Unit 2 checked by your instructor and edited thoroughly – very important unit:
Chapter 7 - Cell - Objectives:
1) What are the goals of microscopy?
The goals are to produce a magnified image of the specimen (magnification), separate the
details on the image (resolving power), and to render the details visible to the human eye or
camera.
2) How do you calculate the magnification of a microscope?
To calculate the total magnification you must multiply the objective by the eyepiece lens.
3) What is the resolving power of a microscope?
The resolving power of a microscope is the measure of image clarity. What cell structures
can you see with the a) naked eye: Human height, length of some nerve/muscle cells, chicken
egg, frog egg; b) light microscope: most plant and animal cells, nucleus, most bacteria,
mitochondrion.
4) What is the difference between light and electron microscopes – which is better for live
specimens? What can you see with a microscope?
The light microscope is better to use for living specimen because to prepare a slide for the
electron microscope you must put the specimen in large amounts of alcohol, ultimately
killing it. You can observe mitochondria and chloroplasts and eukaryotic and prokaryotic
cells with the microscope. Viruses and other organelles are toooo small for the regular
microscope!
5) What is better for studying cell surfaces – Scanning EM or Transmission EM?
A scanning electron microscope is used to see the surfaces of things such as cells two
dimensionally whereas the transmission electron microscope is used to see on the inside of
small cellular things and it is more 3D.
6) What is cell fractionation/ centrifugation used for?
Cell centrifugation is a procedure to break up parts of a substance such as blood. It is
used to separate the major organelles of cells so that their individual functions can be studied.
You spin the cells in a centrifugation apparatus and exert massive g forces on it to separate
the heavy stuff from the light stuff! Nucleus and mitochondria are heavy, ribosomes and
proteins are light….
7) What do ALL cells contain to qualify to be a cell?
Cells must contain a plasma membrane, cytoplasm, chromosomes, genes/DNA, and
ribosomes.
8) What is a PROKARYOTE? What does it contain? Give examples of a prokaryote
ALL bacteria are prokaryotes. It contains the simplest essentials of a cell – cell
membrane, cell wall, DNA, ribosomes, cytoplasm.
9) What is a EUKARYOTE? What does it contain? Give examples of a eukaryote
Eukaryotic cells are those of animal and plant cells for the most part. They contain the
major organelles of cells are more complex than prokaryotic cells.
10) Compare a plant cell and an animal cell
The main differences between plant and animal cells are that animal cells do not have
chloroplasts, central vacuoles, a cell wall, or plasmodesmata. Plant cells do not have
lysosomes, centrioles, or flagella.
11) Complete the table – Cell Parts/Organelles and their Functions (end of this h/o). Use
the following websites for interactive animations to do this:
a) http://www.cellsalive.com/cells/cell_model.htm (Eukaryotic cell animation)
b) http://www.cellsalive.com/cells/bactcell.htm#top (Prokaryotic cell animation)
c) http://www.wisc-online.com/objects/index_tj.asp?objID=AP11403 (Take the quiz by
clicking the next button)
Chapter 8 – Plasma/Cell Membrane
1) Why is the plasma membrane considered to be selectively permeable?
Plasma membrane is selectively permeable because it lets in and out only certain material.
2) What are phospholipids? What chemical features of this macromolecule make it an ideal
candidate to make up the cell membrane?
Phospholipids are amphipathic molecules that have both hydrophobic regions and
hydrophilic regions. This makes it an ideal candidate to make up a cell membrane – because
the cells exterior and interior has water (so the plasma membrane has hydrophilic molecules
on the exterior and the interior) and the interior of the membrane remains hydrophobic..
3) How are proteins included in the structure of the plasma membrane?
Proteins are either on the outside/inside of the membrane (peripheral) or they pass through
the membrane (integral proteins) like the channels and receptors - doorways through the
plasma membrane.
4) What is the fluid mosaic plasma membrane model? Draw the model and label the parts
(outline sketch okay).
Fluid mosaic model means that the
membrane is liquid and it is made of
different macromolecules serving
different functions – like a mosaic
tile/collage.
