Chapter 7 Section 4

A re the simplest form of life C hemical elements organized into cells become living matter. A ll organisms are made-up of cells A ll the substances of an organism are the products of its cells

Some things are only one cell (unicellular) Some have many cells (multicellular)

SINGLE CELL ORGANISM MULTI-CELL ORGANISM

Prokaryotic Eukaryotic

No nucleusHas a nucleus No organellesHas organelles

A colony of single-celled organisms is a colonial organism. It's likely that early colonial organisms were the first evolutionary step from single celled life to multicellular species. Volvox releasing daughter colonies. Ref: volvox01 Synura: Three individual colonies. Ref: synura01. Synura (above) and rotifer egg. Three Scenedesmus. Ref: scened00

T he difference between a multicellular organism and a colonial organism is that individual cells from a colony can, if separated, survive on their own, while cells from a multicellular life form (e.g., liver cells) cannot. Filamentous Algae

I n a multicellular organism the cells have become specialized and taken on specific jobs to help out the whole organism I n a colonial organism, there is little difference between cells. Volvox carteri, a colonial freshwater alga. The small dots are regular cells and the large ones are asexual reproductive cells

c ell differentiation- When cells take on a different shape, size, and chemistry, suitable for a certain function during development. C ells vary in size, shape, and internal components T he variety of cell shapes include round, flat, long, rectangle, etc. S ome cells have different extensions from the cell membrane

c ell specialization- The characteristic of having separate roles for each type of cell in a multicellular organism; the cells is specifically designed for a certain function; it has a certain purpose or job. T he size and shape of a cell is related to its function

d ivision of labor- A more efficient way of getting jobs done in a multicellular organism because the different tasks are given to different cells, each of which is specialized to do that job. T he organelles that make up a certain cell are also determined by the specific functions carried out by the cell

l evels of organization- A system of hierarchy in which a group of things are arranged in order of rank, complexity, or size. Each group is made up of smaller parts and/or are a part of a larger group. (example- cells form tissues, which form organs, etc.)

Cell Tissue Organ Organ system

Many different types of cells are formed during embryonic development.

C ells occur in many different shapes and sizes so they can perform many different functions.

Many different cells work together to form a tissue. CartilageMuscleNerves FatSkinBone

Many tissues working together form an organ

Each organ system is made up of several different organs that work together and enable the system to do its job.

C irculatory D igestive E ndocrine E xcretory I ntegumentary L ymphatic M uscular N ervous R eproductive R espiratory S keletal

1.Cells – have a special job to do (i.e. cell from intestine)

2. Tissues – a group of similar cells that work together to carry out a special job (i.e. group of lining cells in intestine)

3. Organ – a group of tissues that work together to do a job (i.e. small intestine)

4.Organ system – a group of organs that work together to do a certain job (i.e. digestive system)

5. Organism – all organ systems working together (i.e. digestive, respiratory, circulatory, etc.)

Some organisms are made up of only one cell but they have all the features of living things The parts of their cell still work together Other organisms have organs and organ systems like humans Systems work together to keep us alive