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Biology 20A pt. 1
| Question | Answer |
|---|---|
| What are vacuoles? | Large vesicles derived from the ER and Golgi apparatus. |
| What are the different kinds of vacuoles? | Food vacuoles, Contractile vacuoles, and Central vacuoles. |
| What are food vacuoles are formed by? | phagocytosis |
| Where are contractile vacuoles found and what do they do? | found in many freshwater protists and they pump excess water out of cells |
| Where are central vacuoles found, what do they contain and what do they do? | The central vacuole plays a major role in the growth of plant cells. It is the plant cell’s main repository of inorganic ions, including potassium and chloride. It is found in many mature plant cells and it contains a solution called sap. |
| What is the mitochondria and what does it do? | The mitochondria are the sites of cellular respiration. It does the metabolic process that uses oxygen to generate ATP. |
| What are chloroplasts found in plants and algae? | They are the sites of photosynthesis. |
| What are peroxisomes? | Peroxisomes are oxidative organelles; they contain enzymes that remove hydrogen atoms from various substances and transfer them to oxygen. |
| What is the Endosymbiont Theory? | the theory suggests that an early ancestor of eukaryotes engulfed an oxygen-using non-photosynthetic prokaryotic cell and the engulfed cell formed a relationship with the host cell, becoming an endosymbiont. |
| What are the similarities between mitochondria and chloroplasts that support Endosymbiont Theory? | Both mitochondria and chloroplasts enveloped by a double membrane, contain free ribosomes and circular DNA molecules and grow and reproduce somewhat independently in cells. |
| What did endosymbionts evolve into? | mitochondria. |
| What formed the chloroplast? | At least one of these cells may have engulfed a photosynthetic prokaryote, which evolved into a chloroplast. |
| What is found in nearly all eukaryotic cells? | Mitochondria |
| • They have a smooth outer membrane and an inner membrane folded into cristae | |
| • The inner membrane creates two compartments: intermembrane space and mitochondrial matrix | |
| Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix • Cristae present a large surface area for enzymes that synthesize ATP | |
| Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis | |
| • Chloroplasts are found in leaves and other green organs of plants and in algae | |
| • Chloroplast structure includes – Thylakoids, membranous sacs, stacked to form a granum – Stroma, the internal fluid | |
| • The chloroplast is one of a group of plant organelles, called plastids | |
| What is not known peroxisomes? | How are related to other organelles? |
| How many specialized metabolic compartments are peroxisomes bounded to? | By a single membrane. |
| When peroxisomes use enzymes to remove hydrogen atoms from substances and transfer them to oxygen, what does it create? | This forms hydrogen peroxide. |
| • These reactions have many different functions • Functions of peroxisomes | Peroxisomes functions: oxygen breaks fatty acids into smaller molecules, used for fuel for respiration, In the liver, they detoxify alcohol and harmful compounds. Glyoxysomes in the fat-storing tissues of plant seeds, convert fatty acids to sugar |
| The cytoskeleton is a network of fibers extending throughout the cytoplasm | |
| • The cytoskeleton helps to support the cell and maintain its shape • It organizes the cellʼs structures and activities, anchoring many organelles | |
| • It is composed of three types of molecular structures – Microtubules – Microfilaments – Intermediate filaments | |
| • In animal cells, microtubules grow out from a centrosome near the nucleus | |
| • In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring | |
| • Other eukaryotic cells organize microtubules in the absence of centrosomes with centriole | |
| Microtubules control the beating of flagella and cilia, microtubule-containing extensions that project from some cells | |
| • Many unicellular protists are propelled through water by cilia or flagella | |
| • Motile cilia are found in large numbers on a cell surface, whereas flagella are limited to one or a few per cell | |
| • Cilia and flagella differ in their beating patterns | |
| Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM) | |
| • The ECM is made up of glycoproteins such as collagen, proteoglycans, and fibronectin | |
| • Fibronectin and other ECM proteins bind to receptor proteins in the plasma membrane called integrins | |
| • The ECM has an influential role in the lives of cells • ECM can regulate a cell’s behavior by communicating with a cell through integrins • The ECM around a cell can influence the activity of genes in the nucleus | |
| • Mechanical signaling may occur through cytoskeletal changes that trigger chemical signals in the cell | |
| Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact | |
| What are the three types of cell junctions that are common in epithelial tissues? | Tight junctions, desmosomes (anchoring junctions) and gap junctions (communicating junctions) |
| What are tight junctions? | Membranes of neighboring cells are pressed together, preventing leakage. |
| What are Desmosomes (anchoring junctions)? | Fasten cells together into strong sheets |
| What are Gap junctions (communicating junctions)? | Provide cytoplasmic channels between adjacent cells |
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