A Tour of the Cell

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envelope (double membrane)

perforated by nuclear pores.

The nuclear envelope is

continuous with the

endoplasmic reticulum (ER).

(ER)

Houses chromosomes, made of

chromatin (DNA, the genetic

material, and proteins); contains

nucleoli, where ribosomal

subunits are made. Pores

regulate entry and exit os

materials.

Ribosome

Two subunits made of ribo-

somal RNA and proteins; can be

free in cytosol or bound to ER

Protein synthesis

Slide 118

Fig. 6-UN1b

Cell Component

Structure

Function

Concept 6.4

The endomembrane system

regulates protein traffic and

performs metabolic functions

in the cell

Endoplasmic reticulum

(Nuclear

envelope)

Golgi apparatus

Lysosome

Vacuole

Large membrane-bounded

vesicle in plants

Membranous sac of hydrolytic

enzymes (in animal cells)

Stacks of flattened

membranous

sacs; has polarity

(cis and trans

faces)

Extensive network of

membrane-bound tubules and

sacs; membrane separates

lumen from cytosol;

continuous with

the nuclear envelope.

Smooth ER: synthesis of

lipids, metabolism of carbohy-

drates, Ca2+ storage, detoxifica-

tion of drugs and poisons

Rough ER: Aids in sythesis of

secretory and other proteins

from bound ribosomes; adds

carbohydrates to glycoproteins;

produces new membrane

Modification of proteins, carbo-

hydrates on proteins, and phos-

pholipids; synthesis of many

polysaccharides; sorting of

Golgi products, which are then

released in vesicles.

Breakdown of ingested sub-

stances cell macromolecules, and damaged organelles for recycling

Digestion, storage, waste

disposal, water balance, cell

growth, and protection

Slide 119

Fig. 6-UN1c

Cell Component

Concept 6.5

Mitochondria and chloro-

plasts change energy from

one form to another

Mitochondrion

Chloroplast

Peroxisome

Structure

Function

Bounded by double

membrane;

inner membrane has

infoldings (cristae)

Typically two membranes

around fluid stroma, which

contains membranous thylakoids

stacked into grana (in plants)

Specialized metabolic

compartment bounded by a

single membrane

Cellular respiration

Photosynthesis

Contains enzymes that transfer

hydrogen to water, producing

hydrogen peroxide (H2O2) as a

by-product, which is converted

to water by other enzymes

in the peroxisome

Slide 120

Fig. 6-UN2

Slide 121

Fig. 6-UN3