Protein Transport & Exergonic Reaction – Biochemistry
This chapter of Biochemistry is about protein transport and exergonic and reaction.
What led Walter to study the mass extinction of the dinosaurs?
He was following in the footsteps of his mentor, a famous paleontologist
He has previously measured the amount or iridium in the KT boundary
While collecting magnetic samples, he observed some unusual rock markings indicating the KT boundary – correct
While playing with a small child, he began to wonder what had caused the extinction of the dinosaurs
After his surprising observation in the Appenes Mountains, the first scientific question Walter set out to answer was whether the extinction had happened gradually overtime or suddenly. To do this, they measured the concentration of Iridium in the KT boundary.
Match the hypothesis to the expected outcome and the actual results.
Clay was deposited slowly, gradual event
About .1 atoms of Iridium/biollion – correct
Clay was deposited rapidly, sudden event
No Iridium – correct
Actual results (surprise!)
3 atoms of Iridium/billion – correct
The very high levels of Iridium at the KT boundary was confirmed in different parts of the world and supported an already existing hypothesis, a supernova had caused the extinction. How was this hypothesis tested?
Scientists looked for planetary evidence of a supernova
Scientists ruled out all the other hypothesis and only the supernova was left
Scientists tested the amount of plutonium in the KT boundary – correct
Scientists studied craters from ancient asteroids
Initially, Michel and Asaro found plutonium with the iridium in the KT boundary. Which important feature of science proved they were incorrect?
Which observations finally lead to the hypothesis that an asteroid had hit the earth at the KT boundary?
High levels of iridium- correct
Evidence of a mass extinction of global scale- correct
Absence of plutonium- correct
High levels of plutonium
Absence of iridium
How was community feedback important in developing the asteroid hypothesis?
Working alone allowed Walter to remain unbiased
Scientists working together were able to prove all the alternate hypotheses wrong
Scientists collected multiple lines of evidence from different fields to support the hypothesis- correct
Other scientists were able to disprove the asteroid hypotheses
Match each prediction to the type of evidence collected by scientists to support the asteroid hypothesis.
If an asteroid impact had actually caused a global ecological disaster, then we should find many fossils before the KT boundary and few afterwards.
If a huge asteroid had struck Earth at the end of the Cretaceous, the we should be able to find quartz with deformations at the KT boundary.
Shockwaves – correct
If a huge asteroid had struck Earth at the end of the Cretaceous, it would have generated a lot of heat, melting rock, and flinging particles away from the impact site.
If a huge asteroid had struck Earth at the end of the Cretaceous, then we should be able to find the impact site.
If a huge asteroid had struck Earth at the end of the Cretaceous, then we should find bebris flung from the impact site at the KT boundary.
Impact debris– correct
If a huge asteroid had struck one of Earth’s oceans at the end of the Cretaceous, the we should find debris beds containing ocean sediments at the KT boundary.
Tsunami debris– correct
The evidence that an asteroid did hit earth at the KT boundary is strong. But did it cause extinction of the dinosaurs? What additional hypotheses are scientists investigating?
Climate Change– correct
Tectonic Activity– correct
Choose the correct statements.
Many scientific questions were answered- correct
There are no alternate hypotheses that explains the extinction of the dinosaurs
We cannot be 100% certain that an asteroid killed the dinosaurs- correct
Walter’s hypothesis remained the same throughout his journey
While making observations and discussion within the scientific community were vital to this story, which part of the scientific process pushed the process forward? Hint: study the figure on page 11.
Testing Ideas- correct
Which of the following is both in eukaryotic and prokaryotic cells?
In plant cells, the function of the lysosomes is carried out by __________.
Which of the following is not a component of the endomembrane system?
Which of the following do not play a role in intracellular movement?
microfilaments and intermediate filaments
microfilaments and microtubules
intermediate filaments and microtubules
only intermediate filaments– correct
Which of the following are only in plant cells?
Valerie is a studious 15 year old who is also a valuable member of her school’s field hockey team. They are 15-1 this year and have a chance at winning the state championship. However, Valerie recently began feeling ill with noticeable signs of a high fever. After several days, her parents decided to take her to the ER and the attending physician admitted her to the hospital with an ongoing bacterial infection. After several more days, doctors are perplexed that her body is unable to fight off the infection. They decide to take a blood sample and have it sent to the lab for analysis. Lab results indicate that the vacuoles in her white blood cells are successfully trapping the bacteria. However, the bacteria are not being digested by the cell.
