Cellular Transport Flashcards
Describe the role of the plasma membrane in a cell
The plasma membrane is partially permeable, controlling the transport of molecules in and out of the cell, separating the cell’s contents from the outside environment, allowing cell recognition, enabling cell signalling, binding hormones or drugs to receptors, and holding components of chemical reactions in place
List substances that commonly pass across the cell plasma membrane
Nutrients (glucose), water, oxygen, amino acids, ions (Na+, K+, Ca2+, Cl-), waste products (CO2, urea), hormones, enzymes, and other proteins
Define passive transport in cellular mechanisms
Passive transport is the movement of substances across the cell membrane without the use of energy, including processes like diffusion, osmosis, and facilitated diffusion
How do channel and carrier proteins function in the plasma membrane?
Channel and carrier proteins facilitate the movement of specific molecules across the plasma membrane, allowing substances to pass through the semi-permeable membrane
Describe the characteristics of active transport
Active transport requires energy to move substances against their concentration gradient, involving processes such as the sodium-potassium pump, endocytosis, exocytosis, phagocytosis, and pinocytosis
What is the significance of the phospholipid bilayer in the plasma membrane?
The phospholipid bilayer forms a fundamental structure of the plasma membrane, providing a barrier that separates the cell’s interior from the external environment and allowing selective permeability
Explain the process of osmosis in cellular transport
Osmosis is the passive transport of water molecules across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
Identify two roles of the plasma membrane in cellular communication
The plasma membrane allows cells to recognize each other as belonging to the body and enables cells to signal each other through receptor binding.
How do waste products exit the cell?
Waste products such as CO2 and urea exit the cell through the plasma membrane via passive transport mechanisms.
Describe the difference between simple diffusion and facilitated diffusion.
Simple diffusion is the movement of small or nonpolar molecules directly through the phospholipid bilayer, while facilitated diffusion involves the use of channel or carrier proteins to help larger or polar molecules cross the membrane.
Describe active transport.
Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, requiring energy, often in the form of ATP.
Define the sodium-potassium pump.
The sodium-potassium pump is a type of active transport mechanism that moves sodium ions out of the cell and potassium ions into the cell, maintaining the necessary concentration gradients for cellular function.
Explain endocytosis and exocytosis.
Endocytosis is the process by which cells engulf substances from their external environment, while exocytosis is the process of expelling substances from the cell.
Differentiate between phagocytosis and
pinocytosis.
Phagocytosis is the process of engulfing large
particles or cells, while pinocytosis involves the uptake of liquid and small solutes.
How is energy produced in cells?
Energy is produced in cells through the conversion of ATP (adenosine triphosphate) to ADP (adenosine diphosphate), releasing
energy for cellular processes.
Define diffusion in biological terms.
Diffusion is the movement of particles from
an area of high concentration to an area of
low concentration, resulting in a
concentration gradient.
How does gaseous exchange occur in the
alveoli?
During gaseous exchange in the alveoli,
oxygen diffuses from the air, where it is in
higher concentration, into the blood, where it
is in lower concentration.
Explain facilitated diffusion.
Facilitated diffusion is the process by which
large polar molecules and ions move across
the cell membrane through protein channels,
without the use of energy.
What is the role of protein channels in
facilitated diffusion?
Protein channels facilitate the passive
movement of large polar molecules and ions
across the phospholipid bilayer of the cell
membrane.
Differentiate between osmosis and diffusion.
Osmosis is the specific diffusion of water
molecules, while diffusion refers to the
movement of any type of particle.
How do water molecules move across a
partially permeable membrane?
Water molecules will move from a solution
with low solute concentration to a solution
with higher solute concentration until
equilibrium is reached.
Describe the term isotonic in relation to
cellular fluid.
Isotonic refers to a situation where the
surrounding fluid has an equal concentration
to the cellular fluid, resulting in no net
movement of water across the semi
permeable membrane.
Define hypotonic solution and its effect on
cells.
A hypotonic solution is one where the
surrounding fluid is less concentrated than
the cellular fluid, which can cause cells to
swell as water moves into them.
Explain the concept of hypertonic solutions.
A hypertonic solution has a higher
concentration than the cellular fluid, leading
to water moving out of the cells, which can
cause them to shrink.
