Shared Flashcard Set

Details

biology 101 schoolcraft college chapter 5
book is biology concepts & connections by reece, taylor, simon, and dickey
79
Biology
Undergraduate 1
07/23/2012

Additional Biology Flashcards

 


 

Cards

Term
Membranes 
Definition
organize the chemical activities of cells.
Term
Membranes 
Definition
provide structural order for metabolism by compartmentalizing the inside of the cell into organelles.
Term
Membranes 
Definition
are composed of a bilayer of phospholipids with embedded and attached proteins. Biologists call this structure a fluid mosaic
Term
membrane 
Definition

is a “mosaic” in having diverse protein molecules embedded in its “fluid” framework – the phospholipid bilayer. 

Most components of the cell membranes move around – they are not stuck in one place!

 
Term
Cholesterol molecules
Definition
are found only in animal cell membranes – keeps membrane fluid and stable.
Term
Membrane Proteins Perform Many Functions
Definition

Some proteins help maintain cell shape and coordinate changes inside and outside the cell through their attachment to the cytoskeleton & ECM.

Some proteins function as receptors for chemical messengers (signaling molecules) from other cells in a process called signal transduction.

Some membrane proteins function as enzymes.

Membrane proteins may participate in the intercellular junctions that attach adjacent cells to each other.

 
Term
Membrane Proteins Perform Many Functions
Definition

Some membrane glycoproteins are involved in cell-cell recognition.

Example: Attached sugar molecules act as ID tags that enable cells of your immune system to know if a cell is you or foreign!

Membranes may exhibit selective permeability, which means some substances can cross more easily than others.

Certain ions and glucose require help in the form of transport proteins to get in and out of the cell.

 
Term
Phospholipids
Definition

the key ingredient of biological membranes, spontaneously self-assemble into simple membranes.  This was a critical step in the origin of the first cells.

Below a test tube with phospholipids and water is shaken – the phospholipids naturally organize into bilayers.

 
Term
Passive transport
Definition

When molecules diffuse across a membrane without any work by the cell (no output of energy required).

2) When molecules diffuse down their concentration gradient.  In other words molecules move from an area of higher concentration to an area of lower concentration.

Eventually, the molecules reach equilibrium where the concentration of molecules is the same throughout.

 
Term
Diffusion 
Definition
is the tendency of particles to spread out evenly in an available space.
Term
Diffusion 
Definition
Most of the traffic across cell membranes occurs by 
Term
phospholipid bilayer of a membrane by diffusion
Definition
Small, non-polar or hydrophobic molecules such as O2 and CO2 easily cross the
Term
facilitated diffusion
Definition
Many kinds of substances cannot diffuse freely across membranes because they’re too big, are polar, or have a charge.  So they need the help of a transport protein in a process called 
Term
facilitated diffusion
Definition
is a type of passive transport so it doesn’t require energy and relies on a concentration gradient (substance moves from high to low concentration).
Term
facilitated diffusion 
Definition
Sugars e.g. glucose, amino acids, ions, and water (its polar) use ? to cross cell membranes.
Term
aquaporin
Definition
in some cells (kidney cells, plant cells, red blood cells) rapid transport of water is critical and is made possible by a protein channel called an
Term
osmosis
Definition
The diffusion of water across a selectively permeable membrane is called 
Term
osmosis
Definition
is a type of passive transport so it doesn’t require energy and relies on a concentration gradient (water moves from high to low concentration)
Term
osmosis
Definition
water (a solvent) travels from a solution of high solvent concentration (lower solute concentration) to one of lower solvent concentration (higher solute concentration).
Term
Tonicity 
Definition
is a term that describes the ability of a solution to cause a cell to gain or lose water
Term
Isotonic (iso = same) solution
Definition
: A solution having the same solute concentration as inside the cell. The cell volume will not change.
Term
Hypotonic (hypo = below) solution
Definition
The solute concentration is lower outside the cell (and the solvent concentration is higher).  Water molecules move into the cell, and the cell will expand and may burst
Term
Hypertonic (hyper = above) solution
Definition
The solute concentration is higher outside the cell (and the solvent concentration is lower).  Water molecules move out of the cell and the cell will shrink. 
Term

1)  Expend energy (Use the energy molecule, ATP).

2)  Move a substance against its concentration gradient (go from low to high concentration).

Active transport is critical in nerve cells (neurons) for them to generate a nerve impulse.

Definition
In active transport, a cell must
Term
Exocytosis
Definition
is used to export bulky molecules, such as proteins or polysaccharides
Term
Endocytosis 
Definition
(endo = inside) is used to import substances useful to the cell.
Term
Phagocytosis
Definition
“Cell-eating”. The consumption of solid particles e.g. food, cell debris, bacteria, by the plasma membrane wrapping around the object forming a vacuole.
Term
Pinocytosis
Definition
“Cell-drinking”. The bulk transport of fluids containing dilute solutes into the cell with a vesicle.
Term
Receptor-Mediated Endocytosis
Definition
: The plasma membrane forms a pit with receptor proteins in it.  Receptors bind with specific substances and the pit pinches into the cell’s cytoplasm.  Cells use this method to bring cholesterol into the cell.
Term
Energy 
Definition
is simply the capacity to perform work.
Term
Kinetic energy 
Definition

is the energy of motion.  Moving objects perform work by transferring motion to other matter.

