a&p chapter 3
Terms
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- The cellular level of organization
- basic, living, structural and functional unit of the body
- The cellular level of organization is responsible for
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-compartmentalization of chemical reactions within specialized structures
-regulate inflow and outflow of materials
-use genetic material to direct cell activities - cytology
- study of cellular structure
- cell physiology
- study of cellular function
- plasma membrane
- held together by hydrogen bonds
- nucleus
- genetic material of cell
- cytoplasm
- everything between the membrain and the nucleus
- what is found between the membrane and nucleus?
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cytosol
organelles - cytosol
- intracellular fluid
- organelles
- subcellular structures with specific functions
- lipid bilayer of the cell membrane
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2 back to back layers of 3 types of lipid molecules.
cholesterol and glycolipids scattered among a double row of phospholipid molecules - phospholipids
- -compromises 75% of lipids
- phospholipid bilayer
- 2 parallel layers of molecules
- Describe the molecules in a phospholipid bilayer
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2 parts
-polar parts(heads)are hydophilic and face on both surfaces a watery environment
-non polar parts (tails) are hydrophobic and line up next to each other in the interior - Glycolipids
- sugar fat molecules
- Glycolipids within the cell membrane
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-compromises 5% of the lipids of the cell membrane
-carbohydrate groups form a polar head only on the side of the membrane facing the extracellular fluid - cholesterol
- stiff steroid ring inside of every cell wall
- cholesterol within the cell membrane
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-compromises 20% of cell membrane lipids
-interspersed among the other lipids in both layers
-stiff steroid rings and hydrocarbon tail are nonpolar and hide in the middle of the cell membrane - centrosome plays a role in
- formation of cilia and flagella
- 2 types of membrane proteins
- integral, and peripheal proteins
- Describe peripheal proteins
- attached to either inner or outer surface of cell membrane and are easily removed from it
- Formation of channel
- passageway to allow specific substances to pass through
- transporter proteins
- bind a specific substance, change their shape and move it across membrane
- Receptor proteins
- cellular recognition site bind to substance
- Cell identity marker
- allow cells to recognize other similar cells
- linker
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-anchor proteins in cell membrane or to other cells
-allow cell movement
-cell shape and structure - Act as enzyme
- speed up reactions
- Transmembrane proteins
- protein extends completely across
- What do glycoproteins do for the cell?
- gives cell uniqueness, protects it from being digested creates a stickiness to hold it to other cells or so it can hold a fluid layer creating a slippery surface
- Membranes are what type of structures?
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fluid structures(oil layers)
- self sealing if punctured with a needle - Membrane fluidity
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a compromise of fluids --membrane molecules can rotate and move freely
-need to stay in one half of lipid bilayer
-fluidity is reduced by presence of cholesterol - Why does membranes need to stay in one half of the lipid bilayer?
- Its difficult for hydrophilic parts to pass through hydrophobic core of bilipid layer.
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Membrane Fluidity
Describe fluidity is reduced by presence of cholesterol - increases stiffness of membrane it forms hydrogen bonds with neighboring phospholipid heads
- Lipid bilayer
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- permeable to nonpolar, uncharged molecules--oxygen, co2, steroids
- permeable to water which flows through gaps that form in hydrophobic core of membrane as phospholipids move about - Transmembrane proteins act as specific channels.
- small and medium polar and charged particles
- Macromolecules unable to pass through the membrane.
- vesicular transport
- active transport
- uses atp to drive substances against their concentration gradients. (walking up a hill)
- passive transport
- moves substances down their concentration gradient with only their kinetic energy. (jumping on a sled)
- Vesicular transport
- moves material across membranes in small vesicles either by exocytosis or endocytosis. (active)
- Diffusion
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random mixing of particles in a solution as a result of the particles kinetic energy
-more molecules move away from an area of high concentration to an area of low concentration
-when the molecules are evenly distributed, equilibrium has been reached - 5 things about diffusion
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-the greater the difference in concentration between the 2 sides of the membrane, the faster the rate of diffusion
-the higher the temp, the faster the rate of diffusion
- the larger the size of the diffusing substance, the slower the rate of diffusion
-an increase in surface area increases the rate of diffusion
- increases diffusion distance, slows rate of diffusion - Affects of tonicity on rbcs in lab
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normally the osmotic pressure of the inside of the cell is equal to the fluid outside the cell
-cell volume remains constant (solution is isotonic - Effects of fluids on rbcs in lab.
