GCSE Biology (Triple) Eduqas

Cell Biology

Cells and Organisms

• All living things are made up of cells, and these cells arise from other cells.
• Organisms may be unicellular (consist of one cell) or multicellular (consist of many cells).

Cell Components

• Plant, animal and bacteria cells have common components like cell membrane, cytoplasm and genetic material (DNA or RNA).
• Plant and animal cells also have a nucleus which houses the DNA.
• Bacteria cells don’t have a true nucleus. Their genetic material floats in the cytoplasm in an area called the nucleoid.
• Plant cells have additional structures: a rigid cell wall, large central vacuole and chloroplasts.

Cell Specialisation

• In many multicellular organisms, cells are specialised to perform different functions.
• Specialisation allows cells to be incredibly efficient at performing their specific role.

Cell Division

• Cell division in eukaryotes takes place through a process called mitosis.
• Mitosis involves replication of the cell’s DNA, division of the nucleus, followed by cytoplasmic division to produce two identical daughter cells.
• In prokaryotes such as bacteria, cell division takes place through a process called binary fission.

Cell Nutrition

• Cells need nutrients to perform their functions.
• Animal cells get nutrients from food via digestion.
• Plant cells can make their own food through photosynthesis.

Exchange of Substances

• Substances move in and out of cells through the cell membrane.
• This can occur through several processes such as diffusion, active transport or osmosis.
• The movement of substances across membranes depends on the properties of those substances and the permeability of the membrane.

Culturing Microorganisms

• Bacteria and fungi can be grown in culture in a laboratory.
• Cultures must be sterilised to prevent contamination by unwanted microorganisms.
• Aseptic techniques must be used to safely handle cultures.

Role of Enzymes

• Enzymes are proteins that speed up the rate of chemical reactions in biological systems.
• They provide an alternative reaction pathway with a lower activation energy.
• Each enzyme is specific to one type of substrate due to the unique shape of its active site.