1. Section 2

2. Gene structure

3. Gene structure in eukaryotes

4. Operon

5. Transcription

6. Transcription

9. Translation

10. Protein folding

11. Micro-organism

12. Fungi Eukaryotic (have membrane-bound nucleus)
Obtain food from other organisms
Possess cell walls
Composed of
Molds – multicellular; have hyphae; reproduce by sexual and asexual spores
Yeasts – unicellular; reproduce asexually by budding; some produce sexual spores

13. Bacteria Unicellular and lack nuclei Much smaller than eukaryotes
Found everywhere there is sufficient moisture; some found in extreme environments
Reproduce asexually
cell walls contain peptidoglycan; some lack cell walls; most do not cause disease and some are beneficial

14. Algae Unicellular or multicellular Photosynthetic
Simple reproductive structures
Categorized on the basis of pigmentation, storage products, and composition of cell wall

15. Protozoa Single-celled eukaryotes
Similar to animals in nutrient needs and cellular structure
Live freely in water; some live in animal hosts
Asexual (most) and sexual reproduction
Most are capable of locomotion by
Pseudopodia – cell extensions that flow in direction of travel
Cilia – numerous, short, hairlike protrusions that propel organisms through environment
Flagella – extensions of a cell that are fewer, longer, and more whipl ike than cilia

16. Archaea Unicellular and lack nuclei Much smaller than eukaryotes
Found in extreme environments
cell walls composed of polymers other than peptidoglycan

17. Viruses Not independently living cellular organisms
Much simpler than cells- basically a small amount of DNA or RNA wrapped in protein and sometimes by a lipid membrane
Individuals are called a virus particle or virion
Depend on the infected cell’s machinery to multiply and disperse

18. Bacteriology Morphology, Classification, Staining Methods

19. PROKARYOTES
BACTERIA
ARCHAEA

20. Background Information Prokaryotes
Prokaryotes represent two domains, bacteria and archaea.
Archaea live in Earth’s extreme environments.
Bacteria are the most abundant and diversified organisms on Earth.

21. Bacteria Have One of Three Cellular Shapes
Rods (bacilli)
Coccoid-Shaped
Spirilla

22. Other shapes of bacteria
Comma shaped
Spirochetes
Spirilla

23. Reproduction Prokaryotic cell division is binary fission.
Single DNA molecule that first replicates.
Attaches each copy to a different part of the cell membrane.
Cell begins to pull apart.
Following cytokinesis, there are then two cells of identical genetic composition.

24. Anatomy of a Bacterial Cell

25. Anatomy of A Bacterial Cell
Outer layer – two components:
Rigid cell wall
Cytoplasmic (Cell/ Plasma) membrane – present beneath cell wall
Cytoplasm – cytoplasmic inclusions, ribosomes, mesosomes and nucleus
Additional structures – plasmid, slime layer, capsule, flagella, fimbriae (pili), spores

26. Structure of Bacteria All cells have 3 main components:
DNA (‘nucleoid”)
genetic instructions
surrounding membrane (“cytoplasmic membrane”)
limits access to the cell’s interior
cytoplasm, between the DNA and the membrane
where all metabolic reactions occur
especially protein synthesis, which occurs on the ribosomes
Bacteria also often have these features:
cell wall
resists osmotic pressure
flagella
movement
pili
attachment
capsule
protection and biofilms

27. Naturally Wall-less Genus
Mycoplasma

28. Cellular coverage
Cell wall
Plasma membrane
Capsule

29. Capsule & Slime layer Capsule :
Viscous layer secreted around the cell wall.
Polysaccharide / polypeptide in nature
Capsule :
sharply defined structure, antigenic in nature
Protects bacteria from lytic enzymes
Inhibits phagocytosis
Stained by negative staining using India Ink
Can be demonstrated by Quellung reaction (capsule swelling reaction)
Slime layer : loose undemarcated secretion

30. Cell wall protects the bacterium from damage
cell wall acts as a coarse filter
prevent bursting from osmotic pressure (called lysis)

32. Cytoplasmic (Plasma) membrane
Thin layer 5-10 nm, separates cell wall from cytoplasm
Acts as a semipermeable membrane: controls the inflow and outflow of metabolites
Composed of lipoproteins with small amounts of carbohydrates

34. FLAGELLA Some bacteria are motile Locomotory organelles- flagella
Taste environment
Respond to food/poison
Chemotaxis (is the movement of an organism in response to a chemical stimulus)

35. Flagella Made of Flagellin Used for Classification
Monotrichous: 1 flagella
Lophotrichous: having two or more flagella at one end; said of bacterial cells.
Amphitrichous: tuft at both ends
Peritrichous: all around bacteria

36. Monotrichous
Amphitrichous
Lophotrichous
Peritrichous

37. Flagella

38. Pili (fimbriae) hair-like projections of the cell sexual conjugation
adhesion to host epithelium
Short protein appendages
Smaller than flagella
Adhere bacteria to surfaces
Used in conjugation for Exchange of genetic information

39. Other Cytoplasmic Components
Ribosomes – protein synthesis
Mesosomes –
Multilaminated structures formed as invaginations of plasma membrane
Principal sites of respiratory enzymes
Coordinate nuclear & cytoplasmic division during binary fission
More prominent in Gram +ve bacteria
Intracytoplasmic inclusions – reserve of energy & phosphate for cell metabolism e.g. Metachromatic granules in diphtheria bacilli

40. Nucleus No nucleolus No nuclear membrane Genome:
single, circular double stranded DNA.
Haploid
Divides by binary fission

41. Additional Organelles
Plasmid
Extra nuclear genetic elements consisting of DNA
Transmitted to daughter cells during binary fission
May be transferred from one bacterium to another
Not essential for life of the cell
Confer certain properties e.g. drug resistance, toxicity

42. Spores
Highly resistant resting stages formed during adverse environment (depletion of nutrients)
Formed inside the parent cell, hence called Endospores
Very resistant to heat, radiation and drying and can remain dormant for hundreds of years.
Formed by bacteria like Clostridia, bacillus