Unit 1: Cells - Structure, Function, and Organisation

Vocabulary flashcards covering cell structure, organelles, specialised cells, levels of biological organisation, and specimen magnification calculations from Unit 1.

Staining

The process of soaking cells in chemicals or dyes before microscopic examination so organelles take up the dye, making the cells more visible.

Methylene blue

A common chemical stain used to make animal cells more visible under a microscope.

Iodine solution

A common chemical stain used to make plant cells more visible under a microscope.

Cell Surface Membrane

A partially permeable layer enclosing the cell made of lipids and proteins; it prevents cell contents from escaping and controls the entry and exit of substances (not found in virus cells).

Cytoplasm

A jelly-like substance surrounding organelles and filling the entire cell; contains enzymes, salts, and food reserves such as lipids, and serves as the site for most chemical reactions.

Nucleus

A circular or oval, double membrane-bounded structure in the cytoplasm that contains hereditary material and controls cell activities, cell division, and cell development.

Mitochondria

Small spherical or rod-shaped structures in the cytoplasm that serve as the site of cellular/aerobic respiration, releasing energy to sustain metabolic reactions and cellular activities.

Ribosomes

Small, membraneless circular structures in the cytoplasm, either lying free or attached to membranes, that carry out protein synthesis.

Cell wall

A fully permeable, rigid, non-living outer layer that encloses the cell membrane, allows free movement of substances, and protects the cell from bursting (composed of cellulose in plants, peptidoglycan in bacteria, and chitin in fungi).

Vacuole

A membrane-bound structure that contains water, salts, and sugar, serves as a disposal site for by-products, and provides turgidity to plant cells (permanent in plant cells, temporary in animal cells).

Chloroplast

A round, oval, or disk-shaped structure inside plant cytoplasm containing the pigment chlorophyll, which traps light energy for photosynthesis.

Circular DNA

A single, coiled, circular chromosome located inside bacterial cytoplasm that controls cell division, cell growth, and cell activities.

Plasmids

Circular pieces of DNA located inside bacterial cytoplasm containing extra genes beyond the circular DNA to aid in survival and reproduction.

Specialised Cells

Cells that have specific structures adapted to carry out particular functions.

Ciliated cells

Specialised cells responsible for the movement of mucus in the trachea and bronchi away from the lungs.

Neurones

Specialised cells adapted for the conduction of electrical impulses.

Red Blood Cell

A biconcave, flexible, and elastic cell containing haemoglobin that transports oxygen from the lungs to all parts of the body and easily squeezes through capillaries.

Root Hair Cells

Specialised plant cells with long, narrow extensions to increase surface area to volume ratio, numerous mitochondria for active transport, and a concentrated sap vacuole to absorb water via osmosis and mineral salts.

Concentrated sap vacuole

An adaptation of the root hair cell that creates a water potential gradient to facilitate the entry of water into the cell.

Cells

The fundamental units of life that originate from pre-existing cells, can survive independently, and carry out necessary survival functions.

Tissue

A group of cells with similar structures working together to perform a shared, specialised function (e.g., blood or mesophyll layer).

Organ

A structure composed of a group of tissues working together to carry out a specific function (e.g., heart or leaf).

Organ systems

A group of organs with related functions working together to perform a bodily function (e.g., cardiovascular system or shoot system).

Organism

An individual animal or plant formed by all organs and systems working together to produce an independent living thing.

Magnification formula

$$\text{Magnification} = \frac{\text{image size}}{\text{actual size}}$$

Micrometre

A unit of microscopic measurement where $1\,000\,000\text{ micrometres} = 1\text{ metre}$, $10\,000\text{ micrometres} = 1\text{ centimetre}$, and $1\,000\text{ micrometres} = 1\text{ millimetre}$.