5) Why is this membrane model referred to as a) ‘Fluid’ and b)‘Mosaic’? Explain
clearly including the roles of unsaturated fatty acids, cholesterol, carbohydrates
and the function of different integral and peripheral proteins in the membrane.
a) The membrane is referred to as fluid because the integral proteins and
lipids move laterally and can rarely flip. Phospholipids with unsaturated
fatty acids move faster than the saturated ones because unstauration makes
it kinky – more wiggling! . Cholesterol restricts it except at low
temperatures.
b) The membrane is said to be mosaic because the structure is not the same
on the inside and outside. There are peripheral proteins on the inside,
integral proteins than pass thru, cholesterol on the inside, and
carbohydrates on the outside. Carbs (make up antigens) are involved in
different function than the proteins (can be enzymes/G
proteins/receptors…).
6) Why do substances need to move in and out of cells? When do they do this?
The substances need to move in when the cell needs nutrients/during cell signalling
and they move out when the cells have too much waste.
7) What substances can be TRANSPORTED easily across the plasma membrane
without any assistance? Why?
Substances such as small polar molecules and hydrophobic molecules can be
transported easily because the polar molecules are small in size and nonpolar
molecules can go through because the plasma membrane is lipid – that is nonpolar.
8) What substances need assistance to be TRANSPORTED into and out of cells? Why?
Ions, polar molecules and other large charged particles need assistance to get in and
out of cell because these molecules don’t dissolve in hydrophobic substances.
9) What macromolecule helps these substances to get into the cells? Where are they
located?
Integral proteins help these substances to get in and out of cells. These proteins are in
the cell membrane. They make doorways – channels or they are carrier proteins that
bind to substances like glucose and amino acid and ‘carry’ them into the cell –
providing safe passage for a hydrophilic polar molecule in a hostile hydrophobic lipid
membrane world is what its all about!
10) When substances ‘Diffuse’ into a cell, what can you tell about its relative
concentrations inside and outside the cell?
The substances move from a higher concentration to a lower concentration. This
means that the concentration is higher on the outside of the cell.
11) Based on energy requirements, draw a flow chart to indicate the different types of
TRANSPORT in and out of cells.
Energy
Requirements
Diffusion
Simple
Molecules go
through lipid bilayer
Facilitated
Requires transport
by proteins
Carrier
Proteins
Channel
Proteins
12) What is the difference between Passive and Active Transport? Are these both
examples of diffusion?
Passive transport is driven by the intrinsic kinetic energy of the molecules while
active transport requires ATP. Active transport is not diffusion.
13) What is the difference between Simple Diffusion and Facilitated Diffusion?
Simple diffusion is when molecules go through a lipid bilayer and facilitated
diffusion requires carrier/channel helper proteins.
14) How do carrier proteins work? What substances use carrier proteins? What type of
diffusion is this?
Molecules bind with the carrier; then the protein changes shape and the molecule is
released. Amino acids, sugars, nucleotides, and other small molecules use carrier
proteins. This is facilitated diffusion.
15) What is Osmosis? Is it diffusion or Active Transport?
Osmosis is the diffusion of water.
16) Explain the terms – isotonic, hypertonic, and hypotonic with a quick sketch.
Isotonic is when the concentration of
the cell is equal to the concentration
of the environment. Hypertonic cell
is when the solute concentration in
the cell is greater than outside.
Hypotonic cell is when the solute
concentration is lower in the cell
than it is outside. ITS ALL
RELATIVE!
17) What happens to an animal cell and a plant cell when placed in diwater?
The animal cell will lyse; the plant cell will become turgid. They will both absorb
water! Plant cells are in the flaccid state normally in nature. So they are hypotonic in
their normal state!
18) What happens to an animal cell and a plant cell when placed in isotonic saline?
Isotonic means there should be no difference in solute concentration between inside
of cell and outside. So no water should move in or out. Animal cells are in this state
normally inside the body. Plant cells will wilt or become flaccid.
19) What happens to an animal cell and a plant cell when placed in sucrose/sugar water?
The animal cell will shrivel and the plant cell will plasmolyze as water moves out.
20) What is the Sodium Potassium pump – why is it important?
The sodium-potassium pump actively maintains the gradient of sodium and potassium
ions across the membrane. It is important as it generates the membrane potential –
keeps the inside of the membrane negative and outside positive as 3 sodium ions go
out and 2 potassium ions come in. This is like charging a battery! – ready to
discharge and work when cell needs it. This pump needs ATP to pumpions and is
used in active transport.
21) What is cotransport? What gets transported?
In cotransport, a membrane protein couples the transport of two solutes. Here a
proton pump pumps a H+ out to charge up the battery (instead of sodium and
potassium ions) and when it discharges, and comes back in, a “friend” comes along –
that is “cotransport” of a molecule of sugar.
22) What is exocytosis? Does it need ATP?
