cellular structure and function Flashcards
What are the three main ideas of cell theory?
- Everything alive has cells
- Cells arise from preexisting cells - cells beget cells
- Basic unit of life
All cells have what 4 things?
- Cytoplasm
- Ribesomes
- DNA
- Plasma membrane
What is the cell surface to volume ratio?
An increase in surface area allows for more efficient passage of nutrients and wastes in and out of the cell.
And an increase in size is an increase in number of cells
What is the plasma membrane composed of?
It is composed of Phospholipids which are the most abundant lipid in the plasma membrane and they are amphipathic molecules, containing hydrophobic and hydrophilic regions.
what are amphipathic molecules?
molecules that contain hydrophobic and hydrophilic regions.
What does the amphipathic molecules within the plasma membrane create?
It creates a bilayer where the non polar region is inside and the polar heads are outside-
A phospholipid bilayer can exist as a stable boundary between two aqueous compartments.
What does the plasma membrane do?
The plasma membrane is the boundary that separates the living cell from its surroundings. The plasma membrane exhibits selective permeability.
What is selective permeability?
Allows some substances to cross it more easily than others.
What is the Fluid Mosaic Model?
States that a membrane is a fluid structure with a ‘mosaic’ of various proteins embedded in it.
What is a membrane?
a collage of different proteins, often grouped together, embedded in the fluid matrix of the lipid bilayer.
What do proteins do?
determine most of the membranes specific functions
position is important to the function because structure begins function
What are the three types of proteins?
- Peripheral Proteins
- Intergral Proteins
- Transmembrane Proteins
Where are Peripheral Proteins?
they are bound to the surface of the membrane
where are Integral Proteins?
they penetrate the hydrophobic core
where are Transmembrane Proteins
the hydrophobic regions of an intergral protein consists of one or more stretches of non polar amino acids often collies into alpha helixes
What is the role of carbohydrates within the membrane?
cell-cell recognition, cells recognize each other by binding to molecules often containing carbohydrates on the extra cellular surface of plasma membranes
What forms a Glycolipid?
membrane carbohydrates covalently bonded to lipids
What forms Glycoproteins?
membrane carbohydrates covalently bonded to proteins
What determines the asymmetrical distribution of proteins, lipids and associated carbohydrates in the plasma membrane?
The distribution is determined when the membrane is built by the ER and Golgi apparatus (delivery cell) determined by cell behavior.
Why must a cell exchange materials with its surroundings?
Because you need resources - access to outside resources for energy, eating, waste, breathing, ect.
How do things move across the selectively permeable membrane(5 ways)?
- Diffusion
- Osmosis
- Facilitated Transport
- Active Transport
- Endocytosis and Exocytosis
what is Diffusion?
Movement of molecules in space until they hit equilibrium (polar or non polar molecules)
what is Osmosis ?
Specific to one molecule, water!
what is Facilitated Transport?
Does not diffuse across the plasma membrane, facilitated diffusion through an embedded protein. Doesn’t require energy
what is Active Transport?
Transport of molecules across the plasma membrane from lower concentration to higher concentration via a protein carrier which requires energy- uses ATP as energy to power different pumps (opposite direction and same direction)
what is Endocytosis?
transports molecules or cells into the cell via invagination from the plasma membrane to form a vesicle (little piece of membrane acting as a container)
What is a specialized form of Endocytosis?
Phagocytosis- bringing cells into something
what is Exocytosis?
transports molecules outside the cell via fusion of a vesicle with the plasma membrane
What is tonicity?
It refers to the osmotic characteristics of two solutions separated by a selectively permeable membrane. It is commonly used to describe the response of cells in other solutions.
What are the 3 conditions of tonicity?
- Isotonic
- Hypotonic
- Hypertonic
what is Isotonic?
equal amounts of solute inside and outside the cell thus it does not affect the cell
what is Hypotonic?
Less solute than inside the cell- leads to lysis (bursting) because the more water on the outside of the cell it wants to invade the cells -cells will explode