Viruses and Bacteria

Viruses

• Acellular and obligate parasites needing a host to reproduce
• Cannot respire or grow, as they have no metabolism

Structure

• Contains either DNA or RNA
• Has a capsid, which is essentially a protein coat
• Some viruses have a lipid envelope

Viral Reproduction

• Lytic cycle involves the virus injecting DNA into a host cell
• The host cell's machinery is taken over for viral reproduction
• The host cell bursts and is ultimately destroyed
• Lysogenic cycle integrates viral DNA into the host's DNA
• The viral DNA stays dormant before becoming active

Effect on Humans

• Vaccines are used to prevent viral infections
• Antibiotics are ineffective against viruses

Bacteria (Kingdom: Monera)

• The smallest micro-organisms
• Found everywhere, including air, soil, and water
• Prefers moist, dark spaces at 30-37°C
• Can be aerobic (requires oxygen) or anaerobic (lacking oxygen)

Bacteria Diagram

• Capsule is the outer layer
• Includes a cell wall and plasmid
• Flagella aids in movement
• Has cytoplasm, ribosomes, pili, and nucleoid DNA

Characteristics

• Prokaryotic and unicellular

Bacteria Shapes

• Coccus (round)
• Bacillus (rod)
• Spirillum (spiral)
• Vibrio (comma)

Functions

• Slime capsule prevents drying out
• Flagella allows for movement

Nutrition

• Autotrophic bacteria can be photosynthetic or chemosynthetic
• Heterotrophic bacteria can be:
  • Commensalistic (one benefits, the other is mutual)
  • Parasitic (harmful)
  • Saprotrophic (decomposers)
  • Mutalistic (beneficial), e.g., E. coli

Reproduction

• Reproduces through binary fission, splitting to divide

Protista

• Varies in size, shape, environment, mode of nutrition, and appearance
• Most protists are unicellular and basic, but some are multicellular
• Can be animal-like (Protozoans) or plant-like (Algae)
• Features flagella/pseudopodia
• Mostly aquatic and has both sexual and asexual reproduction (binary fission) abilities
• Some engulf food (phagocytosis)
• The four types are: Amoeboids, Ciliates, Flagellates, and parasites

Fungi

• Yeast is a unicellular fungi
• Mushrooms and mold are multicellular fungi,
• Eukaryotic, heterotrophic, and saprotrophic (decomposers)
• Reproduce via spores

Fungi Diagram

• Includes sporangium, sporangiophore, spores, mycellium, hyphae, and rhizoids

Fungi Terms

• Hyphae are fine filaments/threads
• Mycelium is a group of hyphae
• Rhizoids are false roots
• Stolon is a horizontal "root"
• Sporangiophore supports the sporangium by being upright hyphae
• Thallus has no true roots, stems or roots, no chloroplasts, animal-like

Bryophytes - Characteristics

• No vascular tissues (xylem + phloem)
• Small and grow in damp areas
• Grow on rocks and tree trunks
• Has a separate male and female gametophyte structure that are dominant
• No seeds, flowers, or fruit

Bryophytes - Male and Female Gametophyte

• Male releases sperm (n)
• Female releases egg (f)
• Fertilization is a forming zygote
• Sporophyte (2n)

Pteridophytes

• Mature sporophyte has sori (many sporangia) which leads to the sporangium
• Meiosis occurs in the sporangium, halving the chromosome number (2n -> n) and creates haploid spores
• Germinates (mitosis) to young gametophyte -> prothallus (n)
• Sperm from antheridium (male) is transported via water to archegonium (female)

Pteridophytes - Terms

• Sporophyte (2n)
• Gametophyte (prothallus-n-n)
• Vascular tissue is present
• True plant organs is present, cuticle still thin
• Reproduction via water is active
• Special features: prothallus that contains both male and female gametophyte
• Has none of the following; Seeds, flowers, fruit

Angiosperms

• A sporophyte (2n) turns into a anther (male) and ovules (female)
• This sporophyte also creates a microsporocytes (2n) and megasporangia
• Eventually becoming pollen (n) - after meiosis(2n-n) a microspore(n) is formed - and megaspore (egg-n) - after meiosis(2n-n) a megasporocytes (2n) is formed.
• Ends in pollination

Angiosperms - Terms

• Vascular tissue has presence
• True plant organs has presence
• There is no water as a means of active reproduction, only pollination
• Special features: ovary becomes fruit
• Has the following; Seeds, flowers, fruit

Gymnosperms

• Sporophyte (2n) -> male cone or a female cone
• Develops microsporangium (spores=pollen) and megasporangium (ovule)
• Megasporangium undergoes meiosis (2n-n), creating megaspore (egg-n)
• Pollination occurs; sperm cell (n) + pollen meets the ovule contianing egg (n) to start fertilization (n+n=2n)
• Creating a zygote (2n) -> Seed containing zygote

Gymnosperms - Terms

• Vascular tissue is present
• True plant organs are present, thick cuticle
• No water reproduction, via wind pollination instead
• Special features include male and female cones
• Presence of seeds
• Absense of flowers and fruit