Exocytosis is the release of wastes OR secretion of proteins/enzymes by having
vesicles attach to the plasma membrane, fuse with the membrane and then release
their contents to the outside of the cell. This requires ATP.
23) What is endocytosis? What are the 2 types of endocytosis? Do they need ATP?
Endocytosis is when a cell brings in macromolecules and particulate matter by
forming new vesicles from the plasma membrane. Endocytosis includes phagocytosis
(for solids) and pinocytosis (for liquids) and both of them need ATP.
Chapter 9 Cell Respiration Objectives
1) What is cell respiration? What is the overall reaction? Where does it occur?
Cell respiration is the process of breathing oxygen to take into the body convert it
chemically into food and breath out the unneeded parts (CO2) of the result. It mainly
takes place in the mitochondrion of animals.
C6H12O6 + 6O2 = 6CO2 + 6H2O + 36 ATP
2) Where do the reactants of cell respiration come from and where do the products
go?
The reactant glucose comes from all the food we eat and the oxygen from the
breathing and the products go out through exhaling/peeing (CO2 + H2O ) and most
importantly the ATP is used for cellular work.
3) What is the reason for a cell to go through cell respiration?
Cells go through cell respiration so that they can get ATP for activities like
movement as muscle contraction needs ATP, synthesize proteins and make enzymes
which get used in every reaction in the body, move organelles, transport material
against their concentration gradient through active transport, replicate DNA, and
more….
4) How does cell respiration relate to photosynthesis?
Cell respiration is the opposite of photosynthesis in all ways and it occurs in ALL
LIVING ORGANISMS.
5) Do plant cells photosynthesize or respire? ()
Plants photosynthesize and respire – know this! So they fix carbon as glucose in
photosynthesis and use some of it up in cell resp! Whatever glucose is left makes new
plant parts – growth and accounts for net primary productivity.
6) Write the formula for glucose. Why is it a central molecule in cell respiration?
Glucose- C6H12O6 This is a central molecule for cell respiration because this can
be converted into carbon dioxide, water, and ATP.
7) What is ATP? Why is it the most important product made in cell respiration?
ATP is the substance made of 3 PO4 groups and since it is a nucleotide, it has the
phosphates connected to a ribose sugar and adenosine nitrogen base (oh but the ribose
sugar is not used for giving the energy in this molecule). It is necessary in many
situations and for many reactions as listed in ques 3.
8) How does ATP do its job as an energy molecule?
It does its job by releasing one of its three PO4 molecules so that it can attach to
another substrate molecule, energizing it, lowering the free energy, and making it get
together and form bonds with another substrate.
9) What does food or glucose contribute in order to make ATP?
Glucose provides electrons usin the H atom, in order to make ATP. NAD carries
this to the electron transport chain.
10) What happens to the electrons for it to make ATP?
Electrons flow down a hill moving from less electronegative atoms in protein
complexes to more electronegative atoms in the Electron Transport Chain of the
mitochondria. As they do this downward movement (in their potential energy), they
release their energy creating the H+ or proton pump. When the protons charge up
creatin a “battery” situation again – lots of protons on the intermembrane area. The
protons then flow back (discharge) through the ATPase making ATP.
11) What happens to the Carbon and Oxygen in glucose?
The carbon and oxygen in the glucose ends up as parts of water and carbon
dioxide molecules. SO only the H atoms/electrons get to make ATP directly!
12) What molecule ‘CARRIES’ the electrons from glucose to finally make ATP?
NAD = it becomes NADH
13) Fill in Information: Aerobic Cell Respiration Overview from PowerPoint
1. Respiration involves Glycolysis, (Shuttle), the Krebs cycle, Electron Transport
and Oxidative Phosphorylation.
2. Glycolysis - breaks glucose (6Carbon) into two pyruvates (3Carbon in each).
Packages Hydrogen Electrons into NADH.
Glycolysis (in anaerobic/aerobic respiration) Gain – 2 pyruvates, 2 ATP, 2NADH
3. Shuttle - takes pyruvate from cytoplasm to mitochondria matrix. Gain- (2
NADH), 2 CO2 (2 carbons lost), 2 Acetyl CoA (2Carbon in each).
4. Krebs cycle - takes the two 3 Carbon compounds from Glycolysis and extracts all
Carbons and Oxygens as CO2 and Hydrogen electrons in NADH/FADH2.
