Chapter 4 and 5 Lecture Notes
Chapter 4 and 5 Lecture Notes 10120
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This 10 page Class Notes was uploaded by Hannah Kennedy on Sunday February 7, 2016. The Class Notes belongs to 10120 at Kent State University taught by Professor Grampa in Spring 2016. Since its upload, it has received 72 views. For similar materials see Biological Foundations Honors in Biological Sciences at Kent State University.
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Copyright: © Hannah Kennedy, Kent State University 1 CHAPTER 4 1. Cell theory = states that all organisms are made of one or more cells, and the life processes of metabolism and heredity occur within these cells ex a. Cells are the smallest living things and the smallest things that can survive on their own b. Arise only via division of a previously existing cell i. Ex = we come from a sperm and egg cell c. Limited in size due to being only able to handle so much and retain a certain amount of volume for efficient and optimal function d. Similarities of all cells i. Centrally located genetic material 1. Eukaryotes: DNA in a nuclear envelope 2. Prokaryotes: DNA in a nucleoid ii. Cytoplasm = semifluid that fills the interior of the cell and helps to maintain the shape iii. Plasma membrane = component of the cell that makes up the external boundary of the cell, contains everything inside, and controls what can go in and out 1. Our plasma membranes are made of a phospholipid bilayer 2. Prokaryotic Cells (singlecelled organisms i.e. bacteria and archae) a. Have ribosomes and a nucleoid region to contain DNA i. Ribosomes make proteins ii. Have a cytoskeleton for struction iii. Flagella = taillike extensions for motility that some prokaryotes have 1. Human cell with flagella = sperm b. Organization from inside to outside: Plasma membrane cell wall capsule c. Have a tough and rigid cell wall i. Provides protection, shape, and is the target of antibiotics 1. Antibiotics function in a way that targets the differences between our cells and bacteria i.e. the cell wall of the prokaryotic cell ii. Peptidoglycan = a carbohydrate that makes up the cell wall 3. Eukaryotic Cells (i.e. animals, plants, and fungi) a. Contain a nucleus to store DNA with other organelles to specify functions to certains regions (ER, golgi, and lisosomes) that are compartmentalized and surrounded by membranes i. Cells look different depending on their different specialization due to structural and organizational variations 1. Ex = red blood cells (RBCs) get rid of their nucleus to be able to carry more oxygen (O )2more efficiently b. Chromosomes = consolidated and compact DNA Copyright: © Hannah Kennedy, Kent State University 2 i. Formed from DNA winding around proteins ii. Chromatin = large mass of chromosomes that they organize themselves into; towards the center of the cell c. Nuclear envelope = a doublelayer membrane that surrounds the nucleus; made of phospholipids i. Nuclear pores = small holes in the nuclear envelope that allows small molecules to enter and exit the nucleus 1. Things that enter: nucleotides, enzymes, transcription factors and hormones, building blocks of DNA 2. Things that exit: mRNA (messenger RNA) d. Nucleolus = region within the nucleus where ribosomes are produced i. Ribosomes = small structures that can read and interpret mRNA to make proteins (2 subunits—large and small) 1. Add the correct amino acid to the polypeptide chain after interpreting mRNA 2. Found freefloating within cytoplasm or attached to the ER e. Endoplasmic reticulum = ER = structure located right outside the nucleus that has extensive membrane folding and which synthesizes proteins, lipids, and carbohydrates (2 kinds) i. Rough ER = ER that is studded with ribosomes and is the site of protein synthesis; makes slight changes to the protein being made 1. Closer to the nucleus than the smooth ER 2. Makes “rough draft” of the protein ii. Smooth ER = ER that has no ribosomes and is the site of lipid and carbohydrate synthesis; also used for Ca storage and is used to detoxify 1. These kinds of ER are continuous f. Golgi apparatus = golgi = structure located next to the ER that processes and packages synthesized molecules of which are received within vesicles (where the proteins are edited: things are added/rearranged/removed and where they turn into 2°, 3°, or 4° structures) i. Cisternae = stacks of membrane within the golgi ii. Vesicles fuse with the golgi membrane on the cis face iii. As the golgi makes changes to the molecules, they are sent from one cisterna to the next via vesicles and eventually reach the trans face (motor proteins assist in this process) 1. Trans face is closer to the plasma membrane of the cell therefore we are moving outward 2. The molecule is then either released from the cell via