Chapter 6: A Tour of The Cell 2 Flashcards
Mitochondria
sites of cellular respiration. 1-10 um. mobile.
chloroplasts
sites of photosynthesis. 3-6 um. mobile.
endosymbiont theory
early ancestor of eukaryotic cells engulfed prokaryote.
- mitochondria and chloroplasts have a double membrane (possibly like ancestral prokaryote)
- both have DNA and ribosomes
- both are somewhat autonomous
cristae
infoldings of inner membrane of mitochondrion. increases surface area of inner mitochondrial membrane
mitochondrial matrix
second compartment of mitochondrion enclosed by inner membrane. its enzymes catalyze some steps for cellular respiration.
thylakoids
flattened, interconnected sacs within chloroplasts
grana
stacks of thylakoids
stroma
fluid outside thylakoids. contains DNA and ribosomes and membranes
Plastids
family of plant organelles (including chloroplasts).
amyloplast
colorless plastid that stores starch (amylose), particularly in roots and tubers
chromoplast
plastid that stores pigments (orange hue for fruits/flowers)
Peroxisome
single membrane organelle whose removes hydrogen from substrate and transfers it to O2 to form H2O2 (hydrogen peroxide). an enzyme can convert the h2o2 to h20. it can break down fatty acids (with oxygen) or detoxify alcohol/substances (remove hydrogen)
glyoxysome
specialized peroxisomes in plant seeds. converts fatty acids to sugar. (energy for seedling)
cytoskeleton
dynamic network of fibers extending throughout cytoplasm. supports shape and organizes structures + activities of cells.
Motor proteins
assists with cell motility.
microtubules
structure: hollow tubes; 13 columns of tubulin dimers
diameter: 25 nm with 15 nm lumen
subunits: a tubulin and b tubulin
functions: maintenance of cell shape (compression-resisting), cell motility (cilia/flagella), chromosome/organelle movements
microfilaments
structure: two intertwined strands of actin
diameter: 7 nm
subunits: actin
functions: maintenance of cell shape (tension-bearing) changes in cell shape, muscle contraction, cytoplasmic streaming, cell motility (pseudopodia), cell division (cleavage furrow)
intermediate filaments
structure: fibrous proteins supercoiled into thicker cables
diameter: 8-12 nm
subunits: one of several different proteins (depends on cell type)
functions: maintenance of cell shape (tension-bearing), anchorage of nucleus and certain other organelles, formation of nuclear lamina
microtubule structure
two slightly different ends (because of orientation of tubulin dimers). one end accumulates/releases tubulin dimers faster (plus end).
centrosome
microtubule-organizing center for animal cells. (compression resisting)
centrioles
9 sets of triplet microtubules arranged in a ring. a pair for each centrosome.
flagella
undulating motion. 10-200 um length, 0.25 um diameter. 1-2 per cell.
cilia
back and forth motion. 2-20 um length. 0.25 um diameter. several motile cilia per cell, one primary cilia (9+0 pattern) per cell (recieves signals).
cilia/flagella strucure
nine doublets of microtubules arranged in a ring. two single microtubules in the center. sheathed in plasma membrane extension.
Basal body
anchors cilia/flagella. similar structure to centriole
cross-linking proteins
connects outer doublet microtubules in flagella + motile cilia.
dyneins
large moter proteins between the outer doublet microtubules. walks along the doublets (held in place by cross-linking proteins), making them curve/bend.
actin
globular protein.
cortex
outer cytoplasmic layer of cell. supported by microfilaments, and has semisolid gel consistency
myosin
motor protein for actin.
pseuodopodia
cellular extensions that undergo localized contractions due to actin/myosin
cytoplasmic streaming
circular flow of cytoplasm within cells
cell wall
extracellular plant cell structure. thicker than plasma membrane, made up of microfibrils of cellulose
primary cell wall
first layer of cell wall. relatively thin and flexible.
cell wall formation.
cellulose synthase makes cellulose microfibrils, oriented at right angles to direction of cell expansion. microtubules guides cellulose synthase as it deposits cellulose.
middle lamella
between primary walls. thin layer with lots of pectin (sticky polysaccharide).
secondary cell wall
several laminated layers, strong and durable matrix.
ECM
present in animal cells. made mostly of glycoproteins
collagen
most abundunt ECM glycoprotein. forms strong fibers outside the cells.
proteoglycans
small core protein with several carbohydrate chains attached. network of ECM
fibronectin
glycoprotein that attaches cells to ECM
integrins
cell-surface receptor proteins that span the plasma membrane and bind on cytoplasmic side to associated microtubule proteins. attaches to fibronectin and other ECM proteins. transmits signals between ECM and cell.
plasmodesmata
membrane lined channels filled with cytoplasm in cell walls. joins plant cells.
tight junctions
animal cells. plasma membranes of cells pressed very tightly together and bound by specific proteins. prevents leakage of extracellular fluid across layer of epithelial cells
desmosomes
animal cells. fastens cells together (ex: muscle cells). intermediate filaments of keratin anchor desmosomes in cytoplasm.
gap junctions
animal cells. membrane protein surrounding a pore. provide cytoplasmic channels from one cell to an adjacent cell.
