BIO 181 Final Study Guide PDF
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Kylee McKinney
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This study guide provides an overview of core biology concepts, including properties of life, homeostasis, natural selection, evolution, levels of organization, and the scientific method. It is designed for a university-level biology course, BIO 181.
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Bio 181 1 S tudy Guide Exam By: Kylee McKinney Biology: The Scientific study of life. PROPERTIES OF LIFE: 1. Order - organization of cells to create compl...
Bio 181 1 S tudy Guide Exam By: Kylee McKinney Biology: The Scientific study of life. PROPERTIES OF LIFE: 1. Order - organization of cells to create complex systems or organelles. Atoms > molecules > organelles > cells > organism 2. Response to stimuli - organism responds to the environment, such as a plant moving towards a source of light 3. Reproduction - Replicate through DNA and pass on genetic material to offspring 4. Adaptation - living organisms “fit” their environment, natural selection, not static and it changes when the environment changes. 5. Growth and Development - organism grows and develops as a result of genes providing specific instructions from parents 6. Homeostasis - the ability to maintain a stable internal environment 7. Energy Processing - Use a source of energy to perform metabolic processes, such as the energy gained by eating food or when plants convert light to energy. 8. Evolution - the diversity of organisms as a result of mutations, or random changes in heredity material over time. This process allows the organism to grow and change to adapt to their environment. UNIFYING THEMES OF BIOLOGY: 1. Organization - Levels 2. Information - DNA 3. Energy and Matter - Survival needs 4. Interactions - Communities 5. Evolutions - Changes of species over time Homeostasis: The process by which our body maintains a stable internal environment PH LEVELS TEMPERATURE. DRIVEN BY THE PROCESS CALLED NEGATIVE FEEDBACK Natural Selection: Mechanism responsible for evolution in species. Not random, the environment selects which traits are most likely to be passed down to future generations SURVIVAL OF THE FITTEST Requirements for Natural Selection: 1. Inheritance - the process by which genetic traits are passed down to offspring 2. Unequal Reproduction - the phenomenon where individuals in a population do not reproduce at the same rate due to varying FITNESS levels 3. Individual Variation - differences among individuals in a species 4. Overproduction - A species produces more offspring than the environment can support PROCESSES OF NATURAL SELECTION: POSITIVE FEEDBACK: NEGATIVE FEEDBACK: Processes that AMPLIFY CHANGE, encourage a particular Counteract changes and help maintain stability. outcome. Going away from balance to get back to balance. How populations respond to environmental pressures Ex: if a trait leads to a better survival or mating success Contribute to HOMEOSTASIS then that trait will produce more offspring, passing the trait Ex: the process of sweating, evaporation of sweat to cool on. the body. Evolution: the process of gradual change of a species over time. KEY CONCEPTS: iii iiiii i iia.it 1. Natural Selection iiii iiiiiiiiii iiiii.it d iiii'iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iii i.iii.iii.si 2. Genetic Variation iii iiiiii 3. Migration (Gene Flow) 4. Genetic Drift T.si raicomeonenes 5. Speciation 6. Adaptation Mutations: They are “mistakes” or changes in the DNA. Mutations are the only way to get traits or adaptations added to the gene pool of an organism. Film “The making of the fittest: Natural Selection and Adaptation KEY CONCEPTS: Video Summary: A mutation is a random change to an organism’s DNA sequence. Mice living on light-colored sand tend to have The environment contributes to determining whether a mutation is advantageous, light-colored coats, while mice living on patches deleterious, or neutral. of dark-colored rock have mostly dark-colored Mutations that increase the fitness of an organism increase in frequency in a population. coats. Michael Nachman studies the evolutionary Evolution can happen quickly (in hundreds of years, or even less); advantageous genetic processes that led to these marked differences in mutations can increase in frequency in a population quite rapidly, even if the fitness rock pocket mouse populations. He has advantage to the organism is small. quantified the selective pressure imposed by Different mutations in the same gene, or even mutations in different genes, can result in predators and identified the genes involved in the the same phenotype. adaptations of mouse populations to their While mutations can be random, natural selection is not random. substrates. Nachman’s work also demonstrates Selective pressure depends on the environment in which an organism lives. This means that similar selective pressures can drive that other organisms in the environment (in this case, the predators) can be a selective evolution toward similar phenotypic adaptations force. but using very different genetic paths. LEVELS OF ORGANIZATION 1. Atom 2. Molecule 3. Organelle 4. Cell 5. Tissue 6. Organ 7. Organ systems 8. Organisms 9. Populations 10. Communities 11. Ecosystems 12. Biosphere THE SCIENTIFIC METHOD: The method of research with defined steps that include experiments and careful observation. THEORY VS. HYPOTHESIS THEORY: An explanation that has been PROVEN and HYPOTHESIS: a PREDICTION to a CONFIRMED through EXPERIMENTS that all come to the question proposed. An EDUCATED GUESS. SAME conclusions. Steps: 1. Observation - Beginning, observation of a PROBLEM that NEEDS TO BE SOLVED. a. Ex: The classroom feels hot. 2. Question - The observation leads to a question. a. Ex: 1. Classroom feels hot 2. Why does it feel hot? 3. Hypothesis - a Proposed observation explanation a. Ex: might propose the class is hot because the AC is not on 4. Prediction - a Statement about what will happen if the Hypothesis is true a. Ex: if we turn on the AC the class will cool 5. Experiment - an Experiment designed to TEST the Hypothesis a. Ex: check to see if AC is on and functional 6. Result - Data gathered from the Experiment is Analyzed and Interpreted a. Ex: if AC is on but not functional, the hypothesis is rejected. THE BUILDING BLOCKS OF LIFE: Matter: any substance that