Krebs Cycle (aerobic respiration) Gain – 4 CO2 (all Carbons lost now), 2 ATP,
6 NADH, 2 FADH2.
5. Electron Transport Chain: occurs in mitochondrial inner membrane. Input- 10
NADH, 2 FADH2, 6 O2. Gain- H2O
6. Oxidative Phosphorylation: occurs in mitochondrial inner membrane. Input- H+’s
and ADP  ATP in “mill wheel”. Gain- 10 NADH  30 ATP, 2 FADH2 
4ATP = 34 ATP.
Aerobic Cellular respiration generates around 36-38 ATP molecules for each
sugar molecule it oxidizes.
14) What is Substrate Level Phosphorylation?
This is where 4 ATP are made from substrates durin glycolysis and Krebs.
15) What is Oxidative Phosphorylation?
This is where 34 ATP (90%) is made by the electron transport chain in
mitochondria.
16) Compare Substrate Level Phosphorylation and Oxidative Phosphorylation
Most of the ATP is made in Oxidative Phosphorylation.
17) Complete the following: Location of Cell Respiration Pathways




Cytoplasm - Glycolysis (End product is pyruvates, ATP, and NADH)
Shuttle - Cytoplasm into the mitochondria matrix.
Kreb’s Cycle - Matrix of Mitochondria (fluid inside mitochondria)
Electron Transport Chain - Enzymes located all along the mitochondria inner
membrane. H+ ions moved from NADH and make water molecules.
 Oxidative phosphorylation:
H+ ions move back into process where ADP becomes ATP.
 ATP Synthase is in the cristae. ATP is made in the mitochondria matrix.
18) What does the Electron Transport Chain involve? Does it make ATP?
The Electron Transport Chain has electrons from glucose flow down a hill
moving from less electronegative atoms in protein membrane complexes (and one
lipid carrier) to more electronegative atoms like a relay downhill race. These protein
complexes include cytochromes and proteins with Fe-S centers. As the electrons do
this downward ‘flowing’ movement (dropping their potential energy), they release
their energy creating the H+ or proton pump. The final electron acceptor is the most
electronegative atom – namely oxygen and water is the end product. Technically the
electron transport chain does not directly make ATP, as it is made after the electron
transport chain through the use of ATP synthase.
19) What is chemiosmosis? Does this make ATP?
Chemiosmosis is the movement of the H+ ions from the higher concentration in
the intermembrane region of the mitochondria (between the 2 membrane coverings)
to the matrix (juice inside) where it generates ATP by flowing through the ATP
Synthase enzyme.
20) What is the proton gradient or proton motive force? How is it generated? Why
is it important for ATP synthesis?
Proton motive force is the ‘charging up of the battery’ –that means pumping all the
H+ ions first into the intermembrane space to create a high concentration gradient and
because they cannot flow back except through the ATP synthase enzyme- it is a force
that is produced capable of being released to produce ATP.
21) Describe the chemiosmosis process that makes ATP in detail
See answers 18-20 and in summary food energy is used to form the hydrogen ion
gradient across the mitochondrial membrane so it can fuel formation of ATP, by
attaching a PO4 to the ADP (to make ATP).
22) Explain the role of Electron carriers – NADH and FADH2 in the synthesis of
ATP.
These high energy electron carriers are used to transform the reactants into the
needed products. It is like a shuttle or transition; it’s not needed as a substance but it’s
needed to complete the process.
23) What accepts the electrons from glucose FINALLY or at the end of the Electron
Transport Chain in aerobic cell respiration?
Oxygen accepts the electrons to form water from the original glucose.
24) Compare Glycolysis and Kreb’s cycle.
Glycolysis occurs in the cytoplasm, while Kreb’s cycle occurs in the mitochondria
matrix. Also, glycolysis doesn’t need oxygen, while Kreb’s does. Glcolysis is older
in evolution than Krebs and is in all primitive fermenting organisms.
25) What if fermentation? Where do you see this process occur?
Fermentation is the partial degradation of the sugars in places absent of oxygen.
This occurs in substances such as cheese, wine, and yogurt.
26) What are the two types of fermentation?
There are two types of fermentation: Lactic Acid and Ethanol (alcohol).
27) Compare fermentation and cellular respiration
Fermentation uses no oxygen, while cell respiration does use it. They both input
glucose and result in ATP, and their first process is glycolysis. They have different
electron acceptors (pyruvates /oxygen), and fermentation is an incomplete oxidation
of food while cell respiration is not. Also, cell respiration occurs in the cytoplasm and
the mitochondria matrix, while fermentation only occurs in the cytoplasm.
