Biology 1: Prokaryotic and Eukaryotic Cells

Cells are categorized into two main types: prokaryotic and eukaryotic.
Prokaryotic cells are typically unicellular and lack membrane-bound organelles.
Eukaryotic cells can be unicellular or multicellular and possess membrane-bound organelles.

Genetic material of prokaryotes is found in a region called the nucleoid.
Prokaryotes do not have a true nucleus; their genetic material is suspended in the cytoplasm.
Exhibit various arrangements: single, pairs, chains, clusters, aggregates, and colonies.

Eukaryotic cells contain a true nucleus; the term "eukaryote" derives from "eu" (true) and "karyon" (nucleus).
Include organisms such as protozoans, algae, fungi, plants, and animals.
Eukaryotic cells can function independently as single-celled organisms or as part of multicellular structures.

Taxonomy is the science of naming and classifying organisms.
It involves systematic classification of plants and animals in hierarchical groups.
Linnean Binomial Nomenclature is the method used for naming organisms, reflecting their classification.

Cells may undergo modifications to adapt and perform specialized functions, which illustrates the diversity of life forms.
Understanding cell structure and function is crucial for studying biological systems and the evolution of life.

Main component of cell membranes.
Phospholipids arrange in a bilayer, creating a barrier against water-soluble molecules.

Comprises a polar hydrophilic head (glycerol + phosphate group) and two non-polar hydrophobic tails (fatty acids).
Amphipathic nature: possesses both hydrophilic and hydrophobic regions.

Regulates membrane fluidity.
Prevents phospholipids from packing too closely, reducing membrane freezing risk.

Integral proteins span the bilayer and facilitate diffusion and cell recognition.
Transport proteins traverse the bilayer to aid the movement of substances.
Channel proteins allow passive transport of ions and polar molecules along concentration gradients.
Carrier proteins can change shape to transport substances across gradients.

Glycoproteins have carbohydrate chains that function as receptors and cell markers for recognition.
Glycolipids stabilize the membrane and support immune responses via hydrogen bonding with water molecules.

Cell membranes regulate solute movement using embedded proteins for various functions.
Four processes for solute transport:
- Passive diffusion: Movement down a concentration gradient without energy.
- Carrier-mediated transport: Movement down a gradient using carrier proteins.
- Primary active transport: Movement against a gradient, requiring energy.
- Secondary active transport: Co-transport against a gradient, utilizing energy indirectly.