Biology Unit 1 - Diversity of Living Things

Taxonomy

• Science of identifying, naming, and classifying organisms

• Groups species by physical traits and evolutionary lineage

• Establishes standardized global scientific names

Species

• Most specific biological classification rank

• Organisms capable of interbreeding in nature

• Must produce viable, fertile offspring

Binomial Nomenclature

• Two-part naming system created by Carl Linnaeus

• Format: Genus (capitalized) and species (lowercase)

• Written in italics or underlined
  
  Ex:
  Canis familiaris - dog

  Felis domesticus - cat

  Canis lupus - wolf

  Vulpes vulpes - fox

  Homo sapien – human

  H. sapien sapien

Linnaean Hierarchy (DKPCOFGS)

• Order: Domain Kingdom, Phylum, Class, Order, Family, Genus, Species

• Mnemonic: King Philip Came Over For Good Soup - Narrower ranks share more specific shared traits

• Do-Kids-Prefer-Chocolate-Over-Fried-Green-Spinach

Dichotomous Key

• Identification tool using sequential paired choices

• Evaluates contrasting observable physical traits

• Guides step-by-step identification of an organism

Characteristics of the Six Kingdoms

• Archaebacteria: Extremophile prokaryotes lacking peptidoglycan

• Eubacteria: True bacteria with peptidoglycan walls

• Protista: Diverse, mostly unicellular eukaryotes

• Fungi: Absorptive heterotrophs with chitin walls

• Plants: Multicellular photosynthetic autotrophs with cellulose

• Animalia: Multicellular ingestive heterotrophs lacking cell walls

Viruses

• Are microscopic infectious agents composed of genetic material and a protein coat

• Requires a host cell to replicate. (Non-Living)

• Consist of genetic material, either DNA or RNA, enclosed within a protein coat called a capsid.

• Some have an outer lipid envelope derived from the host cell membrane, which helps them infect host cells

Lytic Cycle vs. Lysogenic Cycle

• Lytic cycle = fast replication, kills host quickly.

• Lysogenic cycle = stays hidden and safe, reproduces slowly.

Retroviruses & HIV

• Uses reverse transcriptase to synthesize DNA from RNA

• Destroys CD4+ helper T cells, treated with ART and PrEP

Active vs. Passive Immunity

• Active: Body generates own antibodies/memory cells via pathogen or vaccine (long-term)

• Passive: Direct receipt of external antibodies like breast milk or antivenom (short-term)

What are Vaccines & Bioremediation?

• Train your immune system to create antibodies from weakened diseases (To fight off real one)

• Antigens administered to trigger active immunity safely

• Use of bacterial metabolism to clean environmental contaminants

Gram Staining

• Gram-Positive: Retains purple stain due to thick peptidoglycan

• Gram-Negative: Stains pink/red due to thin peptidoglycan and outer membrane

Binary Fission

• Asexual reproduction of a single parent cell to duplicate into clone cells (daughter cells)

What is Antibiotic Resistance?

• Bacterial survival against antimicrobial drugs (Bacteria adapts)

• Driven by clinical overuse and selective pressures

• Rapidly transferred between cells through plasmid conjugation

Prokaryotes vs. Eukaryotes & Endosymbiosis

• Prokaryotes lack membrane-bound organelles; eukaryotes contain them

• Endosymbiosis: Organelles originated from engulfed prokaryotes, evidenced by double membranes and circular DNA

Protist Subcategories

• Animal-like (Protozoa): Heterotrophic, motile via pseudopodia, cilia, or flagella. Mostly Unicellular

• Plant-like (Algae): Autotrophic and photosynthetic. Unicellular or Multi cellular

• Fungus-like: Heterotrophic (Absorptive decomposers producing spores). Mostly Unicellular

Kingdom Eubacteria

• Domain: Bacteria

• Organisms: Bacteria, cyanobacteria (blue-green algae), and actinobacteria

• Cell Type: Prokaryotic

• Metabolism: Depending on species, oxygen may be toxic, tolerated, or needed for metabolism

• Nutrition Acquisition: Depending on species, nutrition intake may occur through absorption, photosynthesis, or chemosynthesis

• Reproduction: Asexual

Kingdom Archaebacteria

• Domain: Archaea

• Organisms: Methanogens, halophiles, thermophiles, and psychrophiles

• Cell Type: Prokaryotic

• Metabolism: Depending on species, oxygen, hydrogen, carbon dioxide, sulfur, or sulfide may be needed for metabolism

• Nutrition Acquisition: Depending on species, nutrition intake may occur through absorption, non-photosynthetic photophosphorylation, or chemosynthesis

• Reproduction: Asexual reproduction by binary fission, budding, or fragmentation

• Function: Unicellular

Kingdom Animalia

• Domain: Eukarya

• Organisms: Mammals, amphibians, sponges, insects, worms

• Cell Type: Eukaryotic

• Metabolism: Oxygen is needed for metabolism

• Nutrition Acquisition: Ingestion

• Reproduction: Sexual reproduction occurs in most and asexual reproduction in some

• Function: Multicellular

Kingdom Plant

• Domain: Eukarya

• Organisms: Moss, ferns, conifers, and flowering plants

• Cell Type: Eukaryotic

• Metabolism: Oxygen is needed for metabolism

• Nutrition Acquisition: Depending on species, nutrition intake may occur through absorption, photosynthesis, or ingestion

• Reproduction: Sexual or asexual

• Formation: Multicellular

Kingdom Protista

• Domain: Eukarya

• Organisms: Amoebae, green algae, brown algae, diatoms, euglena, and slime molds

