BI101 Exam 2
During which chemical reactions is ATP made during glycolysis?
1,3-bisphosphate to 3-phosphoglycerate & 2-phosphoenolpyruvate(PEP) to pyruvate
The Calvin cycle can be divided into three stages:
1. Carbon fixation 2. G3P synthesis 3. RuBP regeneration
Most eukaryotic cells range in size from __________ to __________.
10 micrometers, 100 micrometers
What is the net gain of ATP from glycolysis?
2 ATP
What is the net gain of ATP molecules that can be produced from the breakdown of glucose?
36
Many metabolic poisons work by inhibiting ATP production. Which type of transport would be most affected?
Active transport
The concentration of sodium ions is lower in the cytoplasm of a heart muscle cell than it is in the extracellular fluid. By what mechanism does the cell maintain this difference?
Active transport
Which of the following processes does a cell use to take up molecules against their concentration gradients?
Active transport
What is the difference between active transport and passive transport?
Active transport requires energy and can move substances against their concentration gradient. Passive transport does not require energy and can move substances only down their concentration gradient.
6CO2 + 6H2O
C6H12O6 + 6O2
What are the accessory pigments of a chloroplast?
Chlorophyll b and beta-carotene
function of cell membrane
Controls what enters and exits the cell, protects and supports cell, and helps cells communicate with other cells
What is the importance of coupled reactions?
Coupled reactions allow an exergonic reaction to drive an endergonic reaction.
Which form of passive or active transport functionally limits the maximum size that any cell can achieve?
Diffusion
osmosis
Diffusion of water through a selectively permeable membrane
What is the importance of ATP production to an organism?
Even though the production of ATP occurs within individual cells, a multicellular organism requires the energy produced to carry out vital functions essential for survival. Any organism would quickly die without constant production of ATP.
Why are living cells limited to remaining microscopic in size?
Exchanges of substances at the membrane surface would take too long to diffuse throughout the interior of the cell.
__________ will continue spontaneously.
Exergonic reactions
Why do phospholipids form a hydrophobic region in the plasma membrane?
Fatty acid tails on the phospholipids cannot form hydrogen bonds with water and orient themselves together, forming a bilayer.
If glucose provides the major source of energy burned through glycolysis and cellular respiration, how do we use fats as an energy source?
Fatty acids combine with Coenzyme A to form many Acetyl-CoA compounds.
Why is feedback inhibition important in metabolic pathways?
Feedback inhibition prevents an enzyme from continuing to function when it is not needed.
What is the role of fermentation in glucose metabolism?
Fermentation regenerates NAD+ under anaerobic conditions.
Which of the following statements concerning fermentation is true?
Fermentation, like glycolysis, occurs in the cytoplasm of cells.
Why are some people able to metabolize breast milk as an infant, but they cannot tolerate milk as an adult?
The enzyme that breaks down milk is made during infancy, but its gene is turned off later.
Lysosomes contain very powerful digestive enzymes that can break down proteins, carbohydrates, and other molecules. Why don't these enzymes digest the cell itself?
The enzymes are separated from the cytoplasm by the lysosomal membrane.
If the law of conservation of energy states that the total amount of energy before and after any process is unchanged, and muscles use about 25% of the energy in ATP, what happens to the 75% that is not used?
The excess energy is converted to heat.
You are comparing two cultures of cells, one that is undergoing cellular respiration and one that is fermenting. Both cultures are producing ATP at the same rate. If this is true, what else would you observe about the fermenting culture?
The fermenting culture would require more glucose to maintain its high rate of glycolysis, thus producing more pyruvate than the respiring culture.
How does a Paramecium survive in fresh water?
The contractile vacuole expels water from the cell.
Which of the following is an example of an endergonic reaction?
The conversion of carbon dioxide and water into sugars
What role is played by the electron transport chain during cellular respiration?
The electron transport system takes energy from the high-energy electrons brought by electron carriers (NADH) and uses it to pump hydrogen ions against their concentration gradients from the matrix into the intermembrane compartment.
How does a plant organelle help to create turgor pressure?
The fluid in central vacuoles is maintained hypertonic to the cytoplasm of the cell, so excess water in the cell enters to vacuole, forming the turgor pressure.
stroma
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.
Why are dill pickles well preserved?
The high salt solution and acid from the vinegar inhibit enzyme functions.
How does a messenger molecule, which stays in the interstitial fluid, cause a response in a cell?
The messenger molecule binds to a receptor protein, which becomes activated and a response in the cell occurs.
Your college roommate is on a diet. She explains that if she consumes only 1000 Kcal from carbohydrates, she can eat as many proteins and fats as she wants because they "don't count" since they do not contain glucose and will not enter into cellular respiration. What is the flaw in her reasoning?
