Cell Structure

1
Cell Structure Function

• Cell Organelles (part a)

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Cytoskeleton

• Key Concept
• The Cytoskeleton is a network of protein
  filaments that helps the cell to maintain its
  shape, The Cytoskeleton is also involved in many
  forms of cell movements
• Contains
• Microtubules Microfilaments

3
Microtubules

• Hollow tubes of protein about 25 nanometers in
  diameter
• Maintain cell shape
• Provide Tracks along which cell organelles move
• Especially important during cell division

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Microtubules-Green
Nucleus
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Microtubules - TEM
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Microtubules Cell Division

• Separates Chromosomes

Centriole?
Animal Yes
Plant No
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Microtubules Locomotion
Photomicrograph
TEM
Cilia
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Microtubules Locomotion
Photomicrograph
Flagella
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Microtubules Locomotion
Photomicrograph
Flagella
Pili
Flagella
E. coli
www.siue.edu/cbwilso/ Ecoli_flagella.jpg
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Microfilaments

• 7 Nanometers in diameter
• Form Extensive Networks To Support Cells
• Also used as Tracks for organelles being moved
  by motor proteins

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Microfilaments - Green
Microtubules
Microfilaments
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Nucleus

• First Identified By Robert Brown in 1831
• Key Concept
• The nucleus controls most cell processes and
  contains the hereditary information of DNA
  (deoxyribonucleic acid)

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Nucleus
Frog Blood
Nucleated RBCs (normal)
Neutrophile(White Blood Cell)
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Nucleus
Human Cheek Cells
Nucleus
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Nucleus
Segmented Neutrophile
Human Blood Smear
Red Blood Cell
Band Cell
Eosinophile
Lymphocyte
Basophile
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Chromatin Chromosomes

• Chromatin
• Granular material within the nucleus which is a
  combination of DNA bound to protein
• Chromosome
• Condensed Chromatin that forms during cell
  division

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Nucleolus

• Dense area within the nucleus which is where
  ribosome formation begins

Nucleolus
Chromatin
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Nuclear Envelope

• Double Membrane
• Surrounds Chromatin
• Contains thousands of Nuclear Pores which allow
  the transfer of material in and out of the Nucleus

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Nuclear Pores
20
Nuclear Pore TEM
21
Ribosomes

• Make Proteins
• Made From
• r-RNA (ribosomal RNA)
• Protein Subunits (from Nucleolus)
• 0.025 micrometers in diameter
• Translate m-RNA (messenger RNA) into protein

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Ribosomes
23
Ribosome
Amino Acid Being Added To The Protein Chain
transfer RNAtRNA(We will learn about later)
messenger RNAmRNA(We will learn about later)
24
Endoplasmic Reticulum

• Key Concept
• The endoplasmic reticulum is the organelle in
  which components of the cell membrane are
  assembled and some proteins are modified.

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Rough Endoplasmic Reticulum

• Synthesizes Proteins
• Looks rough because of ribosomes that stud the
  surface.
• Proteins move from the ribosomes, directly into
  the Endoplasmic Reticulum where the proteins may
  be further modified.

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Rough Endoplasmic Reticulum
Nucleus
Rough ER
Smooth ER
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Free Standing Ribosomes

• Manufacture Proteins For Use In The Cell

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Smooth Endoplasmic Reticulum

• This Section Of The ER does not have any
  Ribosomes attached.
• Smooth ER typically manufactures lipids to make
  membranes

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Golgi Apparatus

• Proteins produced by the Rough ER move into the
  Golgi Apparatus.
• Consists of a stack of membranes like stacks of
  pita bread

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Golgi Apparatus

• Key Concept
• Enzymes in the Golgi apparatus attach
  carbohydrates lipids to proteins.
• Products are then sent to their final destination.

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Vesicles

• Small vacuoles involved in the transport of
  substances
• within the cell