Functions of the Nucleus

1. Role in cell division.

2. Influences cytoplasmic events.

3. Contains codes for protein synthesis.

Nuclear Membrane1. double bilayer

outer + inner membranes = nuclear envelope

2. nuclear pore complexesa. nuclear poresb. exhibit selective permeabilityc. RNA needs to exit the nucleusd. proteins enter nucleus to regulate the DNA

Nucleolusribosomes are built hereribosome subunits exit nucleus through nuclear pores

Ribosomessubstructures that are the “protein factories” of the cellA. Can be free or attachedB. Not membrane-bound

made of rRNA and protein

Endoplasmic ReticulumA. Network of membrane-bound channels (tubules)

- the interior of the tubules is segregated from the rest of the cytoplasm

B. Two types of ERrough and smoothboth types are continuous with each other

(and the nuclear envelope)

1. Rough ERa. ribosomes attached to outer surfaceb. protein synthesis

(often for export)

2. Smooth ERa. lacks attached ribosomesb. lipid synthesisc. detoxification

Golgi ApparatusProcessing and packaging plant

Golgi ApparatusProducts packaged into vesicles for:

insertion into the cell membranesecretion from cell (secretory vesicles)incorporation into lysosome

LysosomesCan destroy harmful substancesCan digest food particlesRemove worn out organellesMust remain membrane-bound

Contain digestive enzymes1. from ribosomes on RER2. packaged in the Golgi

Apoptosis: programmed cell death- takes energy to maintain the integrity of lysosome membranes

MitochondriaConvert nutrient energy into ATP

ChloroplastsHave a double membrane (like mitochondria)

1. thylakoids

2. stroma

Chloroplasts and mitochondria share similar characteristicshave their own circular DNAproduced by division of existing ones

Cell Walls