Download 2. What are the main properties that fats, proteins, and

1. What are the main components of biological membranes?
Membranes are made up of phospholipid bilayer. That means that they have two
layers of phospholipids joined together.
2. What are the main properties that fats, proteins, and steroids give to a
membrane?
Fats, proteins, and steroids help the membrane maintain its structural integrity
and help to protect the cell interior from environmental insults.
3. What does it mean that a membrane is a fluid mosaid?
The mosaic membrane model is that most of the organelles inside the cell are not
fixed, but rather, they move about throughout the cytoplasm.
4. What parts of a phospholipids are hydrophilic and which ones are
hydrophobic?
The membrane consists of a hydrophilic (water loving) head, and hydrophobic
(avoid water) tails.
5. What are the main types of transport across a membrane?
Most membranes move substance across the barrier through the use of simple
diffusion.
6. What are examples that can cross a membrane by simple diffusion?
Water, oxygen, and carbon dioxide can all move across the membrane by simple
diffusion.
7. Define diffusion. How is facilitated diffusion different from diffusion?
Diffusion describes the spread of particles through random motion from regions
of higher concentration to regions of lower concentration. Facilitated diffusion is
the spontaneous passage of molecules or ions across a biological membrane
passing through specific transmembrane integral proteins.
8. Define osmosis
Osmosis is the movement of water molecules through a selectively permeable
membrane into a region of higher solute concentration, aiming to equalize the
solute concentrations on the two sides.
9. What is active transport?
Active transport is used when cells must move materials in an opposite direction
- against a concentration gradient. It requires energy.
10. What is a hypertonic solution?
A solution that has higher osmotic pressure (or has more solutes or substances)
than another solution to which it is compared.
11. What is a hypotonic solution?
A hypotonic solution is the opposite of a hypertonic solution; that is, it is a
solution that has lower osmotic pressure (or has fewer solutes or substances)
than another solution to which it is compared.
12. In what type of solution would a red blood cell burst? In which one
would a red blood cell shrink?
Burst: Hypotonic (the cell swells)
Shrink: Hypertonic (the cell is called crenated)
13. What is endocytosis? What is exocytosis?
Endocytosis: This is known as cell drinking; this is when the cell absorbs fluid
from the area around it.
Exocytosis: This is the reverse of endocytosis; here the cell forces material out
through one of its secretory vesicles.
14. What is pinocytosis
Pinocytosis is used primarily for the absorption of extracellular fluids (ECF), and,
in contrast to phagocytosis, generates very small vesicles.
15. What is phagocytosis?
Phagocytosis is the cellular process of engulfing solid particles by the cell
membrane to form an internal phagosome by phagocytes and protists. In
simpler terms, this is when the cell ‘eats’ an invader or other cell.
16. What are types of specialized cell junctions and their functions?
Specialized cell junctions occur at points of cell-cell and cell-matrix contact in all
tissues, and they are particularly plentiful in epithelia. Cell junctions are best
visualized using either conventional or freeze-fracture electron microscopy
which reveals that the interacting plasma membranes (and often the underlying
cytoplasm and the intervening intercellular space as well) are highly specialized
in these regions.
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Occluding junctions seal cells together in an epithelium in a way that
prevents even small molecules from leaking from one side of the sheet to the
other.
Anchoring junctions mechanically attach cells (and their cytoskeletons) to
their neighbors or to the extracellular matrix.
Communicating junctions mediate the passage of chemical or electrical
signals from one interacting cell to its partner.
17. What is the component of cell walls in plants?
Chloroplasts are the most common feature of the plant cell wall. They are green
because they contain chlorophyll.
18. What is energy?
Energy is the ability to do work.
19. What are the laws of Thermodynamics and what do they state?
The four laws of thermodynamics summarize the most important facts of
thermodynamics. They define fundamental physical quantities, such as temperature,
energy, and entropy, to describe thermodynamic systems and they describe the
transfer of energy as heat and work in thermodynamic processes.
