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cell
- basic unit of structure/function in the body
- characteristics:
- movement
- respond to stimuli
- carry on metabolism
- grow and reproduce (most)
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cell membrane
- outer structure that separates cell contents from external environment
- microthin yet bi-layered
- composed mostly of phospholipid and protein
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phospholipids
- fatty phosphorus
- heads: polar (react w/ H2O)
- tails - nonpolar (do not react w/H2O)
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peripheral proteins
- on outside attached to head
- help anchor cell in position
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integral proteins
- inside among tails
- contain channels and pores that allow substances to enter and exit the cell
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glycocalyx
short chains of sticky carbs that hold cells together
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functions of the cell membrane
- 1. separate inside of cell from outside environment
- 2. receptor site for hormones and enzymes
- 3. allow substances to enter/exit (selective permeability)
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permeability factors
- 1. size of molecule
- 2. charge of molecule (opposites attract)
- 3. fat solubility (must be fat soluble)
- 4. # of integral proteins available (carrier molecules)
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passive transport
- substance moves from greater concentration to lesser concentration
- cell uses no energy
- occurs with or without membrane
- substance moves down concentration gradient
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diffusion
solute moves from greater concentration to lesser concentration (aka down the gradient)
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rate of diffusion
increase in steepness of gradient or temperature speeds up rate of diffusion
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osmosis
- solvent (water) moves from greater concentration to lesser concentration
- requires a membrane
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tonicity
solution's relationship to living body cells
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isotonic
- no net movement of H2O
- cell shape will not change
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hypertonic
- H2O leaves cell (shrinks)
- cell crenates
- used to reduce fluid in body cells
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hypotonic
- H2O enters cell
- cell swells - could lyse
- used for dehydration
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filtration
- solute/solvent forced across a membrane by pressure
- seen in the kidneys and urinary system (forced by BP)
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facilitated diffusion
- large molecular substance trying to cross membrane attaches to integral proteins
- glucose
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active transport
- substances move from lesser concentration to greater concentration
- move up a gradient or against a charge
- cell uses lots of energy
- six processes
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phagocytosis
- cell ingests solid particles (bacteria)
- "cell eating"
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pinocytosis
- cell ingests liquids
- "cell drinking"
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symporters
- 2 substances cross membrane at the same time
- dependent on each other
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antiporters
- 2 substances cross in opposite directions at the same time
- mostly urinary
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receptor mediated endocytosis
the way ligands cross a membrane
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ligand
- any substance found outside a membrane in very small quantities
- (ex. vitamins and minerals)
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Na+ - K+ pump
- moves unequal amounts of Na+ and K+ in and out of cell
- nervous and urinary systems
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cytoplasm
- fluid between nucleus and cell membrane
- contains nutrients and all organelles
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flagella
- tails used for movement
- found only on sperm cells
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cilia
- microscopic hairs found on surface of cells (respiratory)
- moves substances along cell surface
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cytoskeleton
- holds cell contents together/gives shape
- microfilaments: threadlike structures that hold cell contents together
- microtubules: tiny proteins that give cell shape
- intermediate filaments:
- --collagen: strength
- --elastin: elasticity
- --keratin: waterproofs
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endoplasmic reticulum
- series of channels, cavities, and canals that store and transport chemicals
- rough ER: has ribosomes attached
- smooth ER: no ribosomes attached
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golgi body
- packages proteins and sends to other parts of cell
- makes lysosomes
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lysosomes
contain digestive enzymes that kill bacteria
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peroxisomes
destroy hydrogen peroxide (byproduct of metabolism)
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mitochondria
- powerhouse of the cell
- makes ATP
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inclusions
byproducts of cell metabolism
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centrosome
- forms flagella, cilia and mitotic spindle
- always near nucleus
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nucleus
- largest organelle
- always oval
- surrounded by nuclear envelope (double membrane)
- 3 parts: karolymph, nucleoli, chromosomes
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karolymph
nuclear cytoplasm
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chromosomes
genetic material
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cell division
- process by which body cells reproduce
- nucleus and cytoplasm both divide
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mitosis
division of the nucleus
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cytokinesis
division of the cytoplasm
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somatic cells
- forms all body structures other than sex cells
- divide by mitosis / cytokinesis
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gametes
- sex cells
- divide by meiosis
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cell cycle
- all events a cell goes through from production until division is complete
- five phases (IPMAT)
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interphase
- first stage
- cell gets ready to divide
- DNA and X's replicate
- nutrients produced
- X's not visible (chromatin material is jelly like)nuclear membrane in tact
- 3 stages:
- --G1 - growth - nutrients produced
- --S - synthesis - DNA replicates - must continue to divide once this stage is reached
- --G2 - growth
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prophase
- second stage
- nuclear membrane breaks down
- X's visible
- mitotic spindle forms
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metaphase
- nuclear membrane gone
- centromeres line up along the middle
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anaphase
- centromeres split
- pairs of chromatids move to poles
- cytokinesis begins
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telophase
- clevage furrow is complete
- exact opposite of prophase
- 2 identical cells
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