1. CHAPTER 7 CELL STRUCTURE & FUNCTION
PGS
CELL STRUCTURE & FUNCTION

2. ANTON VAN LEEUWNENHOEK
One of the first person’s to use a microscope.
Looked at pond water and saw small organisms.

3. ROBERT HOOKE Looked at plant tissues in 1665.
He specifically looked at cork.
Looked like tiny chambers he called “cells”

4. THE CELL THEORY
1. All living things are composed of cells.
2. Cells are the basic unit of structure & function in living things.
3. New cells are produced by existing cells.

5. Cells are the basic unit of life.
Cells come in all different shapes & sizes.
All living things are made up of cells!

6. Microscopy Today: Compound Light Microscope
Biology, 9th ed,Sylvia Mader
Chapter 04
Microscopy Today: Compound Light Microscope
Cell Structure and Function
Light passed through specimen
Focused by glass lenses
Image formed on human retina
Max magnification about 1000X
Resolves objects separated by 0.2 mm, 500X better than human eye

7. Compound Light Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 85 m
amoeba, light micrograph
eye
ocular lens
light rays
objective lens
specimen
condenser lens
light source
a. Compound light microscope
© Robert Brons/Biological Photo Service

8. Microscopy Today: Transmission Electron Microscope
Biology, 9th ed,Sylvia Mader
Chapter 04
Microscopy Today: Transmission Electron Microscope
Cell Structure and Function
Abbreviated T.E.M.
Electrons passed through specimen
Focused by magnetic lenses
Image formed on fluorescent screen
Similar to TV screen
Image is then photographed
Max magnification 1000,000sX
Resolves objects separated by mm, 100,000X better than human eye

9. Transmission Electron Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
200 nm
pseudopod segment, transmission electron
micrograph
electron source
electron beam
electromagnetic
condenser lens
specimen
electromagnetic
objective lens
electromagnetic
projector lens
observation screen or
photographic plate
b. Transmission electron microscope
© M. Schliwa/Visuals Unlimited

10. Microscopy Today: Scanning Electron Microscope
Biology, 9th ed,Sylvia Mader
Chapter 04
Microscopy Today: Scanning Electron Microscope
Cell Structure and Function
Abbreviated S.E.M.
Specimen sprayed with thin coat of metal
Electron beam scanned across surface of specimen
Metal emits secondary electrons
Emitted electrons focused by magnetic lenses
Image formed on fluorescent screen
Similar to TV screen
Image is then photographed

11. Scanning Electron Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
500 m
amoeba, scanning electron micrograph
electron gun
electron beam
electromagnetic
condenser
lenses
scanning coil
final
condenser
electron
lens
detector
secondary
electrons TV
specimen
viewing
screen
c. Scanning electron microscope
© Kessel/Shih/Peter Arnold, Inc.

12. Microscopy and Amoeba proteus
Biology, 9th ed,Sylvia Mader
Chapter 04
Microscopy and Amoeba proteus
Cell Structure and Function
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 85 m
200 nm
500 m
amoeba, light micrograph
pseudopod segment, transmission electron
micrograph
amoeba, scanning electron micrograph
electron source
electron gun
eye
electron beam
ocular lens
electron beam
light rays
electromagnetic
condenser lens
electromagnetic
condenserl
enses
specimen
electromagnetic
objective lens
objective lens
scanning coil
specimen
condenser lens
final
Condenser
lens
electromagnetic
projector lens
electron detector
secondary
electrons
observation screen or
photographic plate TV
Viewing
screen
specimen
light source
a. Compound light microscope b. T
ransmission electron microscope
c. Scanning electron microscope
a: © Robert Brons/Biological Photo Service; b: © M. Schliwa/Visuals Unlimited; c: © Kessel/Shih/Peter Arnold, Inc.

13. Cells are the basic unit of life.
Cells come in all different shapes & sizes.
All living things are made up of cells!

14. Structures common to most cells
1. cell membrane
2. DNA
3. cytoplasm

15. Biologist divide cells into one of two types:
1. PROKARYOTE: do not contain a membrane bound nucleus
(all bacteria are prokaryotes)
2. EUKARYOTE: DO contain a membrane bound nucleus, and most have other specialized organelles.

16. Chapter 7, Section 2 The Plasma Membrane
Main Idea: The plasma membrane helps to maintain a cell’s homeostasis.
Essential Questions:
How does a cell’s plasma membrane function?
What are the roles of proteins, carbohydrates, and cholesterol in the plasma membrane?

17. Function of the Plasma Membrane
Separates cells from the watery environment
Maintain homeostasis – the process of maintaining balance in an organism’s internal evnrionment
How does it do this?
Selective permeability – a property of the plasma membrane that allows some substances to pass through while keeping others out.

18. Cell Boundries
Cell membrane is selectively permeable & provides protection & support
Small particles move more easily than large particles
Neutral molecules more easily than charged ions
Non polar more easily than polar
Substances that move across the cell membrane can vary from cell to cell, or the same cell from moment to moment
Major component of the cell membrane is a lipid bilayer
Proteins & carbohydrates are also found in the cell membrane

19. Cell membrane

20. Cell Wall Found in plants, algae, fungi, and nearly all prokaryotes.
MAIN FUNCTION: provide support & protection for the cell
Animal cells DO NOT have cell walls!

21. Maintaining Homeostasis
All cells must regulate what materials enter & leave; sometimes no energy is required to do this, other times energy is required
Passive transport – no
energy is required to
move substances from
an area of high
concentration to an
area of low concentration

22. Types of Passive Transport
Diffusion – the movement of a solute from an area of high conc. To an area of low conc. Equilibrium is reached when an equal number of molecules move in both directions

23. Types of Passive Transport
Osmosis – the diffusion of water across a membrane from a region of high water concentration to a region of low water concentration

24. Types of Passive Transport
Facilitated diffusion – process by which transport proteins carry certain molecules across a membrane from high concentration to low concentration

25. Types of Osmotic Solutions
Isotonic solution – solution has the same solute concentration as that of the living cell, there is no net movement of H2O

26. Types of Osmotic Solutions
Hypertonic solution– solution has a higher solute concentration than the inside of the cell; H2O moves out of the cell; animal cell will shrink (crenate); vacuole collapses in plant cells

27. Types of Osmotic Solutions
Hypotonic solution – solution has a lower solute concentration than the inside of the cell; H2O moves into the cell; animal cell will burst (lyse); plant cell will not (why?)

28. Types of Osmotic Solutions
(animation of isotonic, hypertonic, hypotonic solutions)

29. Types of Osmotic Solutions

30. Active Transport
Energy is required to move substances from an area of low concentration to an area of high concentration; allows cells to have internal environments that are different chemically from the external environment

31. Types of Active Transport
Molecular transport - proteins in the cell membrane work as “pumps” to move substances against the concentration gradient

32. Types of Active Transport
Endocytosis - process by which a cell takes material into the cell by infolding of the cell membrane
Phagocytosis – large particles taken in
Pinocytosis – H2O or small particles are taken in
Exocytosis – process by which cell releases large amounts of material; vacuole membrane fuses with the cell membrane

33. Types of Active Transport