Cell size has limits because cells use their membranes to take in nutrients
by diffusion.As cells get bigger, their volume cannot diffuse fast enough to
feed every part of them.
When cells reach their limit, they divide by these two steps
1. replicating their DNA
2. Cytokinesis - splitting apart into two cells
Eukaryotes divide by MITOSIS
Prokaryotes divide by BINARY FISSION
Organisms can be UNICELLULAR - made of one cell
Or they can be MULTICELLULAR - made of many cells connected together
What is a Eukaryote?
- A Eukaryote is an organism whose cells HAVE A NUCLEUS. That is, Its DNA
is located within a NUCLEAR MEMBRANE.
- An example of a UNICELLULAR EUKARYOTE is a protozoan like an amoeba
- Examples of a MULTICELLULAR EUKARYOTES
Animals, Plants, Fungi, Seaweed (algae)
EU are a EUKARYOTE!!!!!
What is a Prokaryote?
- A Prokaryote is an organism which is UNICELLULAR and HAS NO NUCLEUS. Its
DNA is simply floating around in the cytoplasm.
- Examples of prokaryotes are ALL BACTERIA
EUKARYOTIC MULTICELLULAR ORGANISMS are constantly replenishing their cells
your cells are dividing and dying and replacing themselves. Most of your human cells have completely turned over in ten years.
TAXONS are GROUPINGS, or CATEGORIES.
the more GENERAL THE TAXON, the bigger it is. Like russian dolls, smaller taxons into larger ones.
Example of taxons
WEST VANCOUVER SCHOOL DISTRICT
BURNABY SCHOOL DISTRICT
UNDER VSB , smaller taxons
JO, Killarney, Gladstone, DT, Churchill, Hamber, Point Grey, PW, Kits, Templetone, Windermere
Science dept, Music Dept, Modern Languages
Under Music Dept
Band, Choir, Uke and Guitar, Vocal Jazz
Under Vocal Jazz
EMet, Merick, plus sixty others who sing. Mr Braverman -- smallest taxon
In biology, under the previous classification system, the taxons are
KIND PEOPLE CAME OVER FOR GOOD SOUP
BIOLOGICAL BASIS OF CLASSIFICATION
- Organisms are classified in the same taxon based on how related they are by evolution.
- All of life descended from a common ancestor but some life is more closely
related than others.
BIOCHEMICAL BASIS FOR CLASSIFICATION
- Similarity in DNA can determine how closely you are related to something
- similarity in enzymes in the mitochondria - the enzyme cytochrome C is involved in
HETEROTROPH - cannot photosynthesize. all animals are heterotrophs
AUTOTROPH - can photosynthesize, all plants are autotrophs
5 kingdoms of life
ANIMALIA - Eukaryotic multicellular HETEROTROPH with no cell walls.
PLANTAE - Eukaryotic multicellular AUTOTROPH with cellulose cell walls
FUNGI - Eukaryotic multicellular HETEROTROPH with cell walls of chitin
PROTISTA - Unicellular Eukaryote. Some are heterotroph, some autotroph
MONERA - Unicellular Prokaryote. Some are heterotroph, some autotroph.