Chapter 7: Cell Structure and Function Section 7-1: Life is Cellular Harvard - Inner Life of the Cell
The observations and conclusions of many scientists helped to develop the current understanding of the cell Put it in perspective: 1605 – English settlers found the colony at Jamestown, Virginia
The Cell Theory Robert Hooke (1665) • English physicist used primitive compound microscope to look at plant tissue (cork). • He called the chambers “cells” because they reminded him of the small rooms in a monastery
The Cell Theory Rudolph Virchow (1855) • Proposes that all cells come from existing cells • Where did the first cell come from?
THE CELL THEORY • All living things are composed of cells. • Cells are the basic unit of structure and function in living things. • New cells are produced from existing cells.
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 Cells Alive
Two categories of cells 1. Prokaryotic Cells pro = before; karyon = nucleus or kernel • contain cell membranes and cytoplasm but no nucleus • DNA is scattered through cytoplasm examples: bacteria
Two categories of cells 2. Eukaryotic Cells eu = true; karyon = nucleus or kernel contain a nucleus that holds DNA and membrane bound organelles that have specific functions examples: all plants, animals, some fungi, some microorganisms
Two categories of cells Prokaryotic Eukaryotic -No Nucleus -Nucleus -Cell wall (plants and bacteria) -Complex -Less complex -Membrane bound organelles -Smaller Ribosomes less complex -Cell membrane -DNA - Ribosomes larger and complex -Cytoplasm -DNA is circular -Ribosomes -DNA is linear
Prokaryotic Plant Cell - Eukaryotic Animal Cell - Eukaryotic
7-2 Cell Structures • Organelle – a specialized structure that performs a specific function inside a cell Cytoplasm • Found – between the nucleus and cell membrane • Structure – a clear jelly-like fluid • Function – supports the organelles
The Nucleus • Nuclear Envelope • Found: around the outside of the nucleus • Structure: two thin membranes with thousands of pores • Function: allows materials to move in and out of the nucleus.
The Nucleus Found – In cytoplasm near middle of cell Structure – filled with chromatin (tightly coiled DNA) Function: Contains the cell’s DNA, the instructions for making protein and directing cell activities. Chromatin Nucleus Nuclear Envelope
Cytoskeleton Found: Throughout the cell Structure: A network of protein filaments • Microtubules (25 nm) • Microfilaments (7nm) Function: Helps support the cell & maintain shape • Involved in several types of movement
Vacuoles • Found: In the cytoplasm • Structure: Saclike • Very large in plant cells • Smaller in animal cells • Function: Storage (water proteins, carbs, salts)
Vesicles • Found: In the cytoplasm • Structure: membrane bounded sac • Function: transports and/or stores cellular products
Lysosomes “The Cells Clean-up Crew” • Found: In the cytoplasm • Structure: Small enzyme filled organelles • Function: Breakdown large organic molecules, and old nonfunctioning organelles
Ribosomes • Found: In the cytoplasm • Structure: Small and grain-like, made of large and small subunits • Function: produce proteins from directions given by DNA
Endoplasmic Reticulum • Found: just outside the nucleus • Structure: a maze of membranes • Rough ER: (ribosomes imbedded in membrane) produces and transports proteins.
Golgi Apparatus • Found: In the cytoplasm • Structure: A stack of membranes • Function: to modify, sort and package materials from the ER for storage or to be transported outside the cell.
Chloroplast Found: In the cytoplasm of plant cells Structure: Stack of membranes that contain photosynthetic pigments (chlorophyll) Function: Use energy from the sun to make food (photosynthesis)
Mitochondria “Powerhouse of the Cell” Found: In the cytoplasm Structure: Rod-shaped with a folded double membrane Function: Provide the cell with energy.
Cell Wall Found: Located outside the cell membrane Structure: Fibers of carbohydrate, cellulose in plant cells Function: Provide support and protection for the cell
Cell Membrane Found: Located around the perimeter of the cell Structure: Made of a phospholipid bilayer Function: Regulates what leaves and enters the cell and provides protection and support
Centrioles Found: Within the cytoplasm only in animal cells Structure: Made of a microtubules (tubulin) Function: Help organize the cell during cell during division. Centrioles - Miosis
Warm up questions. 1. What are the three parts of the cell theory. 2. Who is credited with discovering cells? 3. What is the typical size range for cells in micrometers? 4. How did plant cells appear under the microscope? 5. What type of cell is this and name an organism it could have come from.
Read the passage about prokaryotic and eukaryotic cells. Complete a Venn Diagram like the one in your notes detailing the similarities and differences between prokaryotic and eukaryotic cells. Lastly, based on the passage write a short paragraph detailing how we think eukaryotic cells may have evolved from prokaryotic cells. Eukaryotic and Prokaryotic Cells
Bryson Reading: Bacteria Multiplying White blood cell vs. bacterium Bonnie Bassler
Bonus question (3 pts.) According to endosymbiotic theory, what two eukaryotic organelles are believed to have been former prokaryotic cells?
After exam: Get a book from the back and turn to pages 162-163. In your notebook construct a Venn diagram that compares and contrasts prokaryotic and eukaryotic cells Eukaryotic Prokaryotic
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