1. Cell Structure and Function

2. Cell Size 1. 1–100µm 2. Why is there a limit to cell size?
a. Surface-to-volume ratio
b. Distance from surface to center

3. diameter of DNA double helix
tallest trees
adult human
chicken egg
frog embryo
most eukaryotic cells
mitochondrion
Figure: 04-01
Title:
Relative sizes.
Caption:
Dimensions commonly encountered in biology range from about 100 meters (the height of the tallest redwoods) through a few micrometers (the diameter of most cells) to a few nanometers (the diameter of many large molecules).
most bacteria
virus
proteins
diameter of DNA
double helix
atoms

4. Cell types Prokaryotic—no nucleus, circular DNA, ribosomes
Eukaryotic—larger, nucleus, linear chromosomes, membranous organelles

5. Prokaryotic Cells Have no membrane-bound organelles
Include true bacteria
On earth 3.8 million years
Found nearly everywhere
Spores in each breath; intestines
Naturally in soil, air, hot springs

6. nucleoid (DNA) ribosomes food granule cytoplasm cell wall
prokaryotic
flagellum
Figure: 04-10
Title:
A generalized prokaryotic cell.
Caption:
plasma membrane
cytoplasm
cell wall

7. Eukaryotic Cells Have numerous internal structures
Various types & forms
Plants, animals, fungi, protists
Multicellular organisms

8. nuclear pore chromatin (DNA) nucleus nucleolus nuclear envelope
flagellum
intermediate
filaments
cytoplasm
plasma
membrane
rough endoplasmic
reticulum
ribosome
lysosome
microtubules
Figure: 04-02
Title:
A generalized animal cell.
Caption:
smooth endoplasmic
reticulum
Golgi
complex
free ribosome
vesicle
mitochondrion
vesicle

9. (part of cytoskeleton)
microtubules
(part of cytoskeleton)
mitochondrion
chloroplast
Golgi complex
central vacuole
smooth endoplasmic
reticulum
vesicle
cell wall
rough endoplasmic
reticulum
plasma
membrane
Figure: 04-03
Title:
A generalized plant cell.
Caption:
nucleolus
nuclear pore
nucleus
chromatin
nuclear envelope
intermediate
filaments
ribosomes
free ribosome

10. Eukaryotic Cell Structure
Cytoplasm is the clear, gelatinous fluid inside of a cell

11. Eukaryotic cell structure
Nucleus is control center of the cell
1. Membrane bound (nuclear envelope)
2. Contains nucleoli; synthesizes ribosomal RNA
3. DNA in chromosomes (DNA and proteins)

12. nuclear envelope nucleolus nuclear pores chromatin Figure: 04-04a
Title:
The nucleus.
Caption:
(a) The nucleus is bounded by a nuclear envelope. Inside are chromatin (DNA and associated proteins) and a nucleolus.
chromatin

13. nucleus nuclear pores Figure: 04-04b Title: The nucleus. Caption:
(b) An electron micrograph of a yeast cell that was frozen and broken open to reveal its internal structures. The large nucleus, with nuclear pores penetrating its nuclear envelope, is clearly visible.

14. chromatin chromosome Figure: 04-05 Title: Chromosomes. Caption:
Chromosomes, seen here in a light micrograph of a dividing cell (on the right) in an onion root tip, are the same material (DNA and proteins) as the chromatin seen in nondividing cells adjacent to it, but in a more compact state.
chromosome

15. Eukaryotic cell structure
Organelles
Endoplasmic reticulum consists of folded membranes attached to the nucleus
Rough ER is site of protein synthesis and protein secretion

16. rough endoplasmic reticulum smooth endoplasmic reticulum
ribosomes
0.5 micrometers
smooth endoplasmic reticulum
Figure: 04-07
Title:
Endoplasmic reticulum.
Caption:
There are two types of endoplasmic reticulum: rough ER, coated with ribosomes, and smooth ER, without ribosomes. Although in electron micrographs the ER looks like a series of tubes and sacs, it is actually a maze of folded sheets and interlocking channels.
0.5 micrometers
vesicles