The monomers of proteins (amino acids) and fats (glycerol and fatty acids) can be broken down by cellular respiration to generate ATP.
rubisco
The most abundant protein on earth. Performs Carbon Fixation in the Calvin Cycle.
In osmosis, water diffuses from the side of the membrane with a higher concentration of water to the side with a lower concentration of water. What determines the concentration of water in a solution?
The number of molecules other than water dissolved in the solution
The oxygen that you breathe is being used by your mitochondria in reactions that produce ATP from sugars and other food molecules you ate. Where did that oxygen come from originally?
The oxygen in the atmosphere is produced by the splitting of water during the light-dependent reactions of photosynthesis.
If there is a high concentration of oxygen on one side of a biological membrane, what will happen?
The oxygen will diffuse across the membrane until the concentration of oxygen on each side is the same.
What is photosynthesis?
The process by which a cell captures energy in sunlight and uses it to make food
How does water pass through a plasma membrane if the center of the structure is hydrophobic?
The random movement of water carries some through the membrane, while transport proteins handle the rest.
How do CAM plants insure high levels of carbon dioxide?
The stomata open at night and the C4 pathway captures the CO2
optimum temperature
The temperature at which an enzyme is most active promotes the fastest rate of growth and metabolism
cuticle
The waxy, waterproof layer that covers the leaves and stems of most plants. outer surface of the epidermis
How do athletes continue to produce energy to power their muscle cells during activity that is so intense they have used up the available oxygen in their tissues?
Their muscles utilize lactate fermentation.
Why is the use of carbon dioxide in the Calvin cycle reactions important?
Fixation of CO2 in the dark reactions makes it usable for all life-forms.
Where can ribosomes be found in bacteria?
Free in the cytoplasm
Which two forms of cell attachments provide pathways between adjacent cells?
Gap junctions and plasmodesmata
Where does the majority of photosynthesis occur in a plant leaf?
In mesophyll cells
Is the cytosol fluid of animal cells hypotonic, hypertonic, or isotonic to the interstitial fluid surrounding them?
Isotonic
If the nucleus is the control center of the cell, how is information encoded and shipped to the cytoplasm?
It is encoded and shipped by RNA
What is chemiosmosis in terms of cellular respiration?
It is the process by which energy stored in the concentration gradient of H+ is captured in ATP as H+ flows down its concentration gradient.
Which of the following is not true of the cytoskeleton?
It is used in cell recognition
What happens to the high energy electrons at the end of the light reactions of photosynthesis?
It is used to make NADPH from NADP+
Why is fat a useful way to store energy?
It stores more energy than sugars and weighs less.
ATP synthase
Large protein that uses energy from H+ ions to bind ADP and a phosphate group together to produce ATP
Vesicle structure
Membrane-bounded sac
Which component of the eukaryotic cytoskeleton contains a protein used in muscle contraction? What is the name of the protein?
Microfilament, actin
chemiosmosis
Process by which a Hydrogen pump pumps protons into the thylakoid membrane. H+ passively flows through the ATP synthase which leads to the creation of ATP.
cellular respiration
Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen breaks down the two pyruvate molecules produced by glycolysis into six carbon dioxide molecules and six water molecules
Which form of energy requiring transport is used to remove whole cells, or major parts of cells, from the interstitial fluid?
Phagocytosis
Which form of energy-requiring transport is used to acquire material in the same concentration as in the interstitial fluid?
Pinocytosis
Exocytosis is the reverse of which process?
Pinocytosis and receptor-mediated endocytosis
Which of the following structures is/are found in all cells? Select the best answer.
Plasma membrane
All cells have four things in common
Plasma membrane DNA Ribosomes Cytoplasm
phospholipid bilayer
Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside.
Which type of membrane protein is used to generate and maintain concentration gradients?
Transport protein
gated protein
Transport protein that opens a "gate" to allow in a molecule that binds to it
Which of the following generalizations can you make about the cytoskeleton?
Various cytoskeletal elements are needed in the performance of numerous essential cellular functions.
coupled reaction
a chemical reaction in which an exergonic reaction powers an endergonic reaction
bilayer
a film two molecules thick (formed e.g. by lipids), in which each molecule is arranged with its hydrophobic end directed inwards towards the opposite side of the film and its hydrophilic end directed outwards.
concentration
a measure of the amount of solute dissolved in a solvent
Facilitated diffusion requires __________.
a membrane transport protein and a concentration gradient
ATP
a molecule that transfers energy from the breakdown of food molecules to cell processes
carrier protein
a protein that transports substances across a cell membrane
A hormone circulating in the bloodstream would most likely bind to __________.
a receptor protein
Which type of cell would you expect to burst when placed in a hypotonic solution?
a red blood cell
electron transport chain (ETC)
a series of electron-transporting molecules, embedded in the inner mitochondrial membrane
Golgi complex structure
a series of interconnected, flattened membranous sacs
G3P synthesis
a series of reactions, driven by energy from ATP and NADPH, produces six G3P. One G3P leaves the cycle and is amiable to form glucose
competitive inhibition
a substance that is not the enzyme's normal substrate that also binds to the active site of the enzyme
non competitive inhibition
a type of enzyme inhibition where the inhibitor reduces the activity of the enzyme and binds equally well to the enzyme whether or not it has already bound the substrate.
