RNA Is Organized in Several Unique Structures

In all prokaryotic and eukaryotic organisms, three main classes of RNA molecules exist: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA

Loop

Table 35-1. Some of the species of small stable RNAs found in mammalian cells.

Loop

Table 35-1. Some of the species of small stable RNAs found in mammalian cells.

Length

Molecules

C

— G

Name

(nucleotides)

per Cell

Localization

C

— G

U1

165

1 x 106

Nucleoplasm/hnRNA

G

— C

U2

188

5 x 105

Nucleoplasm

A

— U

U3

216

3 x 105

Nucleolus

A

— U

U4

139

1 x 105

Nucleoplasm

A

— U

U5

118

2 x 105

Nucleoplasm

U

G

U6

106

3 x 105

Perichromatin granules

U

G Stem

4.5S

91-95

3 x 105

Nucleus and cytoplasm

C

C

7S

280

5 x 105

Nucleus and cytoplasm

G

— C

7-2

290

1 x 105

Nucleus and cytoplasm

U

— A

7-3

300

2 x 105

Nucleus

Figure 35-7. Diagrammatic representation of the secondary structure of a single-stranded RNA molecule in which a stem loop, or "hairpin," has been formed and is dependent upon the intramolecular base pairing. Note that A forms hydrogen bonds with U in RNA.

(rRNA). Each differs from the others by size, function, and general stability.

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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