1. Cell Structure and Function
Chapter 7
Biology
Miller • Levine

2. The Scientists… Robert Hooke (1665) Anton van Leeuwenhoek (1674)
Viewed cork under a microscope
Called the chambers he saw “cells”
Anton van Leeuwenhoek (1674)
First to see living organisms in a drop of water

3. The Scientists… Matthias Schleiden (1838) Theodor Schwann (1839)
All plants are made of cells
Theodor Schwann (1839)
All animals are made of cells
Rudolf Virchow (1855)
All cells come from preexisting cells

4. The Cell Theory All living things are composed of cells
Cells are the basic units of structure and function in living things
New cells are produced from existing cells

5. Unicellular vs. Multicellular
Unicellular – single-celled organism
Multicellular – many-celled organism
Cell specialization – cells are specialized to perform certain functions
Cells → Tissues → Organs → Organ systems → Organism

6. Prokaryotes vs. Eukaryotes
Have a cell membrane & cytoplasm, but do not have a nucleus
Ex. Bacteria such as E.coli
Eukaryotes
Have a nucleus, cell membrane, cytoplasm & organelles
Ex. Plants, Animals, Fungi

7. Prokaryotes vs. Eukaryotes

8. Basic Cell Structures
Cell membrane – thin, flexible barrier around the cell; protects the cell
Present in all cells
Selectively permeable
Contains floating layers SS

9. The Fluid Mosaic Model Hydrophobic vs. Hydrophilic Hydro = water
Phobic = fear/hate Philic = love

10. material inside the cell membrane (not including the nucleus)
Cytoplasm –
material inside the cell membrane (not including the nucleus)
Prokaryotes & Eukaryotes

11. Cell Wall
Found in many organisms, including plants, algae, fungi and nearly all prokaryotes
Not found in animal cells
Lies outside the cell membrane but is porous
Main function is to provide support & protection for the cell

12. Nucleus
Almost all eukaryotic cells, including plants and animals have a nucleus
Prokaryotes do not have a nucleus
Controls most cell process and contains the DNA

13. Nucleolus and Nuclear Envelope
Inside the nucleus
Where ribosomes are made
Nuclear Envelope:
Double-membrane layer around the nucleus
Allows material to move into and out of the nucleus

14. Nucleus

15. Cytoskeleton Found in all eukaryotic cells Not found in prokaryotes
A network of protein filaments that helps the cell maintain its shape
It also is involved in cell movement

16. Microfilaments and Microtubules
made of actin, tough and flexible, functions for cell movement, assemble and disassemble
the microtubules for cell movement
made of tubulis, maintain cell shape, used in cell division with centrioles and build the projections of cilia and flagella

17. Ribosomes Found in all cells Main function is to make proteins
Can be found floating in the cytosol or attached to endoplasmic reticulum

18. Endoplasmic Reticulum (ER)
Found only in eukaryotic cells
Where components of the cell membrane are assembled
Two kinds: Smooth ER & Rough ER
Smooth ER: no ribosomes; makes lipids
Rough ER: has ribosomes; involved in making proteins

19. Endoplasmic Reticulum

20. Golgi Apparatus Found only in eukaryotic cells
Enzymes attach carbohydrates & lipids to proteins
Send proteins to their final destination

21. Lysosomes Found in animal cells only
Break down lipids, carbohydrates & proteins from food into particles that can be used by the cell
Also break down “dead” organelles

22. Vacuoles Not found in prokaryotes
Animal cells have small or no vacuoles
Plant cells have a large central vacuole
Store materials such as water, salts, proteins & carbohydrates

23. How endocytosis and exocytosis works in animal cells: Note the food Vacuole and Lysosomes

24. Chloroplasts They have their own DNA Found in all plant cells
Some prokaryotes have them, but most do not
Use the energy from sunlight to make energy-rich food molecules (carbohydrates) during photosynthesis

25. Mitochondria converts stored energy to a usable form
double membrane with folds to increase surface area
it also has its own DNA

26. Endosymbiotic Theory (CH 19)

27. Diffusion
Molecules move from an area of high concentration to an area of low concentration
Movement continues until equilibrium is reached
Many substances move across the membrane by diffusion
Does not require energy (passive transport)

28. Diffusion Rate of Diffusion is affected by: Temperature
concentration gradient
Rate of Diffusion is affected by:
Temperature
Steepness of the gradient
Size of Molecules

29. Facilitated Diffusion
Some molecules cannot cross the membrane without help
Some of the proteins in the membrane form protein channels
Materials still move from higher to lower concentrations
No energy is required

30. Facilitated Diffusion
htlfacilitated diffusion (fast and specific but energy free)

31. Osmosis: A special name for a special Molecule!
The diffusion of water
Isotonic – equal concentration
Nothing happens (normal)
Hypertonic – higher concentration
Water moves out of the cell (shrivels)
Hypotonic – lower concentration
Water moves into the cell (pops at the extreme)
No energy is required
osmosis

32. Effects of Osmosis on Cells

33. Osmotic Pressure In pure water, an animal cell would burst
Plant cells are protected by their cell wall
Some freshwater organism have special structures like contractile vacuoles to get rid of extra water

34. Active Transport: Working to go Uphill---Up the gradient.
Materials move from lower concentration to higher concentration
Requires an input of energy
Works kind of like a pump

35. Transport of Large Amounts Bulk Transport
Endocytosis – movement into the cell
Phagocytosis – “cell eating” – solid particles
Pinocytosis – “cell drinking” – particles dissolved in water
Exocytosis – movement out of the cell

36. Phagocytosis

37. Pinocytosis
animation

38. (homeo = same Stasis = state
Homeostasis and Cells
(homeo = same Stasis = state
SIngle and cells and Multicellular organisms - maintain a certain level of conditions in its environment
Multicellular organisms divide and conquer tasks and jobs to maintain homeostasis. This takes communication!

39. Cell to cell communication:
cellular signals speed up or slow down cell activities
receptors (1)in the cell membrane and (2) inside the cytoplasm carry electrical and chemical messages.
review of phospholipid membrane and receptor visual