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Bio-Chapter 4-MHS
Structure and Function of the Cell
| Term | Definition |
|---|---|
| What are the three parts of the cell theory? | 1. All living things are composed of one or more cells. 2. Cells are the basic units of structure and function in an organism. 3. Cells come only from the reproduction of existing cells. |
| Cell | The smallest unit of mattresses than can carry on all the processes of life. |
| Who created the cell theory? | Hooke and van Leeuwenhoek |
| Are all cells alike? | No. There are at least 200 different cell types in our bodies alone. |
| Do you need a microscope to see all cells? | No. Some cells can be seen with your unaided eye. |
| Why are cells limited in size by the ratio between their outer surface and their volume? | It is important to know that if a cell grows too large and the surface area becomes too small, it is difficult for the cell to get the nutrients and oxygen it needs. Nutrients and oxygen enter through the surface of the cell. |
| Do cells have different shapes? | Yes. Cells have a variety of shapes. |
| Why do cells have different shapes? | Cell shapes differ depending on what their duty (role) is. Nerve cells have long extensions to receive/transmit impulses. Skin cells are flat to cover the surface of the body. |
| Organelles | A cell component that performs specific functions for the cell. Organelles maintain the life of the cell. (Compare this the "heart" in our body. It pumps blood and oxygen through our body to maintain life.) An organelle maintains the life of the cell. |
| Cell membrane | Thin membrane surrounding a cell Organelles also each have their own membrane. |
| Nucleus | 1. The large organelle near the center of the cell. 2. Contains most of the cell's genetic information. 3. Directs most of the cell's activities |
| Eukaryotes | Organisms whose cells contain a membrane-bound nucleus and other organelles |
| Prokaryotes | Unicellular (one celled) organisms that lack a membrane-bound nucleus and other organelles |
| What is the difference between a eukaryote and prokaryote? | Eurkaryotes have a membrane-bound nucleus and prokaryotes do not. Prokaryotes are placed in a different kingdom. |
| Can a cell survive if it is isolated from its environment? | No. Cells must take in nutrients and dispose of waste. Both actions pass through the cell membrane. |
| Selectively Permeable meaning? | Some substances easily cross the membrane and others cannot. |
| What does the structure of the cell membrane depend on? | the functions that the cell performs |
| What are cell membranes primarily made up of? | lipids and protiens |
| What does a phospholipid molecule have? | a polar "head" and two non polar "tails" |
| Does the head of a phospholipid orient itself away from or close to water molecules? | The head of a phospholipid orients itself CLOSE to water molecules. |
| Does the tail of a phospholipid orient itself away from or close to water molecules? | The tail of a phospholipid orients itself AWAY from water molecules. |
| Aqueous | Watery environment that bathe cells |
| What parts are cells surrounded by water molecules? | The outside AND inside of cells are surrounded by water. The inside of a cell is an aqueous environment. |
| How many layers do water molecules cause the phospholipids of the cell membrane to form? | TWO layers. (A lipid bilayer) Heads point outward and tails are confined to the interior of the cell membrane. |
| What additional thing do eukaryotic cell membranes contain? | steroids molecules. Steroid molecules fit between the tails. Cholesterol is an example of a steroid molecule in animals. |
| Peripheral proteins | located on the interior and exterior surface of the cell membrane |
| integral proteins | proteins embedded in the bilayer of the cell membrane |
| Why must cells have mechanisms for transporting molecules through the lipid bilayer? | Because the cell membrane is selectively permeable |
| Fluid mosaic model | -lipid bilayer behaves like a fluid more than a solid -lipids and proteins can move laterally within the lipid bilayer -pattern/mosiac is constantly changing |
| cytoplasm | -lies between cell membrane and nucleus -contains the organelles of the cell |
| cytosol | gelatin-like aqueous fluid that bathes organelles |
| What is the cytosol made up of? | salts, minerals, and organic molecules are dissolved in the cytosol |
