Structure Meets Function in a Cell • Plasma Membrane and Cell Surface • Nucleus and Ribosomes • Endomembrane System – – – –

• • • •

Endoplasmic Reticulum (ER) Golgi Body Lysosomes Vacuoles

Energy Conversion: Chloroplasts and Mitochondria Cytoskeleton Cilia and Flagella Plastids

Figure 4.6a

Plasma Membrane

Cell Surfaces

– The plasma membrane separates the living cell from its nonliving surroundings.

– Most cells secrete materials for coats of one kind or another • That are external to the plasma membrane.

– Extracellular coats • help protect and support cells • facilitate interactions between cellular neighbors in tissues

– Plant cells and bacterial cells have cell walls,

Structure Meets Function in a Cell

• Which help protect the cells, maintain their shape, and keep the cells from absorbing too much water.

– Animal cells have an extracellular matrix, • Which helps hold cells together in tissues and protects and supports them (not shown).

• Plasma Membrane and Cell Surface • Nucleus and Ribosomes • Endomembrane System – – – –

• • • •

Endoplasmic Reticulum (ER) Golgi Body Lysosomes Vacuoles

Energy Conversion: Chloroplasts and Mitochondria Cytoskeleton Cilia and Flagella Plastids

1

The Nucleus: Genetic Control of the Cell – The nucleus is the manager of the cell. • Genes in the nucleus store information necessary to produce proteins.

Prokaryotes do not have nuclei. Their genes (on DNA) are in the nucleoid region

Ribosomes: Protein Synthesis – Ribosomes are responsible for protein synthesis.

Structure and Function of the Nucleus – The nucleus is bordered by a double membrane called the nuclear envelope. • It contains chromatin and a nucleolus.

Chromatin: long strands of DNA and associated proteins. The DNA stores the genetic information (genes).

Nucleolus: assembles ribosomes

How DNA Controls the Cell – DNA controls the cell by transferring its coded information into RNA. • The information in the RNA is used to make proteins.

Structure Meets Function in a Cell

The Endomembrane System: Manufacturing, Distributing, and Storing Cellular Products

• Plasma Membrane and Cell Surface • Nucleus and Ribosomes • Endomembrane System – – – –

• • • •

Endoplasmic Reticulum (ER) Golgi Body Lysosomes Vacuoles

Energy Conversion: Chloroplasts and Mitochondria Cytoskeleton Cilia and Flagella Plastids Not found in bacterial cells!

2

The Endoplasmic Reticulum – The endoplasmic reticulum (ER) • Produces an enormous variety of molecules. • Is composed of smooth and rough ER.

Rough ER

Smooth ER – The smooth ER lacks the surface ribosomes of rough ER and produces lipids, including steroids.

Rough ER

– The “roughness” of the rough ER is due to ribosomes that stud the outside of the ER membrane.

– The “roughness” of the rough ER is due to ribosomes that stud the outside of the ER membrane.

– The functions of the rough ER include:

– The functions of the rough ER include:

• Producing two types of membrane proteins

• Producing two types of membrane proteins

– Membrane proteins – Secretory proteins

– Membrane proteins – Secretory proteins

• Producing new membrane

– After the rough ER synthesizes a molecule, it packages the molecule into transport vesicles. These vesicles head off to the Golgi Apparatus…

• Producing new membrane

The Golgi Apparatus – The Golgi apparatus • Works in partnership with the ER. • Refines, stores, and distributes the chemical products of cells.

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Vacuoles

Lysosomes

– Vacuoles are membranous sacs. • Contractile vacuoles of protists get rid of excess water. • Central vacuoles of plants store nutrients, absorb water, contain some pigments or poisons.

– A lysosome is a membraneenclosed sac that contains digestive enzymes to break down macromolecules.

– A review of the endomembrane system An amazing system that manufactures, distributes, and stores cellular products!

Structure Meets Function in a Cell • Plasma Membrane and Cell Surface • Nucleus and Ribosomes • Endomembrane System – – – –

• • • •

Energy Conversion: Chloroplasts & Mitochondria – Cells require a constant energy supply to do all the work of life.

Not found in bacterial cells!

Endoplasmic Reticulum (ER) Golgi Body Lysosomes Vacuoles

Energy Conversion: Chloroplasts and Mitochondria Cytoskeleton Cilia and Flagella Plastids

Chloroplasts – Chloroplasts are the sites of photosynthesis, the conversion of light energy to chemical energy.

All little green circles are chloroplasts

Cell walls

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Mitochondria – Mitochondria are the sites of cellular respiration, which involves the production of ATP from food molecules.

Structure Meets Function in a Cell • Plasma Membrane and Cell Surface • Nucleus and Ribosomes • Endomembrane System – – – –

• • • •

The Cytoskeleton: Cell Shape and Movement – The cytoskeleton consists of a network of fibers.

Endoplasmic Reticulum (ER) Golgi Body Lysosomes Vacuoles

Energy Conversion: Chloroplasts and Mitochondria Cytoskeleton Cilia and Flagella Plastids

Cytoskeleton – Mechanical support to maintain cell shape

– Can change cell shape to allow movement

Also, recently found in bacterial cells!

Structure Meets Function in a Cell

Cilia and Flagella – Cilia and flagella are motile appendages.

• Plasma Membrane and Cell Surface • Nucleus and Ribosomes • Endomembrane System – – – –

• • • •

Endoplasmic Reticulum (ER) Golgi Body Lysosomes Vacuoles

Energy Conversion: Chloroplasts and Mitochondria Cytoskeleton Cilia and Flagella Plastids

Not found on most plant cells!

5

– Flagella propel the cell in a whiplike motion. – Cilia move in a coordinated back-and-forth motion.

Structure Meets Function in a Cell • Plasma Membrane and Cell Surface • Nucleus and Ribosomes • Endomembrane System – – – –

• • • •

Endoplasmic Reticulum (ER) Golgi Body Lysosomes Vacuoles

Energy Conversion: Chloroplasts and Mitochondria Cytoskeleton Cilia and Flagella Plastids

Plastids Membrane-bound organelles found only in plants Amyloplast stores starch (stained blue with iodine) All little green circles are Cell walls chloroplasts Chloroplast performs photosynthesis

Chromoplast stores pigments (little orange circles)

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