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 material Cork 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 structure and 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 ribosomes found 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 packages proteins 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 vacuole that 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 energy from 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 chloroplasts to 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 mitochondria to produce more energy for movement
3.
Nerve cells—have fibers called dendrites that allow nerve cells to communicate with 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 through ex: 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
2. Viruses are - parasitic - organism that depends entirely upon another living organism (host) for its existence in such way that it harms that organism.
A flea is a parasite to a dog and is harmful to the dog.
B. Examples 1. Bacteriophage—viruses that infect a bacteria Envelope—has marker 2. Flu (influenza) proteins + carbs derived from host cell
RNA
3. Ebola 4. Common Cold 5. HIV 6. Herpes 7. H1N1 8. Avian Flu
Capsid
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. 2. 3. 4. 5. 6. 7.
Not made of cells! Doesn’t adapt to the environment (evolve) Has to use host cell to reproduce Has DNA OR RNA not both No growth or development Doesn’t get or use energy Don’t respond to the environment
