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The Cell Membane

Terms in this set (22)

All cells have a cell membrane. Cell membranes are made of 2 layers of lipids, known as the __________ _________________. Cell membranes regulate what leaves and enters and also provide _______________.
lipid bilayer, structure
Cell membranes have both a water hating end and a water loving end. The water hating end is called the _______________ tail (non-polar)(lipid). The water loving end is called the _________________ head (polar)(phosphate group).
hydrophobic, hydrophilic
Hydrophobic __________ (non-polar) touch each other at the center of the bilayer. They do not like being in the presence of water. Hydrophilic phosphate _________ (polar) face into and outside the cell. They like being in the presence of water.
tails, heads
Embedded within the membrane are _____________ ___________________ that let substances ______ _________ ______. The protein molecules float in the membrane amongst the lipids. A mosaic is a piece of art that involves different pieces and components. This is why the structure is called a fluid mosaic.

Fluid portion of the model describes the ____________ of the cell membrane. Mosaic describes the other molecules scattered in the membrane (proteins, carbs, cholesterol -- makes the membrane fluid).
protein channels, in and out

consistency
Cells exist in a ______________ environment of primarily water. Substances must be able to move in and out of the cell. Substances enter and exit through the __________ ________________.
liquid, cell membrane
Diffusion is when substances move from an area of __________ concentration to ______ concentration through the cell membrane. Meaning: Substances move from an area where there is a lot to a little. Diffusion is called passive transport, because it does ________ require energy. Substances that are small and _________ soluble may go through the membrane.


Simple diffusion is transport that occurs directly through the cell membrane without energy (oxygen, carbon dioxide, and small lipid soluble).
high, low, NOT, lipid
Osmosis is the passive transport of __________ across the cell membrane. The membrane of a cell is hydrophobic so water must pass through channels called ______________.
water, aquaporins
Ions, large particles, and water soluble molecules can not go ____________ through the membrane. Protein channels allow these substances to ___________. Diffusion occurs through the proteins. This is called ______________ diffusion.

Diffusion through a protein channel, occurs with water soluble molecules that do not dissolve in lipids (ions, glucose).
directly, pass, facilitated
A cell is 70% water and 30% other materials. The environment is 75% water and 25% other materials. Which way will water flow?
Water will flow into the cell, because there is more water outside the cell and less water inside the cell. (high to low).
A cell is 80% water. It is in an environment that is 60% water. Which way will water flow?
Water will flow out of the cell, because there is more water inside the cell and less water outside the cell. (high to low)
Cells exist in ______________ within the body and in the external environment. These words (isotonic, hypertonic, hypotonic) do not describe cells but the solutions.
solutions
Isotonic means the solution has the same ___________________ as the cell. In isotonic solutions, water moves into the cell and out of the cell _____________.
concentration, equally
Hypertonic solutions have ___________ solute than the cell and less water than the cell. Water will move _________ of the cell in hypertonic solutions. This may cause the cell to ____________ and die.
more, out, shrivel
The hypotonic solution has _________ solute than the cell, therefore the solution has more water than the cell. Water will move __________ the cell in hypotonic solutions. This may cause the cell to __________ or burst. Plant cells thrive in hypotonic solutions.
less, into, swell
Active transport occurs when cells move substances against the concentration gradient. The movement occurs from an area of ______ concentration to _________ concentration. Active transport ________ require energy. (low to high)
low, high, does
Active transport may involve __________ _____________ that require energy to work. Example: Sodium/Potassium pump. There is more potassium ___________ the cell and more sodium ____________ the cell, but the pump exchanges 3 sodium inside the cell and brings 2 potassium in. (low to high)
protein pumps, inside, outside
Endocytosis and exocytosis are both types of ________ transport.
bulk
Large substances ____________ the cell through endocytosis. The cell _________ its membrane around larger substances and brings it into the cell.
enter, folds
There are 2 types of endocytosis.
Pinocytosis: ___________ entering the cell (cell drinking).
Phagocytosis: _________ entering the cell (cell eating).
liquids, solids
Large substances __________ the cell through exocytosis. Ex: Vesicles from the Golgi apparatus carry proteins and other substances out of the cell.
exit
Organisms may be _______________ (having only one cell). Unicellular organisms have all of the characteristics of life, including maintaining ________________. Unicellular organisms may be __________ prokaryotes and eukaryotes. Primarily use asexual reproduction.
Prokaryotes: Bacteria and Archaea
Eukaryotes: Protists (algae) and some fungi (yeast)
unicellular, homeostasis, both
The cells of multicellular organisms become specialized for a specific ____________. Ex: Muscle cells for contraction. Multicellular organisms are organized in a specific way: Cells, ____________, Organs, __________ ___________, Organism.
function, Tissues, Organ systems
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