Which organelle is likely disrupted?
Jim and Lisa have lived in the state of New Jersey most of their lives. They are both in their early 30’s and recently married. They have been trying to have their first child for a number of months but Lisa has been unable to get pregnant. Recently, Jim and Lisa decided to go to their family physician to see if there may be something wrong. The physician obtained a sample of Jim’s sperm cells and had it sent to a lab for microscopic analysis. After several days, the physician received a micrograph of the sperm cells and noted a structural defect in the organelle responsible for cell movement. Analyze the micrograph below and determine the organelle responsible for Jim and Lisa’s inability to have a baby. Which organelle is likely defective?
Mary is a fifty-five year old female, who arrived in the ER at 4:35 p.m. with complaints of severe fever and pain. The attending physician took blood work and revealed that there was a high concentration of oxidative enzymes in the blood such as catalase, D-amino acid oxidase, and uric acid oxidase. In addition, there were relatively high levels of fatty acids in the blood, which the physician suggested they were not being properly metabolized. A density gradient procedure found that an organelle approximately 0.5 microns in diameter was missing. The physician also diagnosed Mary with having gout in the joints in her hands and feet, a condition which is caused by the accumulation of uric acid. That same night around 11:00 p.m., Mary began to lose feeling in her lower back. The doctors performed a routine spinal tap (ST) to see if there was an infection in her cerebral spinal fluid. This test turned out to be negative; however, the attending physician did take a biopsy which revealed the nerve cells in Mary’s back were not producing enough myelin, a dielectric material needed for proper nervous system signaling. Which organelle is likely defective?
Lauren is a senior at a nearby high school. She is a good student who does her work on weekdays and likes to party on the weekends with her friends. A few months ago, Lauren developed a persistent cough that has worsened over time. She has also had trouble breathing over the past week or so. Her parents decided it was time she see a doctor and made an appointment with the family physician. Lauren arrived at the doctor’s office the following day. The doctor asked her a number of questions about her health history and daily habits, including, whether or not she smoked cigarettes. Lauren responded that she started smoking cigarettes (about 2 per day) her freshman year of high school and does not intend to quit anytime soon. The doctor decided it was necessary to take a biopsy of the cells that line the bronchus (passageway to the lungs). After several days, the biopsy report has come back along with a micrograph of the bronchial cells. Lauren’s cigarette smoking has badly damaged these organelles which are responsible for mucous and dirt moving up-and-out of her respiratory system. Analyze the micrograph below and determine what cell organelles have been damaged.
Olivia is a sixteen year old track star at a local school nearby. She arrived in the ER at 5:03 p.m. with complaints of extreme muscle weakness and loss of muscle coordination, particularly in her arms and legs! She told the attending physician that for the past few days, she had been pretty exhausted with little energy to do anything. Blood taken did show one particular abnormality. Her glucose levels were rather high although she was an athlete and did mention she ate carbohydrates the night before a race. However, this notion could be dismissed since she did not have a race in the past week. The doctors concurred that something else must be going on to render such high glucose levels (i.e. something was not breaking down these sugar molecules). In addition, the doctors ordered for a muscle biopsy to be performed. After viewing the tissue sample under the microscope, the doctors saw that the muscle fibers were ragged red which contained mild accumulations of glycogen and decreased activity for the enzyme cytochrome c oxidase.
Which organelle’s function is likely disrupted?
For a protein to be an integral membrane protein, it would have to be ________.
amphipathic, with at least one hydrophobic region- correct
exposed on only one surface of the membrane
Which characteristic of a phospholipid contributes to the fluidity of the membrane?
saturated fatty acid tail
A double bond in the fatty acid tail- correct
What kinds of molecules pass through a cell membrane most easily?
large and hydrophobic
small and hydrophobic- correct
small and ionic
In which situation would passive transport not use a transport protein for entry into a cell?
water flowing into a hypertonic environment
glucose being absorbed from the blood
an ion flowing into a nerve cell to create an electrical potential
oxygen moving into a cell after oxygen deprivation- correct
Which of the following statements correctly describes osmosis?
Osmosis only takes place in red blood cells.
Osmosis is an energy-demanding or “active” process.
In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. – correct
In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration.
The force driving simple diffusion is ________, while the energy source for active transport is ________.
a concentration gradient; ADP
a concentration gradient; ATP hydrolysis- correct
transmembrane pumps; an electrochemical gradient
phosphorylated carrier proteins; ATP
What is the combination of an electrical gradient and a concentration gradient called?
electrochemical gradient- correct
In what important way does receptor-mediated endocytosis differ from phagocytosis?
