Organelles Control: *Nucleus (plant and animal) Assembly, Transport, and Storage: *Nucleolus(plant...

Organelles• Control:

*Nucleus (plant and animal)

• Assembly, Transport, and Storage:*Nucleolus (plant and animal)

*Endoplasmic reticulum (plant and animal)*Ribosomes (plant and animal)*Golgi apparatus (plant and animal)*Vacuoles (plant and animal)

-one BIG one in plants; multiple small ones in animals

*Lysosomes (plant and animal)

• Energy transformations:*Chloroplasts (plant only)*mitochondria (plant and

animal)

Nucleus

• Contains most of eukaryotic cell’s genetic library (mitochondria and chloroplasts contain their own DNA…)

• Largest organelle• Enclosed by nuclear envelope or membrane,

which is a double membrane – each of which is a lipid bilayer!!!

• Nuclear envelope has pores in it• Contains inactive DNA – chromatin

Nucleolus

• Prominent structure in non-dividing nucleus

• Ribosomal RNA and ribosomal subunits are made here

Figure 7.9 The nucleus and its envelope 

Endoplasmic reticulum – “highway system”

• EXTENSIVE – accounts for more than half the total membrane system in eukaryotic cells

• Name means “little net within the cytoplasm”• Smooth and rough e.r. are actually connected, not

distinct, separate sections• Job is to transport materials quickly from one

place to another in cell

Figure 7.11 Endoplasmic reticulum (ER)

Smooth e.r.

• Functions in synthesis of lipids, metabolism of carbs, detoxification of drugs and poisons

*Lipids – oils, phospholipids, steroids(sex hormones and adrenal hormones)

*Liver cells – glycogen; gets converted to glucose phosphate which cannot leave cell, so e.r. makes enzyme that converts this to glucose

*Detox – liver; adds hydroxyl groups to drugs, makes them soluble and able to be flushed out of body

Rough e.r.

• Makes secretory proteins

(ex. Insulin made by pancreatic cells)• Most are glycoproteins (proteins covalently bound

to carbs)• Rough e.r. is also a membrane factory – grows by

adding proteins and phospholipids; parts can be taken from here and added to other membrane systems using the vesicles for transport

Ribosomes“protein factories”

• Sites of protein synthesis• Are made of rRNA and protein• Cells with high rates of protein synthesis have MANY

ribosomes (human pancreas cell has MILLIONS of ribosomes)

• Are “free” ribosomes in cytosol that make proteins for the cell that they are INSIDE of

• Ribosomes that are attached to endoplasmic reticulum (bound) are making proteins for packaging and export OUTSIDE OF CELL

Figure 7.10 Ribosomes

Golgi apparatus“Gift wrapper/UPS system”

• Finishes, sorts, ships cell products• Golgi will modify products as needed –

gives more variety by removing some monomers and substituting others

Figure 7.12 The Golgi apparatus

Vacuoles“Bank Vaults” or “trash cans”

• Sites of storage in cells

*good things stored – water, minerals,

food etc.

*bad things stored – broken down cell parts, waste

Lysosomes“suicide bags”

• Membrane-bounded sac of hydrolytic enzymes• Different lysosomes break down each of the major

classes of macromolecules – proteins, polysaccharides, fats, nucleic acids

• Work best at pH of 5• Used in autophagy – recycle the cell’s own

organic material for use

Mitochondria and Chloroplasts“powerhouses”

• Mitochondria – carry on cellular respiration – sites of energy production in cell (glucose broken down to produce ATP)

• Chloroplasts – carry on photosynthesis

– sites where sunlight, CO2 and water are converted into glucose

Figure 7.17 The mitochondrion, site of cellular respiration

Figure 7.18 The chloroplast, site of photosynthesis

Other structural components of cell…

• Cytoskeleton

• Cilia and flagella

Cytoskeleton“hay in mud makes bricks”

• Network of fibers extending into cytoplasm of cell

• Provides structural support, and aids in cell motility and cell regulation

• Made up of microtubules (thickest), microtubules (thinnest), and intermediate filaments

Cilia and Flagella“hairs and tails”

• Cilia are short projections from cell body – hair-like

• flagella are much longer – whip-like• Movement may not be for entire organism;

may be part of a larger unit – ex. Cilia lining windpipe propel foreign substances out…

Organelles do not work alone…

• Cell is a dynamic interaction of ALL of its parts – literally, the basic unit of life….