LIVING THINGS Cells Unit 2, Part 1 H. Carter

Organism Any living thing

Characteristics of Life 1.Have cellular organization ▫All living things are made of cells  basic unit of structure and function in an organism  Unicellular: made of one cell  Multicellular: made of many cells

2. Contain similar chemicals ▫Cells are made up of chemicals  Water: most abundant  Carbohydrates: energy  Proteins & Lipids: building materials of cells  Nucleic Acids: genetic material

3. Use Energy ▫Cells use energy to do what they need to do, to work

4. Respond to their surroundings ▫Stimulus: a change in an organism’s surroundings that caused the organism to react (ex. Changes in temperature, light, sound) ▫Response: an action or change in behavior due to a stimulus (ex. Squinting eyes when light turned on)

5. Grow and Develop ▫Growth: process of becoming larger ▫Development: process of change that occurs during an organism’s life to produce a more complex organism

6. Reproduce ▫To produce more of one’s kind

Life Comes from Life Living things come from other living things through reproduction Spontaneous Generation: idea that living things can come from non- living things

Francesco Redi (1600s) ▫disproved that flies came from decaying meat

Louis Pasteur (1800s) ▫Showed that bacteria come from bacteria

Needs of Living Things Water- all reactions occur in the presence of water **most abundant chemical in cells Food- source of energy ▫Autotrophs- make their own food ▫Heterotrophs- cannot make their own food; feed on others *The sun is the source of energy for all organisms

Living Space Stable Internal Conditions ▫Homeostasis- maintenance of stable internal conditions (ex. Body temperature, feeling thirsty after exercise)

Development of the Cell Theory Invention of microscope made it possible for people to discover and learn about cells Robert Hooke (1663) ▫Looked at a piece of cork ▫Saw empty spaces that looked like rooms ▫Called them “cells” (small rooms)

Anton van Leeuwenhoek (1663) Matthias Schleiden (1838) ▫All plants are made of cells Theodor Schwann (1839) ▫All animals are made of cells ▫All living things are made of cells Rudolf Verchow (1855) ▫New cells are formed only from cells that already exist ▫“All cells come from cells”

The Cell Theory Widely accepted explanation of the relationship b/n cells and living things ▫All living things are made of cells ▫Cells are the basic unit of structure and function in organisms ▫All cells come from other cells

Cell Structure Organelles- tiny structures w/in cells that perform certain jobs ▫Cell wall- surrounds cells of plants and other organisms; protects and supports ▫Cell membrane- controls what comes into and leaves the cell ▫Nucleus- control center, “brain” of cell  Nuclear envelope- protects the nucleus  Chromatin- strands in nucleus that contain genetic material, instructions for the cell  Nucleolus- structure in nucleus that makes ribosomes

▫Mitochondria- powerhouse of cell; converts energy in food to energy the cell can use ▫Endoplasmic Reticulum (ER)- passageways that carry proteins and other materials around the cell (“highway” of the cell)  Rough- have ribosomes attached to it  Smooth- no ribosomes attached ▫Ribosomes- produce proteins (“factories”) ▫Golgi Bodies- receive proteins and other materials from ER, package them, and send out to other parts of the cell (“mailroom”)

▫Chloroplasts- contain chlorophyll (green) which traps energy from the sun and uses it to make food- autotrophs (ex. plants) ▫Vacuoles- storage area of the cell (“storage tank”)  most plants have one large vacuole  Some animal cells have them; others don’t ▫Lysosomes- small, round structures containing chemicals that breakdown certain materials in cell  Ex. Large food particles into smaller; old cell parts

Specialized Cells *Multicelled Organisms* Tissues- group of similar cells that work together to perform specific functions Organ- group of tissues that work together Organ System- group of organs that work together to perform a major function Cells Tissues Organs Systems Organism