1. Cell Structure and Function
Chapter 4

2. Chapter 4 Vocabulary Cell Mitochondrion Cell theory
Endoplasmic reticulum
Plasma membrane
Golgi apparatus
Cytoplasm
Lysosome
Nucleus
Microtubule
Prokaryote
Microfilament
Eukaryote
Cilium
Phospholipid bilayer
Centriole
Nuclear envelope
Cell wall
Nucleolus
Central vacuole
Ribosome
Plastid

3. The History of Cell Biology

4. The Discovery of Cells
All living things are made up of one or more cells
Cell – the simplest unit that can perform all of life’s processes
The use of microscopes allowed scientists to see cells for the first time

5. The Discovery of Cells Hooke Leeuwenhoek English scientist, 1665
Early light microscope
Observed cork cells
Coined the term “cell”
Leeuwenhoek
First to observe living cells
“animalcules” = protists

6. The Cell Theory
Came about 150 years after Hooke and Leeuwenhoek
Developed by scientists Schleiden, Schwann, and Virchow
CELL THEORY:
All living organisms are composed of one or more cells.
Cells are the basic units of structure and function in an organism.
Cells come only from the reproduction of existing cells.

7. Self Quiz What are the three parts of cell theory?
Who discovered the first cells? What were they?
What invention was important in the discovery of cells?

8. Introduction to Cells

9. Cell Diversity Diverse in shape, size, organization
A cell’s function influences its physical features

10. Cell Shape
Cell shape reflects function

11. Cell Size Surface area – to – volume ratio Limits the size of the cell
Relationship of the cell’s outer surface area to its volume

12. Cell Size
Materials needed by cell and waste produced pass in and out of the surface
Surface area must be big enough to allow materials to enter and leave cell quickly
This is why most cells are microscopic

13. Two Types of Cells
Prokaryotes – lack a nucleus and membrane-bound organelles
Ex. Bacteria
Eukaryotes – have a nucleus and membrane-bound organelles
Ex. Plants, Birds, Mammals

14. Prokaryotic Cell

15. Eukaryotic Cell

16. Prokaryotes Lack a nucleus Genetic information is DNA
Genetic information concentrated in a part of the cell called a nucleoid

17. Eukaryotes Have a nucleus Have membrane-bound organelles
Organelles – well-defined, intracellular bodies that perform specific functions for the cell
Generally larger than prokaryotes

18. Cellular Organization
Cells are grouped based on their function
Groups of cells took specific roles

19. Cellular Organization
CELLS
Tissue – a group of similar cells and their products that carry out a specific function
Organ – groups of tissues that perform a particular job in an organism
Organ system – a group of organs that accomplish related tasks

20. Self Quiz What is the difference between prokaryotes and eukaryotes?
What types of organisms are prokaryotes?
What types of organisms are eukaryotes?
Why are cells so small?

21. Basic Parts of a Cell All cells have: An outer boundary
Plasma membrane
Inner substance
Cytoplasm
Control region
Nucleus (in eukaryotes)

22. Plasma Membrane (Cell Membrane)
Only allows certain molecules to enter or leave the cell
Separates internal metabolic reactions from the external environment
Allows cells to excrete waste
Cell can interact with environment

23. Plasma Membrane (Cell Membrane)
Membrane lipids
Membrane proteins
Fluid mosaic model

24. Membrane Lipids Cell membrane made primarily of phospholipids
Hydrophilic phosphate head
Hydrophobic fatty acid tails
Called the phospholipid bilayer

25. Membrane Proteins Cell membrane contains proteins
Integral proteins – embedded
Peripheral proteins – lie only on one side of the membrane

26. Membrane Proteins
Play important roles in transporting molecules into the cell.
Channels
Pores
Transport sites
Chemical messenger attachment site

27. Fluid Mosaic Model
Phospholipid bilayer behaves more like a fluid than a solid.
Can move like a boat on the ocean
Pattern “mosaic” constantly changes

28. Self Quiz What is the role of the cell membrane?
What is a phospholipid composed of?
How does the phospholipid bilayer work?

