Eukaryotic Cell Organelles

• Organelle – “little organs”; the parts of the cell that act as if they are specialized little organs.

• Cytoplasm – the portion of the cell that is outside the nucleus in the eukaryotic cell.

1. NucleusControl center of the

cell.Contains most of the

cells genetic material (DNA)

(DNA is in chromatin form.)

Surrounded by a membrane called the nuclear envelope (w/pores)

May contain several nucleoli(ribosome assembly)

2. RibosomeThe site of protein

synthesisProteins are assembled on

the ribosome.Each ribosome is made up of

two subunits. (assembled in the nucleolus - made of RNA)

3. Endoplasmic ReticulumTubular membrane systemRough ER is studded with

ribosomesSmooth ER lacks

ribosomesER is the site where lipid

components of the cell membrane are assembled (along with proteins and other materials exported from the cell.)

Materials can travel through the ER or can be pinched off of the ER (origin of intracellular transport vesicles that carry proteins)

4. Golgi ApparatusA system of

flattened sacs that modifies, sorts, and packages macromolecules in vesicles for secretion or for delivery to other organelles.

5. Lysosome

A sac containing strong digestive enzymes (vesicle)

Is used for intracellular digestion and the recycling of older cell organelles.

They originate (pinch off) from the Golgi Apparatus.

6. Vacuole

A large storage sacMay occupy more than

50% of volume in plant cells.

In addition to water, may store nutrients and waste materials.

Helps maintain pressure in the plant cell – e.g. keeps plant from wilting when full of water…

7. Mitochondria

Double membrane organelle

Convert the chemical energy stored in food into compounds that are more convenient for the cell to use.

(Cell Respiration)Contain small

amounts of DNACan be hundreds per

cellInherit from mom!

8. Chloroplast

A double membrane organelle

They capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis.(solar power plants)

Light absorbing pigments are found in the chloroplasts. (chlorophyll)

9. CytoskeletonSupport network

made of protein.Two main types:1. Microfilaments2. Microtubules

• Microfilaments – threadlike structures made of the protein actin.

They provide a tough yet flexible framework that supports a cell.

They are constantly dissolved and rebuilt – movement in amoeba

• Microtubules – hollow structures made of tubulin proteins.

They help the cell maintain its shape.

Important in cell division – form the mitotic spindle.

They also help build projections from the cell surface – cilia and flagella.

10. CentriolesCylindrical

structures formed of microtubules

Occur in pairs during animal cell division – produce mitotic spindle

Two main types of eukaryotic cells…

1. A plant cell has…- a cell wall (made of cellulose) outside of its membrane- chloroplasts- no centrioles- a large vacuole- no lysosomes

2. An animal cell…- will never have a cell wall- will never have chloroplasts- will always have centrioles- will have small vacuoles (if any at all…)- has lysosomes