Cell ultrastructure Flashcards
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
