1. Chapter Three: Cell Structure and Function

2. Section One: Cell Theory
Cells were first discovered by Robert Hooke
Anton van Leeuwenhoek was the first to describe cells
Cell Theory
All organisms are made of cells
All existing cells are produced by other living cells
The cell is the most basic unit of life

3. Section One: Cell Theory
Cell Parts and Cell Types
Part of Every Cell
Cytoplasm: a jellylike substance that contains dissolved molecular building blocks (proteins, lipids, carbohydrates)
Types of Cells
Prokaryotic: no nucleus or membrane bound organelles
DNA is suspended in the cytoplasm
All are single celled
Eukaryotic: have a nucleus and other membrane bound organelles
DNA is housed in the nucleus
Can be single or multicellular

4. Section One: Cell Theory

5. Section Two: Cell Organelles
Cell’s Internal Structure
Cytoskeleton: a network of proteins that is constantly changing to meet the needs of the cell
Made of microtubules, intermediate filaments, and microfilaments
Microtubules: give the cell shape and separate DNA during cell division
Intermediate filaments: give the cell strength
Microfilaments: enable the cells to move and divide

6. Section Two: Cell Organelles

7. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Nucleus
The storehouse for most of the genetic information, or DNA in your cells
Protects the DNA and makes it available for use when proteins need to be made
DNA is found inside the nuclear envelope of the nucleus
Contains nucleolus: area where ribosomes are made

8. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Endoplasmic Reticulum
Called the ER
Smooth and Rough ER
And interconnected network of thin folded membranes (cisternae)
Interior of folds are called lumen
Protein and lipids are made here

9. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Ribosome
Tiny organelles that link amino acids together to form proteins
Some are attached to the ER and is why some parts are called rough ER
Site of protein synthesis
Some ribosomes are suspended in the cytoplasm

10. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Golgi Apparatus
Closely layered stacks of membrane-enclosed spaces that process, sort, and deliver proteins
Has enzymes that make additional changes to proteins
Packages and stores some proteins

11. Section Two: Cell Organelles

12. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Vesicles
Small membrane bound sacs that divide some materials from the rest the cytoplasm and transport these materials from place to place within the cell
Usually short lived and are recycled as needed
Transport proteins from the ER to the Golgi Apparatus
Transport proteins after they leave Golgi

13. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Mitochondria
Supply energy to the cell
Bean shaped and have 2 membranes
Converts molecules from the food you eat into energy through chemical reactions
Have their own ribosomes and DNA
Suggests that they were once free living prokaryotes that were “eaten” by larger cells

14. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Vacuoles
Fluid-filled sacs used for storage of materials needed by the cell
Can store water, food, enzymes, etc.
Plants have a central vacuole for water storage

15. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Lysosomes
Membrane-bound organelles that contain enzymes
Defend the cell from invading bacterial and viruses
Break down damaged or worn down cell parts

16. Section Two: Cell Organelles
Eukaryotic Cell Organelles
Centrosome
Small region of the cytoplasm that produces microtubules
Contain centrioles in animals
Centriole
Cylinder-shaped organelles made of short microtubules arranged in a circle
2 centrioles are perpendicular to each other
Doubles with the centrosome before cell division
Can organize microtubles to form cilia or flagella

17. Section Two: Cell Organelles
Cell Walls
Found in plants, algae, fungi, and most bacteria
A rigid layer surrounding the cell membrane that gives protection, support, and shape to the cell
NOT IN ANIMAL CELLS!

18. Section Two: Cell Organelles
Chloroplasts
Organelles that carry out photosynthesis
ONLY IN PLANT CELLS!
Have an outer and inner membrane
Stacks of disc shaped sacs filled with chlorophyll
Have their own ribosomes and DNA
Suggests they were once free-living prokaryotes

19. Section Three: Cell Membrane
Cell Membranes
Also called the plasma membrane
Forms a boundary between cell and the outside environment and controls the passage of materials into and out of the cell
Made of a phospholipid bilayer
Phospoholipids are made of three parts: a charged phosphate group, glycerol, and two fatty acid chains
Glycerol and phosphate form the head and are hydrophilic. This means water loving.
Fatty acids form the tail and are hydrophobic, which means water fearing.