Example: Pumping your legs to move bicycle pedals to get you and your bike to move forward

Term
Heat (thermal energy
Definition
is the random movement of atoms or molecules.
Term
Light or solar energy 
Definition
is used to power photosynthesis.  
Term
Potential energy 
Definition
is stored energy that matter possesses as a result of its location or structure.  It can be converted to kinetic energy
Term
Chemical energy 
Definition
is a form of potential energy available for release in a chemical reaction
Term
Thermodynamics 
Definition
is a branch of physics which deals with the energy and work of a system. 
Term
Thermodynamics 
Definition
is the study of energy transformations that occur in a collection of matter.
Term
first law of thermodynamics (law of energy conservation)
Definition

Energy is constant – it cannot be created or destroyed.

Energy can be changed or transformed from one form to another

Term
second law of thermodynamics
Definition

Energy transformations or conversions increase the disorder (entropy) of the universe!

 
Term
Second Law of Thermodynamics
Definition

Every time energy is put to work or is converted from one form to another, some energy is lost as heat.

Heat is also a form of energy, but it is so chaotic, so unorganized, and so spread out that it cannot be put to work. 

Any energy converted to heat radiates out of the system and so can no longer be put to use by the system. 

All of the energy is conserved, but the energy that is converted to heat escapes the system and is no longer useful. 

 
Term
chemical energy 
Definition
Energy is transferred from organism to organism in the form of
Term
In cellular respiration
Definition
about 34% the chemical energy stored in glucose is converted to energy for cell work; the rest is lost as heat energy.
Term
Endergonic reactions 
Definition
(“energy inward”) require energy and yield products rich in potential energy.  An example is photosynthesis
Term
Photosynthesis 
Definition
starts with energy-poor reactants (CO2 and H2O) and, using sunlight as energy, produces energy-rich sugar molecules.
Term
Exergonic reactions 
Definition
(“energy outward”) release energy and yield products that contain less potential energy than their reactants. These reactions release the stored energy in covalent bonds of the reactants.
Term
metabolism
Definition
The total sum of an organism’s chemical reactions is called
Term
Energy coupling 
Definition
uses energy released from exergonic reactions to fuel endergonic reactions in the cell.
Term
atp
Definition
adenosine triphosphate, powers nearly all forms of cellular work
Term
atp
Definition

ATP acts like a battery for storing and transporting energy. 

ATP is the molecule of energy transfer in living systems.

Every reaction in the body that requires energy uses ATP.

Term
atp
Definition
is composed of a nitrogenous base (adenine) and a five-carbon sugar (ribose) – together they are called adenosine.  The triphosphate group is composed of three negatively charged phosphate groups. 
Term
The energy in an ATP molecule is stored in the bonds between its
Definition
phosphate groups
Term
exergonic and endergonic reactions
Definition
ATP drives cellular work by coupling 
Term
phosphorylation
Definition
Hydrolysis of ATP releases energy (exergonic reaction) by transferring its third phosphate to some other molecule in a process called
Term

chemical, mechanical, and transport.

ATP drives all three of these types of work

Definition
There are three main types of cellular work
Term
enzyme 
Definition
is a biological molecule, usually a protein, that acts as a catalyst.
Term
Catalysts 
Definition
increase the rate of chemical reactions without being consumed by the reaction
Term
Enzymes 
Definition
speed up the cell’s chemical reactions by lowering the activation energy needed for the reaction to begin.
Term
ribozymes
Definition
The 1989 Nobel Prize in Chemistry was awarded jointly to Professors Altman and Cech for their discovery that RNA can act as an enzymes called
Term
Ribozymes 
Definition
typically perform reactions on other RNA molecules, cleaving themselves or other strands, but they also perform other important reactions, such as the reaction that connects amino acids in the ribosome
Term
(“get over the hump”).
Definition
Before any chemical reaction can begin there is an energy barrier that must be overcome
Term
activation energy (EA)
Definition
Energy must be absorbed to weaken bonds in the reactant molecules so they can break and form new bonds.  This energy is called 
Term
specificity
Definition
An enzyme’s shape determines its 
Term
Substrate
Definition
:  A specific substance (reactant) on which an enzyme acts. Each enzyme recognizes only the specific substrate or substrates of the reaction it catalyzes.
Term
Active Site
Definition
A pocket or groove on the surface of the enzyme where the substrate(s) attaches
Term
When the substrate is attached to the active site, an
Definition
enzyme-substrate complex is formed.
Term
Induced fit
Definition

The interaction between a substrate molecule and the active site of an enzyme, which changes shape slightly to embrace the substrate more snugly like a handshake.  

The substrate bonds are contorted or strained during the induced fit catalyzing the reaction

Term
35–40ºC (95-104ºF
Definition
Most human enzymes work best at body temperature
Term
pH 
Definition
Most enzymes work best near neutrality in the range 6-8
Term
cofactors such as metal ions (zinc, iron, and copper) in order to function.
Definition
Some enzymes require non-protein
Term
coenzymes such as vitamins in order to function
Definition
Other enzymes require organic molecules called 
Term
Inhibitors 
Definition
are chemicals that interfere with an enzyme’s activity.
Term
competitive inhibitor 
Definition
is a substance that reduces the activity of an enzyme by directly binding to the enzyme’s active site in place of the substrate
Term
noncompetitive inhibitor 
Definition
is a substance that blocks the activity of an enzyme without entering its active site; it binds elsewhere and changes the shape of the enzyme so that the active site no longer functions. 
Term
competitive inhibitor 
Definition

takes the place of a substrate in the active site.

Can be overcome by adding more substrate

 
Term
noncompetitive inhibitor 
Definition
alters an enzyme’s function by changing its shape.
Term
Enzyme inhibitor
Definition
are important in regulating cell metabolism.
Term
feedback inhibition 
Definition
In some reactions, the product may act as an inhibitor of one of the enzymes in the pathway that produced it. This is called
Term
feedback inhibition 
Definition
it prevents cells from wasting valuable resources by making more of a particular product than is needed.
Supporting users have an ad free experience!