The Structure and Function of Large Biological Molecules

Page
12

Slide 99

Fig. 5-25

EXPERIMENT

RESULTS

X-ray

source

X-ray

beam

Diffracted

X-rays

Crystal

Digital detector

X-ray diffraction

pattern

RNA

polymerase II

RNA

DNA

Slide 100

Fig. 5-25a

Diffracted

X-rays

EXPERIMENT

X-ray

source

X-ray

beam

Crystal

Digital detector

X-ray diffraction

pattern

Slide 101

Fig. 5-25b

RESULTS

RNA

RNA

polymerase II

DNA

Slide 102

Concept 5.5: Nucleic acids store and transmit hereditary information

The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene

Genes are made of DNA, a nucleic acid

Slide 103

The Roles of Nucleic Acids

There are two types of nucleic acids:

Deoxyribonucleic acid (DNA)

Ribonucleic acid (RNA)

DNA provides directions for its own replication

DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis

Protein synthesis occurs in ribosomes

Slide 104

Fig. 5-26-1

mRNA

Synthesis of

mRNA in the

nucleus

DNA

NUCLEUS

CYTOPLASM

1

Slide 105

Fig. 5-26-2

mRNA

Synthesis of

mRNA in the

nucleus

DNA

NUCLEUS

mRNA

CYTOPLASM

Movement of

mRNA into cytoplasm

via nuclear pore

1

2

Slide 106

Fig. 5-26-3

mRNA

Synthesis of

mRNA in the

nucleus

DNA

NUCLEUS

mRNA

CYTOPLASM

Movement of

mRNA into cytoplasm

via nuclear pore

Ribosome

Amino

acids

Polypeptide

Synthesis

of protein

1

2

3

Slide 107

The Structure of Nucleic Acids

Nucleic acids are polymers called polynucleotides

Each polynucleotide is made of monomers called nucleotides

Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group

The portion of a nucleotide without the phosphate group is called a nucleoside

Slide 108

Fig. 5-27

5 end

Nucleoside

Nitrogenous

base

Phosphate