2.4 Flashcards
endocytosis
brings molecules and cells into a eukaryotic cell
phagocytosis - solid particle
pinocytosis - fluid + small substance
receptor-mediated - to bring in only specific molecules
vesicle
consists of liquid enclosed by a lipid bilayer
assists in:
movement of proteins
movement of molecules (macromolecules)
distribution of membrane
exocytosis
process by which materials are released from the cell through vesicle fusion with the cell membrane
primary lysosomes
contain digestive enzymes that hydrolyze macromolecules into monomers under acidic conditions
originate from the Golgi apparatus
contain hydrolytic enzymes but not substrates
R1-R2 + H2O —> R1-OH +R2-H
acidic with a pH of 5.0
secondary lysosomes
phagosomes (from phagocytosis) fuse with primary lysosomes to form secondary lysosomes, where digestion and recycling occur
plant vacuole
provide structure for plant cells
arise from the ER or Golgi
store water and provide structure
store toxic molecules and waste products
hydrolyze proteins into monomers
peroxisomes
collect and break down various substrates by oxidation reactions using peroxisomal enzymes
RH2 + O2 —> R+ H2O
accumulate toxic H2O2 during oxidation and convert it to H2O via catalase
mitochondria
energy is harvested from fuel molecules
inner membrane fold inward to form cristae
–creates large surface area
–contain enzymes for cellular respiration
cells requiring a lot of energy have many mitochondira
chloroplasts
site of photosynthesis
inner membrane forms thykaloids which increases the surface area
contain chlorophyll and other pigments
harvest light energy
mitochondria and chloroplasts
divide independently of the nucleus
both have double membrane and transform energy
scientists propose that they were once free-living
cytoskeleton
dense and complex network of fibers, which provide the cell with shape, strength and movement
cytoskeleton functions
supports and maintains cell shape
hold organelles in position
moves organelles
involved in cell movement/shape change
interacts with extracellular structures to hold cells in place
components of the cytoskeleton
microfilaments, intermediate filaments, microtubules
microfilaments
formed by actin monomers that have - and + ends that permit their polymerization
helps a cell move
determine and stabilize cell shape
ameboid movement
localized change in cell shape
contractile forces at the rear: myosin slides on actin filaments
formation of pseudopodia at the front: actin monomers polymerize
microvilli
formed by a meshwork between intermediate filaments and microfilaments
support the shape of the microvilli
increase the surface area
cannot propel the cell due to lack of motor proteins
microtubules
long, hollow cylinders made from tubulin dimers (alpha and beta)
form a rigid internal skeleton and maintain cell shape
act as a framework for motor proteins (involved in vesicle transport)
kinesin (- to +) and dynein (+ to -) bind to and move along microtubules carrying vesicles
cilia and eukaryotic flagella
made of microtubules in a “9+2” array that move the entire cell
intermediate filaments
tough, ropelike proteins structure and consist of long, fibrous subunits
exist in many types, each consisting of a different protein (eg. keratin)
anchor cell structures in place
resist tension
