Cells PDF

Cells The basic unit of LIFE Cells as Life’s Fundamental Unit Cell Size diffusion Surface/Area Ratio  Cell Theory: A foundation of biology 1) All living organisms are composed of 1+cells 2) Cell basic unit structure, function, organization 3) All cells come...

Cells The basic unit of LIFE Cells as Life’s Fundamental Unit Cell Size diffusion Surface/Area Ratio  Cell Theory: A foundation of biology 1) All living organisms are composed of 1+cells 2) Cell basic unit structure, function, organization 3) All cells come from pre-existing cells.  2 Types of Cells Prokaryote = Before Nucleus – pro = before – karyon = nucleus Eukaryote = True Nucleus – eu = true – karyon = nucleus Prokaryotic Eukaryotic – No Nucleus – Nucleus – Circular DNA – Linear DNA – No membrane bound – Membrane bound organelles organelles – Smaller – Larger – Older – Younger – Single-celled – Many Multicellular Animal Cell  Prokaryotic Cells Ribosomes are the site of PROTEIN SYNTHESIS and DNA is CIRCULAR molecule are in BOTH Prokaryotic and …in Eukaryotes DNA is linear Eukaryotic cells Eukaryotic Cells  Eukaryotic Cell Organelles: “tiny organs” within cells – Carry out specialized functions Cytosol: jelly-like fluid outside nucleus – In which organelles are imbedded Cytoplasm: region of cell – Between nucleus and plasma membrane  Animal Cell nuclear pores Nucleus DNA nuclear envelope nucleolus Smooth Endoplasmic Reticulum Ribosomes (protein synthesis) plasma membrane Cytoskeleton Mitochondria lysosome Rough Endoplasmic Reticulum transport vesicle Golgi Apparatus Cytosol Endomembrane System Figure 4.4 Eukaryotic Cell Organelles  Eukaryotic Cell Organelles Nucleus Endomembrane System Cytoplasm & Cytoskeleton Lysosomes Mitochondria Chloroplasts  Cells w/ same DNA → very different cells muscle skin cells cells stomach cells Hair cells inner ear Blood cells Neuron cells  Nucleus Genetic Control Center Directs Cell Activity Stores hereditary information ❑ Nuclear Envelope ❑ Nucleolus – ribosome assembly ❑ DNA  Nucleus Chromatin ❑ DNA w/ proteins  Nucleolus Where ribosome subunits assembled Ribosome DNA → mRNA → Protein Nucleus nucleolus nuclear envelope DNA DNA mRNA inner membrane outer membrane nuclear envelope nuclear pore  Eukaryotic Cell Organelles Nucleus Endomembrane System Cytoplasm & Cytoskeleton Lysosomes Mitochondria Chloroplasts Endomembrane System  The Endomembrane System ❑ Produces, modifies, transports molecules ❑3 parts: ❑ Smooth ER, Rough ER, Golgi Apparatus Smooth ER LIPIDS Golgi PROTEINS Rough ER  Rough Endoplasmic Reticulum ❑ Ribosomes ❑ Site of Protein Synthesis  Smooth Endoplasmic Reticulum ❑ Synthesis of lipids ❑ Fatty acids, phospholipids, sterols ❑ Detoxifies (alcohol, drugs)  How can long-term use of 1 drug increase your resistance to a different drug that you’ve never had before? Chronic exposure to drugs → increase smooth ER More smooth ER → increases tolerance to drugs → help detox So takes more of drug to have an effect So drug addicts may respond less well to antibiotics  Golgi Complex: Where cell processes proteins/lipids from Rough & Smooth ER ❑ Processes proteins & lipids ❑ Packages & Export ❑ Makes carbohydrates  The Golgi Complex Golgi complex 1. Transport vesicle from RER fuses with Golgi 2. Protein undergoes more processing in Golgi vesicle Side chains are edited (sugars may be trimmed, phosphate to cytosol groups added). 3. Proteins are to plasma for export sorted and membrane out of cell shipped… Figure 4.9  Eukaryotic Cell Organelles Nucleus Endomembrane System Cytoplasm & Cytoskeleton Lysosomes Mitochondria Chloroplasts  Cytoplasm & Cytoskeleton: internal environment, support, movement  Cytoskeleton: 3 Main Purposes ❑ Shape and support ❑ Controls intracellular traffic flow ❑ Control movement  Cytoskeleton: Internal Scaffolding Web of protein strands within cell 3 principal types of cytoskeleton elements: –microfilaments (smallest) –Intermediate filaments –Microtubules (largest)  (a) Microfilaments (in red) (b) Intermediate filaments (c) Microtubules 7 nm 10 nm 25 nm Main function: changes Main function: maintenance in cell shape of cell shape Main functions: maintenance of cell shape, movement of organelles, cell mobility (cilia and flagella) Figure 4.12  Eukaryotic Cell Organelles Nucleus Endomembrane System Cytoplasm & Cytoskeleton Lysosomes Mitochondria Chloroplasts  Lysosomes: Cell’s garbage disposals & recycling centers  Lysosomes ❑ Pickup foreign invaders and dismember ❑bacteria, food, old organelles ❑ ENZYMES @ low pH so very strong  Lysosomes membrane-enclosed, acid-filled vesicles ❑~50 digestive enzymes ❑Super-acidic ❑Dismantle biomolecules ❑Re-use raw materials ❑Return components to cytoplasm  lysosome worn-out digestive organelle enzymes 1. Lysosome fuses with worn-out organelle. 2. Organelle broken down. 5. Usable molecules recycled to make 3. Small new organelles. molecules returned to cytosol. 