occupies SPACE and has MASS Atoms: Smallest unit of matter that retains the chemical properties of an ELEMENT COMPOSITION OF ATOMS: PROTONS: OUTER SHELL: +1 Charge - 1 amu Mass. Located in the nucleus Positive Charge where the electrons (+) are located NEUTRONS: NUCLEUS: includes the No Charge - 0 amu Mass. - Located in the Nucleus No charge protons and neutrons ELECTRONS: 1 Charge. - 1 amu Mass. - Located in outer shells Negative Charge (-) Electrons: Only Electrons are involved in the chemical activity of an atom. Electrons orbit the nucleus of an an atom in specific electron shells. The farther an electron is from the nucleus, the greater its energy. The number of electrons in the outermost shell determines the chemical properties of an atom OUTER SHELL ELECTRON electron outershell nucleus NUCLEUS Hydrogen HYDROGEN ATOM atom Elements: Unique forms of matter with specific chemical and physical properties that cannot break down into smaller substances by ordinary chemical reactions. ELEMENTS FOUND IN ALL LIVING ORGANISMS OXYGEN (O) LIFE = 65% ATMOSPHERE = 21%. EARTHS CRUST = 46% CARBON (C) LIFE = 18%. ATMOSPHERE = TRACE. EARTHS CRUST = TRACE HYDROGEN (H) LIFE = 10%. ATMOSPHERE = TRACE. EARTHS CRUST = 0.1% LIFE = 3%. ATMOSPHERE = 78%. EARTHS CRUST = TRACE NITROGEN (N) TRACE ELEMENTS: Minimal amounts of elements that are necessary for survival. MAIN MINERALS - 1. Potassium (Muscle Function) 2. Sodium (Blood Pressure) 3. Calcium (Bone Health ) 4. Phosphorous (Metabolism) TRACE MINERALS - 1. Iron (oxygen in blood) 2. Zinc (immunity) 3. Copper (Red blood cell production) 4. Iodine (thyroid function) CHEMISTRY OF LIFE ISOTOPE: Different forms of an element that have the SAME MOLECULES: Simply two or more atoms number of PROTONS but a DIFFERENT number of bonded together NEUTRONS. COMPOUNDS: Molecules consisting of two IONS: an atom with an electrical charge. or more elements. BONDS IONIC BONDS: Form between ions with OPPOSITE charges. Ex: Salt = NaCl, when sodium (Na) LOSES an electron, it becomes positively charged, while chloride GAINS an electron and becomes negatively charged, these OPPOSITE charges then attract each other, BONDING. B is SODIUM CHLORIDE POLAR MOLECULE: Atoms within molecules are sharing electrons unevenly which results in a partial charge on each atom, POLAR ◦Ex: Water Molecules, polar due to uneven sharing of electrons between oxygen and hydrogen. H2O, is POLAR because Oxygen wants all of the Hydrogens electrons so it pulls the atom in their direction. The OXYGEN end of the molecule has a slight NEGATIVE charge and the HYDROGEN end has a slight POSITIVE charge. COVALENT BONDS: Atoms that are sharing electrons. Q Stronger than more common ionic bonds in the molecules of living organisms. Proteins and DNA are held together through covalent bonds. Nonpolar Covalent bonds: Polar Covalent bonds: Bond between two atoms of the same element or between Atoms unequally share the electrons and are attracted different elements that share electrons equally. more to one nucleus than the other. HYDROGEN BOND: weak but very important bonds formed HYDROPHOBIC: Water-fearing, NON-POLAR Ex: lipid tails on plasma membrane between polar molecules HYDROPHILIC: Water-loving, attracted to water, ◦Critical in stabilizing the structures of DNA POLAR ◦Provide many of the critical, life-sustaining properties Ex: head of phospholipid in plasma membrane of water. WATER WHY IS WATER SO IMPORTANT? WHAT ARE ITS PROPERTIES? 1. Water is essential to life, without it life as we know it would not exist. 2. Water comprises approx. 60-70% of the human body 3. Water is one of the more abundant molecules and the one most critical to life on Earth 4. Polar!! Most important property of water is that it is POLAR because it has a POLAR COVALENT BOND in its molecular structure. 5. Water has the highest specific heat capacity of any liquids A. Specific heat is the amount of heat one gram of a substance must absorb or lose to change its temp by 1 degree Celsius (1 calorie for Water) 6. High heat capacity - Boiling point is 100 degrees Celsius 7. Has a high heat vaporization that is higher than most other substances. 8. Has cohesion, adhesion and surface tension properties. 9. Solvent properties. A. A substance capable of dissolving other polar molecules and ionic compounds. PROPERTIES OF WATER ADHESION: Attraction between molecules of DIFFERENT substances COHESION: Attraction between molecules of the SAME substances SURFACE TENSION: Weight of an object is not enough to break the bonds (or surface) o SOLVENT: substance that dissolves a Solute Ex: Water SOLUTE: Substance that dissolves in the solvent SOLUTION: Mixture of solvent and solute. MACROMOLECULES GLUCOSE: Main sugar that is used for a source of energy in many living organisms. Instant Energy, Monomer MONOMER: building blocks of all macromolecules HYDROLYSIS: The reverse process of dehydration synthesis. This 1 GLYCEROL 3 FATTY ACIDS 1 TRIGLYCERIDE 3 WATER MOLECULES is adding water to a polymer to break it back down into the monomers. In DEHYDRATION SYNTHESIS the water falls off and lets two molecules combine together. The hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a water molecule. At the same time, the monomers share electrons and form covalent bonds. As additional monomers join, this chain of repeating monomers forms a polymer CARBOHYDRATES N = number of carbons Macromolecule that is vital to ENERGY PRODUCTION INSTANT ENERGY SUGARS Provide structure support for PLANT CELLS, FUNGI, and all ARTHROPODS Ex: Lobster, crab, shrimp, etc. 3 TYPES 1. Monosaccharides - One Sugar, One Molecule ation Dehydr a. Ex: Glucose, Fructose, and Galactose is synthes 2. Disaccharides - Two sugars, One Molecule a. Ex: Lactose, Maltose, and Sucrose 3. Polysaccharides - Many Sugars, Many Monosaccharide monomers joined LIPIDS together. STORAGE a. Ex: Starch and Glycogen Made of hydrocarbon bonds that mainly have carbon-carbon or carbon-hydrogen non- polar bonds. Hydrophobic, Non-polar, insoluble 3 GROUPS 1. Fats and Oils - Long term Energy Storage and insulation for the body a. Glycerol and fatty acids 2. Phospholipids - a bilayer that makes up the cell membranes matrix 3. Steroids - Fused ring structure, does not resemble other lipids, however they are HYDROPHOBIC and INSOLUBLE in water a. Cholesterol Fats and Oils - ◦Glycerol has 3 CARBONS, 5 HYDROCARBONS, and 3 HYDROXYL groups Steroids - ◦Found within