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BIOL 2401

BIOL 2401. Biol 2401 Fundamentals of Anatomy and Physiology Mrs. Willie Grant wgrant4@alamo.edu (210) 486-2370. An Introduction to Cells. Learning Outcomes 3-1 List the functions of the plasma membrane and the structural features that enable it to perform those functions.

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BIOL 2401

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  1. BIOL 2401 Biol 2401 Fundamentals of Anatomy and Physiology Mrs. Willie Grant wgrant4@alamo.edu (210) 486-2370

  2. An Introduction to Cells Learning Outcomes 3-1 List the functions of the plasma membrane and the structural features that enable it to perform those functions. 3-2 Describe the organelles of a typical cell, and indicate the specific functions of each. 3-3 Explain the functions of the cell nucleus and discuss the nature and importance of the genetic code. 3-4Summarize the role of DNA in protein synthesis, cell structure, and cell function. 3-5 Describe the processes of cellular diffusion and osmosis, and explain their role in physiological systems. 3-6 Describe carrier-mediated transport and vesicular transport mechanisms used by cells to facilitate the absorption or removal of specific substances. 3-7 Explain the origin and significance of the transmembrane potential. 3-8 Describe the stages of the cell life cycle, including mitosis, interphase, and cytokinesis, and explain their significance. 3-9 Discuss the regulation of the cell life cycle. 3-10 Discuss the relationship between cell division and cancer. 3-11 Define differentiation, and explain its importance.

  3. An Introduction to Cells Cell Theory Developed from Robert Hooke’s research (17th century) Cells are the building blocks of all plants and animals All cells come from the division of preexisting cells Cells are the smallest units that perform all vital physiological functions Each cell maintains homeostasis at the cellular level Sex Cells (Germ Cells) Reproductive cells: Male (sperm); Female (oocyte) Somatic Cells (Soma—body)

  4. An Introduction To Cells In our model cell, a _____________separates the cell contents, called the____________, from its surroundings. The cytoplasm can be subdivided into the____________a liquid, and intracellular structures collectively known as______________. Organelles are structures suspended within the cytosol that perform specific functions within the cell and can be further subdivided into membranous and non-membranous organelles. Cells are surrounded by a watery medium known as the______________.The extracellular fluid in most tissues is called_______________. The _____________ is usually the largest and most conspicuous structure in a cell.

  5. Organelles Cytosol Cytoplasm Nucleus Extracellular Fluid Plasma Membrane 1 List the three principle parts of a cell?

  6. Plasma Membrane Non-membranousMembranous Nucleus (no membrane) (membrane)

  7. 3-1 Plasma Membrane Functions of the Plasma Membrane Physical Isolation Barrier Regulation of Exchange with the Environment Ions and nutrients enter Wastes eliminated and cellular products released Sensitivity to the Environment Extracellular fluid composition Chemical signals Structural Support Anchors cells and tissues

  8. 3-1 Plasma Membrane Membrane Lipids Phospholipidbilayer Hydrophilic heads — toward watery environment, both sides Hydrophobic fatty-acid tails — inside membrane Barrier to ions and water — soluble compounds

  9. 3-1 Plasma Membrane Membrane Proteins Integral Proteins—within the membrane Peripheral Proteins—bound to inner or outer surface of membrane Anchoring Proteins (stabilizers)—attach to inside or outside structures Recognition Proteins (identifiers)—label cells as normal or abnormal Enzymes—catalyze reactions Receptor Proteins—bind and respond to ligands (ions, hormones) Carrier Proteins--transport specific solutes through membrane Channels--forms pathway across plasma membrane and regulate water flow and solutes through membrane)

  10. 3-1 Plasma Membrane Membrane Carbohydrates Proteoglycans, glycoproteins, and glycolipids Extend outside cell membrane Form sticky “sugar coat” layer (glycocalyx) Functions of the glycocalyx Lubrication and Protection Anchoring and Locomotion Specificity in Binding (receptors) Recognition (immune response)

  11. The Plasma Membrane 2 What is the glycocalyx?

  12. 3-2 Organelles and the Cytoplasm Cytoplasm (All materials inside the cell and outside the nucleus) Cytosol (intracellular fluid) Dissolved materials (Nutrients, ions, proteins, and waste products) High potassium/low sodium; High protein; High carbohydrate/low amino acid and fat Organelles Structures with specific functions Nonmembranous organelles—No membrane Direct contact with cytosol Include the cytoskeleton, microvilli, centrioles, cilia, ribosomes, and proteasomes Membranous organelles—Covered with plasma membrane Isolated from cytosol Include the endoplasmic reticulum (ER), the Golgi apparatus, lysosomes, peroxisomes, and mitochondria

