1. Structure and Function
Cells
Structure and Function

2. What We Will Learn How were cells discovered?
What are the basic differences between types of cells?
How are cells structured?
What are the functions of different cell structures – how do they work?

3. Cellular Basis of Life Cell Smallest living unit of any organism
Capable of carrying out all life functions
Uni-cellular life – single cell
Multi-cellular life – many cells with different functions

4. History of Cell Discovery
Most cells too small to see with naked eye
Invention of microscope enabled scientists to discover and study cells

5. Scientists and Cell Study
Leewenhoek:
Simple microscope
Observed organisms in pond water, blood cells, bacteria
Hooke:
Crude compound microscope
Observed cell walls of cork
Coined term “cells”

6. Schleiden: (Botanist)
Stated all plants are made of cells
Schwann: (Zoologist)
Stated all animals made of cells

7. Virchow: Brown: Stated all cells come from pre-existing cells
First to identify an internal
cell structure (nucleus)
From this research and observation of living
things a scientific theory was developed
(took over 200 years!)

8. Cell Theory All living things made up of cells
Cells are the basic units of structure and function in living things
New cells come from existing cells

9. Exceptions to Cell Theory
Viruses:
Need host cell to carry out life processes

10. Exceptions to Cell Theory
Mitochondria & Chloroplasts:
Organelles that reproduce inside cell
Have own unique genetic material
Can’t survive outside of cell

11. Exceptions to Cell Theory
The First Cell
Where did it come from?
What was it like?

12. 2 Basic Types of Cells Prokaryotes Eukaryotes Both Types: Contain DNA
Are surrounded by cell (plasma) membrane
Carry out all life functions

13. Prokaryotes No nucleus Lack internal membrane bound organelles
DNA in cytoplasm
Metabolic functions take place in cytoplasm
Smaller, simpler more primitive cells
Ex: bacteria

15. Eukaryotes Nucleus encloses DNA
Specialized membrane bound organelles (more compartmentalized)
Larger, more complex
Ex: protists, plants, animals, fungi

16. Cell Structure and Organelles

17. The Cell as a Factory
Each organelle carries out a specialized function.
Ex:
Oversee cell activities
Provide energy
Produce products
Get rid of wastes

18. Cell as Factory

21. Cell Membrane Also called “plasma membrane”
Separates inside of cell from outside environment

22. Made of lipid and protein bi-layer Called the “fluid mosaic model”
Controls substances going in and out of cell (selectively permeable)

23. Channel Proteins:
allow for selective movement of materials in and out of cell membrane

24. Phospholipids: molecules that line up in a bi-layer (two layers) to make cell membrane
Hydrophilic = “water loving” end
Hydrophobic = “water fearing” end

25. Cell Wall Found in plants, fungi, some bacteria and protists
NOT in animal cells
Inflexible structure
Made of cellulose fibers woven together
In fungi made of chitin
Protect cell and give it support and shape

26. Cytoplasm Liquid, gel-like substance inside cell membrane (75% water)
Many substances
dissolved in it
Most chemical
reactions take place
here.

27. “Cyclosis”: the movement of materials through cytoplasm

28. Cytoskeleton Internal framework inside cytoplasm Made of fibrous rods
microfilaments
microtubules
Maintains cell shape
Supports and moves organelles

29. Images of Cytoskeleton

30. Nucleus Directs cell activities Eukaryotic Cells ONLY!!
Control center for metabolic functions and reproduction
Provides instructions for making proteins and other molecules for the cell

31. Structure of the Nucleus

32. Nuclear envelope: membrane surrounding nucleus
Nuclear pores: allow materials to leave or enter
Nucleolus: dark inner area. Ribosomes formed here

33. Chromatin:
coiled DNA, in the nucleus
contains instructions for building proteins
unwound and spread out

34. Communicates with rest of cell by movement of molecules through nuclear pores
During cell division, chromatin condenses to form chromosomes that replicate and divide

36. Endoplasmic Reticulum (E.R.)
Channels to move materials inside cell
Highly folded (increases surface area)

37. Rough ER:
“bumpy” with ribosomes
attached to surface
Smooth ER:
doesn’t have ribosomes
on surface

39. Ribosomes Site of protein synthesis Small round structures
Cell has a lot of them (needs proteins!)
May be free floating in cytoplasm or attached to the “rough” E.R.

40. Golgi Bodies Stack of membranes (like pancakes)
Involved in modifying, packaging, storing and releasing products

41. Vesicles:
packages containing proteins that are pinched off to be used inside cell or transported out.

43. Lysosomes Membrane enclosed vesicles Hydrolytic digestive enzymes
Breaks down food and worn out cell parts
Formed by Golgi Bodies

44. Vacuoles Stores water, food, wastes Much larger in plant cells
Used to help give cell shape, structure

45. Food Vacuoles: merge with lysosomes to digest food

46. Contractile Vacuoles:
Found in single celled freshwater organisms like paramecium
“contract” to pump out excess water from cell

47. Energy and the Cell

48. Mitochondria Powerhouse of the cell Site of cellular respiration
Makes usable energy
(ATP)

49. Simple sugars are broken down to release energy as ATP
The more energy a cell needs the more mitochondria it has!

50. Cristae:
Highly folded inner membrane that allows for increased surface area for cellular respiration reactions

51. Chloroplasts FOUND IN PLANT CELLS ONLY!! Site of photosynthesis
Light energy is transformed to chemical energy in the form of sugar
Chlorophyll: (green pigment) that captures sunlight

52. Grana: Inner membranes in “coin” stacks containing chlorophyll
Stroma: enzyme filled fluid surrounding grana

53. Endosymbiotic Theory
Mitochondria and chloroplasts have own DNA and can reproduce on their own.
Perhaps they were a primitive type of prokayotic cell that became incorporated into another
Symbiotic relationship = both cells benefit
Evolution of Complex Life

54. Centrioles FOUND IN ANIMAL CELLS ONLY!!
Pair of small cylindrical organelles found near nucleus
Function in cell division to pull chromosomes apart

56. Cell Movement
Cilia: short hair like projections used for locomotion

57. Flagella: long whip-like tail used for locomotion

58. Pseudopods: “false foot”
Projections of the cell membrane
Used for locomotion
Used to surround and engulf food

59. Limitations of Cell Size
Size is limited by the cell’s need to intake nutrients and excrete wastes
Smaller the cell is, the closer all parts are to the external environment.
Surface area to volume ratio

60. http://www. youtube. com/watch
Passive transport
Osmosis
Membrane

61. Cellular Organization
In multicelluar organisms cells are just the start of how things are organized.
Cells
Tissues: groups of cells that function together to perform an activity
Organs: groups of tissues performing one main function
Organ Systems: organs working together
Organism