Unit 2 - Cell Biology
The Cell Theory states that:
1) All organisms are made up of one or more cells and the products of those cells. 2) All cells carry out life activities ( require energy, grow, have a limited size). 3) New cells arise only from other living cells by the process of cell division.
What is meant by passive transport?
1) No energy is required. 2) Molecules move down/along a concentration gradient.
The 4 structures that are shared between prokaryotes and eukaryotes include:
1. DNA, 2. cytoplasm, 3. Ribosomes, 4. Cell membrane
Organelles found ONLY in plant cells
1. cell wall, 2. chloroplasts
selective permeability
A property of a plasma membrane that allows some substances to cross more easily than others.
isotonic solution
A solution in which the concentration of solutes is essentially equal to that of the cell which resides in the solution
hypertonic solution
A solution in which the concentration of solutes is greater than that of the cell that resides in the solution
hypotonic solution
A solution in which the concentration of solutes is less than that of the cell that resides in the solution
Diffusion
A type of passive transport that involves the movement of substances directly across the lipid bilayer
Osmosis
Diffusion of water through a selectively permeable membrane
What is the difference between endocytosis and exocytosis?
Endocytosis is the process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane, and bringing it into the cell. Exocytosis describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell.
Active Transport
Energy-requiring process that moves material across a cell membrane against a concentration difference
How does osmosis differ from diffusion?
In diffusion, particles move from an area of higher concentration to one of lower concentration until equilibrium is reached. In osmosis, a semipermeable membrane is present, so only the solvent molecules are free to move to equalize concentration.
Explain why hydrophobic molecules can easily cross the plasma membrane, while hydrophilic molecules cannot.
Molecules that are hydrophobic can easily pass through the plasma membrane, if they are small enough, because they are water-hating like the interior of the membrane. Molecules that are hydrophilic, on the other hand, cannot pass through the plasma membrane—at least not without help—because they are water-loving like the exterior of the membrane, and are therefore excluded from the interior of the membrane.
Are vesicles involved in passive transport? Explain.
No. Vesicles are only used during bulk transport (a type of active transport). Some molecules or particles are just too large to pass through the plasma membrane or to move through a transport protein. So cells use two other active transport processes to move these macromolecules (large molecules) into or out of the cell. Vesicles or other bodies in the cytoplasm move macromolecules or large particles across the plasma membrane.
Microtubules
Part of the cytoskeleton; they support the cell, and they act as a "conveyer belt" or route for vesicles to move about the cell
Main difference between prokaryotes and eukaryotes
Presence of a nucleus
Cell (Plasma) Membrane
Separates cell from external environment; controls passage of organic molecules, ions, water, oxygen, and wastes into and out of cell
Golgi apparatus
Sorting, tagging, packaging, and distribution of lipids and proteins
Smooth ER
That portion of the endoplasmic reticulum that is free of ribosomes. It acts as a storage organelle. It is important in the creation and storage of lipids and steroids.
What is the advantage of having organelles?
The advantage to the cell is that it is more efficient to have membrane-bound organelles specializing in certain functions, than in spreading the cell's necessary functions randomly throughout the cell. The organelles can also be in logical proximity to others that have related functions.
Cytoplasm
The jelly-like substance composed of mainly water and found between the cell membrane and nucleus. Helps support the shape of the cell and keep the organelles anchored
Endocytosis
This is the process of moving extracellular contents into the intracellular environment through engulfing them with the cell membrane which then pinches off to form a vesicle
Exocytosis
This is the process of removing intracellular contents to the extracellular environment through the fusion of vesicles with the cell membrane
Pinocytosis
This term means "cell drinking" and is a type of endocytosis that involves engulfing the liquid environment from the extracellular environment. This allows a cell to obtain nutrients from the liquid environment
Phagocytosis
This term means "cell eating" and is a type of endocytosis that involves engulfing large solid contents from the extracellular environment
Molecular Active Transport
This type of active transport either directly or indirectly uses the energy of ATP to transport substances against their concentration gradient using a transport protein
Primary Active Transport
This type of active transport involves the direct use of ATP. In this type of transport a protein pump is phosphorylated by ATP which activates it and allows it to pump substances against their concentration gradient
Secondary Active Transport
This type of active transport involves the indirect use of ATP. In this situation, transport proteins are used, but they do not get phosphorylated by ATP, instead, the energy used to power these proteins come from concentration gradients created by protein pumps that do use ATP
Bulk Transport
This type of active transport involves the movement of large quantities of substances into or out of the cell through the use of vesicles
Vesicles
are membrane-bound sacs that function in storage and transport.
Mitochondria
are often called the "powerhouses" or "energy factories" of a cell because they are responsible for making adenosine triphosphate (ATP), the cell's main energy-carrying molecule.
Lysosomes
cell organelle filled with enzymes needed to break down certain materials in the cell.
Ribosomes
cellular structures responsible for protein synthesis.
What is a concentration gradient?
difference in the concentration of a substance from one location to another
Vacuole
fluid filled organelle enclosed by a membrane. They can store materials such as food, water, sugar, minerals and waste products (but primarily water)
Receptor Mediated Endocytosis
his type of endocytosis allows the cell to engulf target substances (ligands) from their extracellular environment. These substances bind to receptors on the cell membrane which cause a coated pit to form. This eventually forms a coated vesicle
Nucleus
houses DNA
Orientation of phospholipids in a cell membrane
hydrophilic phosphate head faces outward, hydrophobic fatty acid tails face inward
Rough ER
modifying proteins (such as enzymes, for example) that will be secreted from the cell
phosopholipid bilayer
part of cell membrane, phospholipids are phosphate and fatty acid lipids, has two layers
Why is pinocytosis a form of endocytosis?
pinocytosis, is a mode of endocytosis in which small particles suspended in extracellular fluid are brought into the cell through a pouch or cavity of the cell membrane, resulting in a suspension of the particles within a small vesicle inside the cell.
Facilitated Diffusion
process of diffusion in which molecules pass across the membrane through cell membrane channels
What will happen to a salt water fish if placed in fresh water?
putting them in freshwater will make the water rush into their cells and and eventually kill them.
The rough ER is so named because it has an abundance of _______________ on it.
ribosomes
Passive Transport
the movement of substances across a cell membrane without the use of energy by the cell
Explain how carrier proteins function
transport protein that is specific for an ion, molecule, or group of substances. Carrier proteins "carry" the ion or molecule across the membrane by changing shape after the binding of the ion or molecule.