| Mitochondria | -large organelles scattered throughout the cytosol -mitochondria are the sites of chemical reactions that transfer energy from organic compounds to ATP (molecule that most cells use as their main energy currency) |
| What is true about the amount of mitochondria in cells that need a lot of energy? | The more energy a cell requires, the more mitochondria it needs, |
| How many membranes surround the mitochondria? | Two outer membrane - smooth; a boundary between mitochondrion and cytosol inner membrane - long folds (cristae) - enlarge surface area of inner membrane |
| cristae | inner membrane of mitochondrion -enlarge the surface area of inner membrane -proide more space for the chemical reactions that occur in the mitochondrion |
| Do Mitochondria have their own DNA? | Yes. Mitochondrion have their own DNA. New mitochondria arise only when existing ones grow and divide. |
| ribosomes | -the most numerous organelles in many cells. -are NOT surrounded by a membrane |
| What is a ribosome made up of? | protein and RNA |
| What is the role of a ribosome? | - synthesis of protein |
| endoplasmic reticulum | -ER -system of membranous tubules and sacs -function: intracellular highway where molecules move from one part of the cell to another |
| What are the two types of ER (endoplasmic reticulum)? | -rough endoplasmic reticulum - rough ER - covered with ribosomes -smooth endoplasmic reticulum - smooth ER 0 synthesis of steroids in gland cells , regulation of calcium levels in muscles, and breakdown of toxic substances in liver cells. |
| Golgi apparatus | -the processing, packaging, and secreting organelle of the cell. -system of membranes |
| Lysosomes | -small, spherical organelles that enclose hydrolytic enzymes within single membranes, DNA, RNA, viruses, and bacteria. |
| Are lysosomes common in animal or plant cells? | Lysosomes are common in animal cells and rare in plant cells |
| cytoskeleton | -structure to maintain shape and size in cells -network of protein strands found in the cytosol -not supported by membranes |
| What are the two main components of the cytoskeleton? | -microfilaments and microtubules |
| Microfilament | -threads made of protein called ACTIN that make up part of the cytoskeleton. ---Contribute to cell movement - example - muscle contraction |
| Microtubules | -largest strands of the cytoskeleton -hollow tubes |
| Spindle fibers | -bundles of microtubules that one together and extend across the cell when it is about to divide. -can be quite large |
| cilia and flagella | -hairlike organelles that extend from the surface of the cell -assist in momvement |
| cilia | -organelle that assist in cell movement -when they are short and present in large numbers they are called cilia |
| flagella | -organelle that assist in cell movement -when they are long and less numerous on a cell they are called flagella |
| nucleus | -most prominent structure within a eukaryotic cell -stores heredity information in its DNA -RNA copied from DNA |
| nuclear matrix | - a protein skeleton that helps the nucleus maintain its shape |
| nuclear envelope | a double membrane that surrounds the nucleus |
| chromatin | a combination of DNA and protein found in the nuclear envelope |
| nuclear pores | -small holes in the nuclear envelope -RNA makes its journey through the nuclear pores |
| Nucleolus | the site where ribosomes are synthesized and partially assembled before they pass through the nuclear pores to the cytosol. |
| Plant cells have three additional kinds of structures. What are they? | cell walls, vacuoles, and plastids |
| Cell Wall | a rigid plant cell covers a plant cell and lies outside the cell membrane |
| vacuoles | fluid-filled organelles that store enzymes an metabolic wastes in plant cells |
| plastids | organelles that are surrounded by to membranes and contain DNA in plant cells. |
| chloroplast | the most familiar type of plastid in plant cells. convert sun energy and contains a large amount of green pigment giving leaves a green color |
| thylakoids | flattened membranous sacs in chloroplast (plant cell) |
| tissues | group of cells that carry out a specific function. for example - skin, nervous tissue |
| organ | several type of tissues that interact to perform a specific functions. example, stomach |
| organ system | group of organs that work togther for a specific task. (digestive system - mouth, esophagus, stomach, intestines, etc.) |
| colonial organisms | collection of genetically identical cells that live together in a closely connected group |
Created by:
D. Waara
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