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