Chapter 4: Cell Structure Flashcards
cell wall
- plants: made out of cellulose (polysaccharide)
- fungi: made out of chitin (polysaccharide)
- bacteria: made of peptidoglycan (protein and sugar)
- forms outer layer
cell membrane
- selectively permeable
- composed of lipids and proteins
- forms oily layer between the inside of the cell and the outside so hydrophilic substances cannot cross the hydrophobic barrier
simple diffusion
- movement of a hydrophobic substance (like oxygen, carbon dioxide, and cholesterol) down a concentration gradient from an area of high concentration to low concentration until dynamic equilibrium is reached
- only works when the substance is lipid soluble (hydrophobic) and can interact with the oily barrier
- passive
facilitated diffusion
- hydrophillic particles (like ions and glucose) diffuse across the membrane with the use of membrane proteins that form specialized channels
- passive
- some proteins act as carrier molecules that bind to a substance and “pull” it through a membrane
active transport
- can go against the concentration gradient
- use energy to move something across the membrane
- relies on membrane proteins to transport hydrophobic and hydrophillic particles
bulk transport
-movement of large, bulky items across the membrane through endocytosis or exocytosis
endocytosis
- cell takes in a particle by surrounding and engulfing it into a vesicle
- phagocytosis: cell eating
- pinocytosis: cell drinking
exocytosis
-particle in a vesicle is released to the outside by fusing the vesicle with the cell membrane
osmosis
- diffusion of water across a membrane down the water concentration gradient
- water’s concentration gradient is opposite of the solute’s concentration gradient
- must cross through facilitated diffusion (with aquaporins)
hypertonic solution
- concentrated solution
- causes cell to shrivel or become flaccid
hypotonic solution
- dilute solution
- cell will lyse or become turgid for plants
isotonic solution
- same concentration as cell
- cell will be normal (plant will be shriveled)
cytoplasm
- contains eukaryotic cell’s organelles
- some prokaryotic cells do not have organelles
ribosome
- no membrane
- site of protein synthesis
nucleus
- double membrane bound
- contains genetic material (chromosomes and DNA)
- control center of cell
mitochondria
- functions in cellular respiration (produces ATP for the cell)
- bound by double membrane
vacuole
-storage of wastes and other materials
smooth ER
- transports substances around the cell
- creates lipids
rough ER
-has ribosomes that synthesizes membrane (protein channels) and secreted proteins
golgi body
-sorts and packages proteins made by ribosomes on the ER
lysosomes
-digest foreign substances and worn-out organelles
nucleolus
- small, dense structure in the nucleus
- site of ribosome synthesis
enzyme
- protein (organic molecule) that acts as a catalyst (a molecule that speeds up chemical reactions) in cells
- reusable (not used up)
- induced-fit or lock-and-key model (an enzyme has a specific shape catered to certain reactions bc active site is specific to certain reactants)
- reactants are called substrates
- determines which reactions occur inside a cell
denaturation
- degradation of enzyme (often through heat or change in pH)
- no longer useful because they lose their shape
coenzymes
- molecules that help enzymes work faster (or work at all)
- ex: vitamins
centriole
-help form the mitotic spindle during mitosis (cell division)