17. Eukaryotic Cell Structure
Organelles (cont.)
Ribosomes assemble amino acid into polypeptide chains
a. Associated with the ER
b. Composed of RNA and proteins

18. rough endoplasmic reticulum
ribosomes
Figure: 04-07R-1
Title:
Rough endoplasmic reticulum.
Caption:
rough endoplasmic reticulum
0.5 micrometers

19. smooth endoplasmic reticulum
vesicles
Figure: 04-07R-2
Title:
Smooth endoplasmic reticulum.
Caption:
smooth endoplasmic reticulum
0.5 micrometers

20. Eukaryotic Cell Structure
Organelles (cont.)
Golgi apparatus are membranous sacs associated with ER
a. Processing and transport of proteins, lipids
b. Synthesis and transport of polysaccharides

21. vesicles from ER vesicles leaving Golgi complex Golgi complex
Figure: 04-08
Title:
The Golgi complex.
Caption:
The Golgi complex is a stack of flat membranous sacs. Vesicles transport material from the ER to the Golgi (and vice versa) and from the Golgi to plasma membrane, lysosomes, and vesicles. Departing vesicles bud off from the Golgi on one face; arriving vesicles join it on the opposite face.

22. Eukaryotic Cell Structure
Vacuoles: membrane-bound compartments that are temporary storage of materials
Animal cells do not usually contain vacuoles, if they do they are very small
Plant cells usually use them for water storage

23. Eukaryotic cell structure
Organelles (cont.)
Lysosomes are Golgi-derived vesicles containing digestive enzymes
Digest excess or worn out organelles, food particles, and engulfed viruses or bacteria

24. vesicles from ER vesicles leaving Golgi complex Golgi complex
Figure: 04-08
Title:
The Golgi complex.
Caption:
The Golgi complex is a stack of flat membranous sacs. Vesicles transport material from the ER to the Golgi (and vice versa) and from the Golgi to plasma membrane, lysosomes, and vesicles. Departing vesicles bud off from the Golgi on one face; arriving vesicles join it on the opposite face.

25. Eukaryotic Cells: Organelles Energy sources for cell activities
Mitochondria provide energy for cellular functions (respiration)
a. Membrane bound, numerous
b. Matrix/cristae
c. Have their own DNA and ribosomes; self-replicate

27. 5 micrometers Figure: 04-E4-2d Title: An SEM photo. Caption:
(d) An SEM photo at much higher magnification, showing mitochondria, many of which are sliced open.
5 micrometers

28. Eukaryotic Cells: Organelles Energy sources for cell activities
Chloroplasts—function in photosynthesis
1) Green—contain chlorophyll pigment
2) Stroma/grana (thylakoid stacks)
3) Have their own DNA and ribosomes; self-replicate
4) Up to 100 per cell

31. Eukaryotic Cells: Organelles
Cytoskeleton
Internal infrastructure
Surface structures
extensions of the plasma membrane
aid in movement of simple organisms

32. actin subunits subunit tubulin subunit Figure: 04-2 Title:
Cytoskeleton components.
Caption:
tubulin
subunit

33. Cytoskeleton Microtubules-thin hollow cylinders made of protein
Microfilaments- smaller, solid protein fibers
They work together to maintain the shape of the cell

36. Centrioles Organelles found in the cells of animals and most protists
Occur in pairs and are made up of microtubules
Play an important role in cell division

37. Cilia and Flagella
Cilia are short, numerous projections that look like hairs
Flagella are longer projections that move with a whip-like motion
Both are used for locomotion or feeding

38. Prokaryotes & Eukaryotes
Similarities & differences
Both surrounded by plasma membrane, but very different
Prokaryotes – Archaebacteria and Eubacteria
Eukaryotes – everything else

39. Plant & Animal Cells Similarities
Both constructed from eukaryotic cells
Both contain similar organelles
Both surrounded by cell membrane

40. Plant & Animal Cells Differences Animals have Plants have
Cell wall – provides strength & rigidity
Have chloroplasts, photosynthetic
Animals have
Other organelle not found in plants (lysosomes formed from Golgi)
Centrioles, important in cell division

41. Brief Look at Viruses Viruses are acellular
Not considered to be living
Cause serious diseases in most organisms