The overall equation for glucose metabolism in the presence of O2 is C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP and heat. The majority of the carbon atoms in the CO2 molecules in this equation come from __________ during reactions of __________.
acetyl CoA; the Krebs cycle
The speed of a reaction is determined mostly by its __________.
activation energy
Enzyme regulation can be precisely controlled through a variety of mechanisms such as __________.
activation of an inactive enzyme and competitive inhibition of the enzyme
Leaves include a number of structural modifications for the purpose of photosynthesis, including stomata, which are __________.
adjustable openings in the surface of the leaf that permit the passage of carbon dioxide, water, and oxygen
Where does the carbon dioxide come from that is captured during the Calvin cycle?
air
metabolism
all of the chemical reactions in a cell the combination of chemical reactions through which an organism builds up or breaks down materials
non-gated protein
always open
Diffusion is the movement of molecules from __________
an area of higher concentration of that type of molecule to an area of lower concentration
Due to a high percentage of unsaturated fatty acids in their membranes, certain microorganisms __________.
are able to withstand low temperatures because their membranes do not solidify as rapidly
Biological catalysts __________.
are organic substances that lower the activation energy required to initiate a reaction that would normally take place at a slower rate
If plants evolved on a planet with a weak sun, what color would they appear to be?
black
Electron carrier molecules that transport energy include __________.
both NAD+ and FAD
Which of the following originated by endosymbiosis?
both chloroplasts and mitochondria
Where do C4 plants store CO2?
bundle sheath cells
How do cells recycle NADH back to NAD+ during fermentation?
by converting pyruvate to lactic acid or to ethanol and carbon dioxide
molecules exiting cells
carbon dioxide, metabolic waste products, cell products
carbon fixation
carbon from CO2 is incorporated into organic molecules first step in Calvin Cycle
long-wavelength photons
carry lower energies
Cells are small because
cells need to exchange nutrients and wastes with their external environment through the plasma membrane
Which energy pathway uses oxygen?
cellular respiration
Which pathway produces the most ATP per glucose molecule?
cellular respiration
Which organelle or structure is found in plant cells?
central vacuole
Which of the following organelles is/are found in animal cells, but is/are absent in most plant cells?
centrioles
The most important reason a particular enzyme can function only within certain limits of temperature, salt conditions, and pH is that __________.
changes in temperature, salt, and pH change the shape of an enzyme
types of cellular work
chemical, mechanical, and transport
captures energy in ATP
chemiosmosis
Where does the electron originate from that is passed to the first molecule of the electron transport chain of photosystem II?
chlorophyll a and a primary electron acceptor
light reactions
chlorophyll and other molecules embedded in the thylakoid membranes of the chloroplast capture sunlight energy and convert it into chemical energy
Light energy is initially captured by "photosystems" within thylakoid membranes. Photosystems are organized arrays of __________.
chlorophyll molecules, pigment molecules such as carotenoids, and proteins
Granum is part of which organelle?
chloroplasts
photosynthesis in plants takes place within
chloroplasts, most contained within mesophyll cells
photosystem
cluster of chlorophyll and proteins found in thylakoids
reaction center
consists of a pair of specialized chlorophyll a molecules and a primary electron acceptor molecule embedded in a complex of proteins
lactate fermentation
converts pyruvate to lactic acid, temporary recourse in most vertebrates, especially in muscular activity
Smooth endoplasmic reticulum
creates lipids or fat no ribosomes
In eukaryotic cells, glycolysis occurs in the __________, and cellular respiration occurs in the __________.
cytoplasm and mitochondria
Where does respiration occur in prokaryotic cells?
cytosol
The second law of thermodynamics relates the organization of matter to energy. It states that unless additional energy is used, the orderliness of a system tends to __________, whereas entropy __________.
decrease; increases
The laws of thermodynamics __________.
define the basic properties and behavior of energy
prokaryotic
describes a cell that does not have a nucleus or anyother membrane-covered organelles; also called bacteria
gradient
difference in certain properties like temperature, pressure, electrical charge, or concentration between two regions
Lysosome function
digestion
The second law of thermodynamics states that __________.
disorder tends to increase over time
In aerobic organisms growing in the presence of oxygen, the NADH produced by glycolysis ultimately donates its high-energy electrons to __________.
electron transport chains in the mitochondria
thylakoids
embedded in the storm, interconnected membrane-enclosed compartments
anabolic reactions are
endergonic
Which of the following transport processes require(s) energy?