Phospholipid belayer ◦Fatty acids are made up of 1 or more hydrocarbon ‣ Cholesterol in animal cells chains and have a carboxyl group ‣ Phytosterol in plants ‣ Saturated - single bonds ‣ Unsaturated - one or more double bonds ‣ Dehydration synthesis CHOLESTEROL Phospholipids - Phosphate group ◦Head ‣ Phosphate group ‣ Glycerol group Glycerol group ‣ HYDROPHILIC ◦Tail ‣ Chains of Fatty Acids ‣ Saturated or Unsaturated ‣ HYDROPHOBIC Saturated fatty acid Unsaturated fatty acid PROTEINS Made of AMINO ACIDS, linear FUNCTIONS AND TYPES ◦MUST ALWAYS HAVE: ‣ Central CARBON atom ‣ Carboxyl group ‣ Amino group ‣ Hydrogen atom ‣ “R” Side chain AMINO ACIDS STRUCTURE AND FUNCTIONS OF EACH STRUCTURE NUCLEIC ACIDS Most important macromolecules, carry cells GENETIC BLUEPRINT ◦DNA and RNA ◦All monomers for nucleic acids have: ‣ Sugar ‣ Phosphate group ‣ A base DNA vs. RNA DNA RNA Function - Carries genetic Material Involved in protein synthesis Location - Remains in the nucleus Leaves the Nucleus Structure - Double Helix Usually single-stranded STRUCTURE: Sugar - Deoxyribose Ribose DNA Pyrimidines -Cytosine and thymine Cytosine and Uracil ◦Strands are anti-parallel ◦Bases are held together by HYDROGEN Purines - Adenine and Guanine Adenine and Guanine BONDS ◦Stable and indestructible ◦Phosphate and sugar held together by Nitrogenous Bases COVALENT BONDS GENE - The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA CELLS CELL THEORY 1. The cell is the basic structural and functional unit of every organism. 2. New cells arise from existing cells 3. All organisms are made up of cells Main idea: connection with EVOLUTION Unity and Diversity DISCOVERIES Robert Hooke - 1665 coined the term cell, viewed cork tissue through lens. Van Leeuwenhoek - 1670s Discovered bacteria and protists Schneider and Theodor Schwann - 1830s Unified Cell Theory UNICELLULAR: organism is made up of one cell, no membrane-bounds organelles ORGANELLES: small structures that exist within cells that perform specific functions. Ex: chloroplasts or mitochondrion MULTICELLULAR: organism is made up of multiple cells AUTOTROPH: an organism that can produce its own food using light, water, carbon dioxide, or other chemicals HETEROTROPH: an organism that eats other plants or animals for energy and nutrients PROKARYOTIC CELLS Single-celled organisms Pro = Before Kary = Nucleus No Nucleus No membrane-bound Organelles Bacteria and Archaea ◦Archaea are closely related to Eukaryotes IMPORTANT STRUCTURES ◦Here before eukaryotes and developed into Flagellum - Long whip like structure that enables the cell to move them through ENDOSYMBIOSIS. (locomotion) ◦Pathogens are bacteria that cause Nucleoid Region - Where the cells genetic material, DNA, is stored it is not enclosed by a membrane bound nucleus. Instead their DNA is diseases. But not all bacteria are bad. found in a single, circular chromosome. Pili -Particularly found on bacteria, pili are used for a few different things such as adhesion, communication and reproduction. EUKARYOTIC CELLS Single and multicellular organisms Types: Animals, Plants, Fungi are multicellular Types: Protists are unicellular Means “True Nucleus” Has membrane-bound organelles and a Nucleus PARTS OF BOTH PLANT AND ANIMAL CELLS: Nucleus - membrane-bound sac that houses the cells DNA and controls functions such as growth, metabolism, and reproduction. Rough Endoplasmic Reticulum- covered with ribosomes on the surface which is why it is called rough, the main function is to synthesize and fold proteins. Translate mRNA into proteins then sent to the Golgi Apparatus. Smooth Endoplasmic Reticulum - does NOT have ribosomes on the surface, smooth, primarily involved in lipid and steroid hormone synthesis. Also plays a role in detoxification of harmful substances and in calcium storage for muscle contraction. Ribosomes - Where protein synthesizes. Translates genetic info from messenger RNA to build proteins. FREE ribosomes float PARTS ONLY FOUND IN freely in the cytoplasm and produce proteins that function within PLANT CELLS that cytoplasm. BOUND ribosomes are attached to the Rough Chloroplasts - Specific to PLANT CELLS, ER and they synthesize proteins that are usually for specific these organelles are responsible for the process reasons such as insertion for membranes or transport to of PHOTOSYNTHESIS. Contain and outer specific organelles. membrane that encloses a fluid-drilled space Golgi Apparatus - Responsible for modifying, sorting and called the STROMA. Within these stroma are packaging of proteins and lipids for transport. Made up of stacks of THYLAKOIDS, which are where the stacked pouches called CISTERNAE. light-dependent reactions occur within the cell. Mitochondria - POWERHOUSE of the cell. Responsible for Vacuoles - essential for storage, structural ATP production, Regulation of cellular metabolism, programmed support and maintaining homeostasis within the cell death (apoptosis), and heat production. Mitochondria have cell. their OWN DNA (Mitochondrial DNA) and can replicate Cell Wall - Essential to plant cells for strength independently of the cell. support, protection and ability to function in a Cell Membrane - Plasma membrane, thin, flexible barrier that multicellular organism. surrounds the cell. Plays a crucial role in maintaining the cell’s integrity and regulating the movement of substances in and out of the cell. It has SELECTIVE PERMEABILITY, PHOSPHOLIPID BILAYER, EMBEDDED PROTEINS, and is responsible for cell communication and signaling. ENDOSYMBIOSIS ENDOSYMBIOSIS THEORY A process in which one cell merges A biological THEORY that explains how with another providing mutual certain organelles originated in Eukaryotic benefits to the newly formed cell. cells. Ex: Mitochondria and chloroplasts Mitochondria and chloroplasts were thought to be free-living prokaryotic organisms that were engulfed by ancestral Eukaryotic cells through the process called PHAGOCYTOSIS. Instead of being digested the prokaryotes formed a mutually beneficial relationship with that host cell. Mitochondria - came from aerobic Chloroplasts - came from bacterium (cellular respiration) cyanobacterium (photosynthesis) BIO EXAM 2 Study guide By: Kylee McKinney The movement of particles (atoms, ions or molecules) from a region in which they are in higher concentration to DIFFUSION regions of lower concentration Extracellular fluid having a Hypertonic higher osmolarity