28) How is cell respiration regulated?
Cell respiration is regulated by feedback mechanisms and allosteric regulation.
Chapter 10 Photosynthesis - Objectives
1) What are photoautotrophs and heterotrophs? Give examples of the same.
Autotrophs produce their organic molecules from CO2 and other inorganic raw
materials. Photoautotrophs use light to convert CO2 into C6H12O6. Heterotrophs are
unable to photosynthesize and make food. They use other organisms as their food.
Photoautotrophs are Euglena and Cyanobacteria. Heterotrophs are fungi, animals like
mammals.
2) What are chemoautotrophs – give an example.
Chemoautotrophs make their food using chemicals like H2S. An example of this
would be Purple Sulphur Bacteria.
3) What is the difference between chloroplast and chlorophyll? Why are they
necessary for photosynthesis?
Chloroplasts are little organelles in plants that help photosynthesis, while
chlorophyll is the green pigment inside the chloroplast. Chloroplasts are the sites
of photosynthesis.
4) Explain the statement – the structure of the leaf is exquisitely related to its
function (use ALL parts of a leaf from top surface to bottom in the following
animation website). (http://www.purchon.com/biology/flash/leaf.swf)
(Label the parts here)
5)
6)
7)
8)
9)
Cuticle – Prevents loss of water and entry of germs
Epidermis – Also prevents water loss (does not have chlorophyll), produces the
cuticle.
Mesophyll – Sites for photosynthesis. Consists of palisade mesophyll (columnar
cells) and spongy mesophyll (spherical cells). Full of chloroplasts.
Air Spaces – Used for CO2 and O2 gasses.
Stomata – Surrounded by guard cells, stomata let the CO2 gas in the leaf.
Guard Cells – Surround stomata. These cells open and close the stoma.
Vascular Bundles – Xylem carries water and supports the plant. Phloem brings
the nutrients to and from the leaf.
What are the structures inside the chloroplast? Describe their organization and
function.
Inner Membrane – Protects the inside, lets stuff in and out.
Outer Membrane – Protects the inside, lets stuff in and out.
Stroma – Uses ATP to link up C, O, and H to form Glucose (Calvin’s cycle here).
Granum of Thylakoids – Light dependent reaction occurs there.
What is the overall reaction of photosynthesis?
6CO2 + 6H2O C6H12O6 + 6O2
What is the source of the ‘O’, ‘C’, and ‘H’ atoms in glucose?
They come from carbon dioxide and water. Most important to know that oxygen
released in photosynthesis comes from the splitting of water – this splitting is
done using light – hence the process is called photolysis.
How is photosynthesis similar to cell respiration?
It is the reverse of respiration reaction.
How is photosynthesis different from cell respiration?
IMPORTANT!- Photosynthesis uses Light to make ATP which is then used up to
make glucose while respiration oxidizes/burns glucose to make ATP which is
used not to produce glucose but to do cellular work like protein synthesis, DNA
replication, active transport, and more!
10) What are the two parts of photosynthesis?
Light Reactions and Calvin Cycle (light independent reactions)
11) What happens in Light Reaction? Why do you need ATP to be made?
In the light reaction light energy is absorbed by chlorophyll/carotene and all color
pigments in the thylakoids and the light energy absorbed excites the electrons in the
pigments of Photosystem II. All the energy from these excitations of different pigments
in the photosystem is harnessed and sent out to the ‘Reaction center’ which houses the
special chlorophyll molecule that ends up ejecting an electron right out of its orbital.
This excited electron is then accepted by the PEA (primary electron acceptor) also
located in the thylakoid membrane. Next the ETC (electron transport chain) transfers this
electron from less electronegative atoms in protein complexes int eh thylakoid membrane
to more electronegative atoms also in similar complexes. Remember – this is like a
downhill relay race. The energy lost by the electron allows for the pumping of H+
(protons) into the thylakoid space from the stroma. Now, just as in the mitochondria,
when these protons accumulate, the pH drops inside the thylakoid. The protons then
move back out through the ATPase (chemiosmosis, proton gradient and all that sh..) that
allows for ADP to be coverted to ATP. Story does not end here. The escaped electron is
still journeying – it replaces the electron lost in another Photosystem – (PS I). Next
follows another ETC – the difference being that at the end of it, instead of producing
ATP, you have the high energy carrier NADP (nicotinamide adenine dinucleotide
phosphate) making NADPH. Both ATP and NADPH are in stroma ready for Calvin’s
cycle where the CO2 molecules can be strung together with the ‘H’ that NADP is
carrying to make ahhh you guessed right, glucose – C6H12O6. Now you know the story.
