Cells: What are the Building Blocks of Life?

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Cells What are the Building Blocks of Life?
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What is the cellular nature of life?

• Cells were discovered using microscopes.
• Microscopes have changed considerably in the past
  400 years.

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Robert Hooke

• In 1662, he observed boxes in cork and named them
  cells after small, plain rooms occupied by
  monks.

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Anton van Leeuwenhoek

• Creates his own microscope.
• In 1675, he reported viewing animalcules.

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Cell Theory

• Organisms are composed of one or more cells.
• Cells arise from preexisting cells.
• Cells are the fundamental units of life.

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Where do cells come from?

• Louis Pasteur found microbes grow in broth
  exposed to air.
• No microbial growth with prevention of air entry.
• Refutes theory of spontaneous generation.

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Viruses

• Viruses are acellular.
• Consist of
• nucleic acids and
• protein coat.
• Considered nonliving.

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Viruses

• Dependent on other organisms to
• Reproduce
• Obtain raw materials
• Obtain energy
• Viruses use host cell machinery to produce
  proteins.

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Different types of cells
Liver cell (magnified 3,048 times)
Blood cell (magnified 4,445 times)
Human sperm cell (magnified 1,380 times)
Retinal cells (magnified 720 times)
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What are the major kinds of cells?

• Two types
• Prokaryotic cells
• Have few internal parts
• Simple cells

• Eukaryotic cells
• Possess organelles
• Complex cells

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Prokaryotic cells

• No nucleus
• Possess
• single circular chromosome
• Contains hereditary material
• ribosomes
• Site protein synthesis
• cytosol
• Interior fluid compartment
• cell membrane
• Surrounds cell
• Regulates internal external environment

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Prokaryotic cells

• Possess
• Cell wall
• Capsule
• Helps cell withstand hostile environment
• Flagella, pili or microvilli

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Eukaryotic cells

• Include
• single-celled organisms
• Protista
• multicellular organisms
• Plants
• Animals

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Nucleus

• Largest organelle.
• Surrounded by nuclear envelope.
• porous double membrane
• Contains chromosomes (hereditary material).

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Nucleolus

• Found in nucleus.
• Ribosomes are assembled here.

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Endoplasmic Reticulum (ER)

• Extensive membranous structure.
• Formed by membrane emerging from nuclear
  envelope.
• Two types
• Rough ER
• Smooth ER

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Rough Endoplasmic Reticulum

• Ribosomes are found on the outside.
• Site of protein synthesis.

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Smooth Endoplasmic Reticulum

• Site of lipid and carbohydrate synthesis.

                                     
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Golgi Complex

• Receives transport vesicles from the smooth
  endoplasmic reticulum.
• Cellular products are modified, packaged and
  prepared for their final destination.

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Golgi Complex

• Following modification, products may be released
  from the cell via exocytosis.

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Lysosomes

• Lysosomes arise from Golgi complex.
• May fuse with food vesicles.
• Lysosomal enzymes digest proteins, carbohydrates
  and lipids.
• Process cellular debris and worn-out organelles.