chapter 4 plasma membrane, nucleus and ribosomes

Chapter 4Plasma membrane, nucleus and

ribosomes

What to Know

• The structure and function of the plasma membrane, nucleus and ribosomes.

Figure 4.5

0.1 m

(a) TEM of a plasmamembraneOutside of cell

(b) Structure of the plasma membrane

Insideof cell

Hydrophilicregion

Hydrophilicregion

Hydrophobicregion

Carbohydrate side chains

Phospholipid Proteins

Plasma Membrane

Concept 4.3: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried

out by the ribosomes

• The nucleus contains most of the DNA in a eukaryotic cell.

• Ribosomes use the information from the DNA to make proteins.

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Ribosome

Chromatin

Rough ER

Nucleus

Nucleolus

Chromatin

Nuclear envelope:

Nuclear pore

Inner membraneOuter membrane

Porecomplex

Close-upof nuclearenvelope

Nucleus

Ribosomes: Protein Factories

• Ribosomes are complexes of ribosomal RNA and protein.

• Ribosomes carry out protein synthesis in two locations– In the cytosol (free ribosomes)– On the outside of the endoplasmic reticulum or the

nuclear envelope (bound ribosomes)

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Figure 4.9

TEM showing ER and ribosomes Diagram of a ribosome

Ribosomes bound to ER

Free ribosomes in cytosol

Endoplasmic reticulum (ER)

RibosomesER

0.25 m

Largesubunit

Smallsubunit

Figure 4.7b

CYTO-SKELETON

NUCLEUS

Smooth endoplasmicreticulum

Chloroplast

Central vacuole

MicrofilamentsIntermediatefilaments

Cell wall

Microtubules

Mitochondrion

Peroxisome

Golgiapparatus

Plasmodesmata

Plasma membrane

Ribosomes

NucleolusNuclear envelope

Chromatin

Wall of adjacent cell

Rough endoplasmicreticulum

You should be familiar with the parts of a cell.

1 m

Nuclear envelope:Inner membraneOuter membrane

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