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List the general functions of the plasma membrane
- Physical isolation
- Regulation of exchange with the environment
- Sensitivity to the environment
- Structural support
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Identify the components of the plasma membrane that allow it to perform its characteristic functions
- Membrane Lipids
- Membrane Proteins
- Membrane Carbohydrates
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Which component of the plasma membrane is primarily responsible for the membrane's ability to form a physical barrier between the cell's internal and external environment?
the phospholipid bilayer
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Which type of inegral protein allows water and small ions to pass through the plasma membrane?
channel proteins
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Differentiate between the cytoplasm and the cytosol
- Cytoplasm is the material between the plasma membrane and the nuclear membrane
- Cytosol is the fluid portion of the cytoplasm
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What are the major differences between cytosol and extracellular fluid?
- Cytosol has a higher concentration of potassium ions and suspended proteins
- A lower concentration of sodium ions
- Also includes small quantities of carbohydrates, and larger resrves of amino acids and lipids
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Identify the nonmembranous organelles, and cite a function of each
- Centirole: essential for movement of chromosomes during cell division; organization of microtubules in cytoskeleton
- Cilia: movement of materials over cell surface
- Cytoskeleton: strength and support; movement of cellular structures and materials; cell movement
- Microvilli: increase surface area to facilitate absorption of extracellular materials
- Proteasomes: breakdown and recycling of intracellular proteins
- Ribosomes: protein synthesis
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Identify the membranous organelles, and cite their functions
- Endoplasmic reticulum: synthesis of secretory products: intracellular storage and transport
- Rough ER: modification and packaging of newly synthesized proteins
- Smooth ER: lipid and carbohydrate synthesis
- Golgi apparatus: storage, alteration, and packaging of secretory products and lysosomal enzymes
- Lysosomes: intracellular removal of damaged organelles or pathogens
- Mitochondria: production of 95 % of the ATP required by the cell
- Peroxisomes: neutralization of toxic compounds
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What does the precence of many mitochondria imply about a cell's energy requirements?
a high demand for energy
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Explain why certain cells in the ovaries and testes contain large amounts of smooth endoplasmic reticulum (SER)
The SER functions int he synthesis of lipids such as steroids. Ovaries and testes produce large amounts of steroid hormones, which are lipids, and thus need large amounts of SER
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Describe the contents and structure of the nucleus
- Contains DNA, RNA, Enzymes, Proteins
- Structure:
- Nuclear envelope- double membrane that surounds the nucleus
- Perinuclear space- region between the double membrane
- Nuclear pores- allow for chemical communication between the nucleus and the cytosol
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What is a gene?
a portion of a DNA strand that functions as a hereditary unit
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Define gene activation
the process of uncoiling the segment of DNA containin that gene, and temporarily removing histones so that the gene can be expressed and thus affect cell function
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What is transcription?
the encoding of genetic instructions on a strand of mRNA
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What process would be affected by the lack of enzyme RNA polymerase?
transcription
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WHat is meant by "selectively permeable" when referring to a plasma membrane?
it alows some substances to pass through while restricting others
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Define diffusion
the passive molecular movement of a substance from an area of higher concentration to an area of lower concentration
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List five factors that influence the diffusion of substances in the body
- Diffusion distance
- molecule size
- temperature
- concentration gradient
- electrical foces
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How would a decrease in the concentration of oxygen in the lungs affect the diffusion of oxygen into the blood?
The concentration gradient between oxygen in the lungs and oxygen in the blood would decrease thus oxygen would diffuse more slowly into the blood
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Define osmosis
the diffusion of water across a selectively permeable membrane from one solution to another solution containing a higher solute concentration
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Some pediatricians recommend using a 10 percent salt solution as a nasal spray to relieve congestion in infants with stuffy noses. What effect would such a solution have on the cells lining the nasal cavity, and why?
the 10% salt solution is hypertonic and would draw wate rout of the cells causing them to shrink and relieve congestion
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Describe the process of carrier-mediated transport
intregal proteins bind specific ions or organic substances and carry them across the plasma membrane
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During digestion in the stomach, the concentration of hydrogen ions (H+) rises to higher levels than in the cells lining the stomach. Which transport process must be operation?
Active transport because the process requires expended energy
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Describe endocytosis
movement of substances into the cell
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Describe exocytosis
movement of substance out of the cell
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What is the process called whereby certain types of white blood cells engulf bacteria?
phagocytosis
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What is the transmembrane potential, and in what units is it expressed?
- the difference in electrical potential that results from the uneven distribution of positive and negative charges across the plasma membrane
- Millivolts
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If the plasma membrane were freely permeable to sodium ions (Na+), how would the transmembrane potential be affected?
the transmembrane potential would move closer to zero
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GIve the biological terms for (a) cellular reproduction and (b) cellular death
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Describe interphase, and identify its stages
- the portion of a cell's life cycle during which the chromosomes are uncoiled and all normal cellular functions except mitosis are under way.
- G1, S, G2, G0
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A cell is actively manufacturing enough organelles to serve two functional cells. This cell is probably in what phase of its life cycle?
G1
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Define mitosis, and list its four stages
- the essential step in cell division in which a single cell nucleus divides to produce two identical daughter cell nuclei
- Prophase
- Metaphase
- Anaphase
- Telophase
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What would happen if spindle fibers failed to form in a cell during mitosis?
the cell would not be able to separate the chromosomes into two sets. After cytokinesis, once cell would be left with two sits of chromosomes and one with none
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Define growth factor, and identify several growth factors that affect cell division
- an extracellular compound that can stimulate the division of specific cell types
- Chalones
- Epidermal growth factor (EGF)
- Erythropoietin
- Fibroblast growth factor (FGF)
- Growth hormone
- M-phase promoting factor
- Nerve growth factor (NGF)
- Prolactin
- Thymosins
- Related compounds
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An illness characterized by mutations that disrupt normal control mechanisms and produce potentially malignant cells is termed _______
cancer
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Define metastasis
the spread of cancer cells from one organ to another, leading to the establishment of secondary tumors
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Define differentiation
the gradual appearance of characteristic cellular specialization during development; it results from gene activation or repression
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