Levels of Organization 3.2

Life’s Organization All organisms are made of cells. Atoms combine to make molecules, and molecules combine to from cells. In multicellular organisms, there are all different kinds of cells. Those cells work together to perform its functions. In unicellular organisms, one cell carries out all of the functions for the organism.

Unicellular Organisms Unicellular organisms respond to their environment, get rid of waste, grow and even reproduce. Unicellular organisms can be prokaryotes & some eukaryotes. Prokaryotes – no nucleus, smaller than eukaryotic cells, fewer structures. Some prokaryotes live in colonies.

Eukaryotes Has a nucleus, specialized organelles. Some unicellular organisms have a nucleus such as Algae.

Multicellular Organisms Made of many eukaryotic cells that work together. Each type of cell in a multicellular organisms has a specific job that is important to the survival of the organism.

Cell Differentiation All cells in a multicellular organism comes from one cell – FERTILIZED EGG Cell Differentiation – the process by which cells become different types of cells.

Cell Differentiation Cell’s instructions are contained in the DNA located on the chromosomes. Different cell types use different parts of the instructions on the chromosomes. Stem Cells (Animal)- are unspecialized cells that are able to develop into many different cell types. Stem Cells are important for cell repair and replacement.

Cell Differentiation Meristems are groups of the plant’s unspecialized cells. Found in different area of the plant (roots & stems). Cell division in meristems produces different types of plant cells with specialized structures and functions.

Tissues Are groups of similar types of cells that work together to carry out specific tasks Humans have 4 main types of tissues: muscle, connective, nervous, and epithelial.

Types of Plant Tissues 3 main types of plant tissues are: dermal, ground and vascular.

Organs Are groups of different tissues working together to perform a particular job. Ex. Heart, lungs, stomach, leaves, stems, roots

Organ Systems Are groups of different organs that work together to complete a series of tasks.

Organisms Multicellular Organisms usually have many organ systems. The systems work together to carry out all the jobs needed for the survival of the organisms. Each organ system depends on the other organ systems and cannot work alone.