1. Cell Structure and Function
Unit 7

2. 1 Robert Hooke named cell while looking at cork in 1665

3. 2 Anton van Leeuwenhoek saw tiny organisms in pond water in 1674
called them “animalcules”

4. 3 The cell theory states:
All living things are composed of cells. (1838 Schleiden said all plants; 1839 Schwann said all animals)
Cells are the basic units of structure and function in living things.
New cells are produced from existing cells. (1858, Rudolf Virchow)

5. 4 Tools of the trade: Light vs. Electron

6. 5 electron microscopes
1000 times better magnification than light microscopes
must be placed in a vacuum
chemically preserve their samples first and then carefully remove all of the water
transmission electron microscopes (TEMs)
must be cut first into ultrathin slices so that you can see what is inside
scanning electron microscopes (SEMs)
produces stunning three-dimensional images
See the surface

8. 7 Even though cells come in all shapes and sizes, what do all cells have?
DNA
Cell Membrane
What are the levels of organization for a living thing?
Cell – Tissue – Organ – Organ System
In order to have different tissues and organs, cell must specialize for different functions.

9. Carry out all 8 characteristics of living things, but… No nucleus
Usually smaller and simpler
Usually unicellular organism
Example: bacteria

10. 9 prokaryotes - monerans

11. 10 Have a nucleus Contain several structures and internal membranes
Can be unicellular (protists) or multicellular organisms
Larger, more complex, and have a large diversity (specialized)

12. 11 Prokaryotes vs. Eukaryotes

13. 12 Nucleus: the control center
Contains DNA that contains the code to make proteins and other important molecules
Has double-layer membrane with pores
Has a nucleolus, which is a small dense region where ribosomes are made

14. 13 Cytoplasm Fluid-filled portion of the cell outside the nucleus
Organelles are found here; literally means “little organs”

15. 14 Vacuoles: Storage
Saclike membranes that store things like water, salts, proteins and carbohydrates

16. 15 Specialized Vacuoles
In plants, have one central vacuole that stores water that helps hold cell shape with water pressure
Contractile vacuoles in some protists contract to expel water from the cell

17. 16 Lysosomes: the clean-up crew
Small organelles filled with enzymes
Break down lipids, proteins and carbohydrates into smaller molecules that the cell can use
Break down old organelles and other unwanted/foreign material
All animals have these and some specialized plant cells

18. 17 Cytoskeleton: structure
Helps the cell maintain shape and helps with cell movement
Help with internal organization
Helps with transport within the cell, acting as a conveyor belt

19. The cytoskeleton is made up of microfilaments and microtubules 18
The cytoskeleton is made up of microfilaments and microtubules
Microfilaments: thin structures that help with support and cell movement (contract and relax for amoebic movement)
Microtubules: important for cell shape and cell division

20. 19 Centrioles Microtubules found only in animal cells near the nucleus
Help organize chromosomes on a network of microtubule fibers during cell division

21. 20 Cilia and Flagella
Microtubules found on the cell surface that help with movement
Always in a arrangement

22. 21 Ribosomes: the machine!
Where proteins are assembled
Made of RNA and protein
Found in the cytoplasm and attached the ER

23. 22 Endoplasmic Reticulum (ER)
ER with ribosomes attached is called Rough ER
Rough ER - Modify proteins made by the ribosomes that will be released/secreted from the cell or incorporated into the cell membrane
Once the proteins are modified, they leave the ER by pinching off into a vesicle
Found around the nucleus
Help transport materials in the cell

24. 23 Smooth ER
Smooth ER (no ribosomes attached) is key in creating cell membrane lipids and detoxifying (drugs)

25. 24 Golgi Apparatus Stack of flattened membranes
Vesicles containing proteins leave the ER and then merge with the Golgi Apparatus
Here the proteins are modified, sorted and packaged either for storage in the cell or to be transported outside the cell
They are then shipped out through another vesicle

26. 25 Making a Protein DNA is encoded into mRNA in the nucleus
mRNA leaves the nucleus to go to the ribosomes
Ribosomes read the mRNA and create a protein based on the code
Proteins enter the Rough ER for modification and then are shipped via vesicles
Vesicles merge with Golgi Apparatus where they are further modified and then packaged and shipped out through another vesicle

28. 27 Chloroplasts Found in plants and other photosynthetic organisms
Capture energy from the sun and convert it into a glucose (contains chemical energy): photosynthesis
Two membranes
Contain stacks of membranes called granum
Contain chlorophyll – green pigment that absorbs light

29. 28 Chloroplasts

30. 29 Mitochondria: the power plant
Found in nearly all eukaryotic cells
Convert chemical energy in glucose into energy that the cell can use easier (ATP)
Have two membranes
Inner membrane is folded up inside the organelle

31. 30 Endosymbiotic Theory Mitochondria and chloroplast both contain DNA
So, theory proposes that a symbiotic relationship between primitive eukaryotic cells and the prokaryotic cells within them over time evolved into the eukaryotic cells we know today

32. 31 Cell Wall To support, shape and protect the cell; rigid
Lie outside the cell membrane
Porous to allow things like water, O2, and CO2 to pass easily
In plants (cellulose) and prokaryotes

33. 32 Cell Membrane: traffic control
ALL cell have them!
Flexible lipid bilayer that regulates what enters and leaves the cell, and also protects and supports

34. 33 lipids in the cell membrane
Hydrophobic tails are “protected” from water by forming a double layer with only the hydrophylic end coming in contact with water

35. 34 Fluid Mosaic Model
Various proteins are contained within the cell membrane, and many of these may have carbohydrate chains attached
The variety creates a mosaic
These proteins are able to move freely among the lipids in the lipid bilayer, making it appear to be a fluid

36. 35 Fluid Mosaic

37. 36 What do the proteins and carbohydrates do in the cell membrane?
Proteins serve as channels and pumps to help move things in and out across the cell membrane
Some proteins have a carbohydrate chain attached, and these serve to help cells recognize other cells like an identification card

38. 37 Selectively Permeable
Describes cell membranes because some things are allowed to enter and others are not
Also called semi-permeable

39. 38 Plant vs. Animal Cells

40. 39 Cell Specialization
We have seen the difference in prokaryotes and eukaryotes, and..
We have seen the difference in plant and animal cells.
The human body contains 210 different types of cells out of the approximate 100 trillion cells in your body!
These cells vary in shape, size, and the amount of organelles that they contain, all dependent upon the cell’s function

41. 40 Different Human Cells