4. Waste molecules expelled from cell. Figure 4.10  Lysosome: Tay-Sachs disease ❑ Genetic disorder ❑ Lack a lipid-digesting enzyme in lysosome ❑ Lipids buildup ❑ Lysosomes burst, kill cells ❑ Fatal ~ 4 yrs.  Eukaryotic Cell Organelles Nucleus Endomembrane System Cytoplasm & Cytoskeleton Lysosomes Mitochondria Chloroplasts  Mitochondria: Cell’s energy converters No matter what we eat, our bodies use the energy to breathe, move, and think… Mitochondria make this possible  Mitochondria & Energy Mitochondria are organelles Extract energy from food Transform energy from food into ATP – a form the cell can use to do work Bag-within-a-Bag Structure: intermembrane space & matrix Heavily folded inner membrane much larger than outer membrane provides lots of surface area on which to conduct chemical reactions.  Mitochondria and Energy Mitochondrion food oxygen outer membrane inner membrane water carbon dioxide ATP Figure 4.11  Eukaryotic Cell Organelles Nucleus Endomembrane System Cytoplasm & Cytoskeleton Lysosomes Mitochondria Chloroplasts & Plant Cells  The Plant Cell Plant cells have most of the structures found in animal cells Do not have lysosomes Plants have 3 structures not in animal cells: – cell wall – large central vacuole – chloroplasts  The Plant Cell nuclear envelope nuclear pores nucleus Plant cells have a cell DNA wall, chloroplasts, and a nucleolus central vacuole, while rough endoplasmic animal cells do not. cytoskeleton reticulum smooth endoplasmic reticulum cell wall free ribosomes chloroplast Golgi complex cytosol central vacuole plasma membrane mitochondrion Figure 4.17  Vacuole: multipurpose storage sacs vacuole Filled w/ fluid 50 - 90% of plant cell Stores nutrients Degrades waste products  Plant Cell Wall protection & support Structure Helps regulate water intake and retention Protection  Chloroplasts Site of photosynthesis water carbon dioxide minerals outer membrane inner membrane sugar (food) oxygen Figure 4.19  Chloroplasts: Plant cell’s power plant Stroma: Fluid matrix Site of Calvin Cycle Thylakoids: Flattened sacs Site of photon E capture DNA: Circular  Mitochondria & Chloroplasts Both Energy organelles They are not like the rest of the organelles Leads to…Theory of Endosymbiosis Symbiosis: (Gr. “living together“) Close interaction between 2 different species. Endosymbiosis: One species lives inside another species. Prokaryotes: Binary Fission  Endosymbiosis Theory Chloroplasts & Mitochondria: - Originated via symbiosis between 2+ organisms - Free-living bacteria t/u by cell as endosymbionts  Endosymbiosis Bacteria-Like: Own circular DNA (like bacteria) Replicate ≈ binary fission 2 different membranes ≈ same size as bacteria Host Engulfed Ribosomes bacteria Genetics Mitochondria Derived from aerobic bacteria Chloroplast Derived from photosynthetic bacteria  nucleus smooth and rough endoplasmic reticulum ribosomes cytoskeleton cytosol mitochondria plasma membrane Animal cell Plant cell  Cell-to-Cell Communication Cells use special structures to communicate Plants: plasmodesmata (channels make the cytoplasm of cell continuous) Animals: gap junctions (channels made of protein assemblages open when necessary) – allow movement of small molecules and electrical signals between cells. Plant tissues (a) Plasmodesmata plasma The plant as a whole membrane can be thought of as cell walls having a cytoplasm single complement of continuous cytoplasm. plasmodesmata Animal tissues gap junction (b) Gap junctions plasma membranes Proteins form cytoplasm channels between cells. Figure 4.20  Table 4.1 Structures in Plant and Animal Cells Name Function and Location Name Function and Location Site of most of the cell’s DNA Nucleus Mitochondria Transform energy from food Location: Inside nuclear envelope Location: Cytoplasm Nucleolus Synthesis of ribosomal RNA Rough endoplasmic reticulum Protein processing Location: Nucleus Location: Cytoplasm Ribosomes Sites of protein synthesis Smooth endoplasmic Lipid synthesis, storage; detoxification of Location: Rough ER, Free-standing in reticulum harmful substances cytoplasm Location: Cytoplasm Cytoskeleton Maintains cell shape, facilitates cell Vesicles Transport of proteins and other cellular movement and movement of materials materials within cell Location: Cytoplasm Location: Cytoplasm Cytosol Protein-rich fluid in which organelles and Central vacuole Nutrient storage, cell pressure cytoskeleton are immersed (in plant cells only) maintenance, pH balance Location: Cytoplasm Location: Cytoplasm Golgi complex Processing, sorting of proteins Chloroplasts Photosynthesis Location: Cytoplasm (in plant cells only) Location: Cytoplasm Lysosomes (in animal cells Digestion of imported materials and cell’s Cell walls Limit water uptake; maintain cell only) own used materials (in plant cells only) membrane shape, protect from outside Location: Cytoplasm influences Location: Outside plasma membrane Table 4.1