NH+9-9-07+homework

3.1- What is a cell? 1. What does the cell theory clearly state? The cell theory states that a cell is the basic unit of life. All living things are made up of cells. Nothing smaller than a cell is alive. New cells arise from preexisting cells.

2. Why are cells so tiny? Cells are so tiny because of the surface area-to-volume ratio. The volume corresponds to the function of the cell. Bigger cells need more nutrients and create more waste. But, as the cells gets bigger, the surface area proportionate to its size actually gets smaller.

3. How do the light microscope and electron microscope differ from one another? The light microscope uses mirrors and light shone through the organism to magnify the image to a point that the human eye can still see. The transmission electron microscope uses a stream of electrons to magnify the image. The magnification of an electron microscope is much larger than that of the light microscope. The human eye can not see the magnification through the electron microscope, so the image much be projected onto a fluorescent screen or printed onto photographic film. The scanning electron microscope uses a narrow beam of electrons scanned over the organism to give a 3D image. The light microscope allows you to see living organisms while the electron microscopes kill the organisms in the process.

6.3 White Blood Cells and Defense Against Disease 1. What are the different types of white blood cells? Granular Leukocytes -Neutrophils -Eosinophils -Basophils Agranular Leukocytes -lymphocytes -Monocytes

2. What is the structure and function of each type of white blood cell? Granular Leukocytes -Neutrophils- have a multilobed nucleus. they account for 50-70% of all white blood cells. they are the first responders to bacterial infection. Does phagocytosis which is essential to overcoming an infection by a pathogen. -Eosinophils- have a bilobed nucleus. Increase in number in the event of a parasitic worm infection or allergic reaction -Basophils- have a lobed nucleus. Release histamine associated in allergic reactions. Agranular Leukocytes -lymphocytes- 25-25% of WBCs. They are responsible for specific immunity to particular pathogens and their toxins -B-cells- produce antibodies -T-cells- directly destroy pathogens -Monocytes - largest of WBCs. dendritic cells. phagocytize pathogens, old cells, and cellular debris. stimulate other WBCs to defend the body.

3. Name and describe three disorders of white blood cells. SCID or severe combined immunodeficiency disease occurs when the stem cells of white blood cells lack adenosin deamimase, an enzyme that fights infections. without that enzyme, the body has no chance against an infection. There are two treatments for SCID, either via repeated injection of the enzyme or through gene therapy. Leukemia is a kind of cancer. it is when the white blood cells reproduce uncontrollably, resulting in immature or abnormal WBCs which don't function right. There are many different kinds of leukemia; each is named after the specific kind of WBC that is reproducing uncontrollably. Infectious Mononucleosis is caused by the Epstein-Barr virus (EBV). Causes fever, sore throat, and swollen lymph glands. While the symptoms will go away within a couple months, the virus will live dormant in a few throat and blood cells for the rest of the persons life. These viruses can become reactivated due to stress. When EBV is active, it can be transported via saliva which is why it is commonly called the kissing disease.

18.1 Chromosomes and the Cell Cycle 1. What are the three stages of interphase? G1 Stage, S stage, and G2 stage.

2. How does interphase prepare a cell for cell division? During G1, a cells organelles are doubled and the materials needed for DNA synthesis are accumulated. During the S stage, DNA is replicated. During G2 stage, the cell synthesizes the proteins needed for cell division.