than the Water moves across a membrane cell’s cytoplasm. Water leaves from areas of lower solute OSMOSIS concentration to areas of higher the cell. CELL SHRINKS solute concentration. The extracellular fluid has a lower osmolarity than the fluid inside the Hypotonic cell. Water enters the cell. CELL EXPANDS Isotonic The extra cellular fluid has the same osmolarity as the cell. Factors that 1. Extent of concentration gradient Affect 2. Mass of molecules diffusing Diffusion 3. Temperature 4. Solvent density 5. Solubility SELECTIVE PERMEABILITY 6. Surface area and plasma membrane thickness Plasma membranes allow SOME 7. Distance travelled substances to pass through but not all. Defines the cell PLASMA MEMBRANE Outlines its borders Determines the nature of its interaction with its environment. FLUID MOSAIC MODEL Describes the plasma membrane structure as a mosaic of components - phospholipids, cholesterol, proteins, and carbs - that gives the membrane fluid character. AMPHIPATHIC Dual-loving. meaning a molecule that has PHOSPHOLIPID BILAYER both hydrophilic (water-attracting) and a fundamental structure that forms the cell hydrophobic (water-repelling) parts membrane in living organisms. It consists of two layers of phospholipid molecules, each composed of a hydrophilic (water-attracting) “head” and two hydrophobic (water- repelling) “tails.” MEMBRANE STRUCTURE A hydrophilic head that is attracted to water. TYPES Hydrophobic tails that repel water. 1. Diffusion 2. Facilitated diffusion This dual nature allows phospholipids to form the bilayer structure of the 3. Osmosis plasma membrane, with the hydrophilic heads facing the aqueous environments inside and outside the cell, while the hydrophobic tails face each other, forming the interior of the membrane. This property is essential for the membrane’s function as a selective barrier. PASSIVE TRANSPORT Passive transport is the movement of substances across a cell membrane without the need for energy input from the cell. It occurs down a concentration gradient, meaning substances move from an area of higher concentration to an area of lower concentration until equilibrium is reached. The process relies on the natural kinetic energy of molecules. FACILITATED DIFFUSION Larger or polar molecules (such as glucose or ions) require the help of membrane proteins (like channels or carriers) to move across the membrane, still without energy. AQUAPORIN a type of integral membrane protein that forms channels in the cell membrane to facilitate the transport of water molecules in and out of the cell. These channels are highly selective, allowing only GATED PROTEIN CHANNEL water to pass through while preventing the passage of ions or other small molecules. Aquaporins play a crucial role in maintaining A gated protein channel is a type of membrane water balance in cells and are essential in processes such as osmosis, protein that opens or closes in response to specific where water moves in response to concentration gradients. stimuli, allowing or preventing the passage of ions or molecules across the cell membrane. These channels are highly selective, usually permitting only certain ions CARRIER PROTEIN (such as sodium, potassium, calcium, or chloride) or A channel protein is a type of membrane protein that molecules to pass through when open. forms a passageway or pore in the cell membrane, allowing specific ions or molecules to move across it. ACTIVE TRANSPORT process by which cells move molecules or ions across the cell membrane against their concentration gradient, from an area of lower concentration to an area of higher ATP - adenosine triphosphate concentration. primary energy carrier in cells. It stores and provides energy for many biological processes, such as muscle contraction, nerve PRIMARY ACTIVE TRANSPORT impulse transmission, and chemical reactions. type of active transport where energy is directly used from ATP to move molecules or ions across a cell membrane against their concentration gradient (from lower to higher concentration). This process requires membrane proteins, often called pumps, which hydrolyze ATP to obtain the necessary energy. SECONDARY ACTIVE TRANSPORT Does not require ATP directly. Instead it is the movement due to the electrochemical gradient that is established by the primary active transport that is used. Carrier Proteins in Active Transport Uniporter Carries one specific ion or molecule Carries two different ions or molecules, both in Symporter the SAME direction Antiporter Carries two different ions or molecules but in different directions. SODIUM-POTASSIUM PUMP NA+/K+ Found in animal cells. Main function is to maintain the proper balance of Sodium and potassium ions inside and outside the cel. This is essential for various cellular processes like nerve impulse transmission, muscle contraction and maintaining cell volume. Drive secondary active transport - the sodium gradient created by the pump powers the secondary system. HOW IT WORKS: 1. Binding of sodium ions: The pump binds three sodium ions (Na⁺) from ELECTROCHEMICAL GRADIENT the inside of the cell. the combination of two forces that drive the 2. ATP hydrolysis: The pump then hydrolyzes one molecule of ATP, movement of ions across a cell membrane: breaking it down into ADP and inorganic phosphate. This provides the energy 1. Chemical gradient (concentration gradient): This required for the pump to change its shape. is the difference in the concentration of a specific ion 3. Sodium ions released: Using the energy from ATP, the pump changes (like sodium, Na⁺, or potassium, K⁺) across the its conformation and moves the three sodium ions out of the cell, against membrane. Ions tend to move from areas of high their concentration gradient (since Na⁺ is typically higher outside the cell). concentration to areas of low concentration, which is 4. Binding of potassium ions: In its new shape, the pump binds two the chemical driving force. 2. Electrical gradient (membrane potential): This potassium ions (K⁺) from outside the cell. refers to the difference in charge (voltage) across 5. Return to original shape: The pump releases the phosphate group, the cell membrane. Since ions are charged particles, causing it to return to its original shape, which transports the two they are influenced by the electrical potential across potassium ions into the cell, against their concentration gradient (since K⁺ is the membrane. Positively charged ions (like Na⁺ or higher inside the cell). K⁺) are attracted to negatively charged areas, and 6. Cycle repeats: The pump is now ready to bind sodium ions again, vice versa for negatively charged ions. and the process continues. 