? What factors will determine whether a reaction occurs
spontaneously? What is meant by "free energy"? Correct
Answers By examining these two factors: entropy and whether
or not the reaction is exothermic or endothermic, we can tell if a
reaction is spontaneous using the Gibbs Free Energy equation:
According to this equation, if the free energy, G, of the system is
negative, then the reaction is spontaneous.
According to the Second Law of Thermodynamics, a reaction is
spontaneous if the overall entropy, or disorder, increases. If we
go back to our cleaning the house analogy, when our home
becomes messy, then the entropy increases. The mess that
accumulates is a spontaneous reaction, and as a result, the
entropy increases.
Free energy: Energy this is free, which means we don't need to
do anything to get work done.
1. Describe the three general types of work a cell must do.
Correct Answers 1) Mechanical
Work associated with movement
2) Transport
Pumping substances across membrane against their
concentration gradient
3) Chemical
Endergonic reactions
(anabolic, increased order)
6 following functions of membrane proteins: Correct Answers 1
transport: provides transport channel through membrane
(passive or active)
,2 enzymatic activity: Exposed active site available for speeding
up chemical reactions
3 signal transduction "protein receptor": Binding site to receive
specific chemical signal
4 cell-cell recognition: ID tag for cell; Glycoprotein creates cell-
specific tag; Interacts with membrane protein of another cell
5 intercellular joining: Similar cells held together with tight or
gap junctions
6 attachment: Attach to cytoskeleton and extracellular matrix;
Helps maintain shape
As a cell (with fixed shape) increases in size, what happens to its
surface-area-to- volume ratio? Correct Answers - As the size
increases the surface area becomes smaller
- Ratio to surface area decreases as cell increase
Calvin Cycle three steps Correct Answers Step 1:
Carbon fixation. A CO2 molecule combines with a five-carbon
acceptor molecule, ribulose-1,5-bisphosphate (RuBP). This step
makes a six-carbon compound that splits into two molecules of a
three-carbon compound, 3-phosphoglyceric acid (3-PGA). This
reaction is catalyzed by the enzyme RuBP
carboxylase/oxygenase, or rubisco.
Step 2:
Reduction. In the second stage, ATP and NADPH are used to
convert the 3-PGA molecules into molecules of a three-carbon
sugar, glyceraldehyde-3-phosphate (G3P). This stage gets its
name because NADPH donates electrons to, or reduces, a three-
carbon intermediate to make G3P.
, Step 3:
Regeneration. Some G3P molecules go to make glucose, while
others must be recycled to regenerate the RuBP acceptor.
Regeneration requires ATP and involves a complex network of
reactions, which my college bio professor liked to call the
"carbohydrate scramble.
Can a solute that is unable to cross the phospholipid bilayer
enter a cell? If so, how? Correct Answers Yes, with the help of
transport/carrier proteins. Channels are created or chemical
signals are triggered to allow a protein to assist the movement of
different molecules across the membrane.
Carotenoids Correct Answers -absorbs blue and green
- reflects red and yellow
Cell Wall Correct Answers found in plant cells and it is used for
structure and protection
Chlorophyll a Correct Answers - absorbs blue and red
- reflect green
chlorophyll b Correct Answers - absorbs blue and orange
- reflect green
Chloroplast Correct Answers (only in plants)
- site of photosynthesis
-converts light energy into sugar
Contrast the two broad categories of metabolic pathways.
Correct Answers Anabolic pathways - build up of molecules