29. Nucleus Houses and protects the cell’s genetic information
DNA
Site where DNA is transcribed to RNA

30. Nucleus Nuclear envelope – double membrane that surrounds the nucleus.
Nuclear pores – provide passageways for RNA and other materials

31. Nucleus Nucleolus – a denser area of the nucleus
The site where DNA is concentrated when making ribosomal RNA
Ribosomes – organelles made of protein and RNA that direct protein synthesis in the cytoplasm

32. Mitochondria
Mitochondria – tiny organelles that transfer energy from organic molecules to ATP
ATP powers most cell chemical reactions
“powerhouse” of the cell
Inner and outer phospholipid membrane
Folds in the inner membrane called cristae

34. Ribosomes Responsible for building protein
Made up of protein and RNA molecules
Made up of subunits
Large subunit
Small subunit

35. Self Quiz What is the role of the nucleus?
Why are mitochondria so important?
Why is it important for mitochondria to have many folds?
What is the structure of a ribosome? What do they do?

36. Activity Why is your organelle the best?
Come up with an argument for why your organelle would be the most important in the cell.
What does it do?
Why is it important?
Could the cell function without it?

37. Endoplasmic Reticulum (ER)
System of membranous tubes and sacs called cisternae
Functions as an intercellular highway
Allows molecules to move from one part of the cell to another
Two types:
Rough ER
Smooth ER

38. Rough ER System of interconnected, flattened sacs
Covered with ribosomes
Produces phospholipids and proteins
Ex. Digestive enzymes

39. Smooth ER Has smooth appearance Lacks ribosomes
Builds lipids, such as cholesterol
Forms an interconnected network with the rough ER

40. Golgi Apparatus System of flattened, membranous sacs
Vesicles move through the Golgi
Vesicle contents is modified
Proteins get “address labels” and get directed to other parts of the cell

41. Vesicles Small, spherically shaped sacs
Several types present in the cell
Perform various roles
Classified by their content

42. Types of Vesicles Lysosomes Peroxisomes Glyoxysomes Endosomes
Food vacuoles
Contractile vacuoles

43. Vesicles Vesicle Type Functions Lysosomes
Contain digestive enzymes; break down unused large molecules
Peroxisomes
Neutralize free radicals; break down toxins in the body and kill bacteria
Glyoxysomes
Break down stored fats in seeds
Endosomes
Engulf material to take to the lysosomes to digest
Food vacuoles
Store nutrients
Contractile vacuoles
Contract to expel excess water from a cell

44. Cytoskeleton Network of thin tubes and filaments in cytosol
Gives shape to cell
Like tent poles
Acts as tracks for movement around cell
Composed of
Microtubules
Microfilaments
Intermediate filaments

45. Microtubules Hollow tubes Made of protein called tubulin
Radiate out from centrosome
Hold organelles in place
Maintain cell shape

46. Microfilaments Long threads of protein called actin
Contribute to cell movement
Ex. Contraction of muscle cells

47. Cilia and Flagella
Hair-like structures that extend from the surface of the cell
Assist in movement
Cilia are short and numerous
Flagella are longer and less common

48. Self Quiz What are the different types of vesicles? What do they do?
What is the difference between the rough ER and smooth ER?
What roles do microtubules and microfilaments play in the cell?
What is the role of the Golgi apparatus?

49. Plant Cells

50. Plant Cells Plant cells have some structures not found in animal cells
Cell wall
Central vacuole
Plastids

51. Cell Wall
Cell wall – a rigid layer that lies outside the cell membrane
Contains cellulose, a carbohydrate
Plants have primary and sometimes secondary cell walls

52. Central Vacuole
Central vacuole – a large fluid filled organelle that stores water, enzymes, metabolic wastes, and other materials
A large reservoir
Can make up 90% of the plant cell’s volume

53. Plastids Plastids – organelles surrounded by a double membrane
Contain their own DNA (like mitochondria)
Several types
Chloroplasts
Chromoplasts
Leucoplasts

54. Chloroplasts
Use light energy to make carbohydrates from carbon dioxide and water
Contains thylakoids, flattened membranous sacs
Thylakoids contain chlorophyll
Chlorophyll – absorbs light and captures light energy for the cell

55. control region

56. Eukaryotic Cells include Both of which have Nucleus Which have
Cell wall