Ch 6. A Tour of the Cell Flashcards
big idea: know each organelle's structure & function, as well as know a bit about cell junctions (tight/gap/desmo/plasmodes.)
why are there upper and lower limits to cell size?
-surface area increases slower than volume. more volume = more food needed & more waste generated, but a lower S.A. = less room for food to enter and waste to leave
what are the four main differences between prokaryotic and eukaryotic cells?
- size = prokaryotes are smaller than eukaryotes
- nucleus = prokaryote has no nucleus
- membrane-bound organelles = prokaryotes have none
- organism size = prokaryotes are 1 cell organisms, eukaryotes are uni/multicellular
what are the main benefits of compartmentalization in eukaryotic cells?
-improves the efficiency of cellular functions by allowing many things to occur in one space
-concentrates molecules [eg - digestive enzymes in lysosomes]
-have more membranes for membrane-bound pathways [ETC]
what is the mathematical relationship between diameter, volume, and surface area?
as diameter increases…
-volume goes up by D^3
-surface area goes up by D^2
ex. a diameter increase of 5x = 125x volume but only 25x surface area
what does the cytoplasm consist of?
cell organelles + cytosol (jelly the organelles float in) + cytoskeleton
what is the structure of the nucleus?
-round, central organelle of the cell with:
1. double membrane
2. nuclear pores (holes)
3. nuclear lamina
what is the function of the nucleus?
-enclose and protect genetic material
-transcribe DNA to RNA
what is the difference between cytosol and cytoplasm?
cytosol = the fluid part of the cytoplasm
cytoplasm = organelles / cytoskeleton, which float in the cytosol
what is the structure of ribosomes and what are the two kinds?
structure: 2 subunits of RNA and protein
1. bound = “stuck” to ER, make proteins for secretion
2. free = loose in cytosol, make proteins for inside the cell
what is the function of a ribosome?
to translate mRNA to make proteins
what are the broad components of the endomembrane system?
-endoplasmic reticulum (rough & smooth)
-golgi apparatus
-lysosomes
-vacuoles
-central vacuole [plants only]
what is the structure of the endoplasmic reticulum?
-a membranous maze of tubules and cisterna, continuous with the nucleus
what is the function of both kinds of endoplasmic reticulum?
rough: has ribosomes attached to it, so makes membrane proteins & phospholipids for use outside cell
smooth: lipid synthesis, detoxification, calcium storage in muscle cells
what is the structure of the golgi apparatus (what are the two ends?)
cis end = receives vesicles
trans end = ships out modified vesicles
what is the function of the golgi apparatus?
-synthesizing polysaccharides
-modifying carbohydrates
-sending previously made products to right destination
what is the structure of a lysosome?
-a membrane bound sac with a low pH and a bunch of digestive enzymes
what is the function of a lysosome?
-digesting foreign particles
-removing dead cell debris
what is the structure & function of vacuoles?
structure: membrane bound sacs
function: mostly food storage & contraction
what is the structure & function of central vacuoles? [plants only]
structure: sacs enclosed by a tonoplast membrane
function: storing wastes, proteins, and pigments
what is the structure of mitochondria?
-double membrane with an inner and outer
-membranes have an intermembrane space + a matrix
-has its own DNA and ribosomes
what is the function of mitochondria?
cellular respiration
what are plastids? what are the three kinds?
plastids are double membrane organelles found in photosynthetic organisms
-consist of chloroplasts, amyloplasts, and chromoplasts
what is the structure of chloroplasts?
-are plastids [double membrane organelles]
-have inner sacs called thylakoids stacked like pancakes called grana
-external space is called stroma
what is the function of chloroplasts?
photosynthesis
what do amyloplasts and chromoplasts store?
amyloplasts = store starch and amylase to break down starch
chromoplasts = store pigments
what is the evidence that mitochondria and chloroplasts were once their own organelles?
-both are very similar genetically to bacteria
-both have their own, separate DNA
-have cell membranes similar to bacteria
what is the structure of peroxisomes?
-peroxisomes are a single membrane compartment
what is the function of peroxisomes?
-detoxification of free radicals (atoms with unpaired electrons that can damage cells)
what are the components of the cytoskeleton?
-actin filaments / microfilaments
-intermediate filaments
-microtubules, which include cilia and flagella
what is the structure & function of actin filaments?
structure: thin, long fibers
function: allow for muscle stretch and contraction by changing cell shape
what is the structure and function of intermediate filaments?
structure: intermediate width fibers, diff. types in each cell type
function: maintaining cell shape
what is the structure of microtubules?
-a thick, hollow cylinder composed of repeating tubulin proteins
-can work alone or be grouped together to make larger structures
what is the function of lone microtubules [NOT grouped]?
-cell support
-organization & movement of vesicles
-cell division [mitotic spindle]
what is the function of grouped microtubules [what 3 structures do they make]?
can make larger structures…
1. flagella = whiplike tails that move sperm
2. cilia = hairlike cell projections that move mucus
3. centrioles = organize loose microtubules during cell division
in what kind of organisms are cell walls found?
plants, fungi, algae, protists, prokaryotes
what are the functions of the cell wall?
-protection of the cell from external environment
-maintaining cell shape
-regulating fluid intake
what is the structure of the cell wall?
-thick cellulose embedded in a matrix, 3 walls:
1. primary wall = furthest from cell membrane
2. middle lamella = contains pectin which acts as a glue
3. secondary wall = closest to cell membrane
what are the components of the extracellular matrix / ECM?
-glycoproteins
-proteoglycans
-fibronectin / integrins
what are glycoproteins?
-proteins with carbohydrate chains attached, such as collagen
-work to provide structure & bind tissues together [muscle-skin, skin-bone, muscle-bone]
what are proteoglycans?
carbohydrates with some protein
-work as shock absorbers [GAGs]
what is fibronectin and integrin?
integrin = connects proteins inside cell with fibronectin outside cell
-allows cell to react to external conditions
what are the four kinds of intercellular junctions?
- plasmodesmata [plants ONL]
- tight junctions
- desmosomes
- gap junctions
what are plasmodesmata?
-channels connecting plant cells
-allows water and nutrients to flow from roots to leaves
what are tight junctions?
-fused membranes that prevent fluid leakage
-found in the bladder & stomach primarily
what are desmosomes?
-spot welds that fasten cells together
-found in skin & cardiac muscle cells
what are gap junctions?
-channels between cells that allow them to communicate [NEURONS]
