Cell ultrastructure Flashcards Preview

A level Biology > Cell ultrastructure > Flashcards

Flashcards in Cell ultrastructure Deck (22):

Nucleus Structure

Large organelle enclosed by a double membrane perforated by pores. Contains chromosomes and one or more nucleoli


Ribosome Structure

Very small organelle not bound by a membrane. Consists of a large and small subunit. Made of protein and RNA


golgi apparatus structure

stack of membrane bounded, flattened sacs in the cytoplasm, looking like a pile of pitta bread


centriole function

form a spindle shaped structure of protein fibres on which the chromosomes move during nuclear division


cell surface membrane function

a partially permeable barrier which controls the passage of substances into and out of the cell


nucleus function

chromosomes contain DNA which controls the synthesis of proteins. ribosomes formed in the nucleolus


cell wall function

provides mechanical support and protection. prevents cell from bursting


centrioles structure

a pair of short cylinders. each cylinder is made up of nine fibres.


mitochondria function

the site of aerobic respiration and responsible for producing most of the ATP in a cell


permanent vacuole structure

a sac bounded by a single membrane. contains cell sap which is a solution of mineral salts, pigments, organic acids and other substances.


endoplasmic reticulum function

forms a system of channels for transporting the minerals through the cytoplasm. one type has ribosomes on its surface and is the site of protein synthesis. the other type has no ribosomes and is where steroids and other lipids are synthesised.


golgi apparatus function

receives proteins synthesised on the ER and prepares them for secretion from the cell. this often involves adding carbohydrate to the protein to make them into glycoproteins


lysosomes function

responsible for destroying worn out organelles and for digesting the contents of the vacuole formed by phagocytosis


mitochondria structure

had an outer membrane and an inner one which is folded to form christae. inside the inner membrane is the matrix containing enzymes, a circular DNA molecule and ribosomes


cell surface membrane structure

a phospholipid bilayer with intrinsic and extrinsic molecules


cell wall structure

consists of cellulose microfibrils and other polysaccharides


chloroplast structure

surrounded by two membranes. contains a matrix fluid called stroma which has a system of membranes running through it. these are stacked in places to form grana containing chlorophyll. stroma contains circular DNA, ribosomes and starch grains


lysosomes structure

a vesicle containing digestive enzymes


rough endoplasmic reticulum

a complex network of flattened membrane bounded sacs called cisternae. often has ribosomes on the cytoplasmic side


chloroplast function

the organelle in which photosynthesis takes place. pigments capture the energy of sunlight and transfer it to chemical bonds


permanent vacuole

stores of waste products and other substances. changes in volume affect the turgidity of the cell


ribosome function

uses the information in nucleus acid to synthesise proteins