The Structure and Function of Large Biological Molecules

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The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head

Slide 48

Fig. 5-13

(b)

Space-filling model

(a)

(c)

Structural formula

Phospholipid symbol

Fatty acids

Hydrophilic

head

Hydrophobic

tails

Choline

Phosphate

Glycerol

Hydrophobic tails

Hydrophilic head

Slide 49

Fig. 5-13ab

(b)

Space-filling model

(a)

Structural formula

Fatty acids

Choline

Phosphate

Glycerol

Hydrophobic tails

Hydrophilic head

Slide 50

When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the interior

The structure of phospholipids results in a bilayer arrangement found in cell membranes

Phospholipids are the major component of all cell membranes

Slide 51

Fig. 5-14

Hydrophilic

head

Hydrophobic

tail

WATER

WATER

Slide 52

Steroids

Steroids are lipids characterized by a carbon skeleton consisting of four fused rings

Cholesterol, an important steroid, is a component in animal cell membranes

Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease

Slide 53

Fig. 5-15

Slide 54

Concept 5.4: Proteins have many structures, resulting in a wide range of functions

Proteins account for more than 50% of the dry mass of most cells

Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances

Slide 55

Table 5-1

Slide 56

Animation: Structural Proteins

Animation: Storage Proteins

Animation: Transport Proteins

Animation: Receptor Proteins

Animation: Contractile Proteins

Animation: Defensive Proteins

Animation: Hormonal Proteins

Animation: Sensory Proteins

Animation: Gene Regulatory Proteins

Slide 57

Enzymes are a type of protein that acts as a catalyst to speed up chemical reactions

Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life