1. Chapter 7
The Cell

2. 7.1 Cell Discovery and Theory
The invention of the microscope led to the discovery of cells.
The first microscope was invented and used by Robert Hooke to discover cells in cork.
200 years later scientists came up with the cell theory.
Cell theory is one fundamental idea of modern biology and includes three principles.

3. Cell Theory All living organisms are composed of one or more cells
Cells are the basic unit of structure and organization of all living organisms
Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.

4. Cell Types
Two Different Cell Types 1. Eukaryotic - have a true nucleus and membrane bound organelles (large cells) examples: plant and animal cells 2. Prokaryotic – no specialized internal structures, do not have a nucleus and organelles. ( small cells) examples: bacteria, and unicellular organisms

5. Cell Types

6. Basic Cell Parts
All cells have a plasma membrane that helps them limit what goes in and out of the cell.
Eukaryotic cells have organelles, which are specialized structures that help a cell perform basic functions.
They also have a nucleus. The nucleus is a distinct central organelle that contains the cells genetic material

7. Bell Ringer 11/6 – 11/7 Count the Atoms: Na2CO3
What type of bond is this – HCl?
What are the 3 parts of the cell theory?
What are the differences between eukaryotic and prokaryotic cells (2 major differences)?

8. 7.2 The Plasma Membrane
Cells maintain homeostasis by allowing materials in and out of it through the plasma membrane.
Not everything is allowed to move into and out of a cell, this is a key feature called Selective Permeability.
Plasma Membrane
thin, flexible boundary between the cell and its environment allowing substances in and out of the cell.

9. Structure of the Plasma Membrane
Most of the molecules in the plasma membrane are lipids.
Lipids bind with phosphate to form a phospholipid.

10. Structure of the Plasma Membrane
Phospholipids join together to create a phospholipid bilayer.
In the bilayer the nonpolar tails point towards each other.
The polar heads form the top and bottom of the bilayer which makes it hard for water to pass through the bilayer.

11. Phosphate Group = polar head = attracted to H2O = hydrophilic
2 Fatty Acids (Lipids) = nonpolar tail = repelled by H2O = hydrophobic

12. Plasma membrane continued.
The plasma membrane also contains cholesterol, proteins, and carbohydrates.
Proteins –
Transport Protein (Tunnel) - Moves special material in/out of the cell
Receptor Protein (Outside) – Transmit Signals
Structure Protein (Inside) – Cell structure and shape
Cholesterol (Lipid) – Prevents phospholipid tails from sticking together.
A high cholesterol diet is not recommended BUT it plays a crucial role in structure and homeostasis
Carbohydrates
Defines cell characteristic
Identify chemical signals (Bacteria – Signal – Troops)

13. Fluid Mosaic Model
Together all the phospholipids create a “sea” in which the other molecules float around freely.
This allows the phospholipids and other molecules to change their location from time to time.
This “sea” idea is the fluid mosaic model of the plasma membrane

14. Plasma Membrane Video
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15. 7.4 Cellular Transport
Substances must move inside of the cell and in/out of the cell.
Diffusion is the movement of particles from a area of high concentration to an area of lower concentration.

16. Food Coloring Demo

17. Rate of Diffusion
Key characteristics that affect the rate of diffusion:
Concentration  Concentration = faster diffusion because there are more particles to collide
Temperature
Pressure
 Temp & pressure =  number of collisions = faster diffusion

18. Facilitated Diffusion
Small particles can move in and out of the cell through channel proteins. This is called facilitated diffusion.
Another way substances move in and out is through carrier proteins. They change shape as molecules pass through them.

19. Osmosis
The diffusion of water is called osmosis. Water can pass through the selectively permeable membrane.
Solute is the substance that is dissolved. Solvent is what the solute dissolves in.
Water moves from a low concentration to a high concentration in order to reach equilibrium.

20. Dynamic Equilibrium
Movement continues until the concentration is equal on both sides. This is called dynamic equilibrium.
Isotonic solutions have an equal concentration of water and solutes on both sides of the semi permeable membranes.

