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Chapter 7: Cell Structure and Function

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1 Chapter 7: Cell Structure and Function
Section 7-1: Life is Cellular Harvard - Inner Life of the Cell

2 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

3 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

4 The Cell Theory Rudolph Virchow (1855)
Proposes that all cells come from existing cells Where did the first cell come from?

5 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.

6 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

7 How small are cells?

8 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

9 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

10 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

11 Animal Cell - Eukaryotic
Prokaryotic Plant Cell - Eukaryotic Animal Cell - Eukaryotic

12 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

13 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.

14 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

15 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

16 Vacuoles Found: In the cytoplasm Structure: Saclike
Very large in plant cells Smaller in animal cells Function: Storage (water proteins, carbs, salts)

17 Vesicles Found: In the cytoplasm Structure: membrane bounded sac
Function: transports and/or stores cellular products

18 Lysosomes “The Cells Clean-up Crew” Found: In the cytoplasm
Structure: Small enzyme filled organelles Function: Breakdown large organic molecules, and old nonfunctioning organelles

19 Ribosomes Found: In the cytoplasm
Structure: Small and grain-like, made of large and small subunits Function: produce proteins from directions given by DNA

20 Endoplasmic Reticulum
Found: just outside the nucleus Structure: a maze of membranes Rough ER: (ribosomes imbedded in membrane) produces and transports proteins.

21 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.

22 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)

23 Mitochondria “Powerhouse of the Cell”
Found: In the cytoplasm Structure: Rod-shaped with a folded double membrane Function: Provide the cell with energy.

24 Cell Wall Found: Located outside the cell membrane
Structure: Fibers of carbohydrate, cellulose in plant cells Function: Provide support and protection for the cell

25 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

26 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

27 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.

28 Eukaryotic and Prokaryotic Cells
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.

29 Bryson Reading: Bacteria Multiplying White blood cell vs. bacterium
Bonnie Bassler


31 Bonus question (3 pts.) According to endosymbiotic theory, what two eukaryotic organelles are believed to have been former prokaryotic cells?

32 After exam: Prokaryotic Eukaryotic
Get a book from the back and turn to pages In your notebook construct a Venn diagram that compares and contrasts prokaryotic and eukaryotic cells Prokaryotic Eukaryotic

33 2. 1. 3.

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