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Tuesday, September 13, 2016

Limits of Cell Size

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

big taxons
WEST VANCOUVER SCHOOL DISTRICT
VSB
BURNABY SCHOOL DISTRICT

UNDER VSB , smaller taxons
JO,  Killarney, Gladstone,  DT, Churchill, Hamber, Point Grey, PW, Kits, Templetone, Windermere


UNDER GLADSTONE
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

KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES

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
cell respiration.

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.