1. Inquiry into Life Eleventh Edition Sylvia S. Mader
Chapter 3
Lecture Outline
Prepared by: Wendy Vermillion Columbus State Community College
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 3.1 Cellular level of organization
Cells are the smallest unit of life
Exhibit all characteristics of life
All cells are highly organized
Many cells become specialized for complex functions
Cell theory
All living things are composed of cells
Cells are the functional and structural units of organisms
All cells are derived from previously existing cells
Discovery of cells
Antonie van Leeuwenhoek- invented the light microscope
Robert Hooke- first observed cells in cork
Schleiden and Schwann-proposed cell theory

3. Cellular level of organization, cont’d.
Cell size
Most cells are smaller than 1 mm in diameter
Surface/volume ratio determines cell size
Volume increases as the cube of the radius while surface area increases by the square of the radius
Therefore small cells have a greater surface/volume ratio than larger cells
Nutrients from the environment must cross the surface of the cell to enter
Cells must be small in order for the surface area to be adequate to supply nutrients

4. 3.2 Eukaryotic cells Eukaryotic cells have a membrane-bound nucleus
Nucleus contains genetic material
All plant and animal cells are eukaryotic
Plasma membrane-outer boundary of cell
Phospholipid bilayer-note arrangement of hydrophilic and hydrophobic ends
Embedded proteins
Associated glycolipids and cholesterol

5. Eukaryotic cells, cont’d.
Functions of the cell membrane
Functions as a barrier between the cell and its environment
Plays a role in regulation of transport of substances into and out of the cell
Contains receptors that determine how a cell will respond to stimuli in the environment
Contains proteins that are important in immune responses
It is a very dynamic, fluid structure
Plant cells have an outer cell wall in addition to the plasma membrane which is composed of cellulose for rigidity
Some plant cells have a secondary cell wall which is composed of lignin

6. Eukaryotic cells, cont’d.
Organelles-subcellular structures which perform specific life functions for the cell
Many organelles are found in both animal and plant cells
Some are found exclusively in plants or animals
Plants- chloroplasts, central vacuole
Animals-centrioles

7. Animal cell anatomy
Fig. 3.2

8. Plant cell anatomy
Fig. 3.3

9. Eukaryotic cells, cont’d.
Nucleus
Contains the genetic material DNA
Nucleoplasm-semifluid within nucleus
Chromatin-threadlike DNA which has a grainy appearance
Nucleolus-dark regions of chromatin which produce rRNA which composes ribosomes
Nuclear membrane- double layered, surrounds nucleus and has large pores

10. The nucleus and nuclear envelope
Fig 3.4

11. Eukaryotic cells, cont’d.
Ribosomes-
site of protein assembly
Composed of RNA subunits
Exist either as free ribosomes or bound to endoplasmic reticulum
Endomembrane system-
Includes nuclear membrane, endoplasmic reticulum (er), Golgi apparatus, and vesicles

12. Eukaryotic cells, cont’d.
Endomembrane system cont’d.
Rough endoplasmic reticulum (rer)
Complex system of sacs and channels
Has attached ribosomes
Serves as site of assembly of proteins for export
Assembled proteins enter channels for processing
Addition of sugar chains to form glycoproteins
Released in vesicles
Smooth endoplasmic reticulum (ser)
Synthesizes lipid products such as phospholipids and steroids

13. The endoplasmic reticulum
Fig 3.5

14. Eukaryotic cells, cont’d.
Golgi apparatus
packaging and processing center for cell products
Receives the vesicles from er
Vesicles fuse with Golgi and products are released inside
Further modification of glyoproteins occurs
Products are packaged into secretory vesicles and released to the cell membrane
Golgi also produces lysosomes-protein containing vesicles within cells

15. The endomembrane system
Fig 3.6

16. Eukaryotic cells, cont’d.
Lysosomes
Contain hydrolytic enzymes
Fuse with vesicles from cell membrane containing macromolecules
Digestion occurs and nutrients released to cell
Also may be involved in programmed cell death-”suicide sacs”
Lysosomal membranes in old or damaged cells rupture and enzymes digest the cell

17. Peroxisomes
Fig 3.7

18. Eukaryotic cells, cont’d.
Energy related organelles
Chloroplasts- site of photosynthesis
Capture light energy and convert it to chemical energy in the form of food molecules
Double outer membrane surrounds fluid-filled stroma
Membranous system of thylakoids
Regions of stacked thylakoids are called grana

19. Chloroplast structure
Fig 3.8

20. Eukaryotic cells, cont’d.
Mitochondria-another energy related organelle
Site of aerobic cell respiration-production of ATP
Outer double membrane surrounds fluid-filled matrix
Inner folded membrane-folds are called cristae
Cristae provide increased surface area for the production of ATP

21. Mitochondrion structure
Fig. 3.9

22. Eukaryotic cells, cont’d.
Interrelationship between mitochondria and chloroplasts
Chloroplasts convert light energy to chemical energy in the form of organic food molecules (carbohydrates) which can be used by all organisms in cell respiration to make ATP
Only plants and algae have chloroplasts
All cells, plant and animal, contain mitochondria
Photosynthesis can be summarized by the following:
Light energy + carbon dioxide + water  carbohydrate + oxygen
Cell respiration can be summarized below:
Carbohydrate + oxygen  carbon dioxide + water + energy (ATP)
It can be seen that the chemicals required by cell respiration are produced in photosynthesis, and vice versa

23. Eukaryotic cells, cont’d.
The cytoskeleton
Maintains cell shape
Allows cells and organelles to move
Components include actin filaments, intermediate filaments, and microtubules
Actin filaments interact with motor molecule myosin in muscles
Intermediate filaments support the nuclear membrane
Microtubules protrude from the centrosome and form centrioles, cilia, and flagella

24. The cytoskeleton
Fig. 3.10
Fig 3.11

25. Eukaryotic cells, cont’d.
Centrioles
Short tubules with 9+0 pattern of microtubule triplets
In animal cells, centrosome is composed of 2 centrioles
Believed to be involved in microtubule formation including mitotic spindle
Cilia and flagella
Hair-like projections, cilia generally multiple and flagella single or double
9+2 pattern of microtubules
Whip-like action

26. Actin and intermediate filaments
Fig 3.12
Fig 3.13

27. Centrioles
Fig. 3.14

28. Structure of cilia and flagella
Fig. 3.15

29. 3.3 Prokaryotic cells Archae and bacteria are prokaryotes
Lack a nucleus
Smaller than eukaryotes
Prokaryotic cell structures
Cell wall-contains peptidoglycans
Capsule present in some
Plasma membrane
Nucleoid-region which contains a single chromosome
Ribosomes
Thylakoids-in photosynthetic cyanobacteria

30. Bacterial cells
Fig 3.16

31. 3.4 Evolution of eukaryotic cells
Endosymbiont hypothesis-prokaryotes engulfed by larger cells
Chloroplasts and mitochondria resemble bacteria
Both have double membrane-outer could be from vesicle, inner from original cell membrane
Contain DNA and are self-replicative
Contain their own ribosomes
RNA base sequences suggest relationship with bacteria

32. Evolution of eukaryotic cells
Fig 3.17