1. Chapter 7 Cell Structures

2. Viruses- Considered nonliving in biology a. protein coat- capsid b
Viruses- Considered nonliving in biology a. protein coat- capsid b. DNA/ RNA core

3. Prokaryotes vs Eukaryotes
No nucleus- DNA in nucleiod area
(DNA- circular/ no histone proteins)
Nucleus- DNA stored here
(DNA- linear/ along w/ histone proteins)
Lacks membrane bound organelles
Contains specialized organelles
Unicellular
Multicellular
Smaller/ simpler
Larger/ complex
1-10 microns in diameter
microns in diameter
Domain Bacteria & Archaea
Domain Eukarya Kingdoms: Protista, Fungi, Plantae, Animalia
*** Common features:
- Cell membrane, cytoplasm, chromosomes, ribosomes

5. Contributions to Cytology:
Robert Hooke (1665)- 1st to observe cells viewing a slice of cork/ coined to the term “cells”
Anton van Leeuwenhoek- 1st to view living cells (protists- “animalcules”)
M.J. Schleiden (1838)- plants composed of cells
Theodor Schwann (1839)- animals composed of cells
Robert Virchow (1858)- cells come from pre-existing cells

6. Cell Theory
Schleiden, Schwann, and Virchow contributed to the cell theory
All living things are composed of cells
Cells are the basic unit of structure and function
Cells produced from pre-existing cells

7. Eukaryotic Cell Structures
Domain Protista, Fungi, Plantae, and Animalia
Organelle “Little organ”
Specialized subunits within a cell that has a specific function
Usually enclosed within its own membrane
*** NOTE: [*] =These structures contain DNA and are capable of replication

8. a. Cell Membrane (Plasma membrane)
Double layer of protein and lipid around ALL cells
Separates the interior of a cell from the outside environment
Semi-permeable (selective) allows only certain substances to pass through

9. Cell Membrane- Lipid Bilayer

10. b. Cell Wall Rigid, nonliving structure outside the cell membrane
Not present in Animals, but present in:
1. Plants & some protists (algae) cellulose- provides support to cells
2. Fungi chitin

11. c. Nucleus Double membrane bound organelle
Contains genetic material DNA
Known as the “control center of the cell”

12. d. [*] Chromosome Found within nucleus Single DNA molecule
Segments represent different genes
Within eukaryotic cells: composed of DNA and proteins chromatin
Principal nuclear structure visible during cell division

13. e. Nucleolus (i) Small dense organelle within nucleus
Contains DNA, RNA, & protein
Within eukaryotic cells:assemble ribosomes
Lily parenchyma cell (TEM x7,210) Note the large nucleus and nucleolus in the center of the cell

14. f. Nuclear Membrane (Envelope)
Double membrane that surrounds the nucleus
Semi-permeable (selective)
Consists of protein-lipid molecules

15. g. Cytoplasm (Cytosol)
All living material between the nuclear and plasma membrane
Semi-liquid substance that contains organelles
Ex: ribosomes, chloroplasts, mitochondria

16. h. Ribosomes ***[NOTE: Protein functions=
Small organelles composed of ribosomal RNA (rRNA) and proteins
2 types: 
1) Attached
- Found on rough endoplasmic reticulum (RER)
- Synthesizes extracellular proteins
2) Free
- Found in cytoplasm
- Synthesizes intracellular proteins
***[NOTE: Protein functions=
a. enzymes/ b. structural parts]

17. i. [*] Mitochondrion (ia)
Double membrane bound organelle
Produces ATP energy for ALL cells
Contains own DNA and ribosomes
Site of cellular respiration (Krebs Cycle, respiratory chain, and oxidative phosphorylation)

18. j. Endoplasmic Reticulum (ER)
Extensive system of membrane present in most eukaryotic cells
Material transported through these channels and canals
May connect to nuclear or cell membranes

19. Cont. Endoplasmic Reticulum
2 types:
1)Rough ER (RER)
- Ribosomes attached to RER/ gives “rough” appearance
- Synthesizes proteins and other materials for export
2) Smooth ER (SER)
- No ribosomes attached
- Synthesizes lipids and steroids
- Metobolizes CHOs
- Detoxify drugs and poisons

