chapter 3 study guide Flashcards
define cell
the smallest unit of life that is responsible for all of life’s processes
name and describe the composition of extracellular materials
- a general term for the proteins and polysaccharides that are secreted by some cells, act as connective material
- components are collagen, proteoglycans, bronectin, and laminin
three major regions of a generalized cell
plasma membrane, cytoplasm, and nucleus
plasma membrane
the outer covering of the cell that encloses the cytoplasm
cytoplasm
the jelly like matrix within the cell that contains various organelles
nucleus
round and usually centrally placed structure that controls the various activities of the cell
the chemical composition of the cell membrane
plasma membrane, phospholipids, cholesterol
plasma membrane
composed of phospholipids, cholesterol and proteins that provide a barrier between the external environment of the cell, regulate molecules that enter the cell, and allow communication between cells via protein receptors
phospholipids
have a polar hydrophilic head and non- polar hydrophobic tails, major component in cellular membranes that allow different materials in and out of the cell
relate the cell membrane structure to passive transport mechanisms
- phospholipid bilayer allows small, non-polar molecules to diffuse freely
- protein channels allow for the passive transport of larger and charged molecules
- channel proteins- forms channels that allow ions to move down their concentration gradient through the membrane (facilitated diffusion)
- carrier proteins bind to molecules on one side of the membrane and transport them through, large molecules
simple diffusion
structure of the lipid bilayer allows small, non-polar molecules to pass through the cell membrane, down their concentration gradient
facilitated diffusion
- uses channel and carrier proteins
- channel proteins are less selective and don’t let molecules through based on size and charge
- carrier proteins are very selective and only let one particular type of molecule to cross
osmosis
diffusion of water through a semipermeable membrane down its concentration gradient. if a membrane is permeable to water but not to a solute, water will equalize its own concentration by diffusing to the side of lower water concentration
difference between primary and secondary active transport
- primary active transport uses energy directly from ATP to move molecules, uses a pump
- secondary active transport uses energy stored in the electrochemical gradient to transport a molecule
endocytosis
when a cell envelopes extracellular materials using it’s cell membrane (phagocytosis and pinocytosis)
exocytosis
material is destined for export, packaged into a vesicle inside the cell. The vesicle membrane attaches to the cell membrane and the material is exported
phagocytosis
nonselective, cell takes in large particle
pinocytosis
cell takes in small particle in fluid
receptor- mediated endocytosis
selective, when external receptors bind to a specific ligand, the cell responds by endocytosing the ligand
define membrane potential and explain how the resting membrane potential is established and maintained
- membrane potential is the difference in electrical potential between the interior and the exterior of a biological cell
- resting membrane potential is established by the uneven distribution of ions between the inside and the outside of the cell. It is maintained by ion channels controlling the movement of ions in and out of the cell
mitochondria
- composed of two separate lipid bilayer membranes, various molecules work together in the inner membrane to produce ATP
- energy conversion factories of the cell
ribosomes
- read mRNA to assemble amino acids into proteins using translation
- composed of two subunits made of rRNA and proteins
rough endoplasmic reticulum
*winding network of thin membranous sacs near the nucleus with ribosomes
*function is protein synthesis
smooth endoplasmic reticulum
*winding network of thin membranous sacs near the nucleus
* synthesizes phospholipids, regulates concentration, breaks down toxins
golgi apparatus
*flattened membrane bound sacs, stacked on top of each other
* manipulates products from the rough ER, produces lysosomes, packages and tags products from the ER
lysosomes
*spherical vesicles formed from the Glogi Apparatus filled with hydrolytic enzymes
* degrade cellular waste materials, help plasma membrane repair and nutrient recycling
peroxisomes
- small, single membrane organelles found in cytoplasm
- contain enzymes for detoxifying harmful substances and lipid metabolism
cytoskeleton
- made up of microtubules, microfilaments, and intermediate filaments
- maintains cell shape, promotes cell movement, and aids in cell division
nuclear envelope
- membrane enclosing the nucleus, two adjacent lipid bilayers with a thin fluid space in between
- seperates the contents of the nucleus from the cytoplasm and provides structure to nucleus
nucleolus
*gel-like nucleoplasm with solutes that include the building blocks of nucleic acids
* manufactures the RNA necessary for construction of ribosomes
chromatin
- DNA and proteins
- packages DNA into a unit capable of fitting into the nucleus
process of DNA replication
- process of copying DNA
- helicase seperates the two strands of DNA
- DNA polymerase connects bases that corraspond with the template
- once the two original strands have their own pair, DNA replication is complete
