Cellular Organelles Review

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Cellular Organelles Review
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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.

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Nucleolus

• Nucleoli (pl) found inside nucleus.
• Forms ribosomes.

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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).

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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.

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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.

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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.

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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.

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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.

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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.

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Vacuoles

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

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Table 6-1a
10 µm
Column of tubulin dimers
25 nm
Tubulin dimer
?
?
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Table 6-1b
10 µm
Actin subunit
7 nm
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Fig. 6-23
Direction of swimming
(a) Motion of flagella
5 µm
Direction of organisms movement
Power stroke
Recovery stroke
(b) Motion of cilia
15 µm
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Fig. 6-31
Cell walls
Interior of cell
Interior of cell
Plasmodesmata
Plasma membranes
0.5 µm
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Fig. 6-32
Tight junction
Tight junctions prevent fluid from moving across
a layer of cells
0.5 µm
Tight junction
Intermediate filaments
Desmosome
Desmosome
Gap junctions
1 µm
Extracellular matrix
Space between cells
Gap junction
Plasma membranes of adjacent cells
0.1 µm