Cells as the basis of life
All LIVING things are made of CELLS.
Fibroblasts are cells that help maintain tissue structure by secreting proteins like collagen and elastin - biocanvas.net
The Discovery of Cells
In the seventeenth century, Robert Hooke looked
at thin slices of cork under a microscope that he
had made from lenses. He observed small box-like
shapes inside the cork. He called the little boxes
that he saw cells.
• Exist as part of a multicellular organism.
• Specialisation of cells into many types (cell
• Possess nucleus and membrane bound
Plant vs Animal
Plant and animal cells have many similarities
because they are both eukaryotic.
They also have some differences:
• The surface of exchange for materials
between the inside and outside of the cell.
• IN – oxygen, nutrients and water
• OUT – carbon dioxide, waste and products
such as proteins
Plasma Membrane Function
1. Hold cell together
2. Control what goes in and out – diffusion,
osmosis, active transport
3. Protect the cell
4. Allow the cell to recognise and be
recognised – cell signaling and immunity
5. Bind to other cells and molecules
6. A sit for biochemical reactions – enzymes,
areas for reactions
• Larger cells require more resources to be
imported and more products to be exported.
• As cells get larger the SURFACE AREA to
VOLUME RATIO gets smaller.
• Increasing cell size – less efficient
Brownian Motion – the random movement of
particles in a liquid or gas. Due to Brownian
motion particles will diffuse evenly through the
system over time.
Diffusion is the passive net movement of
molecules from regions of high concentration
to low concentration.
Facilitated diffusion is the passive net
movement of particles from regions of high
concentration to low concentration, through
selectively permeable membrane (plasma
membrane), facilitated by carrier proteins.
Osmosis is the passive net movement of
water molecules from regions of low solute
concentration to high solute concentration,
through partially/selectively permeable
Osmosis is also movement down a concentration
gradient –we are considering the movement of
water molecules, not the solute molecules.
Active transport uses energy (ATP) to move
molecules against a concentration gradient,
using membrane protein pumps.
Parts of a Generalised Animal Cell
• Contains the chromosomes (genetic
information) for the cell.
• Controls the activities of the cell.
• Double membrane - outer membrane and
• Inner membrane is folded forming cristae.
• The interior contains an organic matrix
containing chemical compounds.
• Site of aerobic respiration.
Rough Endoplasmic Reticulum
• A membrane system of flattened parallel
cavities which are interconnected and covered
• An intracellular transport system.
• Consists of a stack of flattened cavities which
package substances produced by the cell into
• These vesicles can fuse with the cell
membrane (exocytosis) or become
lysosomes (digestive vesicles).
Plant Cell Walls
• The main component of plant cell walls is
• Cellulose molecules are arranged in bundles
• The function of the plant cell wall is to provide
strength and support the plant.