A Tour of the Cell

Page
3

20,000 g

20 min

80,000 g

60 min

150,000 g

3 hr

Pellet rich in nuclei and cellular debris

Pellet rich in mitochondria (and chloro-plasts if cells

are from a plant)

Pellet rich in “microsomes” (pieces of plasma

membranes and cells’ internal membranes)

Pellet rich in ribosomes

TECHNIQUE (cont.)

Slide 19

Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions

The basic structural and functional unit of every organism is one of two types of cells: prokaryotic or eukaryotic

Only organisms of the domains Bacteria and Archaea consist of prokaryotic cells

Protists, fungi, animals, and plants all consist of eukaryotic cells

Slide 20

Comparing Prokaryotic and Eukaryotic Cells

Basic features of all cells:

Plasma membrane

Semifluid substance called cytosol

Chromosomes (carry genes)

Ribosomes (make proteins)

Slide 21

Prokaryotic cells are characterized by having

No nucleus

DNA in an unbound region called the nucleoid

No membrane-bound organelles

Cytoplasm bound by the plasma membrane

Slide 22

Fig. 6-6

Fimbriae

Nucleoid

Ribosomes

Plasma membrane

Cell wall

Capsule

Flagella

Bacterial

chromosome

(a)

A typical rod-shaped bacterium

(b)

A thin section through the bacterium Bacillus coagulans (TEM)

0.5 µm

Slide 23

Eukaryotic cells are characterized by having

DNA in a nucleus that is bounded by a membranous nuclear envelope

Membrane-bound organelles

Cytoplasm in the region between the plasma membrane and nucleus

Eukaryotic cells are generally much larger than prokaryotic cells

Slide 24

The plasma membrane is a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell

The general structure of a biological membrane is a double layer of phospholipids

Slide 25

Fig. 6-7

TEM of a plasma

membrane

(a)

(b) Structure of the plasma membrane

Outside of cell

Inside of

cell

0.1 µm

Hydrophilic

region

Hydrophobic

region

Hydrophilic

region

Phospholipid

Proteins

Carbohydrate side chain

Slide 26