Cell structure Flashcards
Cell-surface membrane
Phospholipid bilayer with embedded proteins
Selectively permeable - enables control of passage of substances in and out of the cell
Barrier between internal and external environment of the cell
Nucleus
Nuclear envelope, nuclear pores, nucleolus, DNA/chromatin
Controls the cells activity through transcription on mRNA
Nuclear pores allow substances eg mRNA to move between the nucleus and cytoplasm
Nucleolus makes ribosomes which are made up of proteins and ribosomal RNA
Mitochondria
Double membrane - inner membrane is folded to form cristae.
Matrix containing small 70S ribosomes, small circular DNA and enzymes involved in aerobic respiration (glycolysis)
Site of aerobic respiration producing ATP for energy release
Golgi apparatus
3 or more fluid filled membrane bound sacs with vesicles at edge
Receives protein from rough endoplasmic reticulum
Modifies/processes proteins eg add carbohydrates/sugar
Packages into vesicles eg for transport to cell surface membrane for exocytosis
Also makes lysosomes
Lysosomes
Type of Golgi vesicle containing lysozymes (hydrolytic enzymes)
Release of lysozymes to break down pathogens or worn out cell components
Ribosomes
Float free in the cytoplasm or bound to rough endoplasmic reticulum.
Not membrane bound, made from 1 large and 1 small subunit
Site of protein synthesis, specifically translation
Rough endoplasmic reticulum
Ribosomes bound by a system of membranes
Folds polypeptides to secondary/tertiary structure.
Packages to vesicles, transport to the Golgi apparatus etc
Smooth endoplasmic reticulum
Similar to the rough endoplasmic reticulum but without ribosomes - system of membranes
Synthesises and processes lipids
Chloroplasts (plant and algae)
Thylakoid membranes are stacked up in some parts to form grana, which are linked by lamellae. These sit in the stroma (fluid) and are surrounded by a double membrane. Also contains starch granules and circular DNA.
(Chlorophyll) absorbs light for photosynthesis to produce organic substances.
Cell wall (plants, algae and fungi)
Made mainly of cellulose in plants and algae, and of chitin in fungi
Rigid structure surrounding cells in plants, algae and fungi. Prevents the cell changing shape and bursting (lysis)
Cell vacuole (plants)
Contains cell sap - a weak solution of sugars and salts. Surrounding membrane is called the tonoplast.
Maintains pressure in the cell (stop wilting)
Stores/isolates unwanted chemicals in the cell
Tissue
Group of organised specialised cells; joined and working together to perform a particular function; often with the same origin.
Organ
Group of organised different tissues; joined and working together to perform a particular function
Organ system
Group of organised organs; working together to perform a particular function.
Specialised cell
The most basic structural/functional subunit in all living organisms; specialised for a particular function