  13. 3-2 Organelles and the Cytoplasm The Cytoskeleton Microfilaments — thin filaments composed of the protein actin Provide additional mechanical strength; pair with thick filaments of myosin in muscle movement Intermediate filaments — mid-sized between microfilaments and thick filaments; strengthen cell; maintain shape; stabilize organelles; stabilize cell position; durable collagen Microtubules — large, hollow tubes of tubulin protein Attach to centrosome(cytoplasm surrounding centrioles) Strengthen cell and anchor organelles; change cell shape; move vesicles within cell; form spindle apparatus

  14. 3-2 Organelles and the Cytoplasm Microvilli Increase surface area for absorption Attach to cytoskeleton Centrioles in the Centrosome Centrioles form spindle apparatus during cell division Centrosome cytoplasm surrounding centriole Cilia Small hair-like extensions Cilia move fluids across the cell surface 3 Which cytoskeleton component helps form the structure of centrioles, cilia, and flagella?

  15. 3-2 Organelles and the Cytoplasm Ribosomes Build polypeptides in protein synthesis Two types Free ribosomes (polysomes)in cytoplasm Manufacture proteins for cell Fixed ribosomesattached to ER Manufacture proteins for secretion Proteasomes Contain enzymes (proteases) Disassemble damaged proteins for recycling

  16. 3-2 Organelles and the Cytoplasm Endoplasmic Reticulum (ER) Endo- = within, plasm = cytoplasm, reticulum= network Cisternae are storage chambers within membranes Functions Synthesis of proteins, carbohydrates, and lipids Storage of synthesized molecules and materials Transport of materials within the ER Detoxification of drugs or toxins

  17. 3-2 Organelles and the Cytoplasm Endoplasmic Reticulum (ER) Smooth endoplasmic reticulum (SER) No ribosomes attached Synthesizes lipids and carbohydrates Phospholipids and cholesterol (membranes) Steroid hormones (reproductive system) Glycerides (storage in liver and fat cells) Glycogen (storage in muscles) Rough endoplasmic reticulum (RER) Surface covered with ribosomes Active in protein and glycoprotein synthesis Folds polypeptide protein structures Encloses products in transport vesicles

  18. Figure 3-5a The Endoplasmic Reticulum Nucleus Rough endoplasmicreticulum with fixed(attached) ribosomes Smoothendoplasmicreticulum Ribosomes The three-dimensional relationships between the rough and smooth endoplasmic reticula are shown here. 4 What are the structural and functional differences between rough and smooth endoplasmic reticulum? Cisternae

  19. 3-2 Organelles and the Cytoplasm Golgi Apparatus Vesicles enter forming face and exit maturing face. Vesicles contain flattened membranous discs called cisternae. Functions Modifies and packages secretions Hormones or enzymes Released through exocytosis Renews or modifies the plasma membrane Packages special enzymes within vesicles for use in the cytoplasm

  20. 3-2 Organelles and the Cytoplasm Lysosomes Powerful enzyme-containing vesicles Lyso- = dissolve, soma= body Primary lysosome Formed by Golgi apparatus and inactive enzymes Secondary lysosome Lysosome fused with damaged organelle Digestive enzymes activated Toxic chemicals isolated Functions Clean up inside cells (Break down large molecules, Attack bacteria, Recycle damaged organelles, and Eject wastes by exocytosis). Autolysis (Auto—self; Lysis—breakdown) (Self destruction of damaged cells—lysosome membranes breakdown, digestive enzymes released, cell decomposes, cellular materials recycled) .

  21. Figure 3-8 Lysosome Functions Activation of lysosomesoccurs when: Golgiapparatus A primary lysosome fuses withthe membrane of anotherorganelle, such as a mitochondrion Damaged organelle Autolysis liberatesdigestive enzymes Secondarylysosome Primary lysosome A primary lysosome fuses withan endosome containing fluidor solid materials from outsidethe cell Reabsorption Reabsorption Endosome The lysosomal membranebreaks down during autolysisfollowing injury to, or death of,the cell Secondarylysosome Extracellularsolid or fluid Endocytosis Exocytosisejects residue Exocytosisejects residue 5 What are the three general destinations for proteins that leave the Golgi complex?

  22. 3-2 Organelles and the Cytoplasm Peroxisomes Are enzyme-containing vesicles. The enzymes differ from those of the lysosomes. Break down fatty acids, organic compounds Produce hydrogen peroxide (H2O2) Replicate by division Membrane Flow A continuous exchange of membrane parts by vesicles All membranous organelles (except mitochondria) Allows adaptation and change

  23. Proetin Synthesis 6 How do the entry and exit faces of protein synthesis differ?

  24. 3-2 Organelles and the Cytoplasm Mitochondria Have smooth outer membrane and inner membrane with numerous folds cristae. These cisternae increase the surface area available for chemical reactions and contain some of the enzymes needed for ATP production) Matrix Fluid around cristae Mitochondrion takes chemical energy from food (glucose) and produces energy molecule ATP