The light reaction generates ATP by ‘photophosphorylation’ (light dependent
phosphorylation of ADP to make ATP) for the Calvin cycle.
Oh and remember the very first electron that jumped out of PSII reaction center – that is
replaced by the breaking down of water (photolysis) and oxygen is a waste roduct
produced. This scheme you see on next page is noncyclic photophosphorylation. Know
the light dependent and light independent reactions- the process, its inputs, outputs,–
many ques. On AP exams are on photosynthesis and cell resp.
12) What happens in the Calvin Cycle?
It begins with the incorporation of CO2 into an organic molecule via carbon fixation.
End product is glucose (6 carbons)– the first C fixation step may produced G3P/malate/
or other organic compounds with 3 or 4 Carbons (hence C3 or C4 plants…).
This new piece of carbon backbone is reduced with electrons provided by NADPH.
ATP from the light reaction also powers parts of the Calvin cycle.
13) What is photophosphorylation? When does it occur?
Photophosphorylation occurs in the stroma and it is a process where ATP is
formed using light- the whole thing on previous page.
14) Where does Light Reaction take place? What molecule/s absorb light in the leaf?
Light reactions take place in the thylakoids. The chlorophyll and other accessory
pigments absorb light.
15) What color light does chlorophyll a absorb best? How did Engelmann’s
experiment prove this using algae and aerobic bacteria?
Purple and Red. In this experiment, different segments of a filamentous alga were
exposed to different wavelengths of light. Areas receiving wavelengths favorable to
photosynthesis should produce excess O2. Engelmann used the abundance of aerobic
bacteria clustered along the alga as a measure of O2 production.
16) Why does chlorophyll appear green?
Because it reflects green light the best.
17) What does a Photosystem contain? How many Photosystems exist in the leaf and
what is their function?
A photosystem acts like a light-gathering “antenna complex” consisting of a few
hundred chlorophyll a, chlorophyll b, and carotenoid. There is 1 photosystem in a
chloroplast and many in a leaf.
18) What happens when light hits the thylakoid membrane of chloroplasts?
Green light is reflected while all other light is absorbed and the rest of the story…
19) What is the REACTION CENTER of the chloroplast? What does it contain?
The particular chlorophyll molecules that start the reaction. It contains the
primary electron acceptor and reaction center chlorophyll.
20) What are accessory pigments and why are they needed?
Accessory pigments let the electrons move down the concentration gradient to the
primary electron acceptor.
21) How many electrons are donated by chlorophyll for each photon of light that
strikes it?
1 electron
22) What replaces the electron donated by chlorophyll?
Electron from water
23) How many electrons must be replaced in chlorophyll to make O2 from H2O?
8 Electrons
24) What is the Primary Electron Acceptor – from what molecule does it get its
electron and to what molecule does it donate it?
It takes in electrons from Photosystem II and gives them to Photosystem I.
25) Where have you learned about a similar kind of electron flow?
Cell Respiration
26) Why do electrons flow in the light reactions from one member to another along
the thylakoid membrane?
Because of the increase in electronegativity of acceptors.
27) Name these proteins/molecules in order through which the electrons get passed
on during the Non-cyclic Electron Flow of light reactions.
Noncyclic electron flow pushes electrons from water, where they are at low potential
energy, to NADPH, where they have high potential energy and then there’s
Plastoquinone (Pq), cytochromes (cyt), plastocyanin (pc), Ferrodoxin (Fd) – all
involved in the downhill relay race accetin and passing on electrons – see pix on
previous page.
28) What happens to water during light reactions?
It is Oxidized to O2
29) What is the final electron acceptor during light reactions? What happens to it
when it accepts the electron?
NADP and it makes NADPH
30) When and how is the proton pump or pH gradient developed?
Proton pump powers ATP synthesis and releases H+ back into the stroma
31) What is the power of the proton pump used to make?
It makes ATP
32) Compare cyclic and non-cyclic electron flow (http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter10/animations.html#)
Cyclic photophosphorylation uses Photosystem I only while Noncyclic is in both.
33) What is the purpose of the Calvin’s Cycle? What are its inputs and outputs?
