This document provides an overview of cell structure and function. It outlines several key discoveries and concepts in cell biology, including: 1) The cell theory states that all living things are composed of cells, cells are the basic units of structure and function, and new cells are produced from existing cells. 2) Cells can be either unicellular (single-celled) or multicellular (many-celled). Multicellular organisms have cell specialization where cells perform specific functions. 3) The basic structures of cells include the cell membrane, cytoplasm, nucleus, and organelles that have specific functions like the mitochondria, chloroplasts, and endoplasmic reticulum. 4)

1. Cell Structure and Function
Chapter 7
Biology
Miller • Levine

2. The Scientists…
 Robert Hooke (1665)
 Viewed cork under a
microscope
 Called the chambers he
saw “cells”
 Anton van
Leeuwenhoek (1674)
 First to see living
organisms in a drop of
water

3. The Scientists…
 Matthias Schleiden (1838)
All plants are made of cells
 Theodor Schwann (1839)
All animals are made of cells
 Rudolf Virchow (1855)
All cells come from preexisting cells

4. The Cell Theory
 All living things are composed of
cells
 Cells are the basic units of
structure and function in living
things
 New cells are produced from
existing cells

5. Unicellular vs. Multicellular
 Unicellular – single-celled
organism
 Multicellular – many-celled
organism
Cell specialization – cells are
specialized to perform certain
functions
Cells → Tissues → Organs → Organ
systems → Organism

6. Prokaryotes vs. Eukaryotes
 Prokaryotes
Have a cell membrane &
cytoplasm, but do not have a
nucleus
Ex. Bacteria such as E.coli
 Eukaryotes
Have a nucleus, cell membrane,
cytoplasm & organelles
Ex. Plants, Animals, Fungi

7. Prokaryotes vs. Eukaryotes

8. Basic Cell Structures
 Cell membrane – thin, flexible
barrier around the cell; protects
the cell
Present in all cells
 Cytoplasm – material inside the
cell membrane (not including the
nucleus)
Prokaryotes & Eukaryotes

9. Cell Wall
 Found in many organisms,
including plants, algae, fungi
and nearly all prokaryotes
 Not found in animal cells
 Lies outside the cell membrane
 Main function is to provide
support & protection for the cell

10. Nucleus
 Almost all eukaryotic cells,
including plants and animals
have a nucleus
 Prokaryotes do not have a
nucleus
 Controls most cell process and
contains the DNA

11. Nucleolus and Nuclear Envelope
 Nucleolus:
Inside the nucleus
Where ribosomes are made
 Nuclear Envelope:
Double-membrane layer around
the nucleus
Allows material to move into and
out of the nucleus

12. Nucleus

13. Cytoskeleton
 Found in all eukaryotic cells
 Not found in prokaryotes
 A network of protein filaments
that helps the cell maintain its
shape
 It also is involved in cell
movement

14. Ribosomes
 Found in all cells
 Main function is to make
proteins
 Can be found floating in the
cytosol or attached to
endoplasmic reticulum

15. Endoplasmic Reticulum (ER)
 Found only in eukaryotic cells
 Where components of the cell
membrane are assembled
 Two kinds: Smooth ER & Rough
ER
Smooth ER: no ribosomes; makes
lipids
Rough ER: has ribosomes; involved
in making proteins

16. Endoplasmic Reticulum

17. Golgi Apparatus
 Found only in
eukaryotic cells
 Enzymes attach
carbohydrates &
lipids to proteins
 Send proteins to
their final
destination

18. Lysosomes
 Found in animal cells only
 Break down lipids,
carbohydrates & proteins from
food into particles that can be
used by the cell
 Also break down “dead”
organelles

19. Vacuoles
 Not found in prokaryotes
 Animal cells have small or no
vacuoles
 Plant cells have a large central
vacuole
 Store materials such as water,
salts, proteins & carbohydrates

20. Chloroplasts
 Found in all plant cells
 Some prokaryotes have them,
but most do not
 Use the energy from sunlight to
make energy-rich food
molecules during photosynthesis

21. Chloroplasts

22. Mitochondria
 Found in
eukaryotic
cells only
 Release
energy from
stored food
molecules

23. Cell Membrane
 Regulates what enters and leaves
the cell (selectively permeable)
 Provides protection and support
 Lipid bilayer – two layers of lipids
Proteins run through the layers
Carbohydrates are attached to some
of the proteins
Fluid Mosaic Model

24. Cell Membrane

25. Diffusion
 Molecules move from an area of
high concentration to an area of
low concentration
 Movement continues until
equilibrium is reached
 Many substances move across
the membrane by diffusion
 Does not require energy
(passive transport)

26. Diffusion

27. Osmosis
 The diffusion of water
Isotonic – equal concentration
 Nothing happens
Hypertonic – higher concentration
 Water moves out of the cell
Hypotonic – lower concentration
 Water moves into the cell
 No energy is required

28. Effects of Osmosis on Cells

29. Osmotic Pressure
 In pure water, an animal cell
would burst
 Plant cells are protected by their
cell wall
 Some freshwater organism have
special structures like contractile
vacuoles to get rid of extra
water

30. Facilitated Diffusion
 Some molecules cannot cross the
membrane without help
 Some of the proteins in the
membrane form protein channels
 Materials still move from higher to
lower concentrations
 No energy is required

31. Facilitated Diffusion

32. Active Transport
 Materials move
from lower
concentration to
higher
concentration
 Requires an
input of energy
 Works kind of
like a pump

33. Transport of Large Amounts
 Endocytosis – movement into
the cell
Phagocytosis – “cell eating” – solid
particles
Pinocytosis – “cell drinking” –
particles dissolved in water
 Exocytosis – movement out of
the cell

34. Phagocytosis

35. Pinocytosis