIUM AND METABOLISM Considered the “energy currency” of the cell. Reactions in a closed system eventually reach Releases large amounts of energy when equilibrium and then do no work. Cells are not converted to adenosine diphosphate (ADP). in equilibrium; they are open systems experiencing a constant flow of materials. A defining feature of life is that metabolism is never at equilibrium. A catabolic pathway in a cell releases free energy in a series of reactions. Closed and open hydroelectric systems can serve as analogies. ENZYMES Speed up metabolic reactions by lowering energy barriers. NICOTINAMIDE ADENINE DIPHOSPHATE & Is a catalyst protein. FLAVIN ADENINE DIPHOSPHATE Enzyme-Catalyzed Reaction Energy intermediates. ○ Hydrolysis of sucrose by the enzyme Used at the last stage of cellular respiration sucrase is an example. to create ATP. CATALYST Chemical agent that speeds up a reaction without being consumed by the reaction. ACTIVATION ENERGY BARRIER Every chemical reaction between molecules involves bond breaking and bond forming. The initial energy needed to start a chemical STAGES OF GETTING ENERGY FROM GLUCOSE reaction is called the free energy of activation or activation energy (EA). Activation energy is often supplied in the form of thermal energy that the reactant molecules absorb from their surroundings. Enzymes ○ Catalyze reactions by lowering the EA barrier. ○ Do not a ect the change in free energy ΔG; instead, they hasten reactions that would occur eventually. CATALYTIC CYCLE OF AN ENZYME 1. Substrates enter an active site. 2. Substrates are held in active site by weak interactions. GLYCOLYSIS 3. Active site lower EA and speed up a reaction. Breaks down glucose into two molecules of 4. Substrates are converted to products. pyruvate leading to Pyruvate Oxidation. 5. Products are released. 6. Active site is available for two new substrate CITRIC ACID CYCLE molecules. Completes breakdown of glucose. RESPIRATION OXIDATIVE PHOSPHORYLATION Is the process that the body uses to release Accounts for most of the ATP synthesis. energy from digested food (glucose). ○ Almost 90% of the ATP generated by Process cellular respiration. ○ Glucose + Oxygen -> carbon dioxide A smaller amount of ATP is formed in + water + energy glycolysis and the citric acid cycle by substrate level phosphorylation. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 FATE OF PYRUVATE In the presence of Oxygen, the pyruvate enters the mitochondrion (in eukaryotic cells) where the oxidation of glucose is completed. Before the citric acid can begin, pyruvate must be converted to acetyl Coenzyme A (acetyl CoA), which links glycolysis to the GLYCOLYSIS citric acid cycle. Glycolysis ("sugar splitting") breaks down Three fates of pyruvate glucose into two molecules of pyruvate. ○ Anaerobic Occurs in the cytoplasm and has two major Lactic acid fermentation phases Alcoholic fermentation ○ Energy investment phase ○ Aerobic 2 ATP is used. Oxidation ○ Energy payo phase Fermentation and anaerobic respiration 4 ATP is formed. enable cells to produce ATP without the Glycolysis occurs whether or not O₂ is use of oxygen. present. Without O2, the electron transport chain will cease to operate. In that case, glycolysis couples with anaerobic respiration or fermentation to produce ATP. Anaerobic respiration uses an electron transport chain with a final electron acceptor other than Oxygen, for example sulfate. Fermentation uses substrate-level phosphorylation instead of an electron transport chain to generate ATP CITRIC ACID (KREB’S) CYCLE Has 8 steps, each catalyzed by a specific enzyme. The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chain. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 VERSATILITY OF CATABOLISM Other macromolecules other than glucose can be catabolized. Proteins are digested to amino acids; amino groups can feed glycolysis or the citric acid cycle. Fats are digested to glycerol (used in glycolysis) and fatty acid (used in generating acetyl CoA). OXIDATIVE PHOSPHORYLATION Following glycolysis and the citric acid cycle, NADH and FADH2 account for most of the energy extracted from food. These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation. The yield of ATP is more in Carbohydrates than in Proteins or Fats. