Cellular Organelles Review Bozeman Tutorial: Cellular Organelles (9:37)

Nucleus Most prominent organelle in eukaryotic cells. Contains chromatin (DNA and histone proteins) and RNA. Has double-membrane envelope with pores for movement of materials.

Nucleolus Nucleoli (pl); found inside nucleus. Forms ribosomes.

Mitochondria Double-membrane bound; outer is smooth, inner is folded into cristae; matrix in center. Contain their own DNA and can copy themselves. Produce ATP energy through Krebs and ETC. (36 to 38 ATP per glucose in aerobic respiration).

Plastids Similar in structure to mitochondria; found in photosynthetic organisms; contain pigments. Thylakoids form stacks called grana, surrounded by stroma. Chloroplasts – green. Chromoplasts – colors vary. Leucoplasts – white.

Ribosomes Non-membrane bound; found also in prokaryotes; most numerous. Site of mRNA translation (polypeptide construction). 70S ribosomes found in prokaryotes and on endoplasmic reticulum. 80S free-floating in eukaryote cytoplasm.

Endoplasmic Reticulum (ER) Network of membranes often connected to Golgi body and cell membrane. Rough ER synthesizes, modifies, and transports proteins. Smooth ER… carbohydrates and lipids.

Golgi Complex (apparatus, body) Stacks of flattened membrane sacs. Packages and moves materials in vesicles. Cis face – vesicles join the Golgi (usually from ER). Trans face – vesicles bud off. Golgi produces lysosomes and forms cell wall.

Lysosomes Membrane bound vesicles containing digestive enzymes. Protease (proteins); Nuclease (nucleic acids); Lipase (lipids). Digest old organelles, food particles or bacteria, and cause cell death.

Peroxisomes (microbodies) Vesicles containing enzymes which can break down fats, alcohols, and poisons. Forms hydrogen peroxide which is then broken into water and oxygen by catalase.

Vacuoles Membrane sac formed by pinching of cell membrane. Storage for water, food, wastes, or pigments. Prominent in plants.

Cytoskeleton

Table 6-1b 10 µm Actin subunit 7 nm

Direction of organism’s movement Fig. 6-23 Direction of swimming (a) Motion of flagella 5 µm Direction of organism’s movement Power stroke Recovery stroke (b) Motion of cilia 15 µm

Inner Life of the Cell