1. Cell Structure and Function
Chapter 7
Cell Structure and Function

2. 7-2 Eukaryotic Cell Structure
Objectives
Describe the function of the cell nucleus.
Describe the functions of the major cell organelles.
Identify the main roles of the cytoskeleton.

3. 7-2 Eukaryotic Cell Structure
Divided into two major parts that work together:
Nucleus
Cytoplasm – outside the nucleus

4. 7-2 Eukaryotic Cell Structure
Organelles (“little organs”) - Specialized
Nucleus (Both)
Ribosomes (Both)
Endoplasmic Reticulum (Both)
Golgi apparatus (Both)
Lysosomes (Both)
Vacuoles (Both, but mostly plants)
Mitochondria (Both) and Chloroplasts (Plants)
Cytoskeleton (Both)
Cell membrane (Both)
Cell wall (Plants)

5. 7-2 Eukaryotic Cell Structure
Nucleus
Directs most of cell’s activities
Contains information needed to make proteins
Stores genetic material - DNA
Chromatin
chromosomes
Surrounded by the nuclear envelope
Nucleolus – small, dense region where assembly of ribosomes begins

6. 7-2 Eukaryotic Cell Structure
Ribosomes
In cytoplasm
Small particles of RNA and protein
Make proteins following coded instructions from the nucleus

7. 7-2 Eukaryotic Cell Structure
Endoplasmic Reticulum
Rough – ribosomes on surface
Smooth – no ribosomes on surface

8. 7-2 Eukaryotic Cell Structure
Endoplasmic Reticulum
Membrane system
Lipid parts of cell, proteins and other materials that are exported are assembled
Moves proteins & Carbohydrates to the Golgi Body.

9. 7-2 Eukaryotic Cell Structure
Golgi apparatus
Stacks of flattened sacs
Modify proteins made by the cells
Package, sort & export proteins from the ER

10. 7-2 Eukaryotic Cell Structure
Lysosomes
Break down compounds into small particles that the cell can use.
Remove “junk” that clutter cell

11. 7-2 Eukaryotic Cell Structure
Vacuoles
Saclike structures
Store materials:
Water
proteins,
Salts
carbohydrates

12. 7-2 Eukaryotic Cell Structure
Mitochondria and Chloroplasts
Sources of energy
From food and/or from the sun

13. 7-2 Eukaryotic Cell Structure
Mitochondria
Releases energy in the cell. (The powerhouse of the cell)
Produce ATP (high energy compound) from food.
Plants DO have these.

14. 7-2 Eukaryotic Cell Structure
Mitochondria
The powerhouse of the cell.

15. 7-2 Eukaryotic Cell Structure
Chloroplasts
Uses energy from sunlight to make food molecules (photosynthesis).
Found in plants and some other microscopic organisms

16. 7-2 Eukaryotic Cell Structure
Cytoskeleton
Network of protein filaments that helps the cell maintain shape.
Involved in movement
Made of two different structures:
Microfilaments
Microtubules

17. 7-2 Eukaryotic Cell Structure

18. 7-2 Eukaryotic Cell Structure

19. 7-2 Eukaryotic Cell Structure

20. 7-2 Eukaryotic Cell Structure

21. 7-2 Eukaryotic Cell Structure
Objectives
Describe the function of the cell nucleus.
Describe the functions of the major cell organelles.
Identify the main roles of the cytoskeleton.
End of Section 7-2

22. 7-3 Cell Boundaries Objectives
Identify the main functions of the cell membrane and the cell wall.
Describe what happens during diffusion.
Explain the processes of osmosis, facilitated diffusion, and active transport.

23. 7-3 Cell Boundaries Cell Membrane Thin, flexible barrier Protection
Support
Regulates what enters/leaves the cell

24. The Cell Membrane is known as a “Lipid Bilayer”
7-3 Cell Boundaries
The Cell Membrane is known as a “Lipid Bilayer”
I wonder Why?

25. 7-3 Cell Boundaries Cell Walls
Support
Protection
Plant cellulose cell walls from the ragweed plant anther. The rigid cell wall of plants is made of fibrils of cellulose.

26. 7-3 Cell Boundaries Diffusion Through Cell Boundaries
Particles move from an area of high concentration to an area of low concentration.
Concentration – the mass of solute in a given volume of solution.
Equilibrium – concentration is the same throughout a solution.

27. A simple rule to remember:
7-3 Cell Boundaries
Osmosis – diffusion of water through a selectively permeable membrane.
hypertonic = more solute concentration
hypotonic = less solute concentration
isotonic = same solute concentration
A simple rule to remember:

28. 7-3 Cell Boundaries

29. It lets the water through but not the spaghetti.
7-3 Cell Boundaries
selectively permeable
What?
It lets the water through but not the spaghetti.

30. 7-3 Cell Boundaries Facilitated Diffusion
facilitated diffusion - diffusion through a membrane with help from a transport protein.
Because…some molecules just can’t get across that membrane on their own.
Different proteins allow particular molecules.
Does not require energy.

31. 7-3 Cell Boundaries
Facilitated Diffusion

32. 7-3 Cell Boundaries Active Transport
Transport proteins within the membrane must use energy (ATP) to move substances either to the inside or outside of the membrane. (Against a concentration gradient.)
endocytosis
Phagocytosis
Pinocytosis
exocytosis

33. 7-3 Cell Boundaries
Active Transport

34. 7-3 Cell Boundaries Phagocytosis “CELL EATING” takes in large
particles by
engulfing them

35. pinch off to form vacuoles.
7-3 Cell Boundaries
Tiny pockets form
along cell membrane
fill with liquid,
pinch off to form vacuoles.

36. Vacuole fuses with membrane
7-3 Cell Boundaries
Vacuole fuses with membrane
forces contents out.

37. 7-3 Cell Boundaries Objectives After this section, can you…
Identify the main functions of the cell membrane and the cell wall.
Describe what happens during diffusion.
Explain the processes of osmosis, facilitated diffusion, and active transport.
End of Section 7-3