21. Hyper / Hypo Solutions
Hypotonic solution has a lower concentration of solute outside of the cell than inside of the cell. This causes the cell to grow.
Hypertonic solution has a higher concentration of solute outside of the cell than inside so water leaves the cell and the cell shrinks.

22. Active Transport
Active transport moves substances across the membrane against the concentration gradient. This requires energy.
A common active transport pump is Na+/K+ ATPase pump. It moves sodium and potassium in and out of the cell. This moves sodium and potassium against the concentration gradient.

23. Large Particles
Large particles like hormones and wastes use a different type of transport.
Endocytosis is the process of the plasma membrane surrounding a large particle and it breaks off and takes the particle into the cell.
Exocytosis is the secretion large particles (like hormones) through the plasma membrane.
All cell transport helps maintain homeostasis.

24. Bell Ringer 11/7-11/8
Is this an endothermic or exothermic reaction? How can you tell?
What is an enzyme and what does it do to a chemical reaction?
What type and how many of bonds are present in water (H2O)?
What three elements can the “H” in H2O bind to when talking about hydrogen bonding?
What is the difference between diffusion and osmosis?

25. 7.3 Cell Structures and Organelles
The inside of a cell is filled with specialized structures (organelles) that each perform a specific task. All the organelles are surrounded by a semi-fluid material called cytoplasm. It used to be thought that organelles floated around freely inside the cell. But now we know that all organelles are supported by a cytoskeleton.

26. Animal vs. Plant vs. Bacterial Cell
Animal Cell:
Nucleus
Golgi Apparatus
Vacuole
Mitochondria
Cell Membrane
Ribosome
Endoplasmic
Reticulum
Lyosome
Cytoskeleton
Centrioles
Plant Cell:
Nucleus
Cell Wall
Chloroplast
Golgi Apparatus
Vacuole
Mitochondria
Cell Membrane
Ribosome
Endoplasmic
Reticulum
Lysosome
Bacterial Cell:
Ribosomes
Plasma Membrane
Cell Wall
Capsule
DNA
Cytoplasm
USE PAGE 199 IN YOUR BOOK – TABLE 7.1

27. Cell Structures
The nucleus- The nucleus contains most of the cell’s DNA. It is surrounded by a double membrane called the nuclear envelope. Inside it contains the nucleolus.
The nucleolus is where ribosomes are made.

28. Cell structures
Ribosomes are the organelles that help manufacture proteins.
Endoplasmic reticulum is the site of ribosome attachment and provides a large surface area for cell functions to take place.

29. Cell structures
Golgi apparatus- after proteins are made they are sent to the G-a to be packaged into vesicles.
Vesicles fuse with the plasma membrane to release the proteins outside of the cell.

30. Cell structures
Vacuoles are a place that the cell stores materials temporarily.
Some vacuoles store food, and some store waste products.
The vacuoles in animals cells are smaller than they are in plant cells, and sometimes animals don’t have them at all.

31. Cell structures
There are two types of Endoplasmic Reticulum Smooth has no ribosomes attached and makes phospholipids and complex carbohydrates
Rough has ribosome and forms proteins

32. Cell Structures
Lysosomes- vesicles that contain enzymes to break down food & wastes
Found in animal cells. Scientists debate the lysosomes in plant cells
Centrioles - special microtubules that function during cellular division

33. Cell Structures Mitochondria- convert sugar into usable energy
Has outer and inner membranes
Inner is folded to increase surface area ratio
Make ATP (energy molecule) through a process called cellular respiration

34. Cell Structures
Cilia- short, hair-like projections on the outside surface of a cell
Used for locomotion or “sweeping” of particles
Flagella- long, tail-like projections
Used for locomotion

35. Cell Structures (Plants only)
Chloroplasts- convert light energy into usable energy (sugar) through photosynthesis
Give color to plant structures

36. Cell Structures (Plants only)
Cell Wall- thick, rigid mesh of fibers surrounding the plasma membrane
Protect cell, rigid, and provides support