1. A tour of the cell
1. To study cells, biologists use microscopes and the tools of biochemistry

2. Optical transmission microscope
1.1 Microscopy
1.1.1 Light microscope
Optical transmission microscope
stereo or dissecting
microscope
1. ocular lens, or eyepiece
2. objective turret
3.objective lenses
4. coarse adjustment knob
5. fine adjustment knob
6. object holder or stage
7. Illuminator
8. diaphragm and condenser
Three important parameter
Magnification: the ratio of an object’s image size to its real size (~ X)
Resolution: a measure of the clarity of the image (~ 2 um)
Contrast: accentuates differences in parts of the samples

4. 1.1 Microscopy
1.1.2 Electron microscope
The electron microscope (EM) allows greater magnification than LM and reveals cellular details
Uses a beam of electrons rather than light
Has much greater resolution than LM (2 nm)
Can magnify up to 100,000 times
Cannot be used with living specimens

5. 1.1 Microscopy 1.1.2 Electron microscope Transmission electron
Microscope (TEM)
Scanning electron
Microscope (TEM)
To study the internal
ultrastructure of cells
To study detailed architecture of cell surfaces

6. 1.1 Microscopy
1.1.3 Fluorescence microscope

7. 1.1.4 Confocal laser scanning microscopy
technique for obtaining high-resolution optical images with depth selectivity

8. 1.2 Cell fractionation

9. 1.3 Most cells are microscopic
Cells vary in size and shape
Minimum is determined by the total size of all the molecules required for cellular activity
Maximum is limited by the need for sufficient surface area to carry out functions

10. LE 4-2a Human height Length of some nerve and muscle cells Unaided eye
Chicken egg
Frog egg
Most plant and
animal cells
Light microscope
Nucleus
Most bacteria
Mitochondrion
Mycoplasmas
(smallest bacteria)
Electron microscope
Viruses
Ribosome
Proteins
Lipids
Small molecules
Atoms

11. A small cell has a greater ratio of surface area to volume than a large cell of the same shape
The microscopic size of most cells ensures a sufficient surface area across which nutrients and wastes can move to service the cell

12. 2. Prokaryotic cell

13. http://classes. midlandstech

14. http://classes. midlandstech

15. 2.1 Prokaryotes (Bacteria)
Eubacter "True" bacteria
human and plant pathogens
clinical or environmental
one kingdom
Archaea
Environmental organisms
second kingdom

16. Prokaryotic Cell (versus Eukaryotic Cell)
Not compartmentalized, no sub-organelle of specialized form and function
Cell membranes lack sterols (e.g. cholesterol)
Single circular chromosome
Ribosomal are 70S
- subunits
30S (16S rRNA)
50S (5S & 23S rRNA)

17. Bacteria versus Archaebacteria
Eubacteria
peptidoglycan (murein)
muramic acid
Archaebacteria
pseudomurein
no muramic acid
16S rRNA
sequence different

18. Morphology Shape cocci (round) bacilli (rods)
spiral or curved (e.g. spirochetes)
Single or multiple cells
clusters (e.g. staphylococci)
chains (e.g. streptococci)

19. Plasmids Extra-chromosomal DNA multiple copy number coding
- pathogenesis factors
- antibiotic resistance factors
bacterial replication

20. The Cell Envelope Cell membrane + cell wall (+ plus outer membrane)
peptidoglycan
attached structures

21. Cytoplasm Oxidative phosphorylation occurs at cell membrane
(since there are no mitochondria).
Cell Wall
Cytoplasm
Cell membrane
The cell wall is outside of cell membrane
rigid, protecting cell from osmotic lysis & some antibiotics.