20. k. Golgi Apparatus
Layer of flattened, disc-shaped sacs, tubules, and vesicles near nucleus of gland cells
Synthesizes cell secretions
Source of lysosomes

22. l. Vacuoles Membrane-bound sac
Transport raw materials to cell interior
Also transport wastes
Used for storage of water/ food
In plant cells: typically large and central

23. Vacuole in Plant Cell

24. m. Lysosomes Double membrane bound sac containing hydrolytic enzymes
- Hydrolytic (“water-splitting”) breakdown substances by adding H2O
Fuse with food vacuoles to digest contents
“Suicide bag” digest cytoplasm if membrane ruptures
- Present in white blood cells (WBC): leukocytes

25. n. [*] Plastids Cytoplasmic, often pigmented organelle in plant cells
Includes:
1. Amyloplast
- Stores starch
- Root and internal stem tissue- not exposed to light
2. Chromoplast
- Contain variety of carotenoids yellow, red, orange pigments/
- Ex: carrots, tomatoes
Amyloplasts in a potato cell
Parenchyma cell containing chromoplasts: each red dot is a chromoplast that contains carotenoids

26. Cont. Plastids 3. Chloroplast
- Contain carotenoids and chlorophylls a, b, c, d, e
- Contains DNA and ribosomes
- Site for photosynthesis

27. o. Cytoskeleton
Network of protein scaffolding or “skeleton” of the cytoplasm
Provides shape, organization, and movement
Consists of:
  Microfilaments
- Thinnest, solid protein tubules
- Hold organelles in place
- Enable cells to change shape
2. Intermediate Filaments

28. Cont. Cytoskeleton 3. Microtubules - Thickest, hollow protein rods
- Provides shape and support to cells
- Serve as “tracks” for organelles to move on
- Makes up the following:
a. [*] Centrioles
Forms spindle pole during mitotic and meiotic cell division
Found in pairs at right angles near nucleus of animal cells
Have own DNA
Microtubules in triplets
Present ONLY in animal cells

29. Cont. Microtubules b. Cilium (ia) c. Flagellum (a)
Short, numerous structures embedded in the surface of some eukaryotic cells
Arranged in rows (9 + 2 arrangement of microtubules)
Involved in locomotion and movement of substances across surface
c. Flagellum (a)
Long, single threadlike organelle
Used in locomotion
9 +2 arrangement of microtubules

30. p. Kinetosome
Motion-controlling granules at base of flagella and cilia
q. Fibrils
Protein molecules that form spindles during plant and cell division
Functions in specialized cells: a. muscle contraction
b. nerve cells carry impulses

31. r. Pinocytic Vesicle
Indentation in cell membrane which results in vacuole formation
2 types:
1) Pinocytosis
-“Cell drinking”
- Intake of fluid by cell
2) Phagocytosis
- “Cell eating”
- Intake of solids
- Function of WBC
(leukocytes)

32. s. Contractile Vacuole
Expels excess water in freshwater organisms placed in hypotonic environment/ ex: distilled water
Maintains appropriate concentrations of salts and other molecules

33. EUKARYOTIC CELLS PROKARYOTIC CELLS Nucleus present? Yes, organized
No, lack nuclear membrane
Membrane-enclosed organelles present?
Yes No
Chromosomes present?
Yes, in pairs
Yes, single
Cytoplasmic streaming present?
Cell division by mitosis?
Type of flagella present?
Complex
Simple
Type of ribosomes present?
Large
Small
Type of cytoskeleton present?
Cellulose present in cell wall?
DNA bound to histone proteins?

34. Prokaryotic Cell Structures
- Domain Archeabacteria and Eubacteria
  a. Plasmid small circular DNA separated from main chromosome
b. Mesosome infolding of plasma membrane significant in copying DNA prior to division
c. Nucleiod area of cell containing the main chromosome

35. Prokaryotic Replication