We all have these in common.

8 Characteristics of Life

Living things share 8 characteristics:

1. Living things are made up of units called cells.

a) Every organism is composed of at least one cell

1) Single-celled or unicellular

2) Many celled or multicellular

2. Living things reproduce.

3. Living things are based on a universal genetic code (DNA).

a) The directions for inheritance are found in deoxyribonucleic acid or DNA.

b) The genetic code is basically the same for all organisms on Earth.

4. Living things grow and develop.

5. Living things obtain and use materials and energy.

6. Living things respond to their environment.

7. Living things maintain a stable internal environment.

a.) Maintaining a stable

internal environment is

called homeostasis.

8. Taken as a group, living things change over time (living things evolve).

a) Plants have adapted to living in dry and hot deserts.

b) Fossils of ancient organisms can be used to show how organisms have changed over time.

1. Organism

2. Organ System

3. Organ

4. Tissue

5. Cell

Cell Structure and Function Notes

Discovery of the Cell: • Mid 1600’s scientists began using

microscopes to observe living things

• Robert Hooke used microscope to observe thin slice of cork—dead plant materialCork seemed to be made of box-like chambers—Hooke called cells

• Anton van Leeuwenhoek discovered living cells in pond water

Cell Theory:

• All living things composed of cells

• Cells are the basic unit of structureand function in living things

• New cells are produced from existing cells

Cell and its Environment:

• Organisms made of one cell—unicellular organisms

Ex: bacteria

• Organisms made of many cells—multicellular organisms

Ex: plants, animals

• Each cell must be in “balance” with its environment, exchange food, waste, H2O, CO2, O2 etc.

• Process by which organisms maintain a relatively stable internal environment—homeostasis

Cell:

• Organisms that do not have a distinct nucleus—prokaryotic (PRO = BEFORE)

Ex: bacteria

• Organisms with cells that have true nucleus and organelles—eukaryotic (EU = TRUE)

Ex: plants, animals, fungi

Cell Parts and Their Functions:

Specialized cell parts called organelles—“little organs”

1. Cell membrane—determines what goes in and out of the cell

2. Cytoplasm—gel-like medium that holds the organelles in position

3. Nucleus—control center of the cell

• Double membrane that surrounds the nucleus—nuclear envelope

• Hereditary information inside the nucleus—chromatin (DNA)

• Site where ribosomes are made--nucleolus

4. Ribosomes—makes proteins

5. Rough Endoplasmic Reticulum (rough ER)—makes and transports proteins within the cell

• Called rough ER because of the ribosomesfound on its surface

6. Smooth Endoplasmic Reticulum(smooth ER)—makes and transport lipids and other materials within the cell

• Called smooth ER because no ribosomes found on its surface

7. Cytoskeleton—network of protein filaments that helps cell maintain its shape

8. Golgi apparatus—processes and packagesproteins and other substances produced in the ER

• Golgi apparatus prepares these substances either to be stored in the cell or secreted outside the cell in membrane bound vesicles

9. Mitochondria—supplies energy to the cell (powerhouse)

10. Vacuoles—sac-like structures for storage of materials such as water, salts, proteins and carbs

• Plant cells usually contain a large vacuolethat fills most of the cell—pressure from this large vacuole helps plants support themselves

Found in animal cells only:

11. Lysosomes—cleans up the cell and digests unwanted materials, contains digestive enzymes

Found in plant cells only:12. Cell wall—provides support and

protection for cell• Composed mainly of cellulose (plant starch)—

fiber for our diet

13. Chloroplast—makes glucose using the energyfrom the sun (photosynthesis)

Specialized Parts for movement:

1. Cilia (like little hairs) 2. Flagella (like a tail)

Specialized Cells:

Different cells in your body do different jobs. The structure (how it’s built) of cells matches the function (what it does).

• Plant Examples:

1. Leaf cell—contains many chloroplaststo maximize photosynthesis

2. Root cell (potato)—contains many vacuoles to maximize water and starch storage

• Animal Examples:1. Epithelial cells—have villi to

increase nutrient absorption; found in the intestines

2. Muscle cells—contain many mitochondriato produce more energy for movement

3. Nerve cells—have fibers called dendritesthat allow nerve cells to communicatewith each other

Warm Up:

1. Saliva in your mouth must have digestive

enzymes to help you break down food. For

the specialized cells producing saliva, they

will have high concentrations of what

organelle(s)?

2. Which diagram below shows a prokaryotic

cell? Explain your reasoning.

Cell Membrane:

1. ALL cells have a cell membrane

2. Cell membranes are selectively permeable

control what enters and leaves the cell

not solid, but fluid—always in motion (soap bubbles)

3. Composition – lipids and proteins

• Phospholipid bilayer—small molecules can pass throughex: O2, CO2, H20, alcohol

Proteins—embedded in lipids, allows for passage of large molecules through lipid bilayer

a. marker protein – has a unique carbohydrate chain to identify the cell – how organ donors and recipients are matched

b. protein channel – allows larger molecules needed by the cell to pass through the cell membrane

c. receptor protein – allows cell to communicate with outside environment

d. LDL cholesterol – helps keep membrane fluid and stable

WHAT IS A VIRUS?

A. General Characteristics

1. A virus is an infectious agent made up of – nucleic

acid (DNA or RNA), wrapped in protein coat

a. they have no nucleus, no organelles, no

cytoplasm or cell membrane – non-cellular

particle

b. viruses have either – DNA or RNA, but not both

vs

A flea is a parasite to a dog

and is harmful to the dog.

2. Viruses are - parasitic - organism that depends

entirely upon another living organism (host) for its

existence in such way that it harms that

organism.

http://tinyurl.com/orltmm9

http://tinyurl.com/lng7gx7

RNA

Envelope—has marker

proteins + carbs derived

from host cell

Capsid

B. Examples1. Bacteriophage—viruses that infect a bacteria

2. Flu (influenza)

3. Ebola4. Common Cold5. HIV6. Herpes7. H1N18. Avian Flu

Take 5!

• Take 5 minutes, turn to your table partner

and discuss the following questions:

– Could there be such things as multicellular

prokaryotes? Why or why not?

– A virus cannot reproduce unless they take over

a host organism’s reproductive structures.

Would it be considered alive? Why or why not?

Viruses are not alive

1. Not made of cells!

2. Doesn’t adapt to the environment (evolve)

3. Has to use host cell to reproduce

4. Has DNA OR RNA not both

5. No growth or development

6. Doesn’t get or use energy

7. Don’t respond to the environment