exocytosis or is remains within the cell g. Lysosomes = structures that bud off of the golgi and that contain digestive enzymes of which help break down anything harmful to the cell, recycle cell components (unneeded organelles) Copyright: © Hannah Kennedy, Kent State University 3 i. These can be found in the liver to help with detoxifying alcohol, toxins, and meds ii. Disorder that results from loss of function of lysosomal enzymes: Tay Sachs iii. Have lipid bilayer h. Peroxisomes = stronger versions of lysosomes that contain oxidative enzymes and that make H O 2s2a byproduct (of which is broken down to water and oxygen) i. Mitochondria = structure that makes ATP from glucose and thus provides the cell with energy; divide as the cell divides and contains their own DNA different from the DNA in our nucleus (2 membranes separated by intermembrane space) i. Outer membrane ii. Inner membrane 1. Cristae = folds that are covered with proteins for oxidative metabolism and ATP creation 2. Matrix = where DNA and ribosomes are found j. Chloroplasts = plants only; carry out photosynthesis and have own DNA i. Chlorophyll pigment = pigment within the chloroplast that give them their green color ii. 2 membranes 1. Inner membrane a. Stroma = fluid within the inner membere b. Grana = small, diskshaped stacked compartments i. Thylakoid = individual disk that contain photosynthetic pigments 2. Outer membrane k. Central vacuole = site for storage of proteins, pigments, and wastes (i.e. sugars, ions, water); i. Tonoplast = membrane; very large ii. maintains tonicity of the cell so it is able to expand and contract; responsible for cell growth l. cytoskeleton = cell component made of structural proteins to provide shape and structure in the cell (3 types of filaments that compose the cytoskeleton) i. actin filaments = microfilaments = long and thing filaments made of 2 stands of actin proteins (in 3° structure) to allow the contraction and crawling of the cell 1. involved in the division of the cell and in the creation of cell extensions 2. regularly polymerize = become longer and depolymerize = become shorter Copyright: © Hannah Kennedy, Kent State University 4 ii. microtubules = large hollow tubes that are made of individual tubulin proteins (13/ring) and are involved in cell division and endocytosis 1. regularly polymerize and depolymerize iii. intermediate filaments = tough, fibrous proteins that provide cell stability 1. ex = keratin (found in hair and nails) m. extracellular matrix = ECM = protective layer on the outside surface of the cell that is made of glycoproteins and collagen for strength; contains elastin for flexibility i. integrins = proteins that span the plasma membrane and which anchor the cytoskeleton inside the cell to the ECM outside of the cell Plants Animals Central vacuole Vesicles = sacs that store various items; “bubbles” Vesicles = sacs that store various items; Cytoskeleton “bubbles” Cytoskeleton Mitochondria Chloroplasts Rough ER Nucleus Smooth ER Mitochondria Golgi cytoplasm Peroxisome Golgi Lysosome Rough ER Cytoplasm Smooth ER Nucleus Peroxisome Ribosomes Lysosome Extracellular matrix Plasmodesmata Cell wall 4. Symbiosis a. Examples of symbiotic relationships i. Termites eat wood and the microbes inside of them digest them to get food and also keep the termites alive 1. Mutualism = relationship in which both parties benefit ii. Bacteria in our large intestine help us liberate vitamins we can naturally digest and they get fed and a get an envmt to live in 1. Mutualism 5. Motor Proteins = proteins that use ATP as a source of energy to move materials throughout the cell (2 main kinds) a. Kinesin = motor protein that moves molecules towards the periphery of the cell Copyright: © Hannah Kennedy, Kent State University 5 b. Dynein = motor protein that moves molecules towards the interior of the cell i. Materials are loaded into vesicles and motor proteins bind to the vesicle and walk along skeleton to transport 6. Cell Movement a. As actin polymerizes, it extends the cell membrane outward and myosin helps by pulling the rest of the cell along i. Important in inflammation, clotting, wound healing, and cancer metastasis ii. Cells know to do this primarily when there’s a detectable stimulus (i.e. infection) that is harmful to the cell b. 2 extensions impt in cell movement i. Flagella = lets the cell propel itself in a fluid environment 1. 