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 CELL CYCLE CELL DIVISION CHROMATIDS The ability of organisms to produce more of Each duplicated chromosome has two sister their own kind best distinguishes living chromatids (joined copies of the original things from nonliving matter. chromosome), attached along their lengths The continuity of life is based on the by cohesins. reproduction of cells, or cell division. ○ The centromere is the narrow In unicellular organisms, division of one “waist” of the duplicated cell reproduces the entire organism. chromosome, where the two Multicellular eukaryotes depend on cell chromatids are most closely division for: attached. ○ Development from a fertilized cell During cell division, the two sister ○ Growth chromatids of each duplicated chromosome ○ Repair separate and move into two nuclei. Cell division is an integral part of the cell ○ Once separate, the chromatids are cycle, the life of a cell from formation to its called chromosomes. own division. Most cell division results in daughter cells TERMINOLOGY with identical genetic information, DNA. MITOSIS ○ The exception is meiosis, a special type of division that can produce The division of the genetic material in sperm and egg cells. the nucleus. ○ All the DNA in a cell constitutes the cell’s genome. CYTOKINESIS The division of the cytoplasm. GENOME GAMETES Can consist of a single DNA molecule (common in prokaryotic cells) or a number Produced by a variation of cell division of DNA molecules (common in eukaryotic called meiosis. cells). MEIOSIS CHROMOSOMES Yields non-identical daughter cells that have half as many chromosomes as the Where the DNA molecules in a cell are parent cell. packaged into. CHROMATIN CELL CYCLE Complex of DNA and protein that condenses MITOTIC (M) PHASE during cell division. Mitosis and cytokinesis NUMBER OF CHROMOSOMES INTERPHASE Every eukaryotic species has a characteristic Cell growth. number of chromosomes in each cell Copying of chromosomes in preparation for nucleus. cell division. Somatic cells ○ Nonreproductive cells INTERPHASE ○ Have two sets of chromosomes. About 90% of the cell cycle. Gametes Can be divided into subphases. ○ Reproductive cells: sperm and eggs G1 Phase ○ Have half as many chromosomes as ○ First gap somatic cells. S Phase ○ Synthesis CELL DIVISION PROCESS G2 Phase In preparation for cell division, DNA is ○ Second gap replicated and the chromosomes condense. The cell grows during all three phases, but chromosomes are duplicated only during the S phase. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 KINETOCHORE Protein complexes associated with centromeres. METAPHASE PLATE Where all chromosomes are lined up during metaphase. Plane midway between the spindle’s two poles. SEPARASE Enzyme that cleaves the cohesins during anaphase. ○ Sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell. ○ The microtubules shorten by depolymerizing at their kinetochore ends. MITOTIC SPINDLE Structure made of microtubules that CLEAVAGE controls chromosome movement during Process that leads to cytokinesis and the mitosis. formation of cleavage furrow. In animal cells, assembly of spindle microtubules begins in the centrosome, the microtubule organizing center. Includes the centrosomes, the spindle microtubules, and the asters. The eukaryotic cell cycle is regulated by a molecular control system. The frequency of cell division varies with the type of cell. These di erences result from regulation at the CENTROSOME molecular level. Cancer cells manage to escape Replicates during interphase, forming two the usual controls on the cell cycle. centrosomes that migrate to opposite ends of the cell during prophase and prometaphase. CELL CYCLE CONTROL SYSTEM Directs the sequential events of the cell ASTER cycle. A radial array of short microtubules that Similar to a clock. extends from each centrosome. Regulated by both internal and external controls. Has specific checkpoints where the cell During prometaphase, some spindle cycle stops until a go-ahead signal is microtubules attach to the kinetochores of received. chromosomes and begin to move the chromosomes. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 TRANFORMATION Process where a normal cell is converted to a cancerous cell. Cancer cells that are not eliminated by the immune system form tumors, masses of abnormal cells within otherwise normal tissue. BENIGN TUMOR Abnormal cells that remain only at the original site. MALIGNANT TUMOR Invade surrounding tissues and can metastasize, exporting cancer cells to other For many cells, the G1 checkpoint seems to be parts of the body, where they may form the most important. If a cell receives a go-ahead additional tumors. signal at the G1 checkpoint, it will usually complete the S, G2, and M phases and divide. If Localized tumors may be treated with the cell does not receive the go-ahead signal, it high-energy radiation, which damages the DNA will exit the cycle, switching into a nondividing in the cancer cells. To treat metastatic cancers, state called the G0 phase. chemotherapies that target the cell cycle may be used. MEIOSIS AND SEXUAL LIFE CYCLES HEREDITY Transmission of traits from one generation to the next. VARIATION Demonstrated by the di erences in appearance that o spring show from parents and siblings. CANCER GENETICS Cancer cells do not respond normally to the Scientific study of heredity and variation. body's control mechanisms GENES Units of heredity and are made up of segments of DNA. GAMETES Reproductive cells (sperm and egg) that are used to pass on genes to the next generation. SOMATIC CELLS Contains the 46 chromosomes (or 23 pairs of chromosomes) that has the DNA of humans. ○ All cells of the body except gametes and their precursors. