8318566
Descripción
Fichas por Sofia Ward, actualizado hace más de 1 año
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Creado por Sofia Ward
hace más de 7 años
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| Pregunta | Respuesta |
| How are proteins produced in a cell and secreted? (7) | The gene that has the instructions to make the protein is transcribed into mRNA which passes out through the nuclear envelope to the ribosomes on the RER At the ribosomes, the mRNA is translated and the protein is assembled The protein passes into the cisternae of the RER Vesicles containing the protein are pinched off the ER - these are moved to the Golgi apparatus and fuse Inside the Golgi, the protein molecules are modified for release Vesicles containing the protein are pinched off the Golgi - these are moved to the plasma membrane The vesicles and the membrane fuse and the protein is secreted outside the cell |
| Give 3 similarities between eukaryotic and prokaryotic cells | Both have a plasma membrane Both have cytoplasm Both have ribosomes Both have DNA and RNA |
| Give 3 differences between eukaryotic and prokaryotic cells | Prokaryotic cells are much smaller than eukaryotic cells P. cells have much less well developed cytoskeletons and no centrioles P. cells have no nucleus P. cells do not have membrane bound organelles Cell walls in P. cells are made of peptidoglycan, not cellulose P. cells have smaller ribosomes than eukaryotic cells P. cells have naked DNA which floats in the cytoplasm P. cells have circular DNA, eukaryotic cells have linear DNA P. cells divide by binary fission, E. cells divide by mitosis/meiosis |
| Outline the structure of the nucleus, nuclear envelope and nucleolus (3) | The nucleus is surrounded by the nuclear envelope which is a double membrane that has pores The nucleolus does not have a membrane and contains chromatin Chromatin is the genetic material, consisting of DNA wound around histone proteins |
| Outline the function of the nucleus, nuclear envelop and nucleolus (2) | It stores the organism's genome. It provides the instructions for protein synthesis. |
| Outline the structure of the Endoplasmic Reticulum (2) | The ER is a system of membranes, containing fluid filled cisternae - it is continuous with the nuclear envelope. The rough ER is coated with ribosomes, whereas the smooth ER is not. |
| Outline the function of the Endoplasmic Reticulum (3) | The cisternae are channels used for transporting substances to different areas of the cell. The RER has many ribosomes which assemble amino acids into proteins in protein synthesis. The SER contains enzymes that catalyse reactions involved with lipid metabolism. |
| Outline the structure of the Golgi apparatus (1) | A stack of membrane-bound flattened sacs. |
| Outline the function of the Golgi apparatus (1) | The Golgi apparatus is where proteins are modified and packaged into vesicles that are then pinched off into vesicles and moved to different parts of the cell. |
| Outline the structure of mitochondria (3) | 2-5 µm long Surrounded by two membranes with a fluid filled intermembrane space The inner membrane is highly folded into cisternae. The inner part of the mitochondrion is the matrix. |
| Outline the function of mitochondria (1) | The site of ATP production during aerobic respiration. They can self-replicate in the event that the cell's energy needs increase, and are abundant in cells where a lot of metabolic activity takes place. |
| Outline the structure of chloroplasts (5) | 4-10µm long Surrounded by a double membrane - the inner membrane is continuous with thylakoids Thylakoids are stacks of flattened membrane sacs Each stack is a granum (grana pl.) The fluid-filled matrix is called the stroma Contain loops of DNA and starch grains |
| Outline the structure and function of lysosomes (2 + 1) | Small bags surrounded by a single membrane formed from the Golgi These contain powerful hydrolytic enzymes Lysosomes engulf old cell organelles and foreign matter, digest them and return the digested components to the cell for reuse |
| Outline the structure and function of ribosomes (1 + 2) | Small organelles (20nm in diameter) made up of two sub-units joined together Ribosomes on the RER are mainly for synthesising proteins that will be exported out of the cell Ribosomes in the cytoplasm are primarily the site of assembly of proteins that will be used in the cell |
| Outline the structure of centrioles (3) | The centrioles consist of two bundles of microtubules at right angles to each other The microtubules are made of tubulin protein subunits and are arranged to form a cylinder, in a microtubule triplet formation |
| Outline the function of centrioles (2) | During cell division, the spindle forms from the centrioles Centrioles are involved in the formation of cilia and undulipodia (9+2 formation with a centriole basal body) |
| What is the cytoskeleton? (1) | A network of protein structures within the cytoplasm, consisting of microfilaments, intermediate filaments, microtubules and cytoskeletal motor proteins |
| What is the function of microfilaments in the cytoskeleton? (3) | Give support and mechanical strength Keep the cell's shape stable Allow cell movement |
| What is the function of intermediate filaments in the cytoskeleton? (2) | They anchor the nucleus within the cytoplasm, and extend between cells in some tissues - this enables cell-cell signalling and stabilises tissues |
| What is the function of microtubules in the cytoskeleton? (4) | Provide shape and support to cells Help substances and organelles to move through the cytoplasm within the cell by forming the track along which motor proteins walk along Form the spindle in cell division Form cilia, undulipodia, and flagella |
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