The four principles, or laws, of thermodynamics are:
 The zeroth law of thermodynamics recognizes that if two systems are in
thermal equilibrium with a third, they are also in thermal equilibrium with
each other, thus supporting the notions of temperature and heat.
 The first law of thermodynamics distinguishes between two kinds of physical
process, namely energy transfer as work, and energy transfer as heat. It tells
how this shows the existence of a mathematical quantity called the internal
energy of a system. The internal energy obeys the principle of conservation
of energy but work and heat are not defined as separately conserved
quantities. Equivalently, the first law of thermodynamics states that
perpetual motion machines of the first kind are impossible.
 The second law of thermodynamics distinguishes between reversible and
irreversible physical processes. It tells how this shows the existence of a
mathematical quantity called the entropy of a system, and thus it expresses
the irreversibility of actual physical processes by the statement that the
entropy of an isolated macroscopic system never decreases. Equivalently,
perpetual motion machines of the second kind are impossible.
 The third law of thermodynamics concerns the entropy of a perfect crystal at
absolute zero temperature, and implies that it is impossible to cool a system
to exactly absolute zero, or, equivalently, that perpetual motion machines of
the third kind are impossible.
20. What are enzymes?
Enzymes are proteins that allow certain biochemical reactions to move forward.
Enzymes specifically work by lowering the activation energy of a chemical
process.
21. What is the difference between exergonic and endergonic reactions?
Exergonic: A reaction that releases energy.
Endergoinc: A reaction that absorbs energy.
22. What does the term “coupled reactions” mean?
A chemical reaction having a common intermediate in which energy is
transferred from one side of the reaction to the other.
23. What is the universal biological molecule that stores energy? Where in
the molecule is the energy stored? What kind of biomolecules is it?
ATP is the universal biological molecule that stores energy for life processes. The
energy is stored in the phosphates that are attached to the molecule. ATP is a
multifunctional nucleoside triphosphate (meaning it has three phosphates) used
in cells as a coenzyme.
24. Give an example of an “electron carrier” molecule
Nicotinamide adenine dinucleotide (NAD+) is an example of electron carrier.
25. Mention the main parts of an enzyme
Like all proteins, enzymes are long, linear chains of amino acids that fold to
produce a three-dimensional product. Each unique amino acid sequence
produces a specific structure, which has unique properties.
26. How many ways do you know that an enzymatic activity can be
regulated/controlled/inhibited? What are they?
There are five main ways that enzyme activity is controlled in the cell.
 Enzyme production (transcription and translation of enzyme genes) can be
enhanced or diminished by a cell in response to changes in the cell's
environment. This form of gene regulation is called enzyme induction and
inhibition.
 Enzymes can be compartmentalized, with different metabolic pathways
occurring in different cellular compartments.
 Enzymes can be regulated by inhibitors and activators.
 Enzymes can be regulated through post-translational modification. This can
include phosphorylation, myristoylation and glycosylation.
 Some enzymes may become activated when localized to a different
environment (e.g. from a reducing (cytoplasm) to an oxidizing (periplasm)
environment, high pH to low pH etc.).
27. What is photosynthesis?
Photosynthesis converts light energy from the sun in to chemical energy for the
plant to use.
28. Know the general formula for photosynthesis
Solar energy + carbon dioxide +water = Glucose + oxygen
solar energy + 6CO2 + 6H2O = C6H12O6 + 6O2
29. In leaves, what is the name of the tissue where most photosynthesis takes
place?
Inner leaf surfaces
30. What is a pigment? Examples in plants. Where exactly are they located
within the chloroplast?
The primary function of pigments in plants is Photosynthesis, which uses the green
pigment Chlorophyll along with several red and yellow pigments that help to
capture as much light energy as possible. The chlorophyll pigments are located
within the leaves.
