1. THE TOUR OF THE CELL
CHAPTER 4

2. Cell Theory 1) Every organism is composed of one or more cells
2) Cell is smallest unit having properties of life (movement, respiration, sensitivity, growth, reproduction, excretion & nutrition).
3) All cells come from other cells.

3. Basic Aspects of Cell Structure & Function
The cell:
Smallest unit of life
Can survive on its own or has potential to do so
Is highly organized for metabolism
Senses and responds to environment
Has potential to reproduce

4. Structure of Cell All start out life with: Two types: Plasma membrane
Region where DNA is stored
Cytoplasm
Two types:
Prokaryotic
Eukaryotic

5. Fluid Mosaic Model of Cell Membrane (Phospholipid Bilayer)
Main component of cell membranes
Gives the membrane its fluid properties
Two layers of phospholipids

6. Phospholipid Bilayer

7. Fluid Mosaic Model Membrane is a mosaic of
Phospholipids
Glycolipids
Sterols
Proteins
Most phospholipids and some proteins can drift through membrane

8. Fluid Mosaic Model
EXTRACELLULAR ENVIRONMENT
CYTOPLASM

9. Cell Size & Shape Why Are Cells So Small? Surface-to-volume ratio
The bigger a cell is, the less surface area there is per unit volume
Above a certain size, material cannot be moved in or out of cell fast enough

10. Defining Features of Eukaryotic Cells
Have a nucleus and other membrane bound organelles
Eukaryotic organisms
Plants
Animals
Protistans
Fungi

11. Animal Cell Features Plasma membrane Nucleus Ribosomes
Endoplasmic reticulum
Golgi body
Vesicles
Mitochondria
Cytoskeleton

12. Animal Cell

13. Plant Cell Features Plasma membrane Nucleus Ribosomes
Endoplasmic reticulum
Golgi body
Cell wall
Chloroplast
Central Vacuole
Vesicles
Mitochondria
Cytoskeleton

14. The Nucleus
Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm
Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells

15. Components of Nucleus Nuclear envelope Nucleoplasm Nucleolus
Chromosome
Chromatin

16. Nuclear Envelope Two outer membranes (lipid bilayers)
Pores span bilayer

17. Nucleolus Cluster of DNA and proteins
Materials from which ribosomal subunits are built
Subunits must pass through nuclear pores to reach cytoplasm

18. Chromatin Cell’s collection of DNA and associated proteins
Chromosome is one DNA molecule and its associated proteins
Appearance changes as cell divides

19. The Endomembrane System
Group of related organelles in which lipids are assembled and new polypeptide chains are modified
Products are sorted and shipped to various destinations

20. Endoplasmic Reticulum (ER)
In animal cells, continuous with nuclear membrane
Extends throughout cytoplasm
Two regions - rough and smooth
Protein synthesis (RER), Lipid synthesis (SER)

21. Mitochondria ATP-producing powerhouses Double-membrane system
Carry out the most efficient energy-releasing reactions
These reactions require oxygen

22. Specialized Plant Organelles
Central Vacuole
Chloroplasts

23. Central Vacuole Fluid-filled organelle
Stores amino acids, sugars, wastes
As cell grows, vacuole expands as a result of fluid pressure forces cell wall to expand
In mature cell, central vacuole takes up percent of cell interior

24. Chloroplasts
Convert sunlight energy to ATP through photosynthesis

25. The Cytoskeleton Present in all eukaryotic cells
Basis for cell shape and internal organization
Allows organelle movement within cells and, in some cases, cell movement

26. Components of Cytoskeleton
intermediate
filament
microtubule
microfilament

27. Mechanisms of Movement
Length of microtubules or microfilaments can change
Parallel rows of microtubules or microfilaments actively slide in a specific direction
Microtubules or microfilaments can move organelles to different parts of cell

28. Flagella and Cilia Structures for cell motility
9 + 2 internal structure
Microtubule doublet
Dynein arm

29. Cell Surface Specializations & Junctions
Cell wall
Structural component that wraps around the plasma membrane
Occurs in plants, some fungi, some protistans

30. Cell Junctions Plants Animals Plasmodesmata Tight junctions
Adhering junctions
Gap junctions

31. Animal Cell Junctions
Tight junctions
Gap
junction
Adhering
junction

32. Prokaryotic Cells Archaebacteria and Eubacteria
DNA is NOT enclosed in nucleus
Generally the smallest, simplest cells
No organelles