Cells:Structure and Function

      All organisms are made of cells. Bacteria, protists, fungi, plants and animals all share this feature of life. The cell is often regarded as the fundamental unit of life. In this chapter you will explore the the structure and function of the cell and its components.

Review Questions: [continue to the links or the outline]
  1. This section explores the major tools used to study the biology of cells. Understand the difference between light microscopes and electron microscopes. Read about the early microscopes.
  2. The two different types of electron microscopes yield different kinds of images (TEM and SEM). When would you choose to use either of them? Check out these great SEM images taken by Dennis Kunkel.
  3. Grasp the difference in scale as one explores the different levels of biology. The range from the size of a human being to molecules illustrates the need for different types of tools to explore the different levels.
  4. Why are cells limited in size? Understand the relationship between surface area and volume as the radius of the cell increases.
  5. Be able to describe the basic features of a prokaryotic cell(bacterial cells). It is especially important to be able to contrast these cells with the eukaryotic ones that will follow.
  6. Eukaryotic cells. This section needs special emphasis since it prepares you for understanding all of the sections that follow. Understand the importance of membrane bound structures (organelles) within the eukaryotic cell. They allow the cell to have unique microenvironments within the cell at the same time as the membranes increase the available surface area. Be able to explain the differences and similarities between plant and animal cells. Be able to recognize the structures with both a plant and an animal cell.
  7. Be able to describe the structure and function of the nucleus.
  8. What is an endomembrane system?
  9. Understand the structure and function of the rough endoplasmic reticulum.
  10. Understand the structure and function of the smooth endoplasmic reticulum. Be able to compare the rough and smooth endoplasmic reticulum.
  11. What do ribosomes do?
  12. What is the function of the Golgi apparatus?
  13. The lysosome is often referred to as the digestive organelle of the cell. Explain! How do lysosomes form and how do they digest "food"?
  14. Read about lysosomal storage diseases.
  15. Be able to explain the function of vacuoles in plant cells.
  16. Understand how the dynamic endomembrane system of organelles is functionally connected.
  17. What is the function of a chloroplast? Understand its structure. Which metabolic process takes place within the chloroplasts?
  18. Understand the structure and function of mitochondria. Which metabolic process takes place within the mitochondria?
  19. The cytoskeleton of a cell is composed of several different types of proteins. Be able to give examples of the function of the cytoskeleton (microfilaments)
  20. Understand the basic structure of flagella and cilia. What is their function? Give examples of where we can find flagella and cilia.
  21. Describe the structure of cell walls in plants. What is their function? Do animal cells have cell walls?
  22. What is the difference between a cell wall and a cell membrane?
  23. Test your knowledge of cellular structures. Focus on making a connection between the different structures and their function.
  24. Know the fundamental features of life: All life is made of cells, have DNA as their genetic material and use metabolism (energy, building blocks).
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Lecture Outline

Origin of concept
Hooke’s observations of cork
Schleiden and Schwann
basic unit of life
Unicellularity vs multicellularity
Limit in size: why? Surface to volume ratio
Major types of cells
prokaryotic cells (lack organelles/no nucleus) (bacteria)
eukaryotic cells (has organelles/has nucleus) (protists, fungi, plants and animals)
Size of cells:
 prokaryotic (~1-5 micrometers (micrometers))  (smallest bacteria ~0.2 micrometers)
 eukaryotic (~10-100 micrometers) (e.g. red blood cell in humans is 10 micrometers).
Cell Structure
plasma membrane
 bilayer of lipids
selective barrier
organelles (membrane bound structures)T cells attacking a cancer cell
(only in eukaryotes)
 genetic information
double membrane
 nuclear pores
 deoxyribonucleic acid (AT GC)
Endoplasmic reticulum (ER)
 Rough ER (RER)
  dotted with ribosomes
  protein synthesis
 Smooth ER (SER)
  lipid synthesis
Golgi Apparatus
 “sorting station”; ”postoffice”
 labels and modifies proteins
 ships them off to different destinations in vesicles
 digestive organelles/ contain digestive enzymes (analogous to a stomach)
 made by the Golgi apparatus
 “powerhouse of the cell”
 inner/outer membrane/matrix/cristae
 generates chemical energy (ATP)
(Adenosine TriPhosphate)
 by using cellular respiration
 site of photosynthesis (found only in algae and plants)
  (some bacteria are photosynthetic/ bacteria don’t have organelles)
converts light energy to chemical energy
 inner and outer membrane/ thylakoid membrane/ grana/ stroma
 contains pigments to capture light (mainly chlorophyll)
Endosymbiotic Theory
states that mitochondria and chloroplasts originated from bacteria
 that entered ancestral eukaryotic cells about 1.8-2 billion years ago.
  inner membrane similar to bacteria
  have their own circular DNA (like bacteria)
  divides by binary fission (like bacteria)
  their ribosomes are similar to the ones found in bacteria (70S)
 Benefit: a cell with mitochondria generate 17x as much energy as a cell without
    a cell w/ chloroplasts can use light as energy! Advantage is obvious.
 the liquid within the cell
 mainly water with a large number of different types of solutes
 protein filaments of different size classes spanning the interior of the cell
  directional transport of vesicles
Flagella/ Cilia
 9+2 structure of microtubules
 responsible for movement
 cilia short version of flagella
 e.g. many unicellular organisms such as Paramecium
e.g. in humans: sperm cells (flagella) / oviducts and tracheae (cilia)
Plant versus Animal Cells: plants have three unique organelles compared to animal cells
  1. Chloroplast (described above)
   remember: plants have both chloroplasts and mitochondria
  2. Vacuole (storage of compounds/waste/toxins/pigments)
  3. Cell wall made of cellulose
   shape/strength/turgor pressure
   “cage analogy”
 none of the three organelles (1-3) above are present in animal cells.

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Page created by: Peter Svensson
Updated:March 1,  2010