  25. 3-2 Organelles and the Cytoplasm Mitochondrial Energy Production Glycolysis (takes place in the cytoplasm) Glucose to pyruvic acid (in cytosol) Citric acid cycle (also known as the Krebs cycle and the tricarboxylic acid cycle or TCA cycle) Pyruvic acid to CO2 (in matrix) Electron transport chain Inner mitochondrial membrane Mitochondrial Energy Production Called aerobic metabolism (cellular respiration) Produces 95% of ATP needed to keep cell alive Mitochondria use oxygen to break down food and produce ATP Glucose + oxygen + ADP  carbon dioxide + water + ATP

  26. Figure 3-9a Mitochondria Inner membrane Organic moleculesand O2 Outermembrane Matrix Cristae Enzymes Cristae Cytoplasm of cell Matrix Outermembrane Mitochondrion TEM  46,332 Shown here is the three-dimensional organization and acolor-enhanced TEM of a typical mitochondrion in section.

  27. Figure 3-9b Mitochondria Glucose CYTOPLASM Glycolysis Pyruvate Enzymesandcoenzymesof cristae ADP phosphate Citric AcidCycle MATRIX MITOCHONDRION This is an overview of the role of mitochondria in energy production. Mitochondria absorb short carbon chains (such as pyruvate) and oxygen and generate carbon dioxide and ATP.

  28. 3-3 Cell Nucleus Nucleus Largest organelle. It is the cell’s control center. Nuclear envelope (double membrane around the nucleus) Perinuclear space (between the two layaers of the nuclear membrane) Nuclear pores (communication passages) How the Nucleus Controls Cell Structure and Function Direct controlthrough synthesis of: structural proteins and secretions Indirect control over metabolism through enzymes

  29. 3-3 Cell Nucleus Contents of the Nucleus DNA(all information to build and run organism) Nucleoplasm(fluid containing ions, enzymes, nucleotides, anad some RNA) Nuclear matrix (support filaments) Nucleoli(related to protein production; made of RNA, enzymes and histones (proteins); synthesize rRNA and ribosomal subunits) Nucleosomes(DNA coiled around histones) Chromatin(loosely coiled DNA (cells not dividing) Chromosomes(tightly coilded DNA (cells dividing)

  30. 3-3 Cell Nucleus Information Storage in the Nucleus (“genetic code”) DNA Instructions for every protein in the body Gene DNA instructions for one protein Genetic code The chemical language of DNA instructions Sequence of bases (A, T, C, G) Triplet code 3 bases = 1 amino acid Gene—functional unit of heredity

  31. 3-4 Protein Synthesis The Role of Gene Activation in Protein Synthesis The nucleus contains chromosomes → Chromosomes contain DNA →DNA stores genetic instructions for proteins → Proteins determine cell structure and function. Gene activation – uncoiling DNA to use it Promoter (control segment) at “start” of gene → Terminator “stop” TranscriptionCopies instructions from DNA to mRNA (in nucleus) RNA polymerase produces messenger RNA (mRNA) TranslationRibosome reads code from mRNA (in cytoplasm) and assembles amino acids into polypeptide chain Processing(RER and Golgi apparatus produceg protein) Gene Activation Transcription Translation Processing

  32. 3-4 Protein Synthesis The Transcription of mRNA Step 1: Gene activation (DNA strands separate and RNA polymerase binds to the promoter of the gene). Step 2: DNA to mRNA (RNA polymerase moves from one nucleotide to another along length of the template strand. At each site, complementary RNA nucleotides for hydrogen bonds with the DNA nucleotides of the template stand. RNA polymerase strings the arriving nucleotides together into a strand of mRNA). Step 3: RNA processing (On reaching the stop signal at the end of the gene, the RNA polymerase and the mRNA strand detach, and the two DNA strands reassociate).

  33. Figure 3-12 mRNA Transcription DNA Templatestrand Codingstrand Codon1 mRNAstrand RNApolymerase Codon2 Promoter Codon3 1 Triplet 1 Codon 1 Gene 1 Codon 4(stop codon) Complementarytriplets 2 2 Triplet 2 3 RNAnucleotide 3 Triplet 3 4 4 Triplet 4 KEY Uracil (RNA) Adenine After transcription, the two DNA strands reassociate Guanine Thymine (DNA) Cytosine 7 Where does transcription occur? Where does translation occur?

  34. http://www.youtube.com/watch?v=AGzsgTMgSog

  35. 3-4 Protein Synthesis Translation mRNA moves from the nucleus through a nuclear pore → to a ribosome in the cytoplasm surrounded by amino acids → binds to ribosomal subunits → tRNA delivers amino acids to mRNA. tRNA anticodon binds to mRNA codon Enzymes join amino acids with peptide bonds Polypeptide chain has specific sequence of amino acids At stop codon, components separate

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