plasma membranes Flashcards
to learn the role of different organelles including ribosomes, endoplasmic, Golgi apparatus and associated vesicles in export of a protein product from the cell through exocytosis
ribosome
a ribosome is a non-membrane bound organelle, it is composed of rRNA and protein, that synthesises proteins from an mRNA transcript, by the process of translation. they are either found dispersed throughout the cell or within another organelle called the rough endoplasmic reticulum. ribosomes are present in both eukaryotic and prokaryotic cells
rough endoplasmic reticulum
synthesis and processes proteins by adding carbohydrates to proteins formed by the ribosomes
Golgi apparatus
also known as the Golgi body , is a cell organelle that helps process and package proteins and lipid molecules into vesicles for export from the cell
plasma membranes
- Encloses the contents of the cell.
- Regulates and controls the movement of substances into and out of the cell
- Plasma membrane of organelles have a plasma membrane of similar composition allowing them to fuse for exocytosis and endocytosis.
fluid mosaic model
Referred to as the fluid mosaic model because:
- Fluid: the phospholipid molecules and proteins can move freely or laterally (allowing them to carry out their necessary functions).
- Mosaic: the membrane consists of many different components (including proteins, cholesterol, carbohydrates and phospholipid molecules).
phospholipid molecules
Have a hydrophilic (polar) head (composed of phosphate and glycerol) with a strong affinity for water that will point towards the water.
Have a hydrophobic (non-polar) tail composed of saturated or unsaturated fatty acid) with a weak affinity for water- will point away from water.
Saturated fat and tails have all single carbon bonds and are straight
Unsaturated fatty acids have one or more double carbon bonds and are linked
integral proteins
integral proteins can go straight through the cell without any assistance from other cells.
it is Embedded within the membrane and span part or entire phospholipid bilayer
also known as transmembrane
it is the Outer hydrophobic region and
Inner hydrophilic region
Functions of integral proteins include:
- Allows transport of hydrophilic molecules across the membrane
- Act as enzymes and catalyse reactions
- Signal transduction
- Cell-to-cell recognition
- Allow cells to link together and can anchor to other cells
Peripheral proteins
Peripheral proteins:
Exist outside or on the edge of
the membrane.
- Temporary
- Not used for transport as they
don’t span the entire membrane
Function as:
- Enzymes
- Receptors
- Structural attachment points
- Cellular recognition sites.
what is protein synthesis
the production of a protein through the processes of gene expressions
what is a simple diffusion
simple diffusion is small hydrophobic molecules from a higher concentration to a lower concentration directly through the plasma membrane
what is facilitated diffusion
facilitated diffusions is when hydrophilic molecules passively move down the concentration gradient across the plasma membrane by carrier proteins or protein channels
what is osmosis
osmosis is the diffusion of free water molecules through a semi-permeable membrane from a region of higher concentration of water to a region of lower concentration of water.
what is exocytosis
is the movement of materials out of a cell with the use of a vesicle. the vesicle fuses with the plasma membrane and the contents of the vesicles are released out of the cell.
what is endocytosis
the process in which a cell consumes a particle or a substance by engulfing it and then forming a vesicle with the plasma membrane bringing it into the cell
vesicle
a vesicle is a structure consisting of a liquid or cytoplasm enclosed by a lipid bilayer. vesicles form naturally during the processes of secretion, uptake and transport of materials within the plasma membrane.
