Transcript of the cell
Cell Organelles How small are cells? How much is a micrometer? 1 micrometer (µm) = 1/1,000,000 m Typical cell size = 5 to 50 µm in diameter In a dice that is 1 cm3 We could fit 1,000,000 cells How small are cells? Cell Organelles: Cytoplasm Ribosomes Nucleus Endoplasmic Reticulum Nucleolus Golgi Apparatus Nuclear Envelope Chloroplast Vacuole Mitochondria Lysosome Cell Wall Cytoskeleton Cell membrane Centrioles Cilia & Flagella Cytoplasm: Contains the various organelles Area between the cell membrane and nucleus “Jelly-like” material Nucleus: Stores hereditary information (DNA) Prokaryotic cells lack a nucleus, but they do contain DNA Control center of the cell Chromatin and Chromosomes: Inside the nucleus are fine strands of chromatin (a complex of DNA bound to protein) that coil up and become densely packed, forming chromosomes Chromosomes are visible under a microscope when a cell divides Nucleolus and Nuclear Envelope: Nucleolus – small dense region within the nucleus where ribosomes are synthesized Nuclear Envelope – double membrane (lipid bilayer) that surrounds the nucleus Vacuole: Fluid-filled organelles that store water, salts, proteins, and carbohydrates In many plant cells, there is a single large central vacuole filled with fluid - can occupy up to 90% of the cell’s volume Animal Animal Plant Paramecium’s Contractile Vacuole Contracts rhythmically to pump excess water out of the cell – controls the water content of the organism Lysosomes: Filled with enzymes Breaks down carbohydrates, lipids, and protein that can be used by the rest of the cell Breaks down organelles that have outlived their usefulness Removes “junk” that would clutter the cell Known as the “Clean Up Crew” or “Suicide Sac” of the cell Found in animal cells and specialized plant cells Some humans have diseases that result from lysosomes that fail to function properly. Cytoskeleton: Gives cells structure; helps to maintain shape & size; involved in cell movement Helps to transport materials between different parts of the cell Network of protein strands (scaffold) Made up of microfilaments and microtubules Microfilaments: Thin threads made of actin (structural protein) Supports the cell Contribute to cell movement Microtubules: Larger strands; hollow tubes made of tubulin (proteins) Maintain cell shape Important in cell division – forms the mitotic spindle which helps to separate chromosomes Form centrioles in animal cells Help build cilia and flagella Centrioles: Found near the nucleus Used to organize cell division (mitosis) Made of microtubules arranged in 9 groups of 3 Found only in animal cells 6 Cilia: Short hairs present in large numbers Propel unicellular organisms Line cells of respiratory tract Flagella: Longer hairs that are less numerous Found on sperm cells Whip back and forth Ribosomes: Produce PROTEINS by following coded instructions that come from DNA Most numerous organelle – found throughout the cytoplasm in all cells Not surrounded by a membrane Made of RNA and protein in the nucleolus & transported to the cytoplasm Endoplasmic Reticulum (ER): Moves molecules from one part of the cell to another Intracellular Highway System of membranous tubules & sacs Rough ER: Dotted with ribosomes Involved in the synthesis of proteins Abundant in cells that make large amounts of protein Smooth ER: Does not have ribosomes attached Contains collections of enzymes that perform specialized tasks (i.e. detoxifying - liver) Golgi Apparatus: Modifies, sorts and packages proteins and other materials for storage or release Processing, packaging, and secreting organelle Works with the ER Modifies proteins for export Mitochondria: Convert chemical energy stored in food into compounds that the cell can use - powerhouse Transfer energy to ATP (main energy currency) Surrounded by two membranes and contain DNA Most numerous in cells with high energy requirements (liver & muscle) Chloroplast: Capture solar energy & convert it to chemical energy Surrounded by two membranes and contain DNA Contains the green pigment chlorophyll Found only in plant cells Cell Wall: Supports and protects the cell Rigid structure outside the cell membrane Made of cellulose Found only in plant cells Cell Membrane: Controls what materials pass into and out of the cell Selectively permeable Made primarily of lipids and proteins Fluid Mosaic Model: Components of Cell Membrane: 1. Phospholipids – polar head & nonpolar tails 2. Integral Proteins – imbedded in lipid bilayer; usually have carbohydrates attached to them 3. Peripheral Proteins – surface only Animal Cell: Plant Cell: Animal Cell - Label Plant Cell - Label Great websites to check out! Interactive Cell Models – Cells Alive http://www.cellsalive.com/index.htm Inside a Cell – Learn.Genetics (University of Utah) http://learn.genetics.utah.edu/content/begin/cells/insideacell/ Video – BBC Secret Universe: The Hidden Life of the Cell http://www.youtube.com/watch?v=4GZXRMG5i_w Video – Inside the Cell http://www.youtube.com/watch?v=Ao9cVhwPg84