Chapter 2Living things

THURSDAY, 9/4 Warm-Up:

Please have a seat and take your LROD paper out.Write the HW in your planner

Learning Goal(s): Identify and describe the characteristics of living things.

Agenda:1. Warm-Up/Review Tonight’s HW2. Complete LRODs 3. Begin the class notes/discussion for Chapter 2, Section 1

• HW: No Homework

Section 1: What is life (Part 1, pages 34-37)

• Organism = LIVING THING• Examples: yourself, a pet, insects, plants

• ALL LIVING THINGS SHARE THESE CHARACTERISTICS:

1. Cellular organizations2. Contain similar chemicals3. Use energy4. Respond to their surroundings5. Grow and develop6. Reproduce

Cellular Organization• All organisms are made of small building blocks called cells

• A cell is the basic unit of structure and function

• Cells are so small you need a microscope to see them

Human cheek cellsunder a light microscope

Human cheek cellsunder an electron

microscope

Cellular Organization

• Unicellular: single-celled organisms (Bacteria)• Multicellular: composed of many cells that are

specialized to do certain tasks• Example: in our body, muscle and nerve cells

(work together to keep us alive!)

The bacteria that causesstrep throat

The cells that make upyour stomach lining

The Chemicals of life• Cells are composed of chemicals

• SUCH AS…• Water (most abundant)• Carbohydrates (energy)• Proteins and lipids/fats (building materials)

• Nucleic acid : genetic materials, chemical instructions that direct the cell’s activities

Energy Use

• Cells of organisms use energy to do what living things must do• Example: Repairing injured parts

• An organisms cells are ALWAYS hard at work

Response to surroundings• Plants and all other organisms react to changes in

their environment

• STIMULUS: a change in an organism’s surroundings that causes an organism to react• Example: temperature, light, sound….

• RESPONSE: an action or change in behavior

• Example: A plant stem growing toward the sun. Stimulus?? Response??

Growth and development• Living things GROW (adding mass) and

DEVELOP (gaining new structures)

• Development: the process of change that occurs during an organisms life to produce more complex organisms

Reproduction

• Organisms have the ability to reproduce, or produce offspring that are similar to the parents

• Example: Robins lay eggs… that develop into young robins… that closely resemble their parents!

Life Comes from life• Living things arise from living things through

reproduction

• ….But, four hundred years ago people believed that life could appear from nonliving things… CRAZY!?!?!

• They called this… SPONTANEOUS GENERATION***the mistake idea that living things can arise from nonliving sources

http://www.youtube.com/watch?v=WNByRghR6sw

Redi’s Experiment

• Francesco Redi – Italian doctor (1600’s)

• He designed a CONTROLLED EXPERIMENT to show flies do not arise from decaying meat

• Who remembers what a controlled experiment is???• A scientist carries out 2 tests that are identical in

every respect except for one factor

Redi’s Experiment

• Left jar = UNCOVERED• Right jar = COVERED

• Manipulated Variable?• Whether or not the jar Was covered

Pasteur’s experiment• Louis Pasteur--- French chemist (mid-1800s)

• Some people still did not believe Redi… so Pasteur came up with a new experiment

• His experiment… demonstrated that new bacteria appeared in broth only when they were produced by existing bacteria

• Both experiments convinced people that LIVING THINGS DO NOT ARISE FROM NONLIVING MATERIAL

Pasteur’s experiment