3 TYPES ENDOCYTOSIS 1. PHAGOCYTOSIS cellular process by which a cell takes in materials from 2. PINOCYTOSIS its external environment by engulfing them with its 3. RECEPTOR-MEDIATED ENDOCYTOSIS plasma membrane. This process involves the cell membrane folding around the substance to form a vesicle, which is then brought into the cell. Endocytosis is essential for the uptake of large molecules, particles, or even other cells that cannot pass through the cell membrane by passive transport. PHAGOCYTOSIS “CELL EATING” PINOCYTOSIS “CELL DRINKING” In this process, the cell engulfs large particles, such as bacteria or This type of endocytosis involves the intake of debris. The membrane surrounds the particle, forming a vesicle liquids and dissolved solutes. The cell membrane known as a phagosome, which is then internalized and typically forms small vesicles that capture extracellular digested by lysosomes. fluid and bring it into the cell. RECEPTOR-MEDIATED ENDOCYTOSIS This is a selective form of endocytosis where specific molecules, such as hormones or nutrients, bind to receptors on the cell surface. Once bound, the membrane invaginates and forms a vesicle that carries the bound molecules into the cell. This process allows the cell to take in specific substances in larger amounts. Exocytosis process by which cells expel materials from the cell into the external environment. In this process, vesicles containing substances (such as proteins, waste products, or neurotransmitters) fuse with the plasma membrane, releasing their contents outside the cell. Exocytosis is the reverse of endocytosis, where substances are brought into the cell. Steps in Exocytosis: 1. Vesicle formation: Inside the cell, materials are packaged into vesicles, typically formed by the Golgi apparatus or endosomes. 2. Vesicle transport: The vesicle is transported toward the plasma membrane. 3. Membrane fusion: The vesicle membrane fuses with the plasma membrane. 4. Release of contents: Once the vesicle merges with the membrane, its contents are released into the extracellular space. 1. Catabolism: The process of breaking down complex molecules METABOLISM into simpler ones, releasing energy in the process. For example, all the chemical reactions that occur within a cell during cellular respiration, glucose is broken down into carbon to maintain life. These reactions are responsible for dioxide and water, releasing energy stored in ATP (adenosine converting nutrients into energy, building cellular triphosphate), which the cell uses for various functions. structures, and breaking down waste products. Metabolism can be divided into two main categories: 2. Anabolism: The process of building up complex molecules from simpler ones. This requires energy and is essential for growth, repair, and the synthesis of essential molecules like proteins, nucleic acids, and lipids. An example is the synthesis of proteins from amino acids. ACTIVATION ENERGY The minimum amount of energy required to start a chemical reaction. It represents the energy barrier that must be overcome for reactants to be converted into products. In both biological and chemical reactions, activation energy is necessary to break the initial bonds between atoms in the reactants and form new ones in the products. Enzyme a biological catalyst that speeds up chemical reactions in living organisms without being consumed in the process. Enzymes are AcTIVE SITE typically proteins (though some RNA molecules can act as The specific region on the enzyme where the substrate enzymes, called ribozymes) that facilitate various metabolic binds. It is the part of the enzyme that directly reactions necessary for life, such as digestion, energy production, interacts with the substrate and facilitates the chemical DNA replication, and more. reaction. The active site has a unique shape and chemical HOW IT WORKS environment that fits the substrate like a “lock and 1. Substrate binding: The substrate binds to the key,” ensuring that only the correct substrate can bind and be catalyzed. active site of the enzyme, forming an enzyme-substrate complex. SUBSTRATE 2. Catalysis: Once bound, the enzyme facilitates the The specific reactant molecule that an enzyme acts conversion of the substrate into products by lowering the upon in a chemical reaction. During an enzymatic activation energy required for the reaction. reaction, the substrate binds to the enzyme’s active 3. Product release: After the reaction occurs, the site, forming an enzyme-substrate complex, which allows the enzyme to catalyze the conversion of the products are released from the active site, and the enzyme substrate into products. is free to catalyze another reaction. ENZYME INHIBITOR a molecule that binds to an enzyme and decreases its activity, either by blocking the enzyme’s active site or by altering its shape. Enzyme inhibitors prevent the enzyme from catalyzing its reaction with the substrate, effectively slowing down or stopping the reaction. CELLULAR RESPIRATION 1. GLYCOLYSIS 3 MAIN TYPES a biochemical process in which cells convert glucose and 2. CITRIC ACID CYCLE oxygen into energy (in the form of ATP), carbon dioxide, 3. ELECTRON TRANSPORT CHAIN AND and water. This process is essential for producing the OXIDATIVE PHOSPHORYLATION energy required for various cellular activities, such as growth, repair, and maintenance of cellular functions. f C hao + 6 O To 6 CO2 oct + 6 H O +f ATP Glucose Oxygen Carbon dioxide Water Energy OXIDATION Loss of electrons Loss of energy Gain of electrons REDUCTION Gain in energy and H+ GLYCOLYSIS ANAEROBIC AEROBIC first stage of cellular respiration, where one glucose molecule (a Does NOT use oxygen USES Oxygen six-carbon sugar) is broken down into two molecules of pyruvate (a three-carbon compound). It occurs in the cytoplasm and does not require oxygen, making it an anaerobic process. Glycolysis consists of ten steps, divided into two phases: the ENERGY ENERGY REQUIRING PHASE REQUIRING phase and the ENERGY RELEASING phase. STEPS 1-5 In this phase, energy is produced in In this phase, the cell uses energy in the form of ENERGY RELEASING PHASE the form of ATP and NADH. ATP