Chapter 2 Living things

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 HW 2.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 organizations 2.Contain similar chemicals 3.Use energy 4.Respond to their surroundings 5.Grow and develop 6.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 cells under a light microscope Human cheek cells under 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 causes strep throat The cells that make up your 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

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