what are the 3 parts to a human cell
- plasma membrane
- cytoplasm
- nucleus
what is the plasma membrane
a barrier that surrounds and contains the cytoplasm of a cell, separating internal + external environment
what is a cell
a basic structural and functional unit of living organisms
what is the cytoplasm of a human cell
the intra cellular fluid packed with organelles
what is the nucleus in a human cell
an organelle that controls the cellular activity
what is an organelle
a small structure within a cell surrounded by a membrane that has a specific function
what is the structural model of the membrane called
fluid mosaic model
in the fluid mosaic model what does the plasma membrane resemble
a sea of fluid lipids that contain a mosaic of different proteins
what is the structural framework of the plasma membrane
two back to back layers or lipid molecules called lipid bilayer
what are the 3 types of lipids that constitute the lipid bilayer and what percentage are they
- phospholipids (75%)
- (-OH) (20%)
- (5%)
what are phospholipids
lipids that contain phosphorus
what is cholesterol
a steroid with an attached hydroxyl group (-OH)
what are glycolipids
lipids attached to carbohydrate groups
what can membrane proteins act as
. receptors for hormones
. enzymes
. pumps that transport substances
. form channels
what is selective permeability
when the plasma membrane provides a selective barrier to control what comes in and goes out
what mechanisms are involved in selective permeability
. particle size
. pores
. pumps and carriers
what ways can substances cross the cell membrane?
- passive transport
- diffusion
- osmosis
- endocytosis
- exocytosis
what is passive transport
when substances cross the membrane and move downwards without using energy
what is the golgi apparatus
a stack of flattened membranous sacs that package substances for export from the cell
what is the ribosome
tiny granules responsible for protein synthesis