to prepare glucose for breakdown STEPS 6-10 Step 1: Phosphorylation of Glucose Enzyme: Hexokinase Step 6: Oxidation and Phosphorylation of G3P Process: A phosphate group from ATP is added to glucose, forming glucose-6-phosphate. Enzyme: Glyceraldehyde-3-phosphate dehydrogenase Energy Use: 1 ATP is used. Process: Each G3P is oxidized, transferring electrons to NAD⁺ to form NADH. A phosphate group is also added Step 2: Isomerization of Glucose-6-Phosphate to G3P, forming 1,3-bisphosphoglycerate. Energy Production: 2 NADH molecules are produced (one for each G3P). Enzyme: Phosphoglucose isomerase Step 7: Transfer of Phosphate to ADP Process: Glucose-6-phosphate is rearranged into fructose-6-phosphate. Enzyme: Phosphoglycerate kinase Step 3: Phosphorylation of Fructose-6-Phosphate Process: A phosphate group from 1,3-bisphosphoglycerate is transferred to ADP, forming ATP and 3- Enzyme: Phosphofructokinase phosphoglycerate. Process: Another phosphate group from ATP is added to fructose-6-phosphate, forming Energy Production: 2 ATP molecules are produced (one per G3P). fructose-1,6-bisphosphate. Step 8: Isomerization of 3-Phosphoglycerat Energy Use: 1 ATP is used. Enzyme: Phosphoglycerate mutase Step 4: Cleavage of Fructose-1,6-Bisphosphate Process: 3-phosphoglycerate is rearranged into 2-phosphoglycerate. Enzyme: Aldolase Step 9: Dehydration of 2-Phosphoglycerate Process: Fructose-1,6-bisphosphate is split into two three-carbon molecules: Enzyme: Enolase glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP). Step 5: Isomerization of DHAP Process: Water is removed from 2-phosphoglycerate, forming phosphoenolpyruvate (PEP). Enzyme: Triose phosphate isomerase Step 10: Transfer of Phosphate from PEP to ADP Process: DHAP is converted into G3P, so now there are two molecules of G3P ready to enter Enzyme: Pyruvate kinase the energy payoff phase. Process: The phosphate group from PEP is transferred to ADP, forming ATP and pyruvate. Energy Production: 2 ATP molecules are produced (one per G3P). GLYCOLYSIS SUMMARY Glucose is split into two molecules of pyruvate. Energy use: 2 ATP are consumed during the energy investment phase. Energy production: 4 ATP and 2 NADH are produced in the energy payoff phase. Net gain: 2 ATP (since 4 ATP are produced, but 2 are used) and 2 NADH. CITRIC ACID CYCLE C the second stage of cellular respiration, where the breakdown of glucose continues. Here are the simplified key points: 1. Starts with Acetyl-CoA: The cycle begins when acetyl-CoA (from glucose breakdown) combines with a molecule called oxaloacetate to form citrate. 2. Produces Energy Carriers: During the cycle, energy is captured by producing NADH and FADH₂, which are used later to make a lot of ATP. 3. Releases Carbon Dioxide: Two molecules of CO₂ are released as waste during the process. 4. Makes a Small Amount of ATP: One molecule of ATP (or GTP) is made directly in the cycle. 5. Cycle Repeats: Oxaloacetate is regenerated at the end, so the cycle can start again with a new acetyl-CoA. Outputs per cycle: 3 NADH 1 FADH₂ 1 ATP 2 CO₂ In short, the citric acid cycle breaks down acetyl-CoA to release energy carriers (NADH, FADH₂), a little ATP, and carbon dioxide. These carriers then go on to produce a lot of ATP in the next stage (electron transport chain). Study Guide Exam 3 By Kylee McKinney PHOTOSYNTHESIS Essential to all life on Earth,The process of converting light energy into glucose to power the cell. Equation: 6 CO + 6 H O + Light Energy C6 H O + 6 O 2 2 Stop 12 6 2 Location Primarily in the chloroplasts of plant cells The Process: Consists of two main stages: Light-DEPENDENT reactions And Light- INDEPENDENT reactions Light-Independent Reactions: The Calvin Cycle Takes place in the STROMA of the chloroplasts, This phase uses ATP and NADPH generated from the light-dependent Light-Dependent Reactions: reactions to convert Carbon Dioxide into Glucose and other These occur in the THYLAKOID membranes of the Carbohydrates Each process contains the chloroplasts and require SUNLIGHT. Water is split, electron and oxygen is released as a byproduct. This stage transport chain also produces energy carries ATP and NADPH Important Structures: STroma - Liquid filled space surrounding the granum Stomata - Small regulated openings where gas exchange occurs Thylakoids - Stacked, disc-shaped sacs (Inside these sacs is a pigment called Chlorophyll) Pigment - molecule that absorbs light Chloroplasts - Organelle where photosynthesis occurs in the cell Photosystems - A multi protein complex, this is where the actual steps to convert light energy into chemical energy takes place. (Two types photosystem 1 and photosystem 11) The regulated sequence of The Cell Cycle events that occurs between one cell division and the next Three Phases Interphase (G1, S and G2) - 90% of time spent at this stage Nuclear Division (Mitosis) - 10% of time spent here Cell Division (Cytokinesis) 1. Interphase Growth period for cell. Increases size and mass and carries out normal cellular functions. G1 + S + G2 Phases of Interphase G1 phase - a signal is received telling the cell to divide again. This starts the stage of the cycle where DNA Replicates S phase - This starts the stage of the cycle where DNA Replicates,. (Resulting in each chromosome consisting of two identical sister CHROMATIDS. Relatively short phase, S stands for Synthesis of DNA G2 phase - During this phase the cell continues to grow and the new DNA that has been synthesized is checked for any errors. 