Levels of Organization

Chapter 3 Lesson 2

p.96-105

Organization of Unicellular Organisms

Do unicellular organisms have all the characteristics of life?(i.e. respond to environment, get rid of waste, grow, reproduce)

Prokaryotes

• Without a membrane bound nucleus

• Smaller than eukaryotic cells

• An organism the is a prokaryotic cell is called a prokaryote

• Some can live in extreme environments

Eukaryotes

• Nucleus surrounded by a membrane

• Specialized organelles

• Eukaryotes

Multicellular Organisms

Organisms made up of many eukaryotic cells working together.

Cell Differentiation

• In a multicellular organism there are many types of cells.

• Each type of cell has a specific job, or function

All multicellular organisms start from one cell – a fertilized egg

Cell Differentiation

• By reading different parts of a chromosome, cells become different types.

Cell differentiation

• The process by which cells become different types of cells

Animal Stem Cells

• Stem cell – unspecialized (undiffentiated) cell that is able to develop into many cell types.

• Embryos have many more stem cells than adult organisms.

• Adult organisms have some stem cells for muscle repair and producing blood cells in our bone marrow.

Plant Cells

• Stem cells in plants are called unspecialized cells

• They group in areas called meristems

• Cells in the meristem can become parts of the stem, leaves, flowers, or roots.

Tissues

Plant Tissues

Organs

• Organs are groups of different tissues working together to perform a particular job.

Plant Organs

• Leaves are organs specialized for photosynthesis.

Organ Systems

• Organ systems are grouped of different organs that work together to complete a series of tasks

Plant Organism Systems

• Two major organ systems:– 1. shoot system

– 2. root system

Organisms

• Each organ system depends on the others and cannot work alone.

• Muscle tissue could not work without blood from the circulatory system.

Review

• All unicellular organisms carry out all the activities necessary for survival within one cell

• Cells become specialized in structure and function during cell differentiation

• Organs are groups of different tissues that work together to perform a job.

Homework

• Practice Book: p19-20

• Notebook:– TB page 105

• #1-5