Cell Structure and Living Organisms

Vocabulary terms and definitions covering the characteristics of living organisms and detailed components of animal and plant cell structures.

Respiration

The process by which living organisms release energy from their food.

Excretion

The process by which living organisms get rid of waste products.

Cytoplasm

The living material that makes up a cell, possessing a texture like sloppy jelly between a solid and a liquid and containing many different structures.

Organelles

Structures within a cell that can be seen in detail using an electron microscope due to its high magnification.

Nucleus

The largest organelle in the cell, which controls cellular activities and contains chromosomes carrying genetic material.

Chromosomes

Structures found inside the nucleus ($46$ in human cells) that carry genetic material, or genes.

Ribosomes

Tiny structures in the cytoplasm where proteins are assembled, which are too small to be seen using an ordinary light microscope.

Enzymes

An important group of proteins found in cells that control the chemical reactions taking place in the cytoplasm.

Cell membrane

A thin boundary layer on the surface of the cell that separates the cytoplasm from the outside and is selectively permeable.

Selectively permeable

A characteristic of the cell surface membrane that allows it to control the movement of particular substances into and out of the cell.

Mitochondria

Organelles located in the cytoplasm of all living cells that carry out reactions of respiration, releasing most of the energy the cell can use.

Cell wall

A layer of non-living, freely permeable material outside the plant cell membrane, composed mainly of cellulose, that helps the cell maintain its shape.

Cellulose

A tough carbohydrate material that forms the plant cell wall and helps the cell keep its shape against internal pressure.

Freely permeable

A property of the porous cell wall that allows water and dissolved substances to pass through without forming a barrier.

Vacuole

A permanent large central space surrounded by a membrane in mature plant cells that is filled with cell sap.

Cell sap

A watery liquid filling the permanent vacuole of plant cells, serving as a store of dissolved sugars, mineral ions, and other solutes.

Chloroplast

An organelle found in the green parts of plants that contains chlorophyll and absorbs light energy to make food during photosynthesis.

Chlorophyll

A green pigment found inside chloroplasts that absorbs light energy for photosynthesis.