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Cells 3 Unit 1 Chapter 3 Cell Structure 3 Unit 1 • Plasma membrane • Cytoplasm: cytosol + organelles • Nucleus Figure 3.1 Cell Membrane 3 Unit 1 • Phospholipid bilayer • Cholesterol • Proteins • attached carbohydrates Figure 3.2 Membrane Function • • • • Unit 1 Barrier between inside and outside of cell Controls entry of materials- Transport Receives chemical and mechanical signals Transmits signals between intra- and extra cellular spaces • Note the various proteins in figure 3 Terminology: Body Fluid Pools 3 • Intracellular (ICF) • Extracellular (ECF) -> • Between cells = Interstitial • In blood vessels = Plasma • In lymphatic vessels = Lymphatic Unit 1 2/3 of total Terminology: Solutions 3 • Solvent- doing the dissolving Mostly water • Solute- material dissolved • Concentration • Concentration gradient Difference in concentration between 2 areas of solution Unit 1 Amount of solute in a given amount of solvent Figure 3.3 Passive transport: Diffusion • • • • 3 Requirements for Simple Diffusion Concentration gradient of solute Can diffuse across a membrane either dissolve in the lipid membrane e.g. O2, C O2, lipid soluble vitamins Specialized ion channels that can open and shut = (gated channels) Unit 1 • if charged must go through channels Figure 3.4 Figure 3.5 Facilitated Diffusion Requires a carrier in membrane Only goes down concentration gradient Saturates = maximum speed Maximum speed dependent on carrier number Unit 1 • • • • 3 Figure 3.6 Osmosis 3 Unit 1 • Diffusion of water • Must have a membrane • Membrane impermeable to a solute Figure 3.7 Figure 3.8 • Requires a carrier • Requires energy (ATP) • Can transport up a concentration gradient • Critical for moving important ions • Major active transport in most cells = • Sodium-potassium (Na+/K+) pump 3 Unit 1 Active Transport Figure 3.9 Transport in Vesicles 3 Unit 1 • Requires energy • Involves small membrane sac • Endocytosis- importing materials • Exocytosis- exporting materials Table 3.2 • • • • • • Cytoskeleton- Fig 3.11 Flagella, Cilia & Centrioles- Motion Endoplasmic reticulum- Fig. 3.14 Golgi apparatus- Fig. 3-15 Mitochondrion- Fig 3-16 Nucleus, nucleolus, nuclear envelopeFig. 3-17 • Vesicles, e.g. lysosome- 3 Unit 1 Cell organelles Cytoplasm 3 Unit 1 • Cell contents • Includes organelles and Cytosol • Excludes nucleus • Maintain shape of cell • locate organelles • change cell shape • Includes: microfilments, intermediate flilments, microtubules 3 Unit 1 Cytoskeleton Figure 3.11 Centrosome 3 Unit 1 • Centriole • Pericentiolar material Figure 3.12 Cilia and flagella 3 • Specialized for motion • Flagella- single • Cilia in groups Unit 1 Found in respiratory system- move mucus • Sites of protein synthesis • Ribosomal RNA (rRNA) • Ribosomal Proteins • Can be attached to endoplasmic reticulum or free in cytosol 3 Unit 1 Ribosomes • Synthesis and intracellular transport • lipid synthesis- all • Protein synthesis- rough E.R. • Protein modification • transport around cell 3 Unit 1 Endoplasmic Reticulum- Figure 3.14 Golgi Complex 3 Unit 1 • Modify and package proteins • E.g. lipoproteins and glycoproteins • Some packaged into vesicles=> • Lysosomes or export by exocytosis Figure 3.15 Small bodies 3 • Lysosomes- contain digestive enzymes • Peroxisomes- oxidize for detoxification • Proteasomes- digest proteins Unit 1 Abundant in liver Mitochondrial function 3 Unit 1 • Energy (ATP) production • Where oxygen is consumed • where nutrients are “burned” Figure 3.16 • Round or oval structure • Surrounded by nuclear envelope • Openings = Nuclear pores • Can include a nucleolus- make ribosomes • Store genetic material • copy information for transfer to new cells to the cytosol for protein synthesis 3 Unit 1 Nucleus Figure 3.17 part 1 Figure 3.17 part 2 Protein Synthesis 3 Unit 1 • 2 steps • Nuclear = transcription • Cytoplasmic = translation Figure 3.19a Figure 3.19b Transcription 3 • In nucleus • RNA polymerase transcribes DNA into RNA=> • 1. messenger RNA (mRNA) • 2. Ribosomal RNA Part of ribosomes • Transfer RNA (tRNA) Carries amino acids to ribosome for reaction Unit 1 Directs synthesis of polypeptide Translation 3 • Requires 3 different RNAs • Message RNA -from nucleus (mRNA) • Transfer RNA to carry amino acids (tRNA) • Ribosomes to do the actual work containing ribosomal RNA (rRNA) Unit 1 Figure 3.20 Figure 3.20 part 1 Figure 3.20 part 2 Figure 3.20 part 3 Figure 3.20 part 4 Figure 3.20 part 5 Figure 3.20 part 6 Cell Cycle 3 • Interphase Growth and development of cell prepare for reproduction-DNA synthesis,etc. 4 phases • Cytokinesis= division of cell Unit 1 • Mitotic Phase = division of nucleus and cell • Centrioles move to opposite ends • Nuclear envelope disappears • Chromosomes appear with centromeres • Chromosomes move to spindles 3 Unit 1 Prophase Figure 3.21b Metaphase 3 Unit 1 • Chromosomes lined up in center=> • Metaphase plate Figure 3.21c Figure 3.21c Anaphase 3 Unit 1 • Sister chromosomes move to opposite ends of spindle Figure 3.21d Telophase 3 Unit 1 • Nuclear envelopes reappear • Cytokinesis is completed • May be programmed genetically • Number of factors contribute • Protein cross-links by glucose • Free radical damage • Cessation of mitosis 3 Unit 1 Aging