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Transcript
Chapter 7 Cell Structure and Function 7.1 Life is Cellular •Discovery of the Cell/ Cell Theory formulation: scientists and their contributions •Leeuwenhoek: invented single-lens microscope •Hooke: looked at slice of cork, named the cell •Schleiden: concluded all plants are made of cells •Schwann: concluded all animals are made of cells •Virchow: concluded that cells come from preexisting cells The Cell Theory 1. All living things are made up of cells. 2. Cells are basic units of structure and function in living things. 3. New cells are produced from existing cells. -one cell splitting into two new cells •Prokaryote Cells -Small, simple -No nucleus Have: -Cytoplasm -Cell Membrane -Ribosomes •All Bacteria- Archaebacteria, Eubacteria •Eukaryote -Larger, more complex –Have -Nucleus -Cytoplasm -Cell Membrane -Ribosomes -organelles-specialized structures •Plants, Animals, Fungi, Protists Eukaryotic Cells • Contains Organelles - “tiny organs” inside the cell - are Specialized: have a specific function (job to do) 7.2 Cell Structure and Function Structure Function Location 1. Cytoplasm -site of chemical activity and supports cell structure -inside cell membrane of prokaryotic & eukaryotic cells 2. Cell Membrane -allows certain materials in and out of the cell -outside cytoplasm of prokaryotic & eukaryotic cells 3. Cell Wall -support/protection -outside cell membrane of Prokaryotic cells and some Eukaryotic cells Structure 4. Nucleus 5. Chromatin Function Location -controls cell processes/holds DNA -anywhere in Eukaryotic cells -DNA bound to protein; -inside nucleus in in non-dividing cells eukaryotic cell 6. Chromosomes -tightly coiled chromatin -inside nucleus in /containing genetic info.; in eukaryotic cell dividing cell -inside nucleus in 7. Nucleolus eukaryotic cell -makes ribosomes 8. Nuclear envelope -protects nucleus -surrounds nucleus 9. Nuclear pores -allow things to enter/exit nucleus -in nuclear envelope Structure 10. Ribosomes Function -make protein used inside cell 11. Endoplasmic Reticulum -makes lipids, detoxes a. Smooth ER (ex. liver cells) b. Rough ER -makes proteins and modifies proteins exported or become part of cell membrane Location -free or attached to ER Prokaryotic = free and Eukaryotic cells = both types -within cytoplasm of Eukaryotic cells -within cytoplasm of Eukaryotic cells 12. Golgi Apparatus - attaches carbs/lipids to proteins made by RER and sends off (modify, sort, secrete) -within cytoplasm of Eukaryotic cells Structure 13. Lysosomes Function -break down lipids, carbs and proteins for cell to use (clean up crew) Location -cytoplasm of animal cells (are eukaryotic cells); but not plant cells 14. Vacuoles - store materials/transport -cytoplasm of plant (water, salts, proteins, cells; much smaller in carbs) animal cells 15. Mitochondria -site of ATP synthesis, -cytoplasm of cellular respiration Eukaryotic cells (powerhouse of the cell) Structure Function Location 16. Chloroplast -site of photosynthesis -within cytoplasm of convert sunlight into plant and some protist food cells (eukaryotic cells) 17. Cytoskeleton -maintain cell shape -within cytoplasm of prok. and euk. a. Microtubules -cell shape/tracking •forms -movement cilia: short hair-like projections flagella: long whip-like projections -movement centrioles: help organize cell division -near nucleusanimal cell b. Microfilaments -movement/support 7.3 Cell Boundaries Cell (Plasma) Membrane Function: 1. Regulates what enters/leaves cell 2. Protection/support -Made up of: 1. Lipid bilayer 2. Proteins a. transport proteins: allow molecules to pass through b. identifier (marker) proteins: with carbohydrates attached c. structural proteins: cell flexibility and support d. receptor proteins: receive signals from outside of cell to relay to inside 3. Carbohydrates Movement of Substances: • Passive Transport movement of molecules where the cell uses no ATP energy •Types: 1. Diffusion: •molecules move from high conc. to low conc. 2. Osmosis: •diffusion of water through selectively permeable membrane 3. Facilitated Diffusion: •movement of large particles across the plasma membrane with help of transport proteins Solution Types: Osmotic Pressure • Isotonic Solution: –equal amounts of dissolved particles inside and outside the cell; no net movement of water; cells stays same size •Hypotonic Solution: Extracellular –Fewer dissolved particles outside the cell than inside, so more water; net movement of water into the cell by osmosis; cell swells •Hypertonic Solution: –More dissolved particles outside the cell than inside, so less water; net movement of water out of the cell by osmosis; cell shrinks Movement of Substances: • Active Transport: - Material moves from low conc. to high conc. - Requires energy from the cell in the form of ATP –Types: •Endocytosis: taking material into cell by “folding” - Phagocytosis: extensions of cytoplasm surrounds and engulf large molecule - Pinocytosis: surrounds liquid particles •Exocytosis: –Cell forces out material –Secretion – release useful products (ex. hormones) –Excretion – release of waste (ex. sweat) 7.4 Diversity of Cellular Life • Unicellular: one cell –Prokaryotes = all bacteria –Eukaryotes = yeast, some protists •Multicellular: many cells that are interdependent –Eukaryotes = humans, animals, plants, most fungi, some protists •Cell Specialization: –cell have a specific job/function to do • Levels of Organization: • Cell Tissue Organs Organ System Organism • Specialized group of similar group of tissues cells perform same working together function group of organs working together 7-1 The cell theory states that new cells are produced from a. nonliving material. b. existing cells. c. cytoplasm. d. animals. 7-1 The person who first used the term cell was a. Matthias Schleiden. b. Lynn Margulis. c. Anton van Leeuwenhoek. d. Robert Hooke. 7-1 Electron microscopes are capable of revealing more details than light microscopes because a. electron microscopes can be used with live organisms. b. light microscopes cannot be used to examine thin tissues. c. the wavelengths of electrons are longer than those of light. d. the wavelengths of electrons are shorter than those of light. 7-1 Which organism listed is a prokaryote? a. protist b. bacterium c. fungus d. plant 7-1 One way prokaryotes differ from eukaryotes is that they a. contain DNA, which carries biological information. b. have a surrounding barrier called a cell membrane. c. do not have a membrane separating DNA from the rest of the cell. d. are usually larger and more complex. 7-2 In the nucleus of a cell, the DNA is usually visible as a. a dense region called the nucleolus. b. the nuclear envelope. c. granular material called chromatin. d. condensed bodies called chloroplasts. 7-2 Two functions of vacuoles are storing materials and helping to a. break down organelles. b. assemble proteins. c. maintain homeostasis. d. make new organelles. 7-2 Chloroplasts are found in the cells of a. plants only. b. plants and some other organisms. c. all eukaryotes. d. most prokaryotes. 7-2 Which of the following is NOT a function of the Golgi apparatus? a. synthesize proteins. b. modify proteins. c. sort proteins. d. package proteins. 7-2 Which of the following is a function of the cytoskeleton? a. manufactures new cell organelles b. assists in movement of some cells from one place to another c. releases energy in cells d. modifies, sorts, and packages proteins 7-3 Unlike a cell wall, a cell membrane a. is composed of a lipid bilayer. b. provides rigid support for the surrounding cell. c. allows most small molecules and ions to pass through easily. d. is found only in plants, fungi, algae, and many prokaryotes. 7-3 The concentration of a solution is defined as the a. volume of solute in a given mass of solution b. mass of solute in a given volume of solution. c. mass of solution in a given volume of solute. d. volume of solution in a given mass of solute. 7-3 If a substance is more highly concentrated outside the cell than inside the cell and the substance can move through the cell membrane, the substance will a. move by diffusion from inside the cell to outside. b. remain in high concentration outside the cell. c. move by diffusion from outside to inside the cell. d. cause water to enter the cell by osmosis. 7-3 The movement of materials in a cell against a concentration difference is called a. facilitated diffusion. b. active transport. c. osmosis. d. diffusion 7-3 The process by which molecules diffuse across a membrane through protein channels is called a. active transport b. endocytosis. c. facilitated diffusion d. osmosis 7-4 Cell specialization is characteristic of a. bacteria. b. all unicellular organisms. c. yeasts. d. multicellular organisms. 7-4 Which of the following cells is specialized for contraction? a. muscle cell b. red blood cell c. pancreatic cell d. nerve cell 7-4 The stomach is an example of a(an) a. tissue. b. organ. c. organ system. d. organism. 7-4 Which of the following shows the levels of organization in an organism from the simplest to the most complex? a. organ system, organ, cell, tissue b. tissue, cell, organ, organ system c. cell, tissue, organ, organ system d. cell, organ, tissue, organ system 7-4 Which of the following would probably contain the greatest variety of specialized cells? a. an organ system b. a tissue c. an organ d. a multicellular organism