It transports only small amounts of fluid.
It does not involve the pinching off of membrane.
It brings in only a specifically targeted substance. – correct
It brings substances into the cell, while phagocytosis removes substances.
Which of the following molecules is likely to have the most potential energy?
Determine if each of the following is endergonic or exergonic.
Hydrolysis of ATP
A reaction causes an increase in disorder (entropy)
Dehydration reaction to build a triglyceride
A decrease in the disorder (entropy) of the cell
Catabolism of carbohydrates in muscle cells
Anabolism of peptide chains
Diffusion of glucose across the plasma membrane through a channel protein
Products have a higher free energy than the reactants
endergonic – correct
Reactants have a higher free energy than the products
exergonic – correct
The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following represents the activation energy required for the enzyme-catalyzed reaction in the figure?
Which of the following statements describes a central role that ATP plays in cellular metabolism?
Hydrolysis of ATP provides an input of free energy for exergonic reactions.
ATP provides energy coupling between exergonic and endergonic reactions. – correct
Hydrolysis of the terminal phosphate group stores free energy that is used for cellular work.
Its terminal phosphate bond is stronger than most covalent bonds in other biological macromolecules.
Which of the following is not true about enzymes:
They increase ∆G of reactions. – correct
They are usually made of amino acids.
They lower the activation energy of chemical reactions.
Each one is specific to the particular substrate(s) to which it binds.
An allosteric inhibitor does which of the following?
Binds to an enzyme away from the active site and changes the conformation of the active site, increasing its affinity for substrate binding.
Binds to the active site and blocks it from binding substrate
Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate. – correct
Binds directly to the active site and mimics the substrate.
Choose the correct options to label the mitochondria below.
Inner mitochondrial memebrane
Outer mitochondrial membrane
In which reactions of cellular respiration does oxidative phosphorylation occur? Choose ALL the correct choices.
Citric Acid Cycle
Electron Transport Chain- correct
Fill in the Blank.
- Each molecule of NAD+ can accept 2 ________ and 1 _________ .
- Each molecule of FAD can accept 2 electrons and ________.
proton – correct
hydrogen atoms- correct
Fill in the blanks with the choices below.
- During the citric acid cycle, NAD+ is Reduced to NADH.
- During Cellular Respiration, glucose is Oxidized to carbon dioxide.
- During Cellular Respiration, oxygen is reduced to Water .
- At the electron transport chain, NADH is oxidized to NAD+ .
Which kind of metabolic poison would most directly interfere with glycolysis?
an agent that reacts with oxygen and depletes its concentration in the cell
an agent that binds to pyruvate and inactivates it
an agent that closely mimics the structure of glucose but is not metabolized- correct
an agent that reacts with NADH and oxidizes it to NAD+
In glycolysis, for each molecule of glucose oxidized to pyruvate, ___
two molecules of ATP are used, and two molecules of ATP are produced
two molecules of ATP are used, and four molecules of ATP are produced- correct
four molecules of ATP are used, and two molecules of ATP are produced
two molecules of ATP are used, and six molecules of ATP are produced
If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl CoA?
All of it
Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?
1 ATP, 2 CO2, 3 NADH, and 1 FADH2
3 ATP, 3 CO2, 3 NADH, and 3 FADH2
3 ATP, 6 CO2, 9 NADH, and 3 FADH2- correct
6 ATP, 6 CO2, 3 NADH, and 12 FADH2
How many NADH molecules are produced on each turn of the citric acid cycle?
Which of the following statements best describes the primary role played by oxygen in cellular respiration?
It yields energy in the form of ATP as it is passed down the electron transport chain.
It oxidizes glucose to form two molecules of pyruvate.
It serves as an acceptor for carbon, forming CO2 in the citric acid cycle.
It serves as the final acceptor for electrons from the electron transport chain. – correct
Which of the following maintains the proton gradient across in the inner mitochondrial membrane? Choose ALL the correct choices.
The ETC pumps protons into the matrix
The ETC pumps protons into the inner membrane space- correct
Water is formed in the matrix reducing the hydrogen concentration in the matrix- correct
Water is formed in the matrix increasing the hydrogen concentration in the matrix
Water is formed in the inner membrane space increasing the hydrogen concentration in the inner membrane space
Water is formed in the inner membrane space decreasing the hydrogