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Transcript
Cell Structure and Function Anderson Spring 2017 College of the Redwoods What is a cell? Fundamental unit of LIFE! (Smallest unit of a living thing) Teeny tiny so we have to use a microscope to see them Two Types of Cells Prokaryotic Eukaryotic Bacteria Animal Archaea Plant Fungi Protists Common Cell Components All cells share 4 common components 1. Plasma membrane – outer covering that separates the inside from its surrounding environment 2. Cytoplasm – jelly-like region inside cell where organelles are found 3. DNA – genetic material 4. Ribosomes – particles that synthesize proteins Components of Prokaryotic Cells Unicellular NO nucleus (central thing that holds DNA in eukaryotic cells) DNA contained in nucleiod (no membrane) Pili/ Cell wall Differ between bacteria and archaea Capsule (some) Surface attachment, protection, resistance Flagella, pili, fimbriae Eukaryotic Cells Contain membrane-bound organelles Have central nucleus (with membrane) Come in all shapes and sizes Plasma Membranes Also surrounds organelles Plasma Membranes Phospholipid bilayer Regulates and prevents passage of some substances Actively bring in/removes substances Some compounds move passively through 1. Phospholipids 2. Embedded proteins 3. Cholesterol 4. Carbohydrates Cytoplasm/Cytoskeleton Cytoplasm Contents of the cell between plasma membrane and nuclear envelope (center where the nucleus is) Made up of cytosol (gel-like substance), cytoskeleton, and other chemicals 70-80% water Full of organic molecules and ions This is where all the organelles hang out Cytoskeleton Network of protein fibers that: Three types of fibers 1. Help to maintain shape of cell Microfilaments (actin 2. Secures organelles is specific position Intermediate filaments 3. Allows cytoplasm and vesicles to move within the cell 4. Enables unicellular organisms to move independently filaments) Microtubules (we’ll talk more about these during mitosis) Flagella (flagellum) Cilia (cilium) Long hair-like structures Short hair-like structures Just one or few Many in number Used to move entire cell Used to move entire cell extending from plasma membrane extending from plasma membrane Move substances along outer surface of cell Endomembrane System (organelles surrounded by membranes) Nuclear envelope Endoplasmic reticulum Lysosomes Vesicles Golgi apparatus Nucleus Nuclear envelope Double-membrane phospholipid bilayer structure Covered in pores to control passage of ions, molecules, and RNA Chromatin = DNA and proteins Exists in the form of chromosomes Nucleolus – creates ribosomes Nucleoplasm – gel-like substance in the nucleus Endoplasmic Reticulum Interconnected membranous tubules that modify proteins and synthesize lipids Rough ER Covered in ribosomes (proteins that make proteins) Newly synthesized proteins get modified in lumen (cisternal space) Folded or addition of sugars Makes phospholipids for membranes Smooth ER No ribosomes Synthesis of carbohydrates, lipids, and steroid hormones Detoxification of medications/po isons Metabolizes alcohol Stores calcium Golgi Apparatus Molecules not destined to stay in rough ER will be packaged into vesicles These transport vesicles need to be sorted, packaged, and tagged, which happens in the Golgi apparatus Cis face = receiving end Trans face = releasing end Can have more than 1 per cell – secretory cells have lots of Golgi! Lysosomes Contain digestive enzymes to break down leftover cell bits Digests ingested food for single-celled eukaryotes Come from the Golgi apparatus Destroy disease-causing organisms by phagocytosis Vesicles and Vacuoles Vesicles are membrane-bound sacs Storage and transport Small and usually many Membranes can fuse with other membranes Contractile vacuole – regulates water to keep unicellular organisms from swelling or shrinking Vacuoles are larger vesicles Storage and transport Membranes don’t fuse with other membranes Central vacuole in plants – regulates water Mitochondria Mitochondria “Powerhouse” of the cell Make adenosine triphosphate (ATP) – cell’s main energy molecule ATP is made from the breakdown of glucose – this is cellular respiration Have their own ribosomes and DNA Cells that need lots of energy (muscle cells) have lots of mitochondria Peroxisomes Round organelles with single membrane Break down fatty acids and amino acids via oxidation reactions Detoxify poisons (alcohol) – lots in liver Break down hydrogen peroxide (H2O2), a byproduct of oxidation, which is toxic to cells Bud from the endoplasmic reticulum Cell Wall Found in plants, fungi, protists and prokaryotic cells – NOT ANIMALS! Rigid covering outside plasma membrane Protects, provides structural support, and give shape to cell Made up of cellulose (long strands of glucose) in plants Made up of peptidoglycan in prokaryotes Chloroplasts Function in photosynthesis (making glucose from sunlight) Chlorophyll – green pigment that captures sunlight for energy Located in thylakoid Central Vacuole Regulates plant cell’s concentration of water Provides turgor pressure (outward pressure) Water moves from high to low concentrations – out of the plant and into soil when you forget to water! Animal vs. Plant Cells Organelle Animals Plants Plasma Membrane Yes Yes Cytoplasm Yes Yes Nucleus Yes Yes Endoplasmic reticulum Yes Yes Golgi apparatus Yes Yes Lysosomes Yes Yes Vesicles/Vacuoles Yes Yes Mitochondria Yes Yes Cell wall No Yes Chloroplasts No Yes Central Vacuole No Yes Think about it this way A cell is a big manufacturing company 1. The membrane is the exterior walls with doors and windows to let only certain things in/out – plants have an extra wall (fence?) 2. The nucleus is the CEO, where all the information comes from 3. The endoplasmic reticulum is the manufacturing floor (proteins) 4. Ribosomes are the workers doing the manufacturing 5. The Golgi apparatus is the shipping department 6. Vesicles are vehicles that transport goods inside the company 7. Lysosomes are the recycling plant/compost pile 8. Mitochondria are the power stations keeping everything running 9. Chloroplasts are the kitchen for manufacturing PLANTS (pun intended!) Socrative Time Have you been paying attention?!