9+2 arrangement of microtubules of w hich slide past each other to allow the flagellum to move a. 9 doublets in a circle and a central pair 2. ex = e.coli ii. cilia = thin, hairlike extensions of a cell that are anchored to the plasma membrane to help move things past the cell 1. have a 9 + 2 arrangement of microtubules 2. ex = trapped dirt in mucus is moved by cilia up the throat to get it out a. 2 situations in which cilia are helpless (mucus is too thick) i. Cystic fibrosis ii. Smoker’s cough 7. Plant cell walls = provide protection and support; made of cellulose (polymer of glucose) in plants and protists and made of chitin in fungi a. Primary cell wall = present in cell that are still growing i. Middle lamella = helps adhere the primary cell walls of other cells b. Secondary cell wall = present in cells that aren’t growing anymore and is found in between the primary cell wall and the plasma membrane; thick and rigid 8. Cellcell interactions a. Identifying proteins i. Glycolipids = identifying protein that determines blood type and is specific to tissue types ii. MHC proteins = allows the immune system to identify the cell as “self” rather than “foreign” 1. Arranged in a certain pattern unique to each individual of which every cell in that individual has (identical twins have similar MHC protein patterns) 2. Autoimmune diseases are diseases in which the immune system labels the cell as “foreign” Copyright: © Hannah Kennedy, Kent State University 6 b. Tissue = group of the same cells organized into a function unit (3 types) i. adhesive junctions = functional unit of which attaches the cell’s cytoskeleton to the ECM or to the cytoskeleton of another cell; some components are able to get through them (2 kinds) 1. cadherin = a cell adhesion molecule that passes through the plasma membrane and attaches externall to the cadherins on another cell; helps anchor two neighboring cell 2. desmosomes = adhesion molecules made of cadherins that anchor cells within a tissue and provide support against mechanical stress a. this is the reason cells are able to stay attached ii. tight/separate junctions = functional unit of which adheres adjacent cells and blocks off the space in between cells used for molecule passage; doesn’t allow component to get through them (ex = water and bacteria cannot get through skin) 1. tight junctions are found in vertebrates 2. separate junctions are found in vertebrates and invertebrates 3. if molecules want to pass in between cells now they need some sort of carrier iii. communicating junctions = functional units of which allow cell to communicate with each other through the passing of molecules and ions from one cell to the next 1. gap junctions = six individual proteins in tertiary structure of which for a tube (channel) in the plasma membrane of both cells to share nutrients, ions, and signals a. moves small molecules b. always present but not always open 2. plasmodesmata = plants only; only present where there are gaps in the cell wall; extensions of smooth ER and allow many molecules to pass through CHAPTER 5 1. Membranes a. Phospholipid bilayer = 2 layers of phospholipids that make up the plasma membranes of cells i. Amphipathic = characteristic of phospholipid bilayers that describes them as both polar (phosphate head group) and nonpolar (fatty acid tails) 1. Polar phosphate groups are oriented towards the exterior of the cell, as they are more attracted to water 2. Nonpolar fatty acid tails are oriented towards the interior of the cell as they are shielded from water Copyright: © Hannah Kennedy, Kent State University 7 ii. Fatty acids are packed together to be a solid and cholesterol keeps them from becoming a solid iii. They are both saturated (straight, single carbon bonds) and unsaturated (bent, carboncarbon double bonds) iv. Movement within a layer but little movement between layers 2. Membrane Proteins Membrane Protein Function Transmembrane protein span the plasma membrane; transportation and communication Interior protein network Maintain cell shape Cell surface markers Provide cell ID (ex = glycoproteins, glycolipids, EMC proteins) Transporter Create a channel through which molecules (ex = ions) pass into or out of the cell Enzymes Carry out chemical reactions (can either be inside of the cell or on the plasma membrane to catalyze a rxn) Cellsurface receptors Sites on which chemical messengers can bind and bring about rxns within the cell Celltocell adhesion proteins Bind adjacent cells together (cadherins and desmosomes) Attachments to the cytoskeleton Provide anchors for the cell a. Transmembrane domain = equal to each time in which the transmembrane protein spans the plasma membrane i. Amino acids composing these domains are composed of amphipathic amino acids ii. Pores = betabarrel = composed of beta sheets of which fold back and forth to create a cyclinder 3. Membrane Transport a. Passive transport = membrane transport that doesn’t require energy input and follows the molecule’s natural tendencies (natural tendencies include atoms spreading out from each other to avoid bumping into each other); movement of water is based on solute concentration Solution type Definition Hypertonic A solution that contains more solutes (and thus less water) than