Biology Ch. 6-8
Terms
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- nuclear envelope
- double membrane enclosing the nucleus; perforated by pores; continuous with ER
- nuclear lamina
- a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope
- chromosomes
- structures that carry the information
- chromatin
- each chromosome is made up of chromatin, a complex of proteins and DNA
- nucleolus
- non membranous organelle involved in production of ribosomes; a nucleus has one or more nucleoli
- ribosomes
- non membranous organelles that make proteins; free in cytoplasm or bound to rough ER or nuclear envelope
- endomembrane system
- synthesis of proteins and their transport, metabolism and movement of lipids, and detoxification of poisons. includes: golgi apparatus, lysosomes,various kinds of vacuoles, and the plasma membrane
- vesicles
- (sacs made of membrane)
- endoplasmic reticulum (ER)
- network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes; has rough (ribosome-studded) and smooth regions
- golgi apparatus
- organelle active in synthesis, modification, sorting, and secreting of cell products
- lysosome
- digestive organelle where macromolecules are hydrolyzed
- phagocytosis
- eating by engulfing smaller organisms or other food particles
- food vacuole and contacile vacuole
- formed by phagocytosis / pump excess water out of cell
- central vacuole
- prominent organelle in older plant cells; functions include storage, breakdown of waste products, hydrolysis of a macromolecule; enlargement of vacuole is a major mechanism of plant growth
- tonoplast
- membrane enclosing the central vacuole
- mitochondria
- organelle where cellular respiration occurs and most ATP is generated
- chloroplast
- photosynthetic organelle; converts energy of sunlight to chemical energy stored in sugar molecules
- peroxisome
- organelle with various specialized metabolic functions; produces hydrogen peroxide
- cytoskeleton
- reinforces cell's shape, functions in cell movement; components are made of protein
- micro tubules
- hollow rods. separation of chromosome during cell division
- centrosome
- a region where the cell's microtubules are initiated; in an animal cell, contains a pair of centrioles (function unknown)
- flagellum
- locomotion organelle present in some animal cells; composed of membrane-enclosed microtubules
- cell wall
- outer layer that maintains cell's shape and protects cell from mechanical damage; made of cellulose, other polysaccharides, and protein
- extracellular matrix (ECM)
- main ingredient glycoprotein. Has collagen, proteglycan complex, fibronectin, and integrins
- collagen
- fibers embedded in a web of proteoglycan complexes
- proteoglycan complex
- consists of hundreds of proteoglycan molecules attached non covalently to a single long polysaccharide molecule
- fibronectin
- attaches the ECM to integrins embedded in the plasma membrane
- integrins
- are membrane proteins that are bound to the ECM on one side and to associated proteins attached to microfillaments on the other. this linkage can transmit stimuli between the cell's external and its interior and can result in changes in cell behavior
- plasmodesmata
- channels through cell walls that connect the cytoplasms of adjacent cells
- selective permeability
- allows some substances to cross it more easily than others
- amphipathic molecule
- it has both hydrophilic region and a hydrophobic region
- integral proteins
- penetrate the hydrocarbon core of the lipid bilayer
- peripheral proteins
- not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to the exposed parts of integral proteins
- 6 Functions performed by proteins of the plasma membrane
- 1. transport 2. enzymatic activity 3. signal transduction 4. cell-cell recognition 5. intercellular joining 6. attachment to the cytoskeleton and ECM
- transport protein
- having a hydrophilic channel that certain molecules use as a tunnel through the membrane
- diffusion
- result of thermal motion, the tendency for molecules of any substance to spread out evenly into available space
- concentration gradient
- diffuse from where it is more concentrated to where it is less concentrated
- passive transport
- diffusion of a substance across a biological membrane
- osmosis
- diffusion of water across a selectively permeable membrane
- tonicity
- the ability of a solution to cause a cell to gain or lose water
- isotonic
- there will be no net movement of water across the membrane, same rate in both directions.
- hypertonic
- cell will loose water to its environment and shrivel and probably die
- hypotonic
- water will enter the cell faster than it leaves and cell will swell and burst
- osmoregulation
- control of water balance
- turgid
- very firm. cell wall after hypotonic solution
- flaccid
- limp. isotonic
- plasmolysis
- wilt and be lethal due to hypertonic
- facilitated diffusion
- spontaneous passage of molecules and ions down a concentration gradient with proteins
- ion channels
- stimulus causes them to open or close. stimulus may be electrical or chemical
- active transport
- to pump a molecule across a membrane against its gradient requires work and cell must expend energy
- membrane potential
- voltage across a membrane (negative cytoplasm)
- cotransport
- ATP powered pump that transports a specific solute can indirectly drive the active transport of sever other solutes
- exocytosis
- cell secretes macromolecules by the fusion of vesicles with the plasma membrane
- endocytosis
- the cell takes in macromolecules and particulate matter by forming new vesicles from the plasma membrane
- pinocytosis
- the cell gulps droplets of extra cellular fluid into tiny vesicles. cell needs the molecules dissolved in the droplets
- receptor-mediated endocytosis
- fuzzy layer coat protein. acquire bulk quantities of specific substances
- catabolic pathways
- degenerative process or breakdown pathways
- anabolic pathways
- consume energy to build complicated molecules from simpler ones
- 1st law
- energy can be neither created nor destroyed
- 2nd law
- every energy transfer increases the entropy of the universe
- free energy
- measure the portion of a system's energy that can perform work
- change in G
- = change H (enthalpy) - t(change)S
- exergonic reaction
- proceeds with a net release of energy (change) G is negative
- endergonic reaction
- absorbs free energy from its surroundings change G is positive
- cell's 3 main types of work
- 1. mechanical work - mov. of chrom, beating of cilia 2. transport work - pumping of sub. across membrane 3. chemical work - pushing of endergonic reactions which will not occur spontaneously
- phosphorylated
- recipient of the phosphate group
- catalyst
- chemical agent that speeds up a reaction without being consumed by the reaction
- enzyme
- catalytic protein
- activation energy
- initial investment of energy for starting a reaction
- substrate
- reactant an enzyme acts on
- enzyme-substrate complex
- enzyme binds to substrate
- active site
- restricted region of the enzyme binds to the substrate