366

1. Cells: What are the Building
Blocks of Life?

2. What is the cellular nature of life?
• Cells were discovered using microscopes.
• Microscopes have changed considerably in the
past 400 years.

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

4. Anton van Leeuwenhoek
• Creates his own microscope.
• In 1675, he reported viewing “animalcules”.

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

6. 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.

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

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

9. Different types of cells
Liver cell (magnified 3,048 times)
Human sperm cell (magnified 1,380 times)Retinal cells (magnified 720 times)
Blood cell (magnified 4,445 times)

10. What are the major kinds of cells?
• Two types:
– Prokaryotic cells
• Have few internal parts
• Simple cells
– Eukaryotic cells
• Possess organelles
• Complex cells

11. 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

12. Prokaryotic cells
• Possess
–Cell wall
–Capsule
• Helps cell
withstand hostile
environment
–Flagella, pili or
microvilli

13. • Include
– single-celled organisms
• Protista
– multicellular organisms
• Plants
• Animals
Eukaryotic cells

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

17. Nucleolus
• Found in nucleus.
• Ribosomes are assembled here.

18. Endoplasmic Reticulum (ER)
• Extensive
membranous
structure.
• Formed by membrane
emerging from
nuclear envelope.
• Two types:
– Rough ER
– Smooth ER

19. Rough Endoplasmic Reticulum
• Ribosomes are
found on the
outside.
• Site of protein
synthesis.

20. Smooth Endoplasmic Reticulum
• Site of lipid and carbohydrate synthesis.

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

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

23. 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.