Cell Structure Function EOCT Review Cells Smallest living

Cell Structure & Function EOCT Review

Cells • Smallest living unit that is capable of performing life functions. • Most are microscopic • Discovery: – Robert Hooke (mid 1600 s) • Observed sliver of cork • Coined the term cell

Cell Theory • All living things are made up of cells. • Cells are the smallest working units of all living things. • All cells come from preexisting cells through cell division.

Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell

Two Types of Cells Eukaryotic Prokaryotic

Prokaryotic • Do not have structures surrounded by membranes • Few internal structures • One-celled organisms, Bacteria http: //library. thinkquest. org/C 004535/prokaryotic_cells. html

Eukaryotic • Contains Nucleus • Contain organelles surrounded by membranes • Most living organisms Animal Plant

“Typical” Animal Cell

“Typical” Plant Cell http: //waynesword. palomar. edu/images/plant 3. gif

Plasma Membrane • Contains cell contents • Double layer of phospholipids & proteins Movement Across the Plasma Membrane • A few molecules move freely – Water, Carbon dioxide, Ammonia, Oxygen • Carrier proteins transport some molecules Phospholipids • Polar – Hydrophylic head – Hydrophobic tail

Cell Membrane

Cell Wall • Most commonly found in plant cells & bacteria • Supports & protects cells http: //library. thinkquest. org/12413/structures. html

Nucleus • Directs cell processes • Separated from cytoplasm by nuclear membrane • Contains genetic material - DNA

Chromosomes • In nucleus • Made of DNA • Contain instructions for traits & characteristics

Nucleolus • Inside nucleus • Contains RNA to build proteins

Cytoplasm • Gel-like mixture • Surrounded by cell membrane

Endoplasmic Reticulum • Moves materials around in cell • Smooth type: lacks ribosomes • Rough type (pictured): ribosomes embedded in surface

Ribosomes • Each cell contains thousands • Make proteins • Found on ribosomes & floating throughout the cell http: //library. thinkquest. org/12413/structures. html

Mitochondria • Produces energy through chemical reactions – breaking down fats & carbohydrates • Controls level of water and other materials in cell • Recycles and decomposes proteins, fats, and carbohydrates

Golgi Bodies • Protein 'packaging plant' • Move materials within the cell • Move materials out of the cell http: //library. thinkquest. org/12413/structures. html

Lysosome • Digestive 'plant' for proteins, fats, and carbohydrates • Transports undigested material to cell membrane for removal • Cell breaks down if lysosome explodes

Vacuoles • Membrane-bound sacs for storage, digestion, and waste removal

Chloroplast • Usually found in plant cells • Contains green chlorophyll • Where photosynthesis takes place

Passive Transport • No energy required • Move due to gradient – differences in concentration, pressure, charge • Move to equalize gradient – High moves toward low

Types of Passive Transport 1. Diffusion 2. Osmosis 3. Facilitated diffusion

Diffusion • Molecules move to equalize concentration

Osmosis • Diffusion of water • Fluid flows from lower solute concentration • Often involves movement of water – Into cell – Out of cell

Solution Differences & Cells • solvent + solute = solution • Hypotonic – Solutes in cell more than outside – Outside solvent will flow into cell • Isotonic – Solutes equal inside & out of cell • Hypertonic – Solutes greater outside cell – Fluid will flow out of cell

Facilitated Diffusion • Differentially permeable membrane • Channels (are specific) help molecule or ions enter or leave the cell • Channels usually are transport proteins (aquaporins facilitate the movement of water) • No energy is used

Process of Facilitated Transport • Protein binds with molecule • Shape of protein changes • Molecule moves across membrane

Active Transport • Requires energy (against gradient) • Example is sodium-potassium pump

Endocytosis • Movement of large material – Particles – Organisms – Large molecules • Movement is into cells • Types of endocytosis – bulk-phase (nonspecific) – receptor-mediated (specific)

Process of Endocytosis • Plasma membrane surrounds material • Edges of membrane meet • Membranes fuse to form vesicle

Forms of Endocytosis • Phagocytosis – cell eating • Pinocytosis – cell drinking

Exocytosis • Vesicle moves to cell surface • Membrane of vesicle fuses • Materials expelled

1. Unlike prokaryotic cells, eukaryotic cells have the capacity to a. assemble into multicellular organisms. b. establish symbiotic relationships with other organisms. c. obtain energy from the Sun. d. store genetic information in the form of DNA.

2. Inside eukaryotic cells are membrane-bound structures called_______. a. cell walls. b. cilia c. organelles. d. cytoplasm.

3. The assembly of proteins in the cell takes place in the _______. a. nucleus b. vacuoles c. cytoplasm d. mitochondria

4. Which of the following is an organism whose cell(s) lack(s) membrane-bound organelles? a. nucleolus b. chromatin c. eukaryote d. prokaryotes

5. Which means of particle transport requires input of energy from the cell? A. diffusion B. Osmosis C. Facilitated Diffusion D. Active Transport

6. The complexity of body systems differs greatly among organisms. Which of the following organisms has developed organ systems for obtaining and utilizing energy? a. bacterium b. mushroom c. mouse d. virus

7. Enzymes for intracellular digestion are stored in the a. lysosomes. b. vacuoles. c. nucleoli. d. mitochondria.

8. Besides the nucleus, DNA is found in which of the following cell organelles? a. chloroplasts b. mitochondria c. mitochondria and chloroplasts d. mitochondria and ribosomes

9. The movement of molecules into cells is most dependent on the a. selectivity of the cell membrane. b. selectivity of the cell wall. c. number of the vacuoles. d. number of mitochondria.

10. An organelle that is present in the cells of a mouse but not present in the cells of a bean plant is a a. cell wall. b. chloroplast. c. cell membrane. d. centriole.

11. A student could tell the difference between onion skin cells and cheek cells because the onion skin cells have a a. cell membrane. b. nucleus. c. centriole. d. cell wall.

12. The cell theory states that: A. All living things are made of cells. B. All cells come from other living cells of a different kind. C. Cells are the basic unit of some living things. D. all of the above

13. The mitochondria of a cell A. has only one membrane. B. has no membrane. C. produces ATP. D. is where cell respiration occurs. E. both C and D

14. Which of the following organisms are prokaryotes? A. protozoa B. bacteria C. fungi D. amoeba

15. A nonliving cell structure is a A. Nucleus B. Cell wall C. Golgi body D. Cell membrane

16. An animal cell that is surrounded by fresh water will burst because the osmotic pressue causes A. water to move into the cell B. water to move out of the cell C. solutes to move into the cell D. solutes to move out the cell

17. Which list represents the levels of organization in a multicellular organism from the simplest level of the most complex level? A. cell, tissue, organ system B. organ system, organ, tissue, cell C. tissue, organ system D. cell, tissue, organ system

18. Prokaryotes lack A. Cytoplasm B. A cell membrane C. A nucleus D. Genetic Material