20. Section Three: Cell Membrane
Cell Membranes
Phospholipid Bilayer
The phospholipids arrange themselves in layers
The hydrophobic tail are in the center and the hydrophilic heads are on the outside
The heads of the outside interact with the watery fluid on the outside of the cell and cytoplasm on the inside of the cell
The tails are protected from the watery environment on the inside and outside of the cell by the heads

21. Section Three: Cell Membrane
Cell Membranes
Other molecules are found in the cell membrane
Cholesterol molecules strengthen the cell membrane
Some proteins go through one or both of the phospholipid layers and move materials in and out
Some proteins help make up the cytoskeleton
Carbohydrates serve as ID tags which allow cells to identify one another

22. Section Three: Cell Membrane
Fluid Mosaic Model
Describes the arrangement of molecules that make up the cell membrane
Cell membrane is flexible
Phospholipids can move from side to side, but cannot flip vertically
Proteins cannot move in the membrane

23. Section Three: Cell Membrane
Selective Permeability
Property of the cell membrane
It allows some materials to go into and out of the cell but not all
Allows cell to maintain homeostasis

24. Section Three: Cell Membrane
Chemical Signals and Receptors
Receptor: a protein that detects a signal molecule and performs an action in response
Recognizes and binds to only certain molecules called ligands
Upon binding of the receptor and ligand, they change shape
Two Types of Receptors
Intracellular Receptors
Membrane Receptors

25. Section Three: Cell Membrane
Receptors
Intracellular Receptors
Located inside the cell
Molecules that bind are usually small and nonpolar
Ex: hormones
Membrane Receptors
Located in the cell membrane
Receptor sends message to cell interior

26. Section Three: Cell Membrane

27. Section Four: Diffusion and Osmosis
Passive Transport
The movement of molecules across a cell membrane without energy input from the cell
3 types: Diffusion, Osmosis, and Facilitated Diffusion

28. Section Four: Diffusion and Osmosis
Passive Transport
Diffusion: the movement of molecules in a fluid or a gas from a region of higher concentration to a region of lower concentration
Works through a concentration gradient: the difference in concentration of a substance from one location to another

29. Section Four: Diffusion and Osmosis
Passive Transport
Osmosis: the movement of water across a semipermeable membrane from an area of higher concentration to an area of lower concentration
Solutions can be described as isotonic, hypotonic, or hypertonic relative to another solution or cell
Isotonic: concentration of the solution on the outside is the same as the concentration of a solution on the inside
Hypertonic: solution has a higher concentration of particles than the cell
Hypotonic: solution has a lower concentration of particles than the cell

30. Section Four: Diffusion and Osmosis

31. Section Four: Diffusion and Osmosis
Passive Transport
Facilitated Diffusion: the diffusion of molecules across a membrane through transport proteins
For molecules that can move easily across a membrane
Move down the concentration gradient so no energy is used

32. Section Five: Active Transport, Endocytosis, and Exocytosis
Active Transport: drives molecules across the membrane form a region of lower concentration to a region of higher concentration
Goes against the concentration gradient
Uses transport proteins powered by chemical energy
Most common form of energy used is called ATP

33. Section Five: Active Transport, Endocytosis, and Exocytosis
Endocytosis: the process of taking liquids or fairly large molecules into the cell by engulfing them in a membrane
The cell makes a pocket around the substance and pinches off the pocket inside the cell to form a vesicle
Lysosomal enzmes break down the vesicle components and release it into the cell

34. Section Five: Active Transport, Endocytosis, and Exocytosis
Phagocytosis: a type of endocytosis in which the cell membrane engulfs large particles
White blood cells use this to fight infection

35. Section Five: Active Transport, Endocystosis, andExocytosis
Exocytosis: the release of substances out of the cell by the fusion of a vesicle with the membrane
Used in nerve cells to transmit signals