endocytosis
accessory pigments
energy absorbing plant pigments other than chlorophyll
A coupled reaction is one in which __________.
energy from an exergonic reaction is used to drive an endergonic reaction
potential energy
energy that is stored
During endocytosis, the contents of the endocytic vesicle __________.
enter the cell
In eukaryotic cells, pyruvate produced by glycolysis is transported into the mitochondrial matrix, where __________.
enzymes for the Krebs cycle break down the pyruvate, producing CO2 as a waste product
Calvin cycle
enzymes in the storm surrounding the thylakoids combine CO2 from the atmosphere and chemical energy from ATP and NADH. the "synthesis" part of photosynthesis
catabolic reactions are
exergonic
the coupled reaction is overall
exergonic
If the products of a reaction have less energy than the reactants, then we say this is a(n) __________.
exergonic reaction
The amino acid threonine is converted to isoleucine by a sequence of five enzymatic reactions. When isoleucine levels are high, the first reaction in this sequence is "turned off." This is an example of __________.
feedback inhibition
vascular bundles
form veins in leaves, supply water and minerals to the leaf's cells and carry the sugar molecules produced during photosynthesis to other parts of the plant
What is the key energy molecule used by nearly all organisms?
glucose
What sugar leaves the Calvin cycle half way around the pathway?
glyceraldehyde-3-phosphate (G3P)
What chemical pathway extracts energy from sugars?
glycolysis and cellular respiration
flavin adenine dinucleotide
high energy electron carrier
energy-carrier molecules
high-energy molecules that are synthesized at the site of an exergonic reaction, where they capture and temporarily store some of the released chemical energy
Function of cytoplasm
holds organelles in place Where most chemical reactions take place supports and protects cell organelles
pH
hydrogen ion concentration
When placed in a certain sucrose solution, the volume of a cell decreases; therefore, the sucrose solution is __________ to the cell contents.
hypertonic
cell theory
idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells
Where are ribosomes synthesized?
in the nucleolus
Membrane fluidity within a phospholipid bilayer is based upon __________.
interactions among nonpolar (hydrophobic) lipid tails
Endoplasmic reticulum
interconnected network of thin, folded membranes that produce, process, and distribute proteins
The plasma membrane of the cell __________.
is permeable to water
a reaction is endergonic if
it requires a net input of energy, if the products contain more energy than the reactants
the energy of a photon corresponds to
its wavelength
In photosynthesis, the ____________ "charge up" ADP and NADP+ energy carriers, and the ____________ use the "charged" energy carriers to make 3-cabon sugars that will be used to make glucose.
light reactions; Calvin cycle reactions
photosystems
light-collecting units of the chloroplast
structure of cell membrane
lipid bilayer of phospholipids and proteins
glycolipid
lipid with carbohydrate attached
plasmids are
located in the cytoplasm
mesophyll cells
loosely packed, allowing air to circulated around them and CO2 and O2 to be exchanged through their moist membranes
denatured
loss of an enzyme's normal shape so that it no longer functions; caused by a less than optimal pH and temperature
entropy
measure of disorder
active transport
requires energy the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.
structure of ATP
ribose (sugar), 3 phosphate groups, and adenine
RUBP
ribulose biphosphate; a five-carbon carbohydrate that combines with CO2 to form two molecules of PGA in the first step of the Calvin Cylce
What are thylakoids?
saclike photosynthetic membranes
Krebs cycle
second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions also known as the citric acid cycle
electron transport chain
series of electron carrier proteins that shuttle high-energy electrons during ATP-generating reactions
light independent reactions
set of reactions in photosynthesis that do not require light; energy from ATP and NADPH is used to build high-energy compounds such as sugar; also called the Calvin cycle
hypertonic solutions
solutions that cause cells to shrink or shrivel due to loss of water
Pepsin is an enzyme that breaks down protein but will not act on starch. This fact is an indication that enzymes are __________.
specific
glycolysis
splits a six-carbon glucose molecule into two molecules of pyruvate
grana
stacks of thylakoids
What leaf structures allow gases to diffuse in and out of the leaf?
stomata
function of ATP
store energy
Potential energy represents __________.
stored energy
Where do the Calvin cycle reactions take place?
stroma
A substance that is acted on by an enzyme to produce a product is called a(n) __________.
substrate
bundle sheath cells
surrounding vascular bundles, lack chloroplasts
The endoplasmic reticulum is needed for the __________
synthesis of proteins and lipids
Ribosomes
synthesize proteins tiny organelles that link amino acids together to form proteins
Sorting and modification of proteins is an important function of __________.
