Cells and Mitosis
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- What does the cell doctrine state?
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All living things are composed of cells.
A cell is the smallest unit exhibiting all characteristics of life.
All cells come from preexisting cells. - What are the types of microscopes as we know them today?
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Light microscope- magnifies up to 1000 times.
TEM developed 1950s- shows internal cell structure, magnifies up to 1 million times.
SEM developed 1970s- studies external surface of cells. - Define protoplasm.
- The part of the cell made up by the cytoplasm (internal region of the cell which also includes organelles) and the nucleus.
- Define diffusion.
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A way that substances can pass through the cell membrane.
SMALL molecules from an area of HIGH concentration to LOW concentration. - Define osmosis.
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A way that water can pass through the cell membrane.
WATER from an area of HIGH concentration to LOW concentration. - Define facilitated transport.
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A way that substances can pass through the cell membrane.
A molecule attaches to a transport protien and moves from an area of HIGH concentration to LOW concentration. - Define active transport.
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A way that substances can pass through the cell membrane.
Movement of ions and large molecules against a common gradient. It requires ATP. - Define endocytosis.
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A way that substances can pass through the cell membrane.
Formation of vesicles (pinocytosis) or vacuoles (phagocytosis). - Define pinocytosis.
- "Cell drinking." Cell takes in large molecules that are soluble in water. Forms a vesicle.
- Define phagocytosis.
- "Cell eating." Cell takes in large material that is not in solution. Forms a vacuole.
- What are microvilli and where are they common?
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Foldings of the cell membrane to increase the absorptive surface.
Common in cells that function in absorption of many materials, e.g. cells lining the small intestine. - What are desmosomes?
- Cell junctions between adjacent cells.
- What is the function of endoplasmic reticulum?
- Transports molecules throughout the cell.
- What to ribosomes do?
- They function in protien synthesis- they put amino acids together to form new proteins.
- What are the two parts to the Golgi apparatus, and in what does this organelle function?
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Two parts: Golgi sacs, Golgi vesicles.
Three functions: Synthesizing carbohydrates; packagning proteins into enzymes; forming new membranes. - What does the mitochondria do?
- It's the "powerhouse" of the cell. It is the site of cellular respiration- it produces ATP.
- What do lysosomes do?
- They digest food, and break down cells after death.
- What encloses food in pinocytosis?
- Vesicle. (small)
- What encloses food in phagocytosis?
- Vacuole. (large)
- What are microtubules?
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Narrow, elongate, HOLLOW rods.
(tube = hollow)
Found in cytoskeleton, cilia and flagella, and centrioles. - What are microfilaments?
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Narrow, elongate, SOLID rods.
(fill (filled) = solid)
Found in cytoskeleton and muscle cells. - What are the parts of the nucleus? Describe each.
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Nuclear membrane- double membrane with pores to connect it to cytoplasm.
Nucleolus (1 or 2 present)- dense, contains RNA.
Nucleoplasm- contains chromatin material that consists of DNA. - What are the stages of mitosis?
- Interphase, prophase, metaphase, anaphase, telophase.
- Describe interphase.
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Three events: G1 (cell growth); S (DNA replicated); G2 (prepares for division)
Nuclear memrane distinct; nucleolus present; chromosomes indistinct. - Describe prophase.
- Centrioles replicate and move to opposite poles of cells; chromosomes visible in a circular arrangement; nuclear membrane and nucleoli disappear.
- Describe metaphase.
- Chromosomes are lined in the center of the cell.
- Describe anaphase.
- The centromere divides and the two chromosomes separate and are moved to opposite poles.
- Describe telophase.
- Daughter chromosomes reach opposite poles and stain. Cytokinesis occurs- the cytoplasmic organelles replicate and divide. Cleavage furrow / equatorial plate forms.