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-water enters the cell faster than it leaves
-water enters and leaves the cell in equal amounts
-water leaves the cell - Isotonic solution
- - water concentration the same inside and outside of cell results in no net movement of water across cell membrane
- Hypotonic solution
- higher concentration of water outside of cell results in hemolysis
- Hypertonic solution
- lower concentration of water outside of cell causes crenation
- Diffusion through the lipid bilayer.
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-important for absorption of nutrients--excretion of wastes
-nonpolar, hydrophobic molecules(oxygen, carbon dioxide, nitrogen, fatty acids, steroids, small alcohols, ammonia and fat-soluble vitamins a/e/d/k) - Facilitated diffusion
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-substance binds to specific transporter protein
-transporter protein conformational change moves substance across cell membrane - Facilitated diffusion occurs down concentration gradient only
- if no concentration difference exists, no net movement across membrane occurs
- Rate of movement in facilitated diffusion depends upon
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-steepness of concentration gradient
-number of transporter proteins(transport maximum) - Osmosis
- net movement of water through an area of high water concentration(low particle concentration) to an area of low water concentration.(high particle concentration)
- When does osmosis occur?
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only occurs if membrane is permeable to water but not to certain solutes
-diffusion through lipid bilayer
-aquaporins (transmembrane proteins) that function as water channels - Osmosis of water through a membrane
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-pure water on the left side and a membrane impermeable to the solute found on the right side
-net movement of water is from left to right, until hydrostatic pressure (osmotic pressure) starts to push water back to the left - Active transport requires
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energy
-energy from hydrolosis of atp (primary active transport)
-energy stored in an ionic concentration gradient (secondary active transport) - Active transport exhibits
- transport maximums and saturations
- lysosomes
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Function -digest foreign substances
-autophangy(autophagosome forms)
(recycles own organelles)
-autolysis
(lysosomal damage after death) - Peroxisomes
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function
-part of normal metabolic breakdown of amino acids and fatty acids
-oxides toxic substances such as alcohol and formaldehyde
-contains catalase which decomposes h2o2 - Mitochondria
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Function
-generation of ATP
-powerhouse of cell - Cytoskeleton
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Functions
-cell support and shape
-organization of chemical reactions
-cell and organelle movement - Cell organelles
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-nonmembranous organelles lack membranes and are indirect contact with cytoplasm
- membranous organelles surrounded by one or two lipid bilayer membranes - Primary and secondary active transport are
- atp driven
- Function of nucleus
- 46 human dna molecules or chromosomes
- Ribosomes
- the sites of protein synthesis
- Golgi complex
- processes and packages proteins produced by rough er
- Vesicular transport of particles
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endocytosis
exocytosis - Endocytosis
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bringing something into cell
-phagocytosis
-pinocytosis
-receptor mediated endocytosis=selective input - Exocytosis
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release something from cell
-vesicles form inside cell, fuse to cell membrane
-release their contents(digestive enzymes, hormones, neurotransmitters or waste products)
-replace cell membrane lost by endocytosis - Phagocytosis
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cell eating by macrophages and wbcs
-particle binds to receptor protein
-whole bacteria or viruses are engulfed and later digested - pinocytosis
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cell drinking
-no receptor proteins - Receptor-mediated endocytosis=selective input
- mechanism by which hiv virus enters cells
- Endoplasmic reticulum
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network of membranes forming flattened sacs or tubles called cisterns
-half of membranous surfaces within cytoplasm - Rough er
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-continuous with nuclear envelope and covered with attached ribosomes
-synthesizes, processes and packages proteins for export
-free ribosomes synthesize proteins for local use - Smooth er
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no attached ribosomes
-synthesizes phopholipids, steroids and fats
-detoxifies harmful substances(alcohol) -
Gradients across the plasma membrane
substances move - down their concentration gradient and towards the oppositely charged area
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Gradients across the plasma membrane
membranes can maintain a difference in charged ions between - inside and outside of membrane
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Gradients across the plasma membrane
membrane can maintain difference in - concentration of a substance inside versus outside of the membrane(concentration gradient)