Bio Ch 4 - Cells Membranes & Environments Flashcards
Active Transport
Movement of molecules across a cell membrane from Low concentration to High concentration
Difusion
The spreading of a substance from region of high concentration to a region of low conctration
Extracellular Fluid
All body fluids outside the cells.
E.g. blood plamsa, cranial fluid. In Humans about 33% of the total fluid
partially permeable
Something that will allow only certain molecules or ions to pass through it
Solute
Substance that is disolved in a solvent
e.g. salt in sea water
Cell Membrane
**Eukaryote **cells = **
- Plasma Membrane
- Interconnected network of membranes inside the cell
Prokaryote (bacteria cells) =
- plasma membrane only
Endocytosis
Process by which cells absorb molecules by engulfing them
(Energy using process required because proteins etc can’t move through the cell wall.)
Facilitated diffusion
Process of spontaneous passive transport of molecules/ions across a cell membrane.
(Different to Active Transport, and uses specific protein gateways)
Osmosis
Spontaneous movement of solvent through a semipermeable membrane into a region of higher solute concentraion in a way that equalises the solute concentrations
i.e. Movement of Water from low salt solution into the egg (when it has more salt)
Phospholipids
Class of Lipids that make up cell membranes
Can form lipid bilayers
Solvent
A substance that disolves a solute
e.g. Water in sea water
Cholesterol
Orgainic molecule which is essential structural part of cell wall
Cholesterol enables animal cells to
- not need a cell wall (like plants & bacteria) to protect membrane integrity/cell-viability and thus be able to
- change shape and
- move about (unlike bacteria and plant cells which are restricted by their cell walls).
Exocytosis
Process by which cells excrete molecules by extruding them.
Consumes energy and is different to diffusion methods
Fluid-Mosaic Model
Describes Cell Membranes
Double layer of molecules form ‘blanket’ that can move around (fluidity) with scattered proteins (mosaic). Specific carbohydrates attach which allow cells to link to/recognize one another.
Osmotic Gradient
Difference in concentration between two solutions on either side of a semipermeable membrane
Plasma Membrane
Membrane that encloses the cytoplasm
Surface Area to Volume Ratio
Surface area divided by volume – sa/vol Function of the shape of the cell
Organ structure can be to increase sa/vol:
- Lungs (branching and alveoli)
- Intestine (wrinkles – called villi)
Increased surface area causes problems
- Loss of water
- Temperature control
Individual cells can also be shaped to increase sa/vol
Concentration Gradient
Difference between solute concentrations
External Environment
The fluid in which an organism lives
Unicellular organisms can either
- Tolerate conditions
- Move (slowly) to better conditions
- Die
Internal Environment
Multicellular organisms maintain an internal environment for cells inside their skin. Makes cell function more efficient
Osmotic Pressure
The pressure causing the water to move through an osmotic membrane
Ratio
X divided by Y
X:Y
Turgid
Plant cells with high internal fluid pressures
- Plant cell take in water to the point where the cellulose cell walls stop expanding futher.
- Animal cells will keep swelling until they burst.
active site
the part of an enzyme that interacts with the substrate duringcatalysis.
aerobic
pertaining to or caused by the presence of oxygen.
anaerobic
pertaining to or caused by the absence of oxygen.
ADP
Also called adenosine diphosphate,adenosinediphosphoric acid. Biochemistry. anester of adenosine and pyrophosphoric acid, C 10 H12 N 5 O 3 H 3 P 2 O 7, derived from ATP, andserving to transfer energy during glycolysis.
ATP
Biochemistry. adenosine triphosphate: an ester ofadenosine and triphosphoric acid, C 10 H 12 N 5 O 4H 4 P 3 O 9, formed especially aerobically by thereaction of ADP and an orthophosphate duringoxidation, or by the interaction of ADP andphosphocreatine or certain other substrates, andserving as a source of energy for physiologicalreactions, especially muscle contraction.
catalyst
a substance that causes or acceleratesa chemical reaction without itself being affected.
cellular respiration
the oxidation of organic compounds that occurswithin cells, producing energy for cellularprocesses.
chemical energy
Energy liberated by a chemical reaction or absorbed inthe formation of a chemical compound.
chlorophyll
the green coloring matter of leaves and plants,essential to the production of carbohydrates byphotosynthesis,
chloroplast
a plastid containing chlorophyll.
coenzyme
a molecule that provides the transfer site forbiochemical reactions catalyzed by an enzyme.
Animalia
the kingdom comprising all animals.
cell
a usually microscopic structure containingnuclear and cytoplasmic material enclosed by asemipermeable membrane and, in plants, a cellwall; the basic structural unit of all organisms.
cell mebrane
the semipermeable membrane enclosing thecytoplasm of a cell.
Cell theoy
- All living things are made up of cells.
- Cells are the basic units of structure and function in living things.
- Living cells come only from other living cells.