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A & P 2
Class notes
Question | Answer |
---|---|
cells known as | "the functional units of the body" |
cytology | the study of cells |
irregular shape | nerve cells |
biconcave disc | red blood cells |
cube-shaped | kidney tubule cells |
column-shaped | intestinal lining cells |
spherical | cartilage cells |
cylindrical | skeletal muscle cells |
plasma membrane | a fluid mixture composed of lipid and proteins that forms the outer limiting barrier of cells and separates internal contents of the cell from the external environment and regulates the movements of most substances in and out of the cell |
nucleus | largest structure in the cell and contains the genetic material, DNA |
cytoplasm | the cellular contents between the plasma membrane and the nucleus and includes the cytosol, organelles, and inclusions |
cytosol (intracellular fluid) | viscous fluid of the cytoplasm that has a high water content |
organelles | organized structure within cells that may be referred to as "little organs" with unique shapes and function |
general cell functions performed by most cells | maintain integrity and shape of cell (dependent on plasma membrane and internal contents), obtain nutrients and form chemical building blocks (harvest energy for survival), and dispose of wastes (avoid accumulation disrupting cellular activities) |
general cell functions performed by some cells | cell division (make more cells of the same type and help maintain the tissue by providing new cells) |
membrane transport | the process by which the plasma membrane regulates movement of materials into and out of a cell (can be categorized as passive or active) |
passive processes of membrane transport | do not require energy, depend on substances moving down concentration gradient (move from where there is more of a substance to where there is less) |
types of passive processes | diffusion and osmosis |
active processes of membrane transport | opposes the movement of solution by diffusion and requires energy |
active transport (type of active transport) | the movement of a substance up its concentration gradient |
vesicular transport (type of active transport) | release of membrane-bound vesicle |
diffusion | moves from area of greater concentration to area of lesser concentration (if unopposed, continues until substance reaches equilibrium and molecules are evenly distributed throughout a given area) |
two types of facilitate diffusion | channel-mediated diffusion and carrier mediated diffusion |
channel-mediated diffusion | channels specific for one ion type and allow passage of the ion (leak channel - continuously open and gated channel - usually closed, but open in response to a stimulus) |
carrier-mediated diffusion | small, polar molecules assisted across membrane by carrier protein and release substances on other side of membrane |
osmosis | passive movement of H20 through selectively permeable membrane (membrane allowing passage of H20, but preventing the passage of most solutes) and occurs in response to difs in H20 concentration (with different concentrations on either side of a membrane) |
movement of water into or out of a cell by osmosis | dependent on concentration gradient between cytosol and the solution (water moves into solution with higher concentration of solutes until equilibrium is reached) |
tonicity | ability of a solution to change the volume or pressure of the cell by osmosis |
isotonic solution | both cytosol and solution with same relative concentration of solutes (no net movement of water) |
hypotonic solution | solution with a lower concentration of solutes than cytosol (increased volume and pressure of cell and may cause rupture) |
hypertonic solution | solution with a higher concentration of solutes than cytosol (decreased volume and pressure of cell and may cause cell to shrink) |
sodium potassium pump (active transport) | special kind of ion pump, an exchange pump, that moves one ion into cell against gradient and moves another ion out of cell against gradient (three sodium ions pumped out for two potassium ions pumped in) |
membrane-bound organelles | endoplasmic reticulum, Golgi apparatus, lysosome, peroxisome, and mitochondria |
non-membrane bound organelles | ribosomes, cytoskeleton, centrosomes, and proteasomes |
endoplasmic reticulum (ER) | extends from nuclear envelope to plasma membrane, is the point of attachment for ribosomes (rough ER), but smooth ER lacks ribosomes |
rough ER | ribosomes produce protein and peroxisomes are produced here |