the Golgi apparatus
energy
the ability to do work
feedback inhibition
the activity of an enzyme near the beginning of a metabolic pathway is inhibited by the end product
electromagnetic spectrum
the complete range of electromagnetic waves placed in order of increasing frequency
ATP is well suited to its role as an energy-carrier molecule in cells because __________.
the covalent bond between the last two phosphates can be broken to release substantial amounts of energy
kinetic energy
the energy an object has due to its motion
Acetyl CoA
the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme
intermembrane space
the fluid filled space between the inner and outer mitochondrial membranes
The term carbon fixation refers to __________.
the incorporation of atmospheric carbon dioxide into a larger organic molecule
In eukaryotes, during the process of chemiosmosis, ATP is produced as hydrogen ions move from __________ to __________, passing through __________.
the intermembrane compartment; the matrix; an ATP synthase
law of conservation of energy
the law that states that energy cannot be created or destroyed but can be changed from one form to another
The fluid mosaic model describes membranes as fluid because __________.
the phospholipids and proteins move from place to place within the bilayer
second law of thermodynamics
the physical law stating that when energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes
Where does the membrane of the coated vesicle derived through receptor-mediated endocytosis come from?
the plasma membrane
endocytosis
the process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell
exocytosis
the process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out
chemical reaction
the process by which one or more substances change to produce one or more different substances
chemiosmosis
the process by which some of the energy stored in the concentration gradient of H+ is captured in ATP as H+ flows down its gradient
In endergonic reactions, __________.
the products have more potential energy than the reactants
Photosynthesis and glucose metabolism are related because __________.
the products of photosynthesis are the raw materials for glucose metabolism, and the products of glucose metabolism are the raw materials for photosynthesis
When a drop of food coloring is placed in a glass of water, the spreading out of the molecules of food dye is caused by __________.
the random movement of molecules
reactants
the substances that react in a chemical change
enzyme structure
the substrate enters the active site on the enzyme. the reaction occurs then the products leave the active site. the active site and enzyme are unchanged
a reaction is exergonic if
there is an overall release of heat, if the products contain less energy than the original reactants
Mitochondria structure
•Smooth outer Membrane •Folded inner membrane •Folds called Cristae •Space inside cristae called the Matrix
membrane proteins
proteins that interact with, or are part of, biological membranes
As high-energy electrons are passed from carrier to carrier along the electron transport system in cellular respiration, the electrons lose energy. Some of that energy is directly used to __________.
pump hydrogen ions across a membrane
The end product of glycolysis
pyruvate
The production of what molecule marks the end of glycolysis and the beginning of cellular respiration?
pyruvate
Which molecules are produced in glycolysis and used in fermentation?
pyruvate ... NADH
fermentation
pyruvate is converted either into lactate or into ethanol and CO2, depending on the organism
alcoholic fermentation
pyruvate is converted into ethanol and CO2, converts NADH into NAD+. the anaerobic process by which yeasts and other microorganisms break down sugars to form carbon dioxide and ethanol
substrates
reactants in an enzyme-catalyzed reaction
light dependent reactions
reactions of photosynthesis that use energy from light to produce ATP and NADPH
endergonic
reactions that absorb energy requires energy
exergonic
reactions that release energy
You have just discovered a new plant with red-orange leaves. What wavelengths of visible light are not being absorbed by this pigment?
red-orange
Why is ATP so important to cells?
ATP hydrolysis is exergonic and can be coupled to endergonic reactions.
Suppose that the reactions of mitochondria of a green plant were completely inhibited. What process would immediately be reduced?
ATP production
How is ATP used in cells' energy processes?
ATP synthesis is coupled to an exergonic reaction, the breakdown of glucose.
The energy-harvesting reactions of glycolysis produce four molecules of __________, two molecules of __________, and two molecules of __________.
ATP, NADH, pyruvate
How is it possible for humans to accumulate fat by eating excess sugar?
Acetyl CoA is used as a raw material to synthesize fatty acids that are linked together to form fats.
How are C4 plants different from C3 plants?
C4 plants function better in bright light and relatively dry conditions.
How many ATP are produced each time the Krebs cycle works?
1
functions of membrane proteins
1. Transport 2. Enzymatic activity 3. Signal transduction 4. Cell-cell recognition 5. Intercellular joining 6. Attachment to the cytoskeleton and extracellular matrix
photosynthesis
A process used by plants and other autotrophs to capture light and energy and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates, such as sugars and starches.
What is the overall chemical reaction for photosynthesis?
6 CO2 + 6H2O + light energy → C6H12O6 (sugar) + 6O2
What is the role of coenzyme A (CoA) in cellular respiration?
A carrier molecule for an acetyl group
selective permeability
A property of a plasma membrane that allows some substances to cross more easily than others.
glycoprotein
A protein covalently attached to a carbohydrate.
In the light-dependent reactions of photosynthesis, the difference in hydrogen ion concentration across the thylakoid membrane is used to generate __________.
