2NDQ_Gen Bio

Carrier Proteins
Passive Transport - function – transport. Are specific, combine
- requires no energy with only a certain type of molecule.
- molecules flow across the membrane by - carrier proteins are typically specific for a
diffusion single substance
- no ATP required - example: kidney, aims to spill glucose into
the urine
Active Transport
- requires energy Channel Proteins
- molecules are pumped across the - allows polar compounds to avoid the
membrane non-polar central layer of the plasma
- ATP required membrane that would otherwise slow or
prevent their entry.
Types of Passive Transport Diffusion
- water, lipids, and lipid-soluble substances Osmosis
can pass through the plasma membrane by - the diffusion of water across a
diffusion differentially permeable membrane due to
- it is the passive movement of molecules concentration differences
from a higher to a lower concentration until
equilibrium is reached Tonicity
- is a relative term, comparing two different
How can we explain diffusion? solution
- Gases move through plasma membranes - nag rrefer sya sa concentration ng solute
by diffusion (level of concentration of solute) para syang
- Osmosis – a special case of diffusion to. Doon nakapaloob sina Hypertonic,
Hypotonic at Isotonic.
- gas exchange in lungs by diffusion

Osmolarity
Factors that affects diffusion
- refers to the concentration of solutes
- extent of the concentration gradient
- mass of the molecules diffusing
Hypertonic
- temperature
- a solution with a greater solute
- solvent density
concentration compared to another
- solubility
solution.
- surface area and thickness of the plasma
- one represents the solution of the cell, and
membrane
one represents the solution of its
environment
Facilitated Diffusion
Which way will the water move?
- many molecules and ions need special
- from the cell going out to the environment
protein channels to pass through the cell
- a cell in a hypertonic solution could
membrane.
possibly shrink
- this is still considered diffusion since the
molecules or ions move from high to low
concentration.
Hypotonic Electrical Gradient
- a solution with a lower solute - a difference of charge across the plasma
concentration compared to another membrane.
solution.

Which way will the water move? Electrolyte: Sodium (Na)

- from the environment going inside the cell - most often found outside the cell, in the
- the cell will increase in size and it might plasma of the blood stream.
burst (for RBCs/ animal cells), in plant cells - it is a significant part of water regulation
under the hypotonic does not burst because in the body.
it has a cell wall and membrane. - water goes where sodium goes.
- conditions of sodium imbalance:
Isotonic
- a solution with an equal solute Hypernatremia – too much amount of
concentration compared to another sodium in the blood
solution. Hyponatremia – too little amount of sodium
- should be maintained by an organism. in the blood
Which way will the water move?
- water will interchange between the two Electrolyte: Potassium (K)
- is most concentrated inside the cells of the
· Hypertonic – in a hypertonic solution body.
water leaves the cell which shrivels - conditions of potassium imbalance:
(crenation for animal cell, plasmolysis for
plant cell). In a hypertonic solution, Hyperkalemia – too much potassium in the
vacuoles lose water, the cytoplasm shrinks, blood
and chloroplasts are seen in the center of Hypokalemia – too little potassium in the
the cell. blood
· Hypotonic – in a hypotonic solution, water
enters the cell, which may burst (lysis). In a Na and K ions
hypotonic solution, vacuoles fill with water, - imbalanced between exterior sodium and
turgor pressure develops, and chloroplasts potassium levels is essential in the
are seen next to the cell wall. generation of the electrical impulses in the
body.
· Isotonic – in an isotonic solution, there is - 3 sodium is to 2 potassium
no net movement of the water.
Primary Active Transport
Active Transport - Moves ions across a membrane and
creates a difference in charge across that
- for charged ions and molecules membrane, which is directly dependent on
- transports mechanisms collectively called ATP.
pumps and works against electro-chemical
gradients. Secondary Active Transport
Concentration Gradient - describes the movement of material that is
- differential concentrations of a substance due to the electrochemical gradient
across a space or membrane.
established by primary active transport that - the plasma membrane wraps around the
does not require ATP. solid material and engulfs it.

The Sodium-Potassium Pump

- an electromagnetic pump (a pump that Pinocytosis
creates a charge imbalance), creating - (cell-drinking) occurs when dissolved
imbalance across the membrane and substances enter the cell.
contributing to the membrane potential. - pinocytosis results in much smaller vesicle
1. The sodium-potassium pump binds three than does phagocytosis, and the vesicle
sodium ions and a molecule of ATP. does not need to merge with a lysosome.
2. The splitting of ATP provides energy to
change the shape of the channel. The Receptor-mediated Endocytosis
sodium ions are driven through the channel. - is designed to bring specific substances
3. The sodium ions are released to the that are normally found in the extracellular
outside of the membrane, and the new fluid into the cell.
shape of the channel allows two potassium - a targeted variation of endocytosis
ions to bind. employs receptor protein in the plasma
4. Release of the phosphate allows the membrane that have specific binding
channel to revert its original form, releasing affinity for certain substances.
potassium ions on the inside of the
membrane. Exocytosis
- is the process of removing materials from
Bulk Transport the cell through the vesicles that fuse with
the plasma membrane, subsequently
- cells also need to remove and take in releasing their contents outside the cell.
larger molecules and particles.
- a large particle, however, cannot pass Semi permeable - may mga nakakapasok
through the membrane, even with the na cell pero meron din wala
energy supplied by the cell.
Equilibrium - total spread a.k.a equal yung
exchange lagi basically para syang
Endocytosis
homeostasis, nag maintain sya ng balance
- a form of bulk transport in which a cell
transports molecules into the cell
Tonicity - nag rrefer sya sa concentration ng
(endo-+cytosis) by engulfing them in an
solute (level of concentration of solute) para
energy-using process.
syang to
- a substance outside the cell is captured
when the plasma membrane merges with
Temperature - dito nag ddepent kung
that substance and engulfs it. gaano kabilis yung pag diffuse.
- endocytosis happens either through
phagocytosis, pinocytosis, and potocytosis

Phagocytosis
- (cell-eating) is the most common form of
endocytosis.