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 LOCUS MEIOSIS A Gene's specific position along a Gametes are the only types of human cells chromosome. produced by meiosis, rather than mitosis. Meiosis results in one set of chromosomes ASEXUAL REPRODUCTION in each gamete. A single individual passes all of its genes to Fertilization and meiosis alternate in its o spring without the fusion of gametes. sexual life cycles to maintain chromosome number. CLONE Like mitosis, meiosis is preceded by the Group of genetically identical individuals replication of chromosomes. from the same parent. Meiosis takes place in two consecutive cell divisions, called meiosis I and meiosis II. The two cell divisions result in four SEXUAL REPRODUCTION daughter cells, rather than the two Two parents give rise to o spring that have daughter cells in mitosis. unique combinations of genes inherited Each daughter cell has only half as many from the two parents. chromosomes as the parent cell. KARYOTYPE Ordered display of the pairs of chromosomes from a cell. HOMOLOGOUS CHROMOSOME Also called as homologs. Two chromosomes in each pair. Chromosomes in a homologous pair are the same length and shape and carry genes controlling the same inherited characters. Each pair of homologous chromosomes includes one chromosome from each parent. The 46 chromosomes in a human somatic cell are two sets of 23: one from the mother and one from the father. DIPLOID CELL 2n Has two sets of chromosomes. For humans, the diploid number is 46 (2n = 46). GAMETE PROPHASE I Sperm or egg In early prophase I, each chromosome pairs Contains a single set of chromosomes and with its homolog and crossing over occurs. is haploid (n). X-shaped regions called chiasmata are For humans, the haploid number is 23 (n = sites of crossover. 23). Each set of 23 consists of 22 autosomes and METAPHASE I a single sex chromosome. In metaphase I, pairs of homologs line up In an unfertilized egg (ovum), the sex at the metaphase plate, with one chromosome is X. chromosome facing each pole. In a sperm cell, the sex chromosome may Microtubules from one pole are attached to be either X or Y. the kinetochore of one chromosome of each tetrad. FERTILIZATION Microtubules from the other pole are Union of gametes (the sperm and the egg). attached to the kinetochore of the other chromosome. ZYGOTE Fertilized egg. ANAPHASE I Has one set of chromosomes from each In anaphase I, pairs of homologous parent. chromosomes separate. Produces somatic cells by mitosis and One chromosome of each pair moves develops into an adult. toward opposite poles, guided by the spindle apparatus. Sister chromatids remain attached at the centromere and move as one unit toward the pole. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 TELOPHASE I AND CYTOKINESIS In the beginning of telophase I, each half of the cell has a haploid set of chromosomes; each chromosome still consists of two sister chromatids. Cytokinesis usually occurs simultaneously, forming two haploid daughter cells. PROPHASE II In prophase II, a spindle apparatus forms. In late prophase II, chromosomes (each still composed of two chromatids) move toward the metaphase plate. METAPHASE II In metaphase II, the sister chromatids are arranged at the metaphase plate. Because of crossing over in meiosis I, the two sister chromatids of each chromosome are no longer genetically identical. The kinetochores of sister chromatids attach to microtubules extending from opposite poles. ANAPHASE II In anaphase II, the sister chromatids separate. The sister chromatids of each chromosome now move as two newly individual chromosomes toward opposite poles. TELOPHASE II AND CYTOKINESIS In telophase II, the chromosomes arrive at opposite poles. Nuclei form, and the chromosomes begin decondensing. