9. Ribosomes: Protein factories
– particles made of ribosomal RNA and protein
– Protein synthesis occurs here
• Free ribosomes are localized to the cytosol
• Bound ribosomes are on the ER or the nuclear envelope
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large subunit
Fig. 6-11 Small subunit
Diagram of a ribosome
16. Fig. 6-16-3
Nucleus
Rough ER
Smooth Golgi
ER Transport vessicle
Transport vessicle
Lysosome Plasma
membrane
•Nuclear envelope is connected to rough ER
•Proteins produced by the ER flow in transport vessicles to the Golgi
•Golgi pinches off vessicles that give rise to lysosomes, vessicles and vacuoles
•Lysosomes can fuse with another vessicle for digestion
•Transport vessicle carries proteins to plasma membrane for secretion
•Plasma membrane expands by fusion of vessicles; proteins are secreted from the cell
24. Microtubules assist in motility
(a) EX: Motion of flagella in sperm (b) EX: Motion of cilia in aquatic life
Fig. 6-23
25. Fig. 6-24
Microtubule structure in cilia
Plasma
membrane
Microtubules
(b) Cross section of
Plasma cilium
membrane
Basal body
(a) Longitudinal
section of cilium
(c) Cross section of basal body
32. Fig. 6-32
Tight Tight junctions prevent
junction fluid from moving
across a layer of cells
0.5 µm
Tight junction Desmosomes fasten
cells together in sheets
Intermediate
filaments
Desmosome
Gap Desmosome
junctions
Gap junctions all cells to
communicate with one
Space
Extracellular another via cytoplasmic
matrix
between Gap channels
cells junction
Plasma membranes
of adjacent cells
0.1 µm
33. Fig. 6-UN1
Cell Component Structure Function
Concept 6.3 Nucleus Surrounded by nuclear Houses chromosomes, made of
The eukaryotic cell’s genetic envelope (double membrane) chromatin (DNA, the genetic
instructions are housed in perforated by nuclear pores. material, and proteins); contains
the nucleus and carried out The nuclear envelope is nucleoli, where ribosomal
by the ribosomes continuous with the subunits are made. Pores
endoplasmic reticulum (ER). regulate entry and exit of
materials.
(ER)
Ribosome Two subunits made of ribo- Protein synthesis
somal RNA and proteins; can be
free in cytosol or bound to ER
Concept 6.4 Endoplasmic reticulum Extensive network of Smooth ER: synthesis of
The endomembrane system membrane-bound tubules and lipids, metabolism of carbohy-
regulates protein traffic and (Nuclear sacs; membrane separates drates, Ca2+ storage, detoxifica-
performs metabolic functions envelope) lumen from cytosol; tion of drugs and poisons
in the cell continuous with
the nuclear envelope. Rough ER: Aids in synthesis of
secretory and other proteins from
bound ribosomes; adds
carbohydrates to glycoproteins;
produces new membrane
Golgi apparatus Stacks of flattened Modification of proteins, carbo-
membranous hydrates on proteins, and phos-
sacs; has polarity pholipids; synthesis of many
(cis and trans polysaccharides; sorting of Golgi
faces) products, which are then
released in vesicles.
Lysosome Membranous sac of hydrolytic Breakdown of ingested substances,
enzymes (in animal cells) cell macromolecules, and damaged
organelles for recycling
Vacuole Large membrane-bounded Digestion, storage, waste
vesicle in plants disposal, water balance, cell
growth, and protection
Concept 6.5 Mitochondrion Bounded by double Cellular respiration
Mitochondria and chloro- membrane;
plasts change energy from inner membrane has
one form to another infoldings (cristae)
Chloroplast Typically two membranes Photosynthesis
around fluid stroma, which
contains membranous thylakoids
stacked into grana (in plants)
Peroxisome Specialized metabolic Contains enzymes that transfer
compartment bounded by a hydrogen to water, producing
single membrane hydrogen peroxide (H2O2) as a
by-product, which is converted
to water by other enzymes
in the peroxisome
Notas do Editor
Figure 6.6 A prokaryotic cell
Figure 6.9 Animal and plant cells—animal cell
Figure 6.9 Animal and plant cells—plant cell
Figure 6.10 The nucleus and its envelope
For the Cell Biology Video Staining of Endoplasmic Reticulum, go to Animation and Video Files.
Figure 6.12 Endoplasmic reticulum (ER)
For the Cell Biology Video ER to Golgi Traffic, go to Animation and Video Files. For the Cell Biology Video Golgi Complex in 3D, go to Animation and Video Files. For the Cell Biology Video Secretion From the Golgi, go to Animation and Video Files.
Figure 6.16 Review: relationships among organelles of the endomembrane system
For the Cell Biology Video ER and Mitochondria in Leaf Cells, go to Animation and Video Files. For the Cell Biology Video Mitochondria in 3D, go to Animation and Video Files. For the Cell Biology Video Chloroplast Movement, go to Animation and Video Files.
Figure 6.17 The mitochondrion, site of cellular respiration
For the Cell Biology Video The Cytoskeleton in a Neuron Growth Cone, go to Animation and Video Files For the Cell Biology Video Cytoskeletal Protein Dynamics, go to Animation and Video Files.
Figure 6.22 Centrosome containing a pair of centrioles
Figure 6.23a A comparison of the beating of flagella and cilia — motion of flagella
Figure 6.24 Ultrastructure of a eukaryotic flagellum or motile cilium
For the Cell Biology Video Interphase Microtubule Dynamics, go to Animation and Video Files. For the Cell Biology Video Microtubule Sliding in Flagellum Movement, go to Animation and Video Files. For the Cell Biology Video Microtubule Dynamics, go to Animation and Video Files.
Figure 6.28 Plant cell walls
For the Cell Biology Video Cartoon Model of a Collagen Triple Helix, go to Animation and Video Files. For the Cell Biology Video Staining of the Extracellular Matrix, go to Animation and Video Files. For the Cell Biology Video Fibronectin Fibrils, go to Animation and Video Files.
Figure 6.32 Intercellular junctions in animal tissues