2. Nuclear Division Production of tubulin protein which is used to make M Phase (Mitosis) microtubules for the mitosis spindle. Mitosis - Process of nuclear division by which 2 Genetically IDENTICAL daughter cells are Mitosis Step 1: Prophase produced that are identical do the parent cell. Consists of 4 main stages 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase Mitosis Step 2: Metaphase Important Terms of Cell Division Gametes - Sperm or Egg cells that consist of 23 chromosomes each Diploid - two matched sets of chromosomes, one set from each biological parent. (2n) Haploid - gametes are haploids because they only have 23 chromosomes each instead of the normal 46 (1n) Homologous Chromosomes - Chromosomes that share identical genes as each other Genes - Physical and functional unit of heredity. Locus - Position of a gene on a chromosome Sister Chromatids - the copied chromosomal pair, they are Mitosis Step 3: Anaphase identical to each other and created when the DNA is replicated. Centromere - region at which sister chromatids are bound together Mitosis Step 4: Telophase 3. Cytokinesis Follows the M Phase Once the Nucleus has divided into two genetically IDENTICAL nuclei, the WHOLE cell divides and one nucleus moves into each cell. This creates TWO GENETICALLY IDENTICAL DAUGHTER CELLS Regulation of Cell Cycle The cell cycle is regulated by cyclins, a group of proteins, and kinases, which are enzymes. There are four types of cyclins (D, E, A, and B), and their levels fluctuate throughout the cycle. Each cyclin plays a specific role, triggering critical events needed for the cell cycle to progress. Errors in the Cell Cycle When genes that regulate the cell cycle are mutated, it can lead to either cancer (uncontrolled cell growth) or apoptosis (programmed cell death). Apoptosis Apoptosis is the body’s way of eliminating cells that are too damaged to repair. This process helps prevent cancer by ensuring damaged cells don’t divide. It is triggered by a series of biochemical events where enzymes break down the cell’s components, ultimately destroying the cell. Cancer Cancer typically involves mutations in two types of genes: Proto-oncogenes: These genes normally produce proteins that encourage healthy cell division. When mutated, they become oncogenes, leading to: Overproduction of proteins or proteins that are always active Uncontrolled cell division, which may cause cancer Tumor suppressor genes: These genes produce proteins that either slow down cell division or trigger apoptosis if DNA is damaged. Mutations in these genes can result in: Reduced or inactive proteins Loss of control over cell division, increasing the risk of cancer Meiosis Produces haploid cells called gametes. These gametes are use din Sexual Reproduction. There are 2 divisions that happen in Meiosis. Importance of Meiosis and Genetic Diversity Two mechanisms that increase the genetic diversity of gametes are: 1. Crossing over 2. Independent Assortment Crossing Over Independent Assortment The process by which nonsister chromatids exchange The production of DIFFERENT combos of alleles alleles in daughter cells due to the PROCESS: RANDOM alignment of homologous pairs 1. During Meiosis 1 homologous chromosomes pair up and along the equator of the spindle during are very close to each other. METAPHASE 1 2. When the chromosomes line up at the center In prophase 1 homologous chromosomes during metaphase, they cross over and get pair up and in metaphase 1 they are entangled. pulled towards the equator of the 3. These crossing points are called CHIASMATA spindle 4. Stress is put on the chromosomes, causing them to The chromosome pairs can be arranged break and then rejoin with the other chromosomes with either one on top, this is they are lined up with. completely random and the orientation 5. This trading of alleles can result in a new of each pair is independent of the other combination of alleles on the two chromosomes. pair. The Stages of Meiosis 1 and 11 Meiosis 1 1. Prophase 1 - DNA condenses and becomes visible chromosomes, the homologous chromosomes become two sister chromatids joined by the centromere. This is when crossing over occurs. The centrioles migrate to the opposite poles and the spindle is formed. 2. Metaphase 1 - the pairs of homologous chromosomes line up at the equator of the spindle, spindle fibers attach to centromeres on chromosome pairs. This is when independent assortment occurs. 3. Anaphase 1 - the homologous chromosome pairs are separated as the microtubules pull whole chromosomes to the opposite poles. The centromeres DO NOT divide. 4. Telophase 1 - chromosomes arrive at opposite poles and spindle fibers begin to break down. Nuclear Envelopes form around the two groups of chromosomes and nuclei reform. 5. Cytokinesis - This is when the division of cytoplasm occurs. In ANIMAL cells, the cell surface membrane pinches inwards creating a CLEAVAGE FURROW in the middle of the cell which contracts and Meiosis 1 ends in 2 Haploid cells divides the cells. In PLANT cells, the two cells are separated by a cell plate, that will later become the new cell walls. Meiosis 11 Comparison of Mitosis and Meiosis Inheritance and heredity Mendel - Gregor Mendel was an Austrian monk who lived in a monastery in the mid-19th century. While tending the monastery gardens, he conducted experiments with pea plants to study how traits were passed down through generations. Because of his groundbreaking work on inheritance, he is known as the Father of Genetics. Mendel used a method called artificial pollination, transferring pollen from one plant to another by hand. This allowed him to control which plants reproduced and ensured accurate results. He collected seeds from these plants, grew them under ideal conditions, and observed their traits. Mendel also crossbred the offspring to see how traits appeared in future generations. His research focused on traits like plant height, flower color, and the texture of seed coats. Mendel examined how height in pea plants is inherited in this hybrid. Mendel discovered that traits were passed down in a predictable way. Every pea plant in the first generation shared a trait with one of the parent plants, such as being tall. In a 3:1 ratio, the second-generation offspring plants possessed traits from both parent plants. Mendel had unknowingly found genes, which he called "units of inheritance." Additionally, he found that certain genes are recessive and some are dominant. Alleles are distinct variations of a single gene. Gregor Mendel's rules of inheritance were developed based on these discoveries. Karyotype Final Study Guide Genetics: The study of heredity and variations in organisms. Recessive Genetic disorders: Conditions that occur when an individual inherits two copies of a mutated gene, one from each parent. For a recessive disorder to manifest phenotypically, the individual must be homozygous for the recessive allele (rr). If they inherit one normal allele and one mutated allele (Rr) they typically do not show symptoms of the disorder but can pass the mutated allele to their offspring. Sickle Cell Anemia vs. Malaria Sickle cell anemia and malaria are linked through natural selection. Sickle cell disease is caused by changes in the hemoglobin gene, leading to abnormal red blood cells and health problems. Carriers of