Behavioural Biology B11: Compartmentalizing & Border crossing (Class notes 2)

Flashcards covering key vocabulary terms and definitions related to eukaryotic and prokaryotic cells, their structures, organelles, and plasma membrane functions from Behavioural Biology B11 Class notes 2.

Cell

The smallest living unit capable of performing all the activities of life. All living things are composed of cells and cell products, and all cells come from preexisting cells.

Prokaryotic Cells

Cells characteristic of bacteria and archaea, typically 1-10 μm across, lacking membrane-bound organelles, with circular DNA located in the cytoplasm.

Eukaryotic Cells

Cells characteristic of plants, animals, fungi, and protists, typically 10-100 μm across, possessing membrane-bound organelles and coiled, linear DNA located in the nucleus.

Cell Size Limitation

Cells are limited in size (1-100 μm in diameter) by the surface-to-volume ratio, as the volume that can be nourished is limited by materials passing through the surface membrane.

Cell Structure and Function

The anatomy of a cell reflects its physiology; specialized cells like red blood cells, sperm, and egg cells have structures adapted to their specific functions.

Plasma Membrane

Separates the inside of the cell from the external environment, provides structural support, and regulates the movement of nutrients and wastes into and out of the cell.

Cytoplasm

A thick, transparent fluid filling the area between the plasma membrane and the nucleus, containing organelles.

Organelles

Specialized structures within eukaryotic cells, often membrane-bound, that perform different functions.

Nucleus

The cell's control center, containing the cell's genetic information (DNA) in the form of genes (genome) and directing all cellular activities.

Chromosomes

DNA within the nucleus associated with proteins and organized into structures that shorten and condense during cell division; otherwise, they are extended and called chromatin.

Gene

A section of DNA that codes for a specific protein, which contributes to an organism's unique phenotype.

Nuclear Envelope

The membrane surrounding the nucleus, allowing communication between the nucleus and cytoplasm via nuclear pores.

Endoplasmic Reticulum (ER)

A network of canals that transports newly made proteins from ribosomes to the Golgi complex, accounting for more than half of the total membrane in many eukaryotic cells, and is continuous with the nuclear envelope.

Rough ER

An ER type with membrane-bound ribosomes, involved in producing proteins and lipid membranes, which are then distributed by transport vesicles; it acts as a membrane factory for the cell.

Smooth ER

An ER type without attached ribosomes, rich in enzymes, and involved in synthesizing lipids, phospholipids, and steroids, metabolizing carbohydrates, storing calcium, and detoxifying poisons.

Golgi Complex (Golgi Apparatus/Body)

Flattened membrane sacs that process, sort, and modify proteins for export or cell use, and package materials into transport vesicles.

Lysosome

Organelles responsible for intracellular digestion of bacteria, lipids, proteins, and worn-out organelles (autophagy), recycling their molecules; they are acidic and contain over 40 enzymes.

Vesicles

Hollow spherical, membrane-bound organelles produced by the ER and Golgi, that store and/or transport chemicals throughout the cell.

Vacuoles

Hollow spherical, membrane-bound organelles, similar to vesicles but much larger, produced by the ER and Golgi, that store and/or transport chemicals throughout the cell.

Mitochondria

The 'powerhouse' of the cell, serving as the site of cellular respiration, where glucose (sugar) is converted into energy (ATP); contains inner foldings for increased membrane surface area.

Phospholipid Bilayer

The structural basis of the plasma membrane, also described as a fluid mosaic model, composed of phospholipids arranged in a double layer, with proteins embedded or attached, and carbohydrates linked to lipids or proteins.

Selective Permeability

A function of the plasma membrane, allowing only certain substances (e.g., small gas molecules, water, lipids) to pass through freely while restricting others (e.g., large polar molecules, charged particles, protein hormones).

Passive Transport

One way substances cross the plasma membrane without requiring cellular energy, including simple diffusion, facilitated diffusion, and osmosis.

Active Transport

One way substances cross the plasma membrane that requires cellular energy, including active transport, endocytosis, and exocytosis.

Endocytosis

An active transport process where a region of the plasma membrane engulfs a substance (large molecules, bacteria, liquids) and pinches off, enclosing the substance in a vesicle.

Phagocytosis

A type of endocytosis ('cell eating') involving the engulfment of large particles or bacteria (non-specific) by the cell membrane to form a phagosome or 'food vacuole'.

Pinocytosis

A type of endocytosis ('cell drinking') involving the absorption of extracellular fluids (ECF) and all dissolved solutes.

Exocytosis

An active transport process where large molecules leave the cell; molecules are enclosed in membrane-bound vesicles that travel to the plasma membrane and are released outside the cell (e.g., neurotransmitters, hormones).