ATP
pigment
A colored chemical compound that absorbs light, producing color.
concentration gradient
A difference in the concentration of a substance across a distance.
feed back inhibition
A form of metabolic control in which the end product of a chain of enzymatic reactions reduces the activity of an enzyme early in the pathway.
phospholipid function
A lipid that makes up the cell membrane and helps to regulate what enters and leaves the cell
stoma
A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant.
fluid mosaic model
A model that refers to how the lipid bilayer tends to act more like a liquid than a solid.
Cytoskeleton
A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement
Nucleus
A part of the cell containing DNA and RNA and responsible for growth and reproduction
active site
A pocket or groove on the surface of the enzyme.
catabolic
A process in which large molecules are broken down
anabolic
A process in which large molecules are built from small molecules
Energy is stored for chemical reactions in the bonds of __________.
ATP
What are metabolic pathways?
A sequence of chemical reactions in a cell in which the product of one reaction is the reactant for the next
Where does a noncompetitive inhibitor attach on an enzyme molecule?
A site distinct from the active site
isolated system
A system that exchanges neither matter nor energy with its surroundings.
metabolism
All of the chemical reactions that occur within an organism
NADPH
An electron carrier involved in photosynthesis. Light drives electrons from chlorophyll to NADP+, forming NADPH, which provides the high-energy electrons for the reduction of carbon dioxide to sugar in the Calvin cycle.
Rough endoplasmic reticulum
An endomembrane system covered with ribosomes where many proteins for transport are assembled.
What factors in the substrate enzyme interaction promote the specific chemical reaction catalyzed by a particular enzyme?
Substrate orientation and temporary, weak chemical bonds
How much ATP does a person produce and regenerate every day?
Approximately equivalent to their body weight.
How do some anticancer drugs work?
As competitive inhibitors to enzymes in DNA synthesis
metabolic pathway
Begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product.
What is the product of the fermentation of sugar by yeast in bread dough that is essential for the rising of the dough?
CO2
Why is carbon dioxide a key molecule in the light-independent reactions of photosynthesis?
Carbon dioxide is the raw material for the synthesis of sugars in the Calvin cycle, which are the key products of the light-independent reactions.
Vacuole
Cell organelle that stores materials such as water, salts, proteins, and carbohydrates
eukaryotic
Cell with a nucleus (surrounded by its own membrane) and other internal organelles.
What is the principle component of plant cell walls?
Cellulose
Calvin benson cycle
Cyclic carbon-fixing pathway that builds sugars from CO2; the light-independent reactions of photosynthesis.
What is the role of electron transport in ATP synthesis?
Electron transport helps create a proton gradient that is used to supply energy for the synthesis of ATP.
How is electron transport related in chloroplasts and mitochondria?
Electron transport is used in each case to synthesize ATP, although the electron donors and acceptors differ.
During photosynthesis, electrons are continuously lost from the reaction center of photosystem I. What source is used to replace these electrons?
Electrons from the first electron transport chain
membrane function
Encloses cells, regulates passage of materials between cell and surroundings
products
Ending materials in a chemical reaction.
Which of the following correctly lists organelles that are part of the endomembrane system of eukaryotic cells?
Endoplasmic reticulum, Golgi apparatus, and lysosomes
first law of thermodynamics
Energy cannot be created or destroyed
Why is it necessary to invest two ATP molecules during the first stage of glycolysis?
Energy from ATP is used to break a six carbon sugar into two three carbon ones.
Glycolysis can be broken down into what two parts?
Energy investing and energy harvest
activation energy
Energy needed to get a reaction started
Which of the following statements is correct about how enzymes work?
Enzymes catalyze specific chemical reactions because the shape of their active site allows only certain substrate molecules to enter.
Which of the following is not required for the light-independent reactions of photosynthesis?
H2O
Where do the light-independent, carbon-fixing reactions occur?
In the chloroplast's stroma
Where do the light reactions of photosynthesis take place?
In the thylakoid membrane
catalyst function
Increases the rate of a chemical reaction but lowering the activation energy
Cholesterol levels can be a health hazard in human beings, yet cholesterol is an important component of plasma membranes. Why?
Interactions between cholesterol and phospholipids help to stabilize the membrane during temperature fluctuations.
Where are "gatekeeper proteins" found?
Lining the nuclear pores on the surface of nuclei.
How do living organisms battle against disorder?
Living organisms use a continuous influx of solar energy to combat the disorder.
electron carrier
Molecule that can transport energized electrons within the cell
Why do most reactions occur more rapidly at high temperature?
Molecules move more rapidly, allowing for more frequent and forceful collisions between electron shells.
How do molecules such as proteins and RNA enter into or exit from the nucleus?
Molecules move through pores in the nuclear envelope.
What is a catalyst?
