Cells Flashcards
Cell
Smallest structural and functional unit of any living thing
Cell membrane
Phospholipid bilateral, plasma membrane.
Surrounds the cell and differentiates what is inside the cell and outside the cell.
Hydrophilic
Water loving
Hydrophobic
Water avoiding
Membrane proteins
Proteins embedded in the cell membrane. Substance- specific, designed to interact only with one particular substance and no other.
Name the 4 passive processes
Diffusion
facilitated diffusion
Osmosis
Filtration
What is a passive process?
Passive processes get substances in or out of the cell by using kinetic energy of the substance crossing the membrane. No energy is needed from the cell
Diffusion
The movement of a substance from an area of higher concentration to lower concentration .
Oxygen and carbon dioxide can diffuse.
Ex- there is more oxygen outside than inside the cell, kinetic energy of oxygen mole uses will cause the oxygen to diffuse down the concentration gradient.
Osmosis
The diffusion of water.
If there are more sodium ions outside than inside the cell, there will be a higher concentration of water inside the cell. By osmosis, the water molecules will move down the concentration gradient and out of cell.
Facilitated Diffusion
Membrane proteins called channels, gates and carriers provide passage for molecules and ions that are too big to freely diffuse across cell membrane
Cell channel
Provide pathway for small substances like sodium. Sometimes pocess a ‘door’ that opens and closes in which they are called gates.
Carriers/Transporters
Change shape to pass larger molecules like glucose across the cell membrane.
Receptors
Receive information (hormones and neurotransmitters) from outside the cell and use it to direct activity inside the cell. Ex- insulin receptors tell the cell to start facilitated diffusion of glucose (through carriers).
Filtration
Water is pushed through a specialized cell membrane that has large pores (cells of the kidneys) allowing small substances to pass through with the water and keeping large molecules behind.
Active processes
Require the expenditure of energy by the cell to get a substance in and out across the membrane.
Active process
The movement of ions or small molecules up a concentration gradient ( from an area of lower concentration to an area of higher concentration) by membrane proteins called pumps. Requires energy from the cell
Endocytosis
A process where a cell uses energy to bring particles in that are too large for facilitated diffusion.
Phagocytosis “cell eating”
Pinocytosis “cell drinking”
Phagocytosis
The cell surrounds the substance with pseudopodia (“false feet”) and brings it into the cell
Pinocytosis
“Cell drinking”. The cell membrane invaginates to bring particles into the cell.
An endosome is created when the cell membrane encircles the particles into the cell.
Exocytosis
The cell uses energy to get substances out by forming a membrane around a substance inside the cell and then merging to the cell membrane and emptying contents outside the cell.
Excretion
During exocytosis, if the substance being exocytosed is waste, it is excreted
Secretion
During exocytosis if the substance being exocytosed is a product synthesized in the cell, it is secreted
Organelles
Organs of the cell which perform specific functions.