1.1 Intro to Cells

Archaea Bacteria Eukaryotes

• A plasma membrane_that separates the cell from its environment. • Cytoplasm_comprised of the jelly-like cytosol inside the cell. • Ribosomes_that are important for protein synthesis. • DNA_to store and transmit hereditary informatiom.

means “before nucleus” • prokaryotes don’t have a nuclei. • instead the cell_ is comprised of single circular chromosomes in the central part of the part of the cell called the nucleoid.

Has nucleus. - A nucleus with a double membrane_that enclose DNA. In addition.. Eukaryotic cells tend to have_a variety of membrane bound organelles._ compartmentalisation functions.

• As cells increase in size._Its surface area -to volume decreases. • As cells grow in size- they become less efficient._the plasma membrane will not have sufficient surface area to support the rate of diffusion required for the increased volume.

-As nutrients diffuse into the cell-sphere is the shape where nutrients would travel less to reach the centre. Shorter the distance- the faster the nutrients and waste have to travel.

Surface area alone cannot influence the rate of exchange_its the volume to surface area ratio that key. Increasing number of cell -> theres less area for materials to diffuse.

• The volume of an organism determines the number of substances that need to be taken in or out. • Increase in volumes = to more materials needed for metabolism.

Have a large SA:V ratio._Large surface area • More materials are needed metabolism. • Slower rates of exchange compared to eukaryotes.

-Reduces diffusion distance.

Allow for higher concentration gradient. Allow substances to move closer to each other. eg. Blood vessels xylem lungs gills

Similarities • both contain organelles • both have a phospholipid bi-layer cell membrane.

Differences -prokaryotic cells make up single celled prokaryotic organisms. • Eukaryotic cells make up complex Eukaryotic organisms(animals, plants, fungi and algae) • Eukaryotic cells-larger eg. 10-100 micro m • Prokaryotic cells-smaller eg. 0.1 -5.0 micro m) • Prokaryotes_ cells arise from other cells by binary fission. • Eukaryotes_cell arise through mitosis and meiosis .