Molecules that speed up reactions but are not permanently altered by them
electron carriers
Molecules that transfer electrons.
diffusion
Movement of molecules from an area of higher concentration to an area of lower concentration.
facilitated diffusion
Movement of specific molecules across cell membranes through protein channels
What is the role of NAD+ in glycolysis?
NAD+ molecules accept high energy electrons and are converted to NADH.
What products of the Krebs cycle feed the electron transport chain?
NADH and FADH2 (flavin adenine dinucleotide)
Which of the following represents the products of the light-dependent reactions of photosynthesis? For what process are these products needed?
NADPH and ATP; Calvin-Benson cycle
simple diffusion
Net movement of dissolved particles from higher concentration to a region of lower concentration
What is the arrangement of microtubules in a cross section of cilia or flagella?
Nine fused pairs surrounding one unfused pair
A chloride ion is in a cell that has no channel proteins in its membrane. Will the chloride be able to get out of the cell?
No, there is no channel through which to diffuse
The terms prokaryote and eukaryote both specifically refer to which organelle or structure in the cell?
Nucleus
An investigator identifies an organelle in an unknown cell that has a double membrane. Which organelle could this be?
Nucleus, mitochondria, chloroplast
Where are proteins that are going to be exported from the cell synthesized?
On the rough ER
pyruvate
Organic compound with a backbone of three carbon atoms. Two molecules form as end products of glycolysis
Where is interstitial fluid found?
Outside the cell
If ATP and NADPH are the energy carriers from the light reactions, what are the wastes?
Oxygen
What is the final electron acceptor in the electron transport chain?
Oxygen
Match the type of membrane transport associated with each of the following: oxygen, glucose, chloride ions, water.
Oxygen = simple diffusion, glucose = facilitated diffusion through carrier proteins, chloride ions = facilitated diffusion through channel proteins, water = osmosis
What is the final fate of oxygen that is breathed in during respiration and used in cellular respiration?
Oxygen is converted to H2O.
Why does death result from any situation that prevents a person from breathing?
Oxygen is needed for cellular respiration, so lack of oxygen prevents cells from making sufficient ATP.
What enzyme is initially responsible for capturing CO2 in C4 cells?
PEP carboxylate
What is photorespiration?
Photorespiration is the process that reduces the efficiency of glucose production in C3 plants when CO2 levels are low and O2 levels are high.
Where do living organisms ultimately get the energy to fuel endergonic reactions?
Photosynthesis
Oxygen gas first became available on Earth with the development of __________.
Photosynthetic cells in the seas
Golgi complex function
Receives and modifies newly synthesized polypeptides, synthesizes carbohydrates, adds carbohydrates to glycoproteins; packages cell products into Golgi vesicles
Both facilitated diffusion and receptor-mediated endocytosis require the use of plasma-membrane proteins. What is different about these processes?
Receptor-mediated endocytosis requires the use of energy, while facilitated diffusion does not.
passive transport
Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient
What is the most abundant enzyme on Earth?
Rubisco
Mitochondria function
Site of ATP synthesis; powerhouse of the cell
Chloroplast function
Site of photosynthesis captures energy from sunlight and creates food in the process of photosynthesis
Which of the following types of molecules must pass through membranes via the pores formed by membrane proteins?
Small charged ions such as Na+ and Ca++
Substances are able to cross the lipid bilayer of a cell at different rates that are unique for each substance. Which of the following characteristics would favor the simple diffusion of a substance across a cell membrane?
Small molecule size
stomata
Small openings on the underside of a leaf through which oxygen and carbon dioxide can move
Which organelle would you expect to be in abundance in the liver of a drug addict?
Smooth ER
Kentucky bluegrass is a C3 plant, whereas spiky crabgrass is a C4 plant. Which plant(s) would survive better in the hot and dry conditions of summer?
Spiky crabgrass
mesophyll
Spongy tissue in the interior of the leaf where most chloroplasts are found.
What is the function of the central vacuole?
Store water and wastes, provide turgor pressure to support the cell
Vesicle function
Stores, transports, or digests materials within the cell
How does temperature affect enzyme activity?
Temperature increases enzyme activity.
allosteric regulation
The binding of a molecule to a protein that affects the function of the protein at a different site. the most important mechanism for adjusting the rate at which metabolic reactions occur to meet the needs of the cell
Which of the following situations illustrates the coupling of exergonic to endergonic reactions in cells?
The breakdown of glucose, producing ATP
hydrophobic core
The center of the phospholipids bilayer, that doesn't allow polar molecules to move through
tonicity
The ability of a solution surrounding a cell to cause that cell to gain or lose water.
What exactly is the activation energy of a chemical reaction doing?
The activation energy is needed to overcome the forces present due to the presence of electrons on the molecules.
