3.2 A Whole New World - Year 8 Science: Cells

Vocabulary and key concepts from the Year 8 Science lecture on general overviews, cell discovery, cell theory, and cellular scale.

Term 1 Science Topic

Chemistry: Elements, Compounds and Chemical Change.

Term 2 Science Topic

Biology: Cells and Systems.

Term 3 Science Topic

Geology: Rocks and Dynamic Earth.

Term 4 Science Topic

Physics: Energy.

Cells

The 'building blocks' of all living things.

Average Cell Size

Approximately $0.002\,\text{cm}$ ($20\,\mu\text{m}$) across.

Total cells in a person

About $100$ trillion ($100 \times 10^{12}$).

Mammalian Cell Diversity

There are about $200$ different types of cells in mammals.

Robert Hooke

A 17th-century scientist who used a simple microscope to observe thin slices of cork and named the small box-like shapes "cells".

Nucleus

A structure identified in many cells as microscopes allowed for more detailed observations of living things.

Unicellular

An organism made up of a single cell, such as bacteria, algae, or yeast.

Multicellular

An organism composed of more than one cell, such as humans, plants, horses, and insects.

Matthias Schleiden

A German Botanist who in $1838$ concluded that all plants are made of cells and cells are the basic unit of plants.

Theodor Schwann

A German Physiologist who in $1839$ stated that all animal tissues were composed of cells.

Rudolf Virchow

A German Physician who in $1855$ concluded that cells arise from pre-existing cells and can 'reproduce'.

Cell Theory

A scientific theory stating all organisms are composed of cells, the cell is the basic unit of structure and organisation, and all cells come from pre-existing cells.

Micrometre ($\mu\text{m}$)

One of the units used to describe small distances in the microscopic world, commonly used for describing cells.

Nanometre ($\text{nm}$)

A unit of measurement used for extremely small distances, such as those found in the microscopic world.

Microorganisms

Also referred to as microbes; single or multicellular organisms that can only be seen under a microscope.

Cell membrane

A barrier that provides separation from the external environment and controls the movement of nutrients in and waste products out of the cell.

Surface Area-to-Volume Constraint

Large cells have more difficulty staying alive because nutrients must travel a long way to reach the center; small cells keep parts healthy more easily.