• Cell Type: Eukaryotic

• Metabolism: Oxygen is needed for metabolism

• Nutrition Acquisition: Depending on species, nutrition intake may occur through absorption, photosynthesis, or ingestion

• Reproduction: Mostly asexual, but meiosis occurs in some species

• Formation: Mostly unicellular & some multicellular

Kingdom Fungi

• Domain: Eukarya

• Organisms: Mushrooms, yeast, and molds

• Cell Type: Eukaryotic

• Metabolism: Oxygen is needed for metabolism

• Nutrition Acquisition: Absorption

• Reproduction: Sexual or asexual through spore formation

• Function: Mostly multicellular & some unicellular

Prokaryotes

• Unicellular organisms

• Lack a true nucleus and membrane-bound organelles

• Domain Bacteria and Archaea

Eukaryotes

• Multicellular & Unicellular organisms

• Contain a true membrane‑bound nucleus, Mitochondria, Golgi apparatus, Endoplasmic reticulum

• Domain Animal, Plant, Fungi, Protist

How do vaccines work against viruses?

• Vaccines protect the body from viral infections

• Train the immune system to recognize and respond quickly to a virus (Given weakened virus)

What are T-cells?

• Type of white blood cell (lymphocyte)

• Recognize fragments of pathogens displayed on infected cells via MHC molecules (Fights off germs and help against diseases)

• Each T-cell has a unique T‑cell receptor (TCR) that binds a specific antigen.

• They multiply and mount a targeted immune response

What are Heterotrophs?

• Organism that cannot produce their own food

• Obtain energy and nutrients by consuming other organisms or organic matter

What are Autotrophs?

• Organism that produce their own food from inorganic substances

What is a retro virus?

• A virus that uses RNA as its genetic material

• Relies on an enzyme called reverse transcriptase to convert its RNA into DNA

• Sometimes causes diseases that integrates into the host cell’s genome

• HIV, COVID-19 etc.

What causes retrovirus and what are its effects on the host?

• Viruses that carry RNA as their genetic material and use reverse transcriptase to integrate into the DNA of host cells (If RNA messes up it creates cellular damage from stress, leading to diseases)

• Target and destroy immune system cells that impairs their ability to fight off infections

What is DNA? & What is RNA?

• DNA - a double‑stranded helical molecule

Stores and transmits long term genetic information in all living organisms

• RNA - a single‑stranded helical molecule

Carries genetic information and performs essential cellular functions

Conjugation

• Involves direct physical contact between two organisms or cells,

• Exchange of genetic material through a mating bridge

• Transfer or exchange of genetic material

Transduction

• Genetic form of horizontal gene transfer mediated by bacteriophages. (Gene from another bacteria is injected)

• Increases bacterial diversity and can spread traits such as antibiotic resistance.

Transformation

• Form of horizontal gene transfer (Takes genes from the environment “dead cells”)

• DNA enters a competent cell and becomes part of its genome

• No cell to cell contact

What is a plasmid?

• Small extrachromosomal DNA molecule

• Replicates independently of chromosomal DNA

• Carries genes that provide advantages to its host

Bacteria Arrangments

• Diplo - (pairs)

• strepto - (chains)

• staphylo - (clusters)

Bacteria Shapes

• Coccus (spheres),

• bacillus (rods),

• spirillum (spirals)

Protist Movement: Flagella

• Whiplike appendages movement used for motility

• Paramecium (unicellular, ciliated eukaryotic organism)

Protist Movement: Cytoplasmic Streaming

• Cytoplasm extensions of pseudopodia (fake feet)

• Amoeba (single‑celled eukaryotic organism)

Protist Movement: Cilla

• Hairlike extensions all around the cell membrane

• Euglena (single-celled, flagellate eukaryotes)

Protist Sexual Reproduction

• Sexual reproduction in multicellular protists may involve the formation of sex cells—male sperm cells and female eggs.

• Protist’s sex cells contain only half the usual number of chromosomes; they are haploid.

• When a sperm cell fuses with an egg, the resulting cell is called a zygote with two copies of every chromosome (diploid).

Harmful Protist

• Many protists are parasites (they live in, or on, other organisms) while harming the host organism

• Some protists cause serious disease:

  • Malaria caused by Plasmodium species, a single-celled protist

  • Giardiasis caused by Giardia lamblia from contaminated water (affects the gut)

Useful Protist

• Photosynthetic protists, along with prokaryotes, are the major producers in the world’s oceans (i.e., algae)

• Seaweed used to wrap the sushi rolls is Phophyra or “Nori” (a multicellular protist)

Types of Protozoans

• Zooflagellate

Have one or more flagellum (some have hundreds)

• Amoeba (Sarcodines)

Create pseudopods – temporary projections of cytoplasm

• Ciliate

Defined by the presence of cilia—short, hair-like structures—during at least one stage of its life cycle. 

Rapidly moving

• Sporozoan

No movement: Mature sporozoans cannot move on their own because they lack legs, cilia, or flagella.

Types of Euglena

• Euglenoids

Unicellular

Have flagella

Photoautotroph during the day – undergoes photosynthesis

Heterotroph at night – feeds on dead organisms

• Algae

Type of Fungi-Like

• Slime

• Water Moulds

What are Photoautotrophs?

• Photoautotrophs are organisms capable of photosynthesis

• Convert light energy and inorganic carbon (CO₂) into organic molecules that sustain their metabolism.

• They are primary producers in most ecosystems

What are Photoheterotrophs?

• Photoheterotrophs absorb light for energy but cannot use carbon dioxide; instead, they acquire carbon from pre-existing organic compounds such as carbohydrates, fatty acids, or alcohols

• Often found in aquatic and nutrient-limited environments, where light is available but less inorganic carbon