smooth ER | continuous with rough ER and serves in the synthesis, transport, and storage of lipids, carbohydrate metabolism, and detoxification of drugs, alcohols, and poisons (plentiful in liver and cells of testes - testosterone production) |
Golgi apparatus | composed of several elongate, saclike membranous structures (cisternae) and is the warehouse of the cell (acting as a receiving and shipping region) |
functions of Golgi | modification, packaging and sorting of proteins; transport or material from cis-face (closer in proximity to the ER and receives stuff) to trans-face (farther from ER and ships stuff); and formation of lysosomes |
lysosomes | contain digestive enzymes formed by Golgi and participate in digestion of unneeded substances |
peroxisomes | membrane-enclosed sacs smaller than lysosomes that were pinched off vesicles from the rough ER and contain oxidizing enzymes (serves in detoxification - produces hydrogen peroxide), engages in oxidation of fatty acid and is most abundant in the liver |
mitochondria | oblong shaped organelles with double membrane that engages in aerobic cellular respiration and completes digestion of fuel molecules to synthesize ATP (termed "powerhouses" of the cell) |
ribosomes | contains protein and ribonucleic acid, some are bound to rough ER (make proteins for plasma membrane, export, or lysosomes), and others are freely suspended in the cytosol (synthesize all other proteins) |
cytoskeleton | plays roles in maintaining cell shape, organization of organelles, cell division and movement of materials |
cytoskeleton description | extends through interior of cell and anchors proteins in plasma membrane (include microfilaments, intermediate filaments, and tubules) |
centrosome | usually in close proximity to nucleus, contains pairs of perpendicularly oriented cylindrical centrioles, organized microtubules within the cytoskeleton, and is best known for function in cell division |
proteasomes | large, barrel-shaped protein-digesting organelles |
cilia and flagella | projection extending from the cell that help in locomotion |
cilia | usually found on exposed surfaces of specific cells (small, little structures) |
flagella | similar to cilia in structure, but longer and usually appear alone to help propel an entire cell |
nucleus | largest structure in the cell and is the cell's control center |
nuclear envelope | double phospholipid membrane enclosing nucleus and externally continuous with rough ER |
nucleolus | composed of protein and RNA and produces small and large ribosome subunits |
cell division | occurs when one cell divides to produce two cells and is necessary for development, tissue growth, replacement of old cells, and tissue repair |
two types of cell division | mitosis and meiosis |
mitosis | cell division that occur in somatic cells (cells other than sex cells) |
meiosis | cell division in sex cells (cells that give rise to sperm or secondary oocytes) |
cell cycle | depicts steps in division of somatic cells (divides into two identical daughter cells) |
two major phases in cell cycle | interphase and mitotic (M) phase |
interphase | time between cell division where cells spend the most time (three phases - G1, S, and G2) allowing cell maintenance and normal metabolic activities and may prepare cell to divide again |
G1 phase | first gap stage - involves growth and production of new organelles and continue metabolic activities |
S phase | synthesis - brief phase |
G2 phase | second gap phase - brief phase in which organelle production continues and enzymes for cell division are synthesized |
M phase (mitotic phase) | follows interphase and includes mitosis (division of the nucleus) and later cytokinesis (division of the cytoplasm) |
four consecutive phases of mitosis | prophase, metaphase, anaphase, and telophase |
prophase | first stage of mitosis in which the nucleolus is broken down and microtubules (spindle fibers) grow from the centrioles, the centriole pairs are pushed apart at opposite poles and the nuclear envelope dissolves |
metaphase | second stage of mitosis in which chromosomes align on equatorial plate of cell and spindle fibers extend from centriole and attach at centromere of the chromosome (mitotic spindle) |
anaphase | starts as spindle fibers move sister chromatids apart toward poles and each chromatid is then a chromosome of one DNA helix |
telophase | arrival of new chromosomes at each pole, and they begin to uncoil. New nucleolus formed in each cell and the mitotic spindle is broken up and a new envelope forms around chromosomes |
cytokinesis | the division of cytoplasm between two newly formed cells |