Chapter 3 (Part 2)
Terms
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- factors affecting diffusion
- 1) distance; 2) molecule size; 3) temperature; 4) gradient size; 5) electrical forces
- pinocytosis
- "cell drinking" whereby endosomes fill with extracellular fluid; no ligand binding,
- translation
- protein synthesis using a linear strand of amino acids specified by mRNA
- DNA polymerase
- an enzyme that 1) promotes bonding between nitrogenous bases of DNA and complimentary DNA nucleotides dissolved in the nucleoplasm and 2) linds the nucleotides by covalent bonds
- active transport
- movement of a substance across cell membrane against its concentration or electrochemical gradient with the help of energy input and carrier proteins. It moves from low to high concentration.
- sodium-potassium exchange pump
- carrier protein that exchanges intracellular sodium for extracellular potassium
- filtration
- the movement of fluid across a membrane whose pores resist passage of solute on the basis of size
- diffusion
- the random movement of molecules from an area of high concentration to an area of low concentration
- ion pumps
- carrier proteins that transport cations/anions across cell membrane using energy source such as ATP
- endocytosis
- process of packaging extracellular materials at the cell surface and importing them into the cytoplasm
- exocytosis
- reverse of endocytosis
- selectively permeable
- the property of a membrane that permits free passage of some materials and restricts the passage of others
- characteristics of carrier-mediated transport
- 1) specificity: carrier proteins are specific to a substrate; 2) saturation limits: finite number of carrier proteins and substrate molecules limits rate of transport: 3) regulation: hormones affect activity of carrier proteins
- concentration gradient
- the difference between areas of high and low concentration
- osmotic pressure
- the force with which water moves from one concentration gradient to another
- phagocytosis
- "cell eating" whereby phagosomes containing solid objects are formed
- hypertonic
- net flow of water out of the cell causing crenation
- mRNA
- the protein that carries the information needed to synthesize proteins
- facilitated diffusion
- passive transport of substances across the cell membrane by carrier proteins without energy use
- vesicles
- small membranous sacs that form at or fuse with the cell membrane
- gene
- a functional unit of heredity
- osmosis
- the diffusion of water across a selective permeable membrane is called
- differentiation
- a process of cell specialization caused by the switching on and off specific genes
- tumor
- a mass or swelling produced by abnormal cell growth and divison
- isotonic
- a solution that does not cause an osmotic flow of water into or out of the cell
- transmembrane potential
- differntial charge that exists across the cell membrane due to the presence of positive (outside cell)/negative (inside cell) ions
- RNA processing
- the editing of mRNA involving splicing, capping and tailing
- codon
- a three-base mRNA sequence
- tonicity vs. osmolarity
- tonicity refers to how a solution affects a cell whereas osmolarity refers to the solute concentration of the solution
- RNA polymerase
- an enzyme that binds to the promoter on a gene
- carrier-mediated transport
- integral proteins bind to a substrate and carry them across the cell membrane
- transcription
- the encoding of genetic instructions on a strand of mRNA
- hypotonic
- net flow of water into the cell causing lysis