Calvin cycle is Carbon Fixation (light independent rxn) in C3 plants (80% of
plants on earth). Occurs in the stroma. Uses ATP and NADPH from light rxn. –
Also uses CO2. Fixes 1C per turn – so you need 6 turns. In reality Calvin’s
makes a 3C compound (2 of them join to form the 6C Glucose) To produce
glucose: it takes 6 turns and uses 18 ATP and 12 NADPH.
34) How does light reaction connect with Calvin’s cycle? Where does Calvin’s cycle
take place?
Light reaction produces ATP and NADPH that are used in Calvin Cycle. Calvin
cycle takes place in the stroma.
35) Go to this website: http://faculty.nl.edu/jste/calvin_cycle.htm and describe how
glucose is made through Calvin’s cycle from carbondioxide. Use the animations
to observe the changes.
A carbon atom from carbon dioxide enters the cycle and joins with a five carbon
molecule that is present. The six carbon molecule that results, breaks up into two
molecules, each with three carbon atoms. As the reactions in the cycle continue,
ATP is dephosphorylated (loses a phosphate) to ADP. Further energy is supplied
by the oxidation of NADPH to NADP. A carbon atom (actually connected to
other atoms not shown here) breaks off and is available to be used to make G3P, a
high energy molecule that has three carbons. The five carbons that remain,
combine and continue in the cycle. Another ATP is dephosphorylated to ADP to
provide the necessary energy. The cycle repeats continuously, each time making a
carbon atom available for G3P. When three cycles are completed, one G3P can
be removed for making glucose and other organic molecules.
36) What is the C3 cycle?
It is Calvin cycle
37) What is photorespiration – why is it a waste?
It occurs on hot, dry, bright days. Stomates close = more O2 and less CO2 . Fixation
of O2 instead of CO2 because RUBISCO (first enzyme in Calvin’s cycle) acts as an
OXYGENASE = acts different when oxygen concentration rises in a leaf cell. Light
reaction and Calvin’s cycle take place, BUT Produces 2-C molecules (not glucose)
instead of 3-C sugar molecules. Produces no glucose molecules and uses up ATP.
38) What do plants do to minimize photorespiration?
Plants use C3 or CAM as a strategy to avoid photorespiration – see organizer
table for details.
39) Describe and compare the strategy used by C4 and CAM plants (very important)
CAM Plants like cactus take in CO2 at night when stomata are open. Then they fix
CO2 to glucose during the day when the stomata are closed. C4 Plants form C4
compound instead of the C3 compound in Calvin’s cycle. This 4C compound is
made in the mesophyll cell – then they transport it to the Bundle Sheath cells
where Calvin’s cycle takes place and extracts the Carbons to make glucose. This
way rubisco enzyme cannot transform it to its inefficient 2C structure in the
mesophyll cell where CO2 levels are low and therefore it undergo the wasteful
photorespiration.
Chapter 11 – Cell Communication Objectives:
1) What is cell communication?
Cell communication is how cells communicate between one another as if they were
talking like humans do.
2) What are the different types of cell communication?
In all cell communication, there is cell talk, which consists of local talk (paracrine
signaling, direct cell to cell talk/ via diffusible substances) and long-distance talk
(synaptic signaling, hormones released into blood by endocrine glands).
3) Give examples of paracrine signaling, synaptic signaling, and hormonal signaling
Paracrine signaling- local secretions from neighboring cells – example -growth
factors; AND ethylene gas which increases the ripening of fruit. Synaptic signalingelectrical or chemical neutron talk in the brain. Hormonal signaling- released into the
blood by the endocrine glands; epinephrine.
4) Compare the above three types of signaling
Of the three above types of signaling, only the paracrine signaling is local talk, while
the other two are long distance talk. Also, all three of these signals work differently in the
different parts of the body.
5) What are growths factors and what disease condition can they cause if their
production is not regulated?
A growth factor is a chemical produced by neighboring cells that acts as a signal for a
cell to start dividing, but when there is a lot of a growth factor the cell division increases
which sometimes results in cancer.
6) What is the flight or fight response? What triggers the response in the body after the
stimulus is received by the senses?
The flight or fight response is when the body uses long distance talk when a human
may have a panic attack or freak out. There is a rush of adrenaline from the adrenal
gland, which goes to the muscles such as the legs to help with the person’s response to
run or “fight”. Many other effects occur as well, such as the liver releasing extra glucose
to send to the muscles by breaking down glycogen to release glucose – this gucose cn be
broken down to produce ATP in mitochondria of muscle cells for muscle contraction.
7) What are some different physiological responses in the body when epinephrine or
adrenaline is released?
