Explain the three parts of the Cell Theory
All living things are made of one or more cells. The cell is the basic unit of structure and function in living things. All cells come from pre-existing cells.
Structures Found in ALL Cells
Cell membrane: Thin barrier that controls what enters and leaves the cell.
Cytoplasm: Jelly-like fluid where chemical reactions occur.
Ribosomes: Structures that build proteins.
DNA (genetic material): Holds the instructions for the cell’s traits and
Identify three characteristics that are present in all prokaryotic cells
No nucleus; DNA floats in the cytoplasm. No membrane-bound organelles. Small, simple, single-celled organisms (like bacteria).
Identify three characteristics that are present in all eukaryotic cells
Have a nucleus containing DNA. Have membrane-bound organelles (mitochondria, ER, Golgi, etc.). Larger and more complex; can be multicellular.
Endosymbiotic Theory and Evidence
Eukaryotic cells formed when larger prokaryotes engulfed smaller prokaryotes that lived inside them and eventually became organelles like mitochondria and chloroplasts.
Mitochondria and chloroplasts have their own circular DNA. They reproduce by binary fission like bacteria.
Autogenous Theory and Evidence
Eukaryotic cells evolved from a single prokaryotic ancestor through internal processes, where the cell membrane folded inward to form new organelles.
Many organelles share membrane structures similar to the cell membrane. Internal compartments (ER, Golgi) could form from membrane infolding.
All the cell organelles
Cell Membrane: Controls movement of substances in/out of the cell; provides protection.
Cytoplasm: Fluid that holds organelles; site of many chemical reactions.
Nucleus: Stores DNA and controls cell activities.
Chromosomes: Organized DNA that contains genetic instructions.
Ribosomes: Build proteins from amino acids.
Rough ER: Makes and folds proteins; has ribosomes attached.
Smooth ER: Makes lipids and detoxifies chemicals.
Mitochondria: Produces energy (ATP) for the cell.
Golgi Apparatus: Modifies, sorts, and packages proteins.
Vesicles: Small sacs that transport materials around the cell.
Vacuoles: Store water, nutrients, or waste.
Lysosomes (animals): Break down waste, old parts, and food.
Centrioles (animals): Help organize cell division.
Cell Wall (plants): Rigid outer layer for support and protection.
Chloroplasts (plants): Perform photosynthesis to make food.
Explain three characteristics only found in Plant cells
Cell wall for structure. Chloroplasts for photosynthesis. Large central vacuole.
Explain three characteristics only found in Animal cells
Centrioles. Lysosomes (more active/common). No cell wall (flexible shape).
Pathogen and Examples
A microorganism or particle that causes disease. Examples are Parasites, Viruses, Fungi, and Bacteria.
Bacterial cell walls
Bacterial cell walls are made of peptidoglycan, while plant cell walls are made of cellulose. Peptidoglycan is unique to bacteria and is targeted by certain antibiotics.
Characteristics of a Gram-positive bacteria cell
Gram-positive bacteria have a thick peptidoglycan wall, no outer membrane, and stain purple.
Characteristics of a Gram-negative bacteria cell
Gram-negative bacteria have a thin peptidoglycan wall, an outer membrane, and stain pink.
How Penicillin works as an antibiotic
Penicillin works by blocking the building of the bacterial cell wall, causing the bacteria to weaken and burst.
Explain three ways that bacteria can be beneficial
Bacteria help us digest food and keep our gut healthy. They fix nitrogen in the soil to help plants grow. Some bacteria produce antibiotics that we use to fight infections.
Describe three reasons why a virus is classified as non-living rather than living
They cannot reproduce on their own. They must invade a host cell to make more viruses. They do not use energy or perform metabolism.
Viral Structures
Genome: Holds genetic instructions.
Capsid: Protects the genome.
Envelope: Helps enter host cells.
Surface spikes: Attach to host cells.
Viral replication cycle
Attachment: Virus binds to host cell.
Entry: DNA/RNA enters the host.
Replication: Host makes viral parts.
Assembly: New viruses form.
Release: Viruses exit the cell.
Lytic Cycle and Lysogenic
Lytic - Virus takes over immediately. Host makes viral parts. Cell bursts to release viruses.
Lysogenic - Viral DNA fuses with host DNA. Virus stays dormant as host divides. Trigger can switch it to lytic.
Virus vs. Cell Comparison
Characteristic: Virus: No; Cell: Yes.
Genetic Material: Virus: DNA or RNA; Cell: DNA.
Reproduction: Virus: Only in host; Cell: Independently.
Uses Energy?: Virus: No; Cell: Yes.
Structure: Virus: Capsid and envelope; Cell: Organelles and Membranes.
Describe six ways viruses can spread
Direct Contact: Touch or exchange of fluids.
Indirect Contact: Touching contaminated surfaces.
Droplet Transmission: Droplets from coughs, sneezes, or talking.
Airborne Transmission: Particles in the air that are inhaled.
Vector-Borne Transmission: Animals carry pathogens to hosts.
Food and Water Transmission: Eating or drinking contaminated food or water.
Emerging diseases
Emerging diseases are dangerous because humans have little or no immunity and effective treatments or vaccines may not exist yet.
