The Building Blocks of Life
What cell part is never found in animal cells?
One theory of the origins of cells states that the first life on earth consisted of several types of tiny protocells, cell-like organisms. These organisms were able to survive and reproduce in a very limited environment because of their simplicity. Over time, some of these protocells came together and shared their specialization in a symbiotic relationship. These colonies of protocells eventually became the cells we know today.
Except for bacteria, all organisms we will study this year will be eukaryotes.
Plant cells and animal cells are similar, but do not have exactly the same cell parts and shape.
1. What is the animation in the box showing? (explain in at least one paragraph) You may need to hit refresh on your browser to reactivate the animation.
2. Watch the animation of water molecules moving across a selectively permeable membrane. Why are the water molecules moving to the right? Hint: Osmosis (Explain in at least a paragraph)
3. Look at the section on "Types of Solutions". Explain what would happen to a cell if it was put in the following solutions:
4. What is Active Transport and when is it needed by the cell?
1. Read through each of the concepts (1-5)
2. Complete each of the practice items within each concept
3. Print completed: concept 1 practice & concept 4 practice.
4. Complete the practice quiz at the end, must get a 100% (print it off)
· On the outside of some cells, bacteria and plants, this structure functions for support and protection.
· There are pores in the cell wall allowing substances to come in contact with the cell membrane.
· Types of cell walls:
a. Primary cell wall - formed during cell growth, it is composed of parallel layers of cellulose and pectin. This structure allows the cell to expand as it grows. While it does provide support, it is not nearly as strong as the secondary cell wall.
b. Secondary cell wall - formed after cell growth stops, it is composed of interwoven cellulose and lignin fibers. This structure is very strong, but does not give. It gives plants their "woody" characteristic.
Size of living things:
The smallest known living thing on Earth is a bacteria in the genus Coxiella. These bacteria are about 8 millionths of an inch (0.2 micrometers) in diameter. Their small size means these bacteria contain only 100 million to 120 million atoms. While this may seem like a large number, keep in mind that the human body has over 5 Billion cells. It is believed that fewer atoms would be unable to build the structures needed to store information and carry out the metabolic processes needed for life.
The largest known animal is the blue whale, Balaenoptera musculus. It is known to reach lengths over 100 feet (30+ meters) and weigh 120 tons. The chart below indicates that all animal cells are about 10 micrometers in diameter. This means that the cells of a blue whale and a human are essentially the same size.
*After completing the table, answer the “to do” question (stated above) here. Explain your answer.
· Webcytology Simulation - Create your own unicellular species
· Cellular Biology - Altruis Biomedical Network
· Biology 100 - Wayne's World
· The Cell - Thinkquest
· Cell Structure - Carroll College
· Cell Biochemistry - Carroll College
· Virtual Cell - Virtual Cell
· The Cell Nucleus - University of Texas Medical Branch at Galveston
· Cell Membranes - Texas A&M University
· Cells Alive - By James A. Sullivan
· Cell & Molecular Biology Online - Links by Pamela Gannon
· Cell Biology Hypertextbook - Massachusetts Institute of Technology
· Digital Learning Center for Microbial Ecology - Michigan State University
· Cell Membrane Tutorial - The Biology Project
Animal cells never have a cell wall.
Red blood cells do not have a nucleus.