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 MENDELIAN GENETICS “BLENDING” HYPOTHESIS LAW OF SEGREGATION Is the idea that genetic material from two When Mendel crossed contrasting, true- parents blends together. breeding white and purple-flowered pea ○ Like blue and yellow to make green. plants, all of the F₁ hybrids were purple. When Mendel crossed the F₁ hybrids, many “PARTICULATE” HYPOTHESIS of the F₂ plants had purple flowers, but Is the idea that parents pass on discrete some had white. heritable units or genes. ○ A ratio of about three to one, purple ○ Mendel documented a particular to white flowers, in the F₂ generation mechanisms through his Only the purple flower factor was a ecting experiments with garden peas. flower color in the F₁ hybrids ○ Purple flower color a dominant CHARACTER trait and the white flower color a recessive trait. Heritable features that vary among The factor for white flowers was not individuals. diluted or destroyed because it reappeared ○ Such as flower color. in the F₂ generation. TRAIT Each variant for a character. ○ Such as purple or white color for flowers. ADVANTAGES OF USING PEAS Short generation time. Large numbers of o spring. Mating can be controlled. ○ Plants could be allowed to self-pollinate or could be cross pollinated. Mendel observed the same pattern of inheritance in six other pea plant characters, each represented by two traits. What Mendel called a "heritable factor" is what we now call a gene. HYBRIDIZATION Process of mating two contrasting, true breeding varieties. P GENERATION True-breeding parents. F1 GENERATION Hybrid o spring of the P generation. F2 GENERATION When F1 individuals self-pollinate or cross-pollinate with other F1 hybrids, the F2 generation is produced. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 PUNNETT SQUARE MONOHYBRID CROSS Can show possible combinations of sperm A cross between heterozygotes following and egg. one character. Capital Letter ○ Represents a dominant allele. Lowercase Letter ○ Represents a recessive allele. HOMOZYGOUS Organism with two identical alleles for a character. HETEROZYGOUS Organism that has two di erent alleles for the gene controlling that character. LAW OF INDEPENDENT ASSORTMENT Developed by Mendel using a dihybrid cross (following two characters at the same time). It states that each pair of alleles segregates independently of each other pair of alleles during gamete formation. Applies only to genes on di erent, non-homologous chromosomes or those far apart on the same chromosome. Genes located near each other on the same chromosome tend to be inherited together. Crossing two true-breeding parents di ering in An organism’s trait does not always reveal its two characters produces dihybrids in F1 genetic composition due to the di erent e ects generation. Heterozygous for both characters. of dominant and recessive alleles. DIHYBRID CROSS PHENOTYPE A cross between F1 dihybrids. Physical appearance Can determine whether two characters are transmitted to o spring as a package or independently. GENOTYPE Genetic makeup Example would be the flower color in pea plants. ○ PP and Pp plants have the same phenotype (purple) but di erent genotypes. Inheritance patterns are often more complex than predicted by simple Mendelian genetics. The relationship between genotype and phenotype is rarely as simple as in the pea plant characters. DOMINANT PHENOTYPE Many heritable characters are not determined by Could be either homozygous dominant or only one gene with two alleles. However, the heterozygous. basic principles of segregation and independent If any o spring display the recessive assortment apply even to more complex patterns phenotype, the mystery parent must be of inheritance. heterozygous. Dr. Brian M. Limson, LPT FUNDAMENTALS OF ZOOLOGY ZOOLFUN | Term 1 | 2024 - 2025 COMPLETE DOMINANCE PLEIONTROPY Complete dominance occurs when Most genes have multiple phenotypic phenotypes of the heterozygote and e ects, a property called pleiotropy. dominant homozygote are identical. Example is Sickle-Cell Disease. ○ INCOMPLETE DOMINANCE Phenotype of F₁ hybrids is somewhere between the phenotypes of the two parental varieties. CODOMINANCE Two dominant alleles a ect the phenotype in separate, distinguishable ways. RELATIONSHIP BETWEEN DOMINANCE AND PHENOTYPE A dominant allele does not subdue a recessive allele; alleles don't interact that way. Alleles are simply variations in a gene's nucleotide sequence. For any character, dominance / recessiveness relationships of alleles depend on the level at which we examine the phenotype. FREQUENCY OF DOMINANT ALLELES Dominant alleles are not necessarily more common in populations than recessive alleles. Ex: one baby out of 400 in the United States is born with extra fingers or toes The allele for this unusual trait is dominant to the allele for the more common trait of five digits per appendage. In this example, the recessive allele is far more prevalent than the population's dominant allele. MULTIPLE ALLELES Most genes exist in populations in more than two allelic forms. Ex: the four phenotypes of the ABO blood group in humans are determined by three alleles. Dr. Brian M. Limson, LPT