At the beginning of most recipes for bread, you are instructed to dissolve the yeast in a mixture of sugar (sucrose) and hot water, in some cases with a small amount of flour. Within a short time, this yeast mixture begins to bubble and foam. What is happening?
The bubbles are carbon dioxide that yeast produce as they break down the glucose and produce ATP via fermentation.
Why is a bioartificial organ, based on the patient's own cells, a major advantage in reconstructive surgery?
The immune system is less likely to reject the new cells.
carbon fixation
The initial incorporation of carbon into organic compounds.
What is the linkage between the light and dark reactions?
The light reactions produce ATP and NADPH, and the dark reactions require ATP and NADPH.
A scientist studying photosynthesis illuminated a culture of algae with bright visible light. She then turned out the light and simultaneously began to bubble radioactive CO2 gas into the culture. After 30 minutes, she stopped the reaction and measured the amount of radioactivity inside the cells. What did she find? Explain your answer.
There was radioactivity in the cells, because the CO2 is used to synthesize sugar, even in the dark.
Which of the following statements about mitochondria is true?
They are able to take energy from food molecules and store it in high-energy bonds of ATP.
Which of the following lists the correct order in which newly synthesized proteins are delivered to the plasma membrane?
They are delivered from the endoplasmic reticulum to the Golgi apparatus to the plasma membrane.
When glucose goes through glycolysis and all the way through the Krebs cycle, what is the fate of the six carbon molecules of glucose?
They become carbon dioxide
RuBP regeneration
Three RuBP molecules are regenerated from the remaining five G3P using ATP energy, allowing the cycle to continue.
How is most of the energy extracted from the molecules going through the Krebs cycle?
Through high energy electrons attaching to NAD+ and FAD
How do heavy metals impact enzymes?
Through noncompetitive inhibition of enzymes
White blood cells are attracted to the site of an inflammation. How do they begin to destroy invading bacteria?
Through phagocytosis and the digestion of the bacteria
How do light reactions transfer the captured solar energy to the Calvin cycle reactions?
Through the use of ATP and NADPH
Where does ATP attach in the process of active transport?
To the inside membrane of the active transport membrane protein
How are the electrons lost from photosystem II replaced?
Water is split to yield two electrons, with oxygen and two hydrogen ions as by-products.
A cell is placed in a hypotonic solution. What will happen?
Water will move into the cell
oxidative phosphorylation
When energy is released at each step of the chain is stored in a form the mitochondrion can use to make ATP.
Respiration is the process of gas exchange (breathing in oxygen and breathing out carbon dioxide); cellular respiration is the process of __________.
production of ATP via the electron transport system
In most land plants, photosynthesis occurs in the ________ cells of the leaves, because these cells contain the largest numbers of chloroplasts.
mesophyll
In eukaryotic cells, the enzymes for the Krebs cycle are located in the __________, and those for chemiosmosis are located in the __________.
mitochondrial matrix; inner mitochondrial membrane
phospholipid
molecule that forms a double-layered cell membrane; consists of a glycerol, a phosphate group, and two fatty acids.
catalysts are
neither used up nor permanently altered
anaerobic
no oxygen
epidermis
outermost layer of skin
Choose the substance that will diffuse most rapidly across the plasma membrane.
oxygen
Photorespiration occurs when __________.
oxygen combines with ribulose bisphosphate while the stomata are closed
aerobic conditions
oxygen is present
molecules entering cells
oxygen, sugars, amino acids
photons
particles of light
Recognition proteins function to __________.
permit the cells of the immune system to distinguish between pathogens, such as bacteria, and cells of your own body
Potatoes contain large numbers of __________.
plastids
What determines whether pyruvate goes to cellular respiration or fermentation?
presence or absence of oxygen
pinocytosis
process by which a cell takes in liquid from the surrounding environment
phagocytosis
process in which phagocytes engulf and digest microorganisms and cellular debris cell eating
hypotonic solutions
those with lower solute concentrations and higher water concentrations; cells placed in these solutions gain water; and if they lack a cell wall, may burst
carbon fixation
three RuBP capture three CO2, forming six PGA
Photosystems I and II are contained in the __________.
thylakoid membrane
The function of the mitochondria is __________.
to convert energy from food molecules to high-energy bonds in ATP
Chloroplast structure
two membranes, stacks of thylakoids (called granum) inside surrounded by stroma
For each glucose molecule,
two pyruvate molecules are formed during glycolysis the energy generated per glucose molecule is twice that generate for one pyruvate
short-wavelength photons are
very energetic
Lysosome structure
vesicles containing digestive enzymes
What colors are absorbed by chlorophyll a?
violet-blue and red
hypertonic
when comparing two solutions, the solution with the greater concentration of solutes
hypotonic
when comparing two solutions, the solution with the lesser concentration of solutes
isotonic
when the concentration of two solutions is the same