the cell; when a cell is placed in a hypertonic solution, water goes from the cell into the solution to achieve equilibrium creating cell shrinkage Hypotonic A solution that contains fewer solutes (and thus more water) than the cell; when a cell Copyright: © Hannah Kennedy, Kent State University 8 is placed in a hypotonic solution, water goes from the solution into the cell to achieve equilibrium creating the cell to possibly lyse Isotonic A solution in which the solute concentration is the same in the solution and the cell; water moves in an out of the cell at an equal rate Ways to maintain osmotic balance Definition Extrusion Contractile vacuoles collect water from the cell via a small pore opening and the vacuole contracting causing to force the water out isosmotic regulation A method in which humans and others animals tweak the concentrations of solutes in the blood so it’s the same as the cells Turgor pressure Pressure that presses the plasma membrane against the cell wall to maintain shape i. Diffusion = simple diffusion = passive transport in which there is movement from an area of high concentration to an area of low concentration; requires no ATP 1. Equilibrium = the goal of simple diffusion a. Ex = if there is an abundance of Na inside of the cell and not as much outside of the cell, diffusion acts to even this out 2. Molecules prefer to move to an area of lower concentration because there are fewer like charges and more space to lessen the collision of molecules 3. Examples of a molecule that can diffuse through the plasma membrane = cholesterol, lipids, steroids, O , and CO 2 2 a. All of these substances are nonpolar (gases can pass through because theyre inert) b. “like diffuses through like” ii. Facilitated diffusion = diffusion in which molecules get help from channels/carriers to diffuse through the plasma membrane; still no ATP required; ions move in the direction of high concentration to low concentration 1. “channel” can be thought of as a tunnel going through plasma membrane and when open, ions can move through Copyright: © Hannah Kennedy, Kent State University 9 2. “carrier” can be thought of as a door; changes shape so it faces the opposite side of the membrane when a molecule binds a. Movement can only happen if theyre unoccupied therefore diffusion slows when concentration is too high iii. Osmosis = the movement of water from an area of low solute concentration to an area of high solute concentration 1. Aquaporins = exclusive channels that water moves through to get across the membrane 2. Solutes = things being dissolved (sugar) 3. Solvents = things doing the dissolving (coffee) 4. This happens instead of diffusion when molecules cannot come through but water still can b. Active transport = energy (ATP) needs to be added to force molecules to move against their natural tendencies i. Primary active transport = active transport that forces a molecule to move from an area of low solute concentration to an area of high solute concentration; requires ATP (to act as a transporter) bc the solute is moving up its concentration gradient Transporter Function Uniporters Transports one molecule across the plasma membrane at the same time Symporters Transports 2 molecules across the plasma membrane at the same time in the same direction Antiporters Transports 2 molecules across the plasma membrane at the same time in the opposite direction (ex = sodium potassium pump) 1. sodiumpotassium pump = mechanism in which 3 Na + + molecules are pumped out of the cell while 2 K are pumped into the cell; equilibrium is not the goal a. this is used to correct leaky channels within animal cells that maintain a high Na concentration within the cells + and a high K concentration inside the cells ii. secondary active transport = transport in which ATP is used indirectly; ATP is requires at some point but is not used by the transporter moving the molecule (2 carriers) 1. 1 carrier moves molecules using ATP and creates a gradiesnt 2. Gradient is used to force other molecules to move to a lower concentration are a. Involved symporters or antiporters iii. Endocytosis = moving large amounts of molecules into a cell (3 methods) Copyright: © Hannah Kennedy, Kent State University 10 Type of endocytosis Function Phagocytosis Brings in small organisms or larger fragments by sending out extensions to wrap around the material and pull into the cell Pinocytosis Brings in smaller solutes or fluids by forming a pocket to contain the materials and pinching off to create a vesicle Receptormediated endocytosis Materials bind to receptors on the cell surface before being taken to the cell iv. Exocytosis = moving large amounts of molecules out of a cell 1. Materials being released are packed into vesicles of which fuse with the plasma membrane and release materials out of the cell