Cell Organelles J Beauchemin 2006 Bell ringer 1
Cell Organelles © J Beauchemin 2006
Bell ringer 1. Provide two differences between eukaryotic and prokaryotic cells 2. Which organism can only be unicellular? 3. Which macromolecule is responsible for the production of enzymes? 4. How are RNA and DNA different?
Why are most cells small? Cells are small because their size is limited by their outer surface area. Smaller they are the more efficient the cells can be Surface area to volume ratio
Surface to Volume Ratio Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. One 4 -cm cube Eight 2 -cm cubes Sixty-four 1 -cm cubes Total surface area (height × width × number of sides × number of cubes) 96 cm 2 192 cm 2 384 cm 2 Total volume (height × width × length × number of cubes) 64 cm 3 Surface area: Volume per cube (surface area ÷ volume) 1. 5: 1 3: 1 6: 1 4
Hypothesized Origin of Eukaryotic Cells Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Original prokaryotic cell DNA 1. Cell gains a nucleus by the plasma membrane invaginating and surrounding the DNA with a double membrane. 2. Cell gains an endomembrane system by proliferation of membrane. 3. Cell gains mitochondria. aerobic bacterium mitochondrion 4. Cell gains chloroplasts. Animal cell has mitochondria, but not chloroplasts. photosynthetic bacterium chloroplast Plant cell has both mitochondria and chloroplasts. 5
Cell Organelles Organelle= “little organ” Found only inside eukaryotic cells All the stuff in between the organelles is cytosol Everything in a cell except the nucleus is cytoplasm The club bouncer
Cell Membrane Boundary of the cell Made of a phospholipid bilayer
Bell ringer (write the questions) 1. What part of the cell is made up of phospholipids? 2. Which part of the phospholipid is hydrophobic? 3. The tails of the phospholipids are_____
Nucleus Control center of the cell Contains DNA Surrounded by a double membrane Usually the easiest organelle to see under a microscope Usually one per cell
Cytoskeleton Acts as skeleton and muscle Provides shape and structure Helps move organelles around the cell Made of three types of filaments
Endoplasmic Reticulum A. k. a. “ER” Connected to nuclear membrane Highway of the cell Rough ER: studded with ribosomes; it makes proteins Smooth ER: no ribosomes; it makes lipids
Bell ringer 1. What is the difference between the smooth and rough ER? 2. Proteins provide support for different areas of the body, what are three filaments created by protein? 3. What is the main function of the nucleus
Ribosome Site of protein synthesis Found attached to rough ER or floating free in cytosol Produced in a part of the nucleus called the nucleolus That looks familiar…what is a polypeptide?
Golgi Apparatus Looks like a stack of plates Stores, modifies and packages proteins Molecules transported to and from the Golgi by means of vesicles
Bell ringer (write the questions) What is the main function of the Golgi apparatus? What two places can protein synthesis occur at? Lipid synthesis occurs in which organelle? What is the main function of the cytoskeleton?
Lysosomes Garbage disposal of the cell Contain digestive enzymes that break down wastes Which organelles do lysosomes work with?
Mitochondria “Powerhouse of the cell” Cellular respiration occurs here to release energy for the cell to use Bound by a double membrane Has its own strand of DNA Creates energy in form of ATP
Bell ringer: 1. What organelle is known as the powerhouse of the cell? 2. Refer to question 1: This organelle creates energy in the form of what? 3. What is the primary function of lysosomes?
Energy-Related Organelles: Mitochondria Smaller than chloroplast Contain ribosomes and their own DNA Surrounded by a double membrane n n Inner membrane surrounds the matrix and is convoluted (folds) to form cristae. Matrix – Inner semifluid containing respiratory enzymes Break down carbohydrates Involved in cellular respiration Produce most of ATP utilized by the cell 19
Mitochondrial Structure Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. 200 nm a. double membrane outer membrane cristae matrix inner membrane b. a: Courtesy Dr. Keith Porter 20
Chloroplast Found only in plant cells Contains the green pigment chlorophyll Site of food (glucose) production Bound by a double membrane
Energy-Related Organelles: Chloroplasts Bound by a double membrane organized into flattened disc-like sacs called thylakoids Chlorophyll and other pigments capture solar energy Enzymes synthesize carbohydrates 22
Chloroplast Structure Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. 500 nm a. double membrane outer membrane grana thylakoid space stroma thylakoid membrane inner membrane b. a: Courtesy Herbert W. Israel, Cornell University 23
Cell Wall Found in plant and bacterial cells Rigid, protective barrier Located outside of the cell membrane Made of cellulose (fiber)
Vacuoles Large central vacuole usually in plant cells Many smaller vacuoles in animal cells Storage container for water, food, enzymes, wastes, pigments, etc. What type of microscope may have been used to take this picture?
Bell ringer: 1. 2. 3. 4. 5. What things do vacuoles store? Between plant cells and animal cells, which one has a smaller vacuoles? Why are chloroplast green? In what part of the cell are ribosomes created? The Golgi apparatus is known as the ups of the cell, one reason is due to the transporting of molecules. Molecules are transported by means of _______
Peroxisomes Similar to lysosomes n n Membrane-bounded vesicles Enclose enzymes However n n n Enzymes synthesized by free ribosomes in cytoplasm (instead of ER) Active in lipid metabolism Catalyze reactions that produce hydrogen peroxide H 2 O 2 Toxic Broken down to water & O 2 by catalase 27
Peroxisomes Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. 100 nm © S. E. Frederick & E. H. Newcomb/Biological Photo Service 28
Centriole Aids in cell division Usually found only in animal cells Made of microtubules Where else have we talked about microtubules?
Bell ringer: 1. Which organelle holds the cell together? 2. Which organelles are not found in animal cells? 3. Which organelle helps plant cells make food? 4. Centrioles aid in _______
Quick Review Which organelle is the control center of the cell? Nucleus Which organelle holds the cell together? Cell membrane Which organelles are not found in animal cells? Cell wall, central vacuole, chloroplasts Which organelle helps plant cells make food? Chloroplasts What does E. R. stand for? Endoplasmic reticulum
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