Biology Key Term Definitions

Plasma Membrane
Structure: Composed of phospholipid bilayer, wth proteins embedded in the layer. Function: Its selectively permeable and controls what is transported in and out of the cell.
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Cytoplasm
Structure: Cytoplasm is thick, gelatinous, semi-transparent fluid. Function: The cytoplasm maintains the cells shape and stores chemicals needed by the cell for metasolic reactions
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Nucleus
Structure: Surrounded by nulcear envelope. Envelope contains pores which allow movement of molecules. The nucleus contains chromatin. Function: Nucleus controls cellular activity and contains DNA which jas inctruciton on making protein
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Nucleolus
Structure: Dense spherical structure in the middle of the nucleus. Function: The nucleolus makes RNA and ribosomes
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Rough endoplasmic reticulum (ER)
Structure: Network of membrane bound flatenned sacs called cisternae studded with ribosomes. Function: Protein synthesis takes place on the ribosomes and are then trasnported to the golgi apparatus
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Smooth ednoplasmic reticulum (ER)
Structure: Network of membrane bound flattened sacs called cisternae. No ribosomes. Function: Responsible for synthesis and transport of lipids and carbohydrates
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Golgi Apparatus
Structure: A stack of membrane bound flatenned sacs. Function: Proteins made from the rough ER are transported here. The gologi apparatus modifies them and are packaged into vesicles to be transported to where they are needed
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Vesicles
Structure: Small spherical membrane bound sacs with fluid inside. Function: Transport vesicles are used to tranport materials inside the cell. Secretory vesicles transport proteins that are to be released from the cell, to the cells surface membrane
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Lysosomes
Structure: Small spherical membrane bound sacs containing hydrolytic enzymes. Function: They break down waste materials including old organelles
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Ribosomes
Structure: Tiny organelles. They consist of two sub-units and they are not surrounded by a membrane. Function: Protein synthesis occurs at ribosomes
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Mitochondria
Structure: They have two membranes. The inner membrane is highly folded to form cristae. The central part is called the matrix. Function: They are the site of the final stages of cellular respiration
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Centrioles
Structure: They are small tubes of protein fibres. Function: They form spindle fibres during cell division
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Cell wall
Structure: Made of cellulose forming a sieve like network. Function: Protects and supports each cell and the whole plant
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Chloroplast
Structure: Has a double membrane and is filled with a fluid called stroma. Grana contain chlorophyll pigments. Function: Light energy is trapped by the chlorophyll and used to produce carbohydrate moleclues from water and carbon dioxide
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Vacuole
Structure: Membrane bound sac in cytoplasm that contains cell sap. Function: Maintains turgor to ensure a rigid framework in the cell
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Tonoplast
Structure: The partially permeable membrane of the vacuole. Function: Selectively permeable to allow small molecules to pass through
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Amyloplast
Structure: A double membrane bound sac containing starch granules. Functions: Responsible for the synthesis and storage of starch granules
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Plasmodesmata
Structure; Mircroscopic channeles which cross the cell walls of the plant cells. Function: Enable transport and communication between individual plant cells
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Pits
Structure: Pores in the cell walls of the xylem. Function: Allow water to enter and leave xylem vessels.
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Other cards in this set

Card 2

Front

Cytoplasm

Back

Structure: Cytoplasm is thick, gelatinous, semi-transparent fluid. Function: The cytoplasm maintains the cells shape and stores chemicals needed by the cell for metasolic reactions

Card 3

Front

Nucleus

Back

Preview of the front of card 3

Card 4

Front

Nucleolus

Back

Preview of the front of card 4

Card 5

Front

Rough endoplasmic reticulum (ER)

Back

Preview of the front of card 5
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