31. What are the main products of the light-dependent reaction?
Generally, the light-dependent reactions remove low energy electrons from water
when chlorophyll absorbs energy; these electrons move down an electron transport
system to produce ATP from ADP and (P); energized electrons are also taken up by
NADP+1, which temporarily holds energy to fuel upcoming CO2 reduction.
32. What are the main products of the light-independent reaction?
Generally, the light-independent reactions use ATP and NADPH formed in
thylakoids to reduce CO2 in the stroma; the CO2 from the air is fixed by a substrate of
the Calvin cycle to produce CH2O.
33. Which photosystem generates ATP? Which one NADPH?
Electrons from photosystem I are passed down a short electron transport chain to
reduce NADP to NADPH
Photosystem II makes ATP.
34. What are NAD+ and NADP+?
NAD is a dinucleotide, since it consists of two nucleotides joined through their
phosphate groups, with one nucleotide containing an adenine base and the other
containing nicotinamide. With NADP, they function as electron acceptors for
biochemical reactions.
35. What molecule provides with low energy electrons for photosynthesis?
NADH
36. What is chemiosmosis? Where does it take place?
Chemiosmosis is the movement of ions across a selectively permeable membrane,
down their electrochemical gradient. More specifically, it relates to the generation of
ATP by the movement of hydrogen ions across a membrane during cellular
respiration.
37. What is the relationship between light-dependent and light-independent
reactions?
The light-dependent reactions, known as the light reactions, need direct energy to
undergo their process. The light-independent reactions, known as the dark
reactions or the Calvin Cycle, do not need direct light energy, but rely on light
energy indirectly because they need the products from the light reactions to
proceed with the full reaction.
1) What is the overall reaction of aerobic respiration?
The overall chemical equation for aerobic respiration is as follows: C6H12O6 + 6O2
+ 6H2O 6CO2 + 12H2O + Energy (36-38 ATP) Glucose + molecular Oxygen + water
? carbon dioxide + water + energy Often, you will see the equation written like this:
C6H12O6 + 6O2 6CO2 + 6H2O + Energy (36-38 ATP) This is the same equation.
They simply crossed off 6H2O from each side of the equation to simplify it.
2) What are the possible products of fermentation? Do they produce extra
ATP? How does Fermentation help ATP production?
There are many possible end products, the most common ones are: lactic acid,
ethanol, carbon dioxide and hydrogen. Other compounds can include butyric acid
and acetone. Fermentation does not produce extra ATP. The NADH produced in
glycolysis is used to reduce the pyruvic acid and the regenerated NAD+ can be
reused in glycolysis so that it continues and generates a net gain of 2 ATP per
glucose.
3) Know the parts of the mitochondria; where do the processes of glycolysis,
fermentation, Krebs cycle, and Electron Transport chain take place.
Mitochondrial membrane
4) What is the net ATP production of glycolysis?
There are four ATP molecules but two are used, making a net production of two in
the end.
5) What are the two stages of glycolysis?
Glycolysis occurs in two major stages, the first of which is the conversion of the
various sugars to a common intermediate, glucose-6-phosphate. The second major
phase is the conversion of glucose-6-phosphate to pyruvate.
6) In aerobic respiration, what is the final electron acceptor?
Oxygen
7) What is the function of NAD+ ?
They are co-enzymes, proton acceptor (carrier in forms of NADH and FADH2, then
becomes proton donators at electron transport chain)
8) In what part of the mitochondria do the H+ from NADH and FADH2 get
concentrated?
The cristae.
9) How many ATP’s are produced by the Electron Transport Chain?
32 from FADH2 and 34 from NADH.
10) Besides glucose, what other biomolecules can be used to produce ATP?
 Glycerol breaks down to PGAL, which enters glycolysis.
 Fatty acids are broken into acetyl groups, which enter the Krebs cycle.
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Fats are very efficient energy storage molecules, since they have 3 fatty acid
chains and a fatty acid with 18 carbons can produce 108 ATP molecules.