Topic 1: Cells as basic units of life

CORE CONTENT:

Cell structure

• the cell is the basic structural and functional unit of all living organisms. Cells can be seen under a microscope (they are microscopic)

• plant and animal cells have a cell membrane, cytoplasm, nucleus, and organelles such as mitochondria, vacuoles and chloroplasts

-- the cell membrane encloses the contents of the cell. It allows specific substances to pass into and out of the cell

-- the cytoplasm is the jelly-like medium in which many chemical reactions take place

-- the nucleus contains DNA

o the nucleus is enclosed by a nuclear membrane (in plants and animals)

o DNA contains inherited characteristics, such as whether eyes are blue or brown

o DNA is unique to each person; this variation accounts for differences within species

-- Mitochondria are responsible for respiration to release energy from food

Differences between plant and animal cells

• plant cells differ from animal cells

-- plant and animal cells are enclosed by a cell membrane, and plant cells also have rigid cellulose cell walls to provide support for the plant

-- plant cells also contain organelles such as large vacuoles and chloroplasts. Chloroplasts contain chlorophyll to absorb light energy for photosynthesis (refer to Grade 8 Life & Living). Vacuoles in plant cells have several functions including support and storage (Vacuoles in animal cells are small and temporary or absent)

Cells in tissues, organs and systems

• cells come in many different shapes and sizes

• cells are adapted to perform specific functions, such as muscle cells which are specialised to contract and enable movement

• microscopic organisms such as bacteria, consist of a single cell. Macroscopic organisms such as humans, consist of large numbers of cells

• a group of cells performing a specific function form a tissue, a group of tissues make up an organ, and organs working together in groups form systems, systems make up an organism

• stem cells are cells that have the ability to divide and develop into many different cell types [No detail required]

2. Important Terminology:

Below is a list of the key terms in Topic 1. Use the "Key word" text boxes on pages 1 - 14 to compile a list of important terminology with definitions in your workbooks

• cell

• microscopic

• DNA

• organelle

• chlorophyll

• photosynthesis

• microscope

• magnifying lens

• wet-mount

• unicellular

• macroscopic

• multicellular

• specialise

• epithelial tissue