Glucose

(a) Linear and ring forms (b) Abbreviated ring structure

Disaccharides

(b) Dehydration reaction in the synthesis of sucrose

Glucose Fructose Sucrose

MaltoseGlucoseGlucose

(a) Dehydration reaction in the synthesis of maltose

Different Ring Strucutres

(a) and glucose ring structures

Glucose Glucose

and Configurations

Cellulose

Glucosemonomer

Cellulosemolecules

Microfibril

Cellulosemicrofibrilsin a plantcell wall

0.5 µm

10 µm

Cell walls

Chitin

The structureof the chitinmonomer.

(a) (b) (c)Chitin forms theexoskeleton ofarthropods.

Chitin is used to makea strong and flexiblesurgical thread.

Fats (Triacylglycerols)

Fatty acid(palmitic acid)

(a) Dehydration reaction in the synthesis of a fat

Glycerol

Saturated Fats

(a) Saturated fat

Structuralformula of asaturated fatmolecule

Stearic acid, asaturated fattyacid

Unsaturated Fats

(b)Unsaturated fat

Structural formulaof an unsaturatedfat molecule

Oleic acid, anunsaturatedfatty acid

cis doublebond causesbending

Phospholipids

(b)Space-filling model(a) (c)Structural formula Phospholipid symbol

Fatty acids

Hydrophilichead

Hydrophobictails

Choline

Phosphate

Glycerol

Hyd

rop

ho

bic

tai

lsH

ydro

ph

ilic

hea

d

Fig. 5-14

Hydrophilichead

Hydrophobictail WATER

WATER

Steroids

Fig. 5-16

Enzyme(sucrase)

Substrate(sucrose)

Fructose

Glucose

OH

H O

H2O

Fig. 5-UN1

Aminogroup

Carboxylgroup

α carbon

Amino Acids

Amino Acids

Peptide Bond

Sickle-cell Disease

Secondary Structure

Tertiary Structure

Quaternary Structure

4 Levels of Protein Structure

What determines a proteins structure?

The unique conformation endows each protein with a specific function

Physical and chemical environment affects struture- _________________: protein unravels and losses its conformation

- pH, [salt], temperature

Protein Folding in the Cell

It is hard to predict a protein’s structure from its primary structure

Go through several intermediate structures

____________ are protein molecules that assist the proper folding of other proteins

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 5-24

Hollowcylinder

Cap

Chaperonin(fully assembled)

Polypeptide

Steps of ChaperoninAction:

An unfolded poly-peptide enters thecylinder from one end.

1

2 3The cap attaches, causing thecylinder to change shape insuch a way that it creates ahydrophilic environment forthe folding of the polypeptide.

The cap comesoff, and the properlyfolded protein isreleased.

Correctlyfoldedprotein

DNA, RNA and Proteins

mRNA

Synthesis ofmRNA in thenucleus

DNA

NUCLEUS

mRNA

CYTOPLASM

Movement ofmRNA into cytoplasmvia nuclear pore

Ribosome

AminoacidsPolypeptide

Synthesisof protein

1

2

3

Fig. 5-27ab5' end

5'C

3'C

5'C

3'C

3' end

(a) Polynucleotide, or nucleic acid

(b) Nucleotide

Nucleoside

Nitrogenousbase

3'C

5'C

Phosphategroup Sugar

(pentose)

Fig. 5-27c-1

(c) Nucleoside components: nitrogenous bases

Purines

Guanine (G)Adenine (A)

Cytosine (C)Thymine (T, in DNA)Uracil (U, in RNA)

Nitrogenous bases

Pyrimidines

Fig. 5-27c-2

Ribose (in RNA)Deoxyribose (in DNA)

Sugars

(c) Nucleoside components: sugars

Fig. 5-27ab5' end

5'C

3'C

5'C

3'C

3' end

(a) Polynucleotide, or nucleic acid

(b) Nucleotide

Nucleoside

Nitrogenousbase

3'C

5'C

Phosphategroup Sugar

(pentose)

Fig. 5-28

Sugar-phosphatebackbones

3' end

3' end

3' end

3' end

5' end

5' end

5' end

5' end

Base pair (joined byhydrogen bonding)

Old strands

Newstrands

Nucleotideabout to beadded to anew strand

DNA and Proteins as Tape Measures of Evolution

Siblings share similarity in DNA and protein sequences than unrelated species members

Two species that appear closely related based on fossil and anatomical evidence should more similar in DNA sequences than more distantly related species

Molecular biology can be used to assess evolutionary kinship

You should now be able to:

1. List and describe the four major classes of molecules

2. Describe the formation of a glycosidic linkage and distinguish between monosaccharides, disaccharides, and polysaccharides

3. Distinguish between saturated and unsaturated fats and between cis and trans fat molecules

4. Describe the four levels of protein structure

You should now be able to:

5. Distinguish between the following pairs: pyrimidine and purine, nucleotide and nucleoside, ribose and deoxyribose, the 5 end and 3 end of a nucleotide