chapter-3-cell-and-its-structures.pdf

Chapter 03 Lecture Outline See separate PowerPoint slides for all figures and tables pre- inserted into PowerPoint without notes. Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 ...

Chapter 03 Lecture Outline See separate PowerPoint slides for all figures and tables pre- inserted into PowerPoint without notes. Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1  2 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Functions Basic unit of life Synthesis of molecules Communication Cell metabolism and energy release Reproduction and inheritance (DNA) 3 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cell Structure Organelles: - specialized structures in cells that perform specific functions - Ex. Nucleus, mitochondria, ribosomes, etc. Cytoplasm: jelly-like substance that holds organelles 4 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cell Membrane What is it? outermost component of a cell Functions: - selective barrier - encloses cytoplasm Extracellular: material outside cell Intracellular: material inside cell 6 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Structure of Cell Membrane Called Fluid Mosaic Model Made of phospholipids and proteins Phospholipids form a double layer or bilayer Phospholipids contain 2 regions: polar and nonpolar 7 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Polar regions: - “heads” - hydrophilic (H2O loving) - exposed to H2O Nonpolar regions: - “tails” - hydrophobic (H2O fearing) - away from H2O 8 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 2.14b 9 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 3.2a Copyright © McGraw-Hill Education. Permission required for reproduction or display.  11 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Movement through Cell Membrane Cell membrane selectively determines what can pass in and out of the cell. Enzymes, glycogen, and potassium are found in higher concentrations INSIDE the cell. Sodium, calcium, and chloride are found in higher concentrations OUTSIDE the cell. 12 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Ways molecules Pass through Cell Membrane 1. Directly through (diffusion): O2 and CO2 (small molecules) 2. Membrane channels: - proteins that extend from one side of cell membrane to other - size, shape, and charge (+/-) determine what can go through - Ex. Na+ passes through Na+ channels 13 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. 3. Carrier molecules: - bind to molecules, transport them across, and drop them off - Ex. glucose 4. Vesicles: - can transport a variety of materials - fuse with cell membrane 15 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Copyright © McGraw-Hill Education. Permission required for reproduction or display. Na+ Please update to 9e copyright K+ leak K+ channel Gated Na+ Gated Na+ (always open) channel (closed) channel (open) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Diffusion What is it? movement of molecules from areas of high to low concentration Solution: solid, liquid, or gas that contains one or more solutes Solute: substance added to solvent that dissolves Solvent: substance such as H2O that solute is being added to Ex. Add salt to H2O. H2O =solvent, salt=solute, mixture=solution 18 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Concentration gradient: - measures conc. difference at 2 points - greater the distance the faster the solute will travel Filtration: movement of fluid through a partition with holes 20 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Mediated Transport Mechanisms Facilitated diffusion: - diffusion with aid of a carrier molecule - requires no ATP Active transport: - moves substances from low to high conc. - requires ATP - Ex. Sodium-potassium pump 21 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Copyright © McGraw-Hill Education. Permission required for reproduction or display. Na+–K+ pump 1 Three sodium ions (Na+) and adenosine triphosphate (ATP) bind to the sodium–potassium (Na+–K+) pump. Na+ ATP 1 Na+–K+ pump changes shape Na+ (requires energy). K+ 2 The ATP breaks down to adenosine diphosphate (ADP) and a phosphate (P) and releases energy. That energy is used to power the shape change in the Na+–K+ pump. P 2 ADP 3 The Na+–K+ pump changes shape, and the Na+ are 3 transported across the membrane and into the Na+ K+ 4 extracellular fluid. 4 Two potassium ions (K+) bind to the Na+–K+ pump. 5 5 The phosphate is released from the Na+–K+ pump P binding site. Na+–K+ pump resumes original shape. 6 The Na+–K+ pump changes shape, transporting K+ across the membrane and into the cytoplasm. The Na+–K+ pump can again bind to Na+ and ATP. 6 K+ Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Copyright © McGraw-Hill Education. Permission required for reproduction or display. Carrier molecule Na+–K+ pump Na+ 2 Glucose 1 K+ Na+ Glucose 1 A Na+–K+ pump maintains a concentration of Na+ that is higher outside the cell than inside. 2 Na+ move back into the cell by a carrier molecule that also moves glucose. The concentration gradient for Na+ provides the energy required to move glucose, by cotransport, against its concentration gradient. 24 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Osmosis What is it? diffusion of water across a cell membrane Osmotic pressure: force required to prevent movement of water across cell membrane 25 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Copyright © McGraw-Hill Education. Permission required for reproduction or display. * Because the tube contains salt ions (green and pink spheres) as well as water molecules (blue spheres), there is proportionately less water in the tube than in the beaker, which contains only water. The water molecules diffuse with their concentration gradient into the tube (blue arrows). Because the salt ions cannot leave the tube, the total fluid volume inside the tube increases, and fluid moves up the glass tube (black arrow) as a result of osmosis. 3% salt solution Weight Selectively of water permeable Salt solution column membrane rising The solution stops rising when the weight of the water column prevents further movement of water into the tube by osmosis. Distilled water Water Osmosis 1 The end of a tube 2 The tube is immersed in 3 Water moves by osmosis into containing a 3% salt distilled water. Water the tube until the weight of solution (green) is closed moves into the tube by the column of water in the at one end with a osmosis (see inset above*). tube (hydrostatic pressure) selectively permeable The concentration of salt in prevents further movement membrane, which allows the tube decreases as of water into the tube. The water molecules to pass water rises in the tube hydrostatic pressure that through but retains the (lighter green color ). prevents net movement of salt ions within the tube. water into the tube is equal to the osmotic pressure of the solution in the tube. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Types of Osmotic Solutions Hypotonic solution: - lower conc. of solutes outside cell - higher conc. of H2O outside cell - H2O moves into cell - lysis (burst) Hypertonic solution: - higher conc. of solutes outside cell - higher conc. H2O inside cell - H2O moves out - crenation (shrinks) 27 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Isotonic solution: - equal conc. of solutes - water doesn’t move - cell remains intact 28 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Endocytosis What is it? process that brings materials into cell using vesicles 2 types - Phagocytosis: cell eating (solid particles) - Pinocytosis: cell drinking (liquid particles) 30 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Exocytosis What is it? process that carries materials out of cell using vesicles 31 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  33 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cell Structures Cytoplasm Location: inside cell Characteristic: jelly-like fluid Function: give cell shape and hold organelles in place Nucleus Location: center of cell Characteristic: all cells contain nucleus at some point Function: houses DNA 35 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Nuclear envelope: Location: edge of nucleus Nuclear pores: Location: surface of nucleus Function: where materials pass in and out of nucleus 37 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Chromosome: Location: inside nucleus Characteristic: made of DNA and proteins Function: part of genetic makeup Chromatin: Location: inside nucleus Characteristic: loosely coiled chromosomes 39 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Nucleolus Location: in nucleus Function: produce ribosomes Ribosome Location: attached to RER or cytoplasm Function: produce proteins 41 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 Ribosomal proteins, produced in the cytoplasm, are transported through rRNA nuclear pores into the nucleolus. Nucleolus 2 rRNA, most of which is produced in the nucleolus, is assembled with ribosomal proteins to form small and large ribosomal 2 subunits. Nucleus 3 The small and large ribosomal subunits leave the nucleolus and the nucleus DNA through nuclear pores. (chromatin) 4 The small and large subunits, now in the Nuclear pore cytoplasm, combine with each other and with mRNA during protein synthesis. 3 Large ribosomal 1 unit Small Ribosomal ribosomal proteins from unit 4 cytoplasm mRNA Ribosome 42 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  RER (Rough Endoplasmic Reticulum) Location: cytoplasm Characteristic: membranes with ribosomes attached Function: site of protein synthesis SER (Smooth Endoplasmic Reticulum) Location: cytoplasm Characteristic: membranes with no ribosomes Function: site of lipid synthesis (Ex. Cholesterol) 43 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Golgi apparatus Location: cytoplasm Characteristic: closely, packed stacks of membranes Function: collect, sort, package, and distribute proteins and lipids Secretory vesicle Location: cytoplasm Function: distributes materials out of cell 45 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lysosome Location: cytoplasm Function: enzymes that digest foreign material Mitochondria Location: cytoplasm Characteristic: contains folds (cristae) Function: produces ATP 47 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cilia Location: cell surface Characteristic: many per cell Function: move materials across cell’s surface Flagella Location: cell surface Characteristic: 1 per cell Function: move cell, Ex. sperm 50 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Microvilli Location: cell surface Characteristic: shorter than cilia Function: increase surface area 51 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cytoskeleton What is it? - cell’s framework - made of proteins Functions: - provide support - hold organelles in place - enable cell to change shape 52 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Types of Cytoskeleton Microtubules: - largest diameter - provide structural support - form cilia and flagella Intermediate filaments: - medium diameter - maintain cell shape Microfilaments: - smallest diameter - involved in cell movement 53 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Copyright © McGraw-Hill Education. Permission required for reproduction or display. Centriole (in cross section) Centriole (in longitudinal section) Microtubule triplet TEM 60,000x (a) (b) (b): © Biology Media/Photo Researchers, Inc. 55 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Whole Cell Activity A cell’s characteristics are determine by the type of proteins produced Proteins’ function is determined by genetics Information in DNA provides the cell with a code for its cellular processes 56 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  DNA What is it? - double helix in nucleus - composed of nucleotides - contains 5 carbon sugar (deoxyribose, nitrogen base, phosphate 57 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Flow of Genetic Information Also called Central Dogma Occurs in three stages: – DNA replication – Transcription – Translation Copyright © McGraw-Hill Education. Permission required for reproduction or display.  DNA Replication Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Gene Expression What is it? - information in DNA directs protein synthesis - proteins provide code for gene expression - enzymes regulate chemical reactions - uses transcription and translation 61 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Transcription What is it? - process by which DNA is “read” - occurs in ribosomes - produces mRNA (messenger RNA) - mRNA contains codons - codons: set of 3 nucleotide bases that code for a particular amino acid 63 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Translation What is it? - process by mRNA is converted into amino acids (polypeptides) - produces proteins - codons pair with anticodons - anticodons: 3 nucleotide bases carried by tRNA 65 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cell Division What is it? - formation of 2 daughter cells from a single parent cell - uses mitosis and meiosis - each cell (except sperm and egg) contains 46 chromosomes (diploid) - sperm and egg contain 23 chromosomes 67 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Mitosis What is it? - cell division that occurs in all cells except sex cells - forms 2 daughter cells 68 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Components of Mitosis Chromatid: 2 strands of chromosomes that are genetically identical Centromere: where 2 chromatids are connected Centrioles: small organelle composed of 9 triplets 69 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Stages in Mitosis 1. Interphase: - time between cell divisions - DNA is in strands (chromatin) - DNA replication occurs 2. Prophase: - chromatin condenses into chromosomes - centrioles move to opposite ends 71 Copyright © McGraw-Hill Education. Permission required for reproduction or display. 3. Metaphase: chromosomes align 4. Anaphase: - chromatids separate to form 2 sets of chromosomes - chromosomes move towards centrioles 5. Telophase: - chromosomes disperse - nuclear envelopes and nucleoli form - cytoplasm divides to form 2 cells 72 Copyright © McGraw-Hill Education. 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