the sickle cell trait usually have no symptoms but are better protected against malaria. In certain parts of Africa and southern Italy, where malaria is common, more people carry the sickle cell trait because carriers are less likely to die from malaria than those with normal hemoglobin. Dominant Genetic Disorders Dominant disorders manifest even if an individual only has one copy of the mutated gene (just one parent needs to contribute the dominant allele. EXAMPLE: Huntingtons disease Incomplete Dominance A genetic situation where the traits of mixed individuals show a middle expression between those two parent types. Unlike complete dominance where one gene completely hides the other, both genes in incomplete dominance influence appearance, leading to a blend. Co-dominance Co-dominance is a genetic concept where bth alleles in an organism express their traits equally. Both traits are displayed distinctly. EXAMPLE: if one flower parent has red petals and the other has white, the offspring can have both red and white petals. Polygenic Inheritance When many genes work together to affect one trait, creating a range of different appearances. These genes can show many different forms, like skin tone or height. Linked Genes Genes located closely together on the same chromosome and are often inherited together during meiosis. Experiments like Mendel’s show unexpected ratios because linked genes do not assort independently. If two genes are very close, they are less likely to be separated during crossover, leading to fewer offspring with new trait combinations compared to unlinked genes. DNA Structure RNA Structure Deoxyribonucleic acid, has a double helix shape with Ribonucleic acid, typically single-stranded and two strands that run in opposite directions. Each consists of a sequence of nucleotides. Each strand consists of nucleotides, made up of nucleotide is made up of a ribose sugar, a deoxyribose sugar, phosphate group, and one of phosphate group and one of the four nitrogen four nitrogen bases: ADENINE (A), THYMINE (T), bases: ADENINE (A), URACIL (U), CYTOSINE (C), OR CYTOSINE (C), OR GUANINE (G). GUANINE (G) A pairs with T A pairs with U C pairs with G C pairs with G DNA Directionality DNA Replication The two strands run in opposite directions, Replication occurs in preparation for mitosis during the which is called anti parallel orientation. One S phase of the cell cycle. The hydrogen bonds between the strands goes to 5’ to 3’ and the other strand base pairs on the two strands are broken which causes goes from 3’ to 5’ the DNS helix to unzip to form two single polynucleotide DNA strands. Catalyzed by the enzyme DNA HELICASE Each of these strands then acts as a template for the formation of a new strand. The original strand and the new strand combine to create a new DNA molecule. Leading Strands vs Lagging Strands 2 types of DNA strands formed during replication. The LEADING strand is created continuously towards the replication fork, moving from 3’ to 5’ end of the template. DNA polymerase works at the 3’ end, producing new DNA smoothly. DNA Polymerase The LAGGING strand is made in short segments called An essential enzyme in DNA replication that creates new DNA Okazaki fragments, moving away from the fork. As the DNA strands. It combines nucleotides by linking their sugars and unwinds, DNA polymerase builds these fragments in the opposite directions, needing to start and stop. Afterward phosphate groups, forming the DNA backbone. It attaches to the DNA ligase connects them to form a continuous strand. DNA template and builds new strand from the 5’ to 3’ end. DNA polymerase forms the leading strand continuously and the lagging strand in short segments called Okazaki fragments, which are later joined by DNA ligase. Polymerase Proofreading Central Dogma A Correction mechanism performed by DNA Explains the flow of genetic information and RNA polymerases during the synthesis of within a biological system. This describes the DNA and RNA. These enzymes check for process of DNA being transcribed into RNA. errors as they add nucleotides to the DNA encodes instructions for building growing strand and can remove incorrectly proteins. paired nucleotides before continuing synthesis. Insertion Deletion Involves the removal of Mismatch Repair Refers to the addition of one or Mutation one or more nucleotide A cellular mechanism more nucleotide bases into the A change in the DNA sequence that can that corrects errors DNA sequence. Shift the reading bases from the DNA affect how a gene works. They can in DNA that occur frame potentially altering the strand, which can lead happen for many reasons. during replication. resulting proteins structure to a shift in the reading EXAMPLE: Cystic Fibrosis or Sickle cell and function. frame. Protein Synthesis The process by which cells create proteins from genetic information in DNA and occurs in TWO main stages: Transcription and Translation 1. Transcription A Specific DNA segment unwinds and the RNA polymerase Promoter synthesizes a single-stranded mRNA by pairing RNA A Specific region of DNA that initiates the transcription of a gene. It is a nucleotides with exposed DNA bases (Uracil replaces binding site for RNA polymerase. They Thymine). The mRNA then exits the nucleus to carry the determine when and how much of a gene genetic code to ribosomes for translation will be transcribed. 2. Translation Ribosomes in the cytoplasm read the mRNA while transfer RNA (tRNA) brings corresponding amino acids, matching them to mRNA codons via anticodons. Ribosomes facilitate the assembly of amino acids into proteins as specified by the mRNA. Translation in Eukaryotes is the process where messenger rNA (mRNA) is translated into a sequence of amino acids to form a protein. Occurs in the cytoplasm after the mRNA exits the nucleus. The mRNA attaches to a ribosome, which is made of ribosomal RNA (mRNA) and proteins, and initiates the translation at a start codon (AUG) that signals the beginning of protein synthesis. During this process, transfer RNA (tRNA) brings specific amino acids to the ribosome. Each tRNA has an ANTICODON that pairs with a complementary codon on the mRNA. The ribosomes facilitates the formation of peptide bonds between amino acids, creating a polypeptide chain. This continues until a STOP CODON on the mRNA is reached. Then the completed amino acid chain folds into a functional protein.