22. Peptidoglycan single macromolecule highly cross-linked surrounds cell
provides rigidity

23. Peptidoglycan glycan backbone peptide side chain peptide cross-bridge
muramic acid
glucosamine
peptide side chain
peptide cross-bridge
D- and L- amino acids
diaminopimelic acid

24. L-alanine
D-glutamic acid
L-lysine/Diaminopimelic acid
D-alanine

25. GRAM POSITIVE CELL ENVELOPE
Degradative enzyme
Peptidoglycan-teichoic acid
Lipoteichoic acid
Cytoplasmic membrane
Cytoplasm

26. GRAM NEGATIVE CELL ENVELOPE
Outer Membrane
(Major permeability barrier)
Lipopolysaccharide
Porin
Braun lipoprotein
Periplasmic space
Degradative enzyme
Periplasmic binding protein
Permease
Inner (cytoplasmic) membrane
Cytoplasm

27. Outer Membrane
lipopolysaccharide
phospholipids
Proteins
porins

28. Outer Membrane Gram negative bacteria major permeability barrier
space between inner and outer membrane
periplasmic space
store degradative enzymes
Gram positive bacteria
no periplasmic space

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30. FLAGELLA Some bacteria are motile Locomotory organelles- flagella
Taste environment
Respond to food/poison
chemotaxis

31. Flagella embedded in cell membrane A: monotrichous project as strand
Flagellin (protein) subunits
move cell by propeller like action
A: monotrichous
B: Lophotrichous
C: Amphitrichous
D: Petritrichous

32. Pili (fimbriae) hair-like projections of the cell sexual conjugation
adhesion to host epithelium

33. Capsules and slime layers
outside cell envelope
well defined: capsule
not defined: slime layer or glycocalyx
usually polysaccharide
often lost during in vitro culture
protective in vivo

34. Endospores (spores) Dormant cell Produced when starved
Resistant to adverse conditions
- high temperatures
- organic solvents
contain calcium dipicolinate
Bacillus and Clostridium

36. 3. Eukaryotic cell
3.1 Eukaryotic cells have internal membranes that compartmentalize their functions

37. Eukaryotic cells are partitioned into functional compartments
Eukaryotic cells are usually larger than prokaryotic cells ( (m diameter)
Distinguished by a true nucleus
Contain both membranous and nonmembranous organelles
Compartmentalize metabolism
Increase membrane surface area for reactions

38. 3.2 Animal & plant cell Smooth endoplasmic reticulum Rough endoplasmic
Nucleus
Flagellum
Not in most
plant cells
Lycosome
Centriole
Ribosomes
Peroxisome
Golgi
apparatus
Microtubule
Intermediate
filament
Cytoskeleton
Plasma membrane
Microfilament
Mitochondrion

39. 3.2.1 Animal cells
Are bounded by the plasma membrane alone
Lack a cell wall
Contain centrioles and lysosomes
Often have flagella

40. Rough endoplasmic
reticulum
Nucleus
Ribosomes
Smooth endoplasmic
reticulum
Golgi
apparatus
Microtubule
Central
vacuole
Intermediate
filament
Cytoskeleton
Not in
animal
cells
Chloroplast
Microfilament
Cell wall
Mitochondrion
Peroxisome
Plasma membrane

41. 3.2.2 Plant cells and tissues are diverse in structure and function
Most plant cells have three unique structures
Chloroplasts, the sites of photosynthesis
A central vacuole containing fluid
A cell wall that surrounds the plasma membrane
Usually lack centrioles, lysosomes, and flagella

42. 3.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes
The nucleus contains the cell's DNA
Controls cellular activities by directing protein synthesis
Forms long fibers of chromatin that make up chromosomes
The nucleus is separated from the cytoplasm by the nuclear envelope
Pores in the envelope control flow of materials in and out
Ribosomes are synthesized in the nucleolus

43. LE 4-5 Nucleus Chromatin Two membranes of nuclear envelope Nucleolus
Pore
Rough
endoplasmic
reticulum
Ribosomes

44. Nuclear pore complex:
A gate for the entry and exit of most proteins, and RNAs, as well as large complexes of macromolecules
Nuclear lamina:
A netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelop
Nuclear matrix:
a framework of fibers extending throughout the nuclear interior

45. Ribosomes
are composed ribosomal RNA and ribosomal proteins (ribonucleoprotein or RNP)
are classified as being either “free ribosomes” or “bound ribosomes”
Most of the proteins made on free ribosomes function within the cytosol
Bound ribosomes generally make proteins that are destined for insertion into membranes

46. 3.4 The endomembrane system regulates protein traffic and performs metabolic functions in the cell