Chapter 03. Lecture and Animation Outline

Chapter 03 Lecture and Animation Outline To run the animations you must be in Slideshow View. Use the buttons on the animation to play, pause, and turn audio/text on or off. Please Note: Once you have used any of the animation functions (such as Play or Pause), you must first click on the slide s background before you can advance to the next slide. See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes and animations. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1

Basic unit of life Functions Synthesis of molecules Communication Cell metabolism and energy release Reproduction and inheritance (DNA) 2

Cell Structure Organelles: - specialized structures in cells that perform specific functions - Ex. Nucleus, mitochondria, ribosomes, etc. Cytoplasm: jelly-like substance that holds organelles 3

Mitochondrion Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cell membrane Cytoplasm Nuclear envelope Nucleolus Nucleus Ribosome Free ribosome Rough endoplasmic reticulum Smooth endoplasmic reticulum Lysosome Lysosome fusing with incoming phagocytic vesicle Phagocytic vesicle Centrosome Centrioles Golgi apparatus Peroxisome Microtubule Secretory vesicles Cilia Microvilli 4

What is it? Cell Membrane outermost component of a cell Functions: - selective barrier - encloses cytoplasm Extracellular: material outside cell Intracellular: material inside cell 5

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 6

Polar regions: - heads - hydrophilic (H 2 O loving) - exposed to H 2 O Nonpolar regions: - tails - hydrophobic (H 2 O fearing) - away from H 2 O 7

Figure 2.14b 8

Figure 3.2a

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. 11

Ways molecules Pass through Cell Membrane 1. Directly through (diffusion): O 2 and CO 2 (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 12

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 14

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Na + K + K + leak channel (always open) Gated Na + channel (closed) Gated Na + channel (open)

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 H 2 O that solute is being added to Ex. Add salt to H 2 O. H 2 O =solvent, salt=solute, mixture=solution 17

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 19

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 20

Copyright The McGraw-Hill Companies, Inc. 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 + 1 ATP 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. Na + K + pump changes shape (requires energy). Na + K + P 2 ADP 3 The Na + K + pump changes shape, and the Na + are transported across the membrane and into the extracellular fluid. Na + 3 K + 4 4 Two potassium ions (K + ) bind to the Na + K + pump. 5 The phosphate is released from the Na + K + pump binding site. 5 P 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. Na + K + pump resumes original shape. 6 K +

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Carrier molecule Na + K + pump 1 Na + 2 Glucose K + Na + Glucose 1 2 A Na + K + pump maintains a concentration of Na + that is higher outside the cell than inside. 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. 23

Osmosis What is it? diffusion of water across a cell membrane Osmotic pressure: force required to prevent movement of water across cell membrane 24

Copyright The McGraw-Hill Companies, Inc. 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 Selectively permeable membrane Salt solution rising Weight of water column 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 containing a 3% salt distilled water. Water solution (green) is closed moves into the tube by at one end with a osmosis (see inset above*). selectively permeable The concentration of salt in membrane, which allows the tube decreases as water molecules to pass water rises in the tube through but retains the (lighter green color ). salt ions within the tube. Water moves by osmosis into the tube until the weight of the column of water in the tube (hydrostatic pressure) prevents further movement of water into the tube. The hydrostatic pressure that prevents net movement of water into the tube is equal to the osmotic pressure of the solution in the tube.

Types of Osmotic Solutions Hypotonic solution: - lower conc. of solutes outside cell - higher conc. of H 2 O outside cell - H 2 O moves into cell - lysis (burst) Hypertonic solution: - higher conc. of solutes outside cell - higher conc. H 2 O inside cell - H 2 O moves out - crenation (shrinks) 26

Isotonic solution: - equal conc. of solutes - water doesn t move - cell remains intact 27

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What is it? Endocytosis process that brings materials into cell using vesicles 2 types - Phagocytosis: cell eating (solid particles) - Pinocytosis: cell drinking (liquid particles) 30

Exocytosis What is it? process that carries materials out of cell using vesicles 31

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Molecules to be transported Receptor molecules 1 1 Receptor molecules on the cell surface bind to molecules to be taken into the cell. Cell membrane 2 The receptors and the bound molecules are taken in to the cell as a vesicle is formed. 2 Vesicle 3 The vesicle membrane fuses and the vesicle separates from the cell membrane. 3 33

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 36

Nuclear envelope: Location: edge of nucleus Nuclear pores: Location: surface of nucleus Function: where materials pass in and out of nucleus 38

Figure 3.13a

Chromosome: Location: inside nucleus Characteristic: made of DNA and proteins Function: part of genetic makeup Chromatin: Location: inside nucleus Characteristic: loosely coiled chromosomes 40

Nucleolus Location: in nucleus Function: produce ribosomes Ribosome Location: attached to RER or cytoplasm Function: produce proteins 42

1 Ribosomal proteins, produced in the cytoplasm, are transported through nuclear pores into the nucleolus. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleolus rrna 2 rrna, most of which is produced in the nucleolus, is assembled with ribosomal proteins to form small and large ribosomal subunits. Nucleus 2 3 The small and large ribosomal subunits leave the nucleolus and the nucleus through nuclear pores. DNA (chromatin) 4 The small and large subunits, now in the cytoplasm, combine with each other and with mrna during protein synthesis. 3 Nuclear pore 1 Large ribosomal unit Ribosomal proteins from cytoplasm Small ribosomal unit 4 Ribosome mrna 43

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) 44

Figure 3.16

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 46

Lysosome Location: cytoplasm Function: enzymes that digest foreign material Mitochondria Location: cytoplasm Characteristic: contains folds (cristae) Function: produces ATP 48

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 51

Microvilli Location: cell surface Characteristic: shorter than cilia Function: increase surface area 52

Cytoskeleton What is it? - cell s framework - made of proteins Functions: - provide support - hold organelles in place - enable cell to change shape 53

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 54

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Centriole (in cross section) Microtubule triplet Centriole (in longitudinal section) (a) (b) (b): Biology Media/Photo Researchers, Inc. TEM 60,000x 56

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 57

DNA What is it? - double helix in nucleus - composed of nucleotides - contains 5 carbon sugar (deoxyribose, nitrogen base, phosphate 58

Flow of Genetic Information Also called Central Dogma Occurs in three stages: DNA replication Transcription Translation

DNA Replication

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 62

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 64

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 66

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 69

Mitosis What is it? - cell division that occurs in all cells except sex cells - forms 2 daughter cells 70

Chromatid: Components of Mitosis 2 strands of chromosomes that are genetically identical Centromere: where 2 chromatids are connected Centrioles: small organelle composed of 9 triplets 71

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 73

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 74