The release of epinephrine (A.K.A adrenaline) is to help protect the body so that it
can be safe in a time of stress if it is needed. It lets the body use the fighting or running.
8) What are the three stages of cell communication (and epinephrine action)?: The three
stages are signal reception, signal transduction, and response.
9) What type of macromolecule are receptors?
Receptors are integral proteins in membranes or they may be in the cytoplasm (bind
steroid hormones that diffuse through the plasma membrane).
10) Where are these receptors found in the cell?
They are found at the cell’s surface or in the cytoplasm.
11) What is the general term given for signal molecules like epinephrine that bind to
receptors and start a signal transduction process?
In reception, the signal molecule is called “ligand”.
12) What is signal transduction?
Signal transduction is where many hormones and other signals trigger the formation
of second messengers like camp and phosphorylation cascades; a domino effect of
proteins hitting/attaching to one another.
13) What is a G protein? What causes it to become activated? What does an activated G
protein do? How can it be shut off?
A G protein is the result of a receptor binding to epinephrine. Where GTP is present it
means that the G protein is activated, whereas it is inactivated when GDP is present. An
activated G protein binds with other membrane proteins. Having one less phosphate
attached can shut it off.
14) What is Adenylyl cyclase? How is it activated? What does it do when it is activated?
How can it be shut off?
Adenylyl cyclase is an enzyme, which is activated by an active G protein leading to a
cellular response or more signal transduction. This also converts ATP to cAMP (a second
messenger). A phosphatase that can inactivate it or taking away the trigger at the
reception site can shut it off.
15) What is cAMP? How is it generated? What does it do? How can its action be shut
off?
cAMP is cyclic adenosine monophosphate. It is also called the second messenger.
This diffuses through the cell and activates protein kinase A, which phosphorylates other
proteins. Dephosphorylation can deactivate cAMP.
16) Why is cAMP referred to as a Second Messenger?
It is referred to as a second messenger because it is the second reaction in the domino
effect line.
17) Are there other second messengers like cAMP?
Yes, there are other second messengers other than cAMP, which occur in signal
transduction.
18) What is the general role of enzymes that are ‘kinases’?
It activates proteins usually by phosphorylation – addition of phosphates to substrates,
energizing them using ATP.
19) What is the general role of enzymes that are ‘phosphatases’?
It deactivates proteins usually by causing the reversal of phosphorylation.
20) Describe the process that leads from epinephrine binding to the receptor to the final
cellular response – i.e. the breakdown of glycogen
The signal molecule- epinephrine attaches to the receptor, the now activated receptor
that is in the plasma membrane, turns on a G protein (the domino effect begins) that now
becomes activated by replacing its bound GDP with GTP (activated). Next the G protein
activates the next protein (adenylyl cyclase) to produce a scond messenge cAMP which
can help activate kinase enzymes which continue on to activate other enzymes , finally
resulting in the activation of the enzyme that breaks down glycogen to make glucose. –
(the cellular response).
21) How does testosterone and the steroids “not abused” by Barry Bonds carry out their
effects in the cell?
When a steroid enters the body, it connects directly to the receptors in the cytoplasm,
which moves to the nucleus and activates transcription factors that can turn on genes to
make (muscle) proteins.
22) How can the same hormone or ligand have multiple effects in the body? Give an
example – see below:
23) How does epinephrine cause heart muscles to beat faster – describe the signal
transduction pathway that involves Calcium ions getting pumped through ion
channels in the ER and cell membrane
Epinephrine triggers liver and skeletal muscle cells to break down glycogen, but
cardiac muscle cells are stimulated to contract, leading to a rapid heartbeat. The various
protein pumps transport Ca2+ outside the cell or inside the ER or other organelles. The
calcium ions are needed for muscle contraction – heart rate goes up because the calcium
ion concentration inside the cytoplasm is increased when epinephrine binds!
24) How do tyrosine kinase receptors work (not covered in class)? How is this
similar/different from G protein linked receptors?
Tyrosine kinase receptors add phosphates to the tyrosine tails of the other
polypeptide. They activate many different intracellular proteins simultaneously. These
receptors are not linked to the G proteins.
25) What are scaffolding proteins?
They are proteins that link together signal pathways and make themselves relay
proteins, which attach to other relay proteins. It also speeds up the accuracy of signal
transfer between cells.
26) How is cell communication involved in mating?
Pheromones and other mating signals may be ligands that trigger the sexual respose using
cell communication.