Basis of Life Flashcards
Temperature and enzymes
As temperature increases the rate of enzyme action increases, until an optimum temperature is reached. After optimal temperature heat alters the shape of the active site of the enzyme molecule and deactivates it leading to a rapid drop in rate
pH and enzymes
Optimal pH, above and below that activity declines. Maximal activity of many human enzymes occurs around 7.2.
Reaction rate
Concentrations of substrate and enzyme greatly affect the reaction rate
Competitive Inhibition
A similar molecule is present in a concentration comparable to the concentration of the substrate, it will compete with the substrate for binding sites on the enzyme and interfere with enzyme activity
Noncompetitive Inhibition
Substance that forms strong covalent bonds with an enzyme and consequently may not be displaced by the addition of excess substrate, irreversible
Hydrolysis
digest large molecules into smaller components
Lactase
hydrolyzes lactose to the monosaccharides glucose and galactose
Proteases
Degrade proteins to amino acids
lipases
break down lipids to fatty acids and glycerol
Cell Theory
All living things are composed of cells
Cell is the basic functional unit of life
Chemical reactions of life take place inside the cell
Cells arise only from pre-existing cells
Cells carry genetic information in the form of DNA, passed from parent cell to daughter cell
Fluid Mosaic Model
The cell membrane consists of a phospholipid bilayer with proteins embedded throughout. Lipids and many of the proteins can move freely within the membrane
Plasma membrane
Readily permeable to small nonpolar hydrophobic molecules and small polar molecules. Small charged particles are usually able to cross the membrane through protein channels. Charged ions and larger charged molecules cross the membranes with the assistance of carrier proteins.
Nucleus
Controls activities of the cell, surrounded by a nuclear membrane, contains DNA. Ribosomal RNA synthesis occurs in the nucleolus
Ribosome
Site of protein production and are synthesized by the nucleolus. Free ribosomes are found in the cytoplasm and bound ribosomes line the outer membrane of the endoplasmic reticulum
Endoplasmic Reticulum
Network of membrane enclosed spaces involved in the transport of materials throughout the cell, especially materials destined to be secreted by the cell
Golgi apparatus
receives vesicles and their contents from the smooth ER, modifies them, repackages into vesicles and distributes them to the cell surface by exocytosis
Mitochondria
Sites of aerobic respiration within the cell and hence the suppliers of energy. Each contains an outer and inner phospholipid bilayer
Vacuoles/Vesicles
Membrane bound sacs involved in the transport and storage of materials that are ingested, secreted, processed or digested by the cell
Centrioles
involved in spindle organization during cell division and are not bound by a membrane. Plant cells do not have centrioles.
Lysosomes
Membrane bound vesicles that contain hydrolytic enzymes involved in intracellular digestion. Break down material ingested by the cell.
Cytoskeleton
Supports the cell, maintains its shape and functions in cell motility. Composed of microtubules, microfilaments, and intermediate filaments.
Microtubules
hollow rods made up of polymerized tubulin that radiate throughout the cell and provide it with support. Provide framework for organelle movement. Cilia and flagella are specialized arrangements of microtubules that extend from certain cells and are involved in cell motility and cytoplasmic movement.
Microfilaments
Solid rods of actin, important in cell movement as well as support. Muscle contraction is based on the interaction of actin with myosin. Move materials across plasma membrane.
Simple Diffusion
net movement of dissolved particles down their concentration gradients, requires no external source of energy
Osmosis
Simple diffusion of water from a region of lower solute concentration to a region of higher solute concentration.
Hypertonic
When the cytoplasm of a cell has a lower solute concentration than the extracellular medium, water will flow out of the cell, cell will shrivel (PLASMOLYSIS)
Hypotonic
If the extracellular environment is less concentrated than the cytoplasm of the cell, water will flow into the cell causing it to swell and lyse.
Facilitated Diffusion
Passive transport, net movement of dissolved particles down the concentration gradient through special channels or carrier proteins in the cell membrane, does not require energy.
Active Transport
Net movement of dissolved particles against their concentration gradient with the help of transport proteins, requires energy. Carrier molecules aid in the regulation of the cell’s internal content of ions and large molecules.
Energy Independent Carriers
Facilitate the movement of compounds along a concentration gradient.
Symporters
active transport, move two or more ions or molecules
Antiporters
Active transport, exchange one or more ions for another ion or molecule
Pumps
Active Transport, energy dependent carriers, require ATP
Endocytosis
process in which the cell membrane invaginates, forming a vesicle that contains extracellular medium.
Pinocytosis
Endocytosis, ingestion of the fluids or small particles
Phagocytosis
Endocytosis, engulfing of large particles. Particles may bind to receptors on the cell membrane
Exocytosis
Vesicle within the cell fuses with the cell membrane and releases its contents to the outside. Can play an important role in cell growth and intercellular signaling.
Brownian movement
Intracellular Circulation, kinetic energy spreads small suspended particles throughout the cytoplasm of the cell
Cyclosis or streaming
Intracellular Circulation, circular motion of cytoplasm around the cell transports molecules
Endoplasmic Reticulum,
Intracellular Circulation, provides channels throughout the cytoplasm and provides direct continuous passageway from the plasma membrane to the nuclear membrane
Diffusion
Extracellular Circulation, if cells are in direct or close contact with the external environment, can serve as a sufficient means of transportation for food and oxygen from the environment to the cell. Diffusion is important for the transport of materials between cells and the interstitial fluid that bathes the cells.
Circulatory System
Extracellular Circulation, for complex animals whose cells are too far from the external environment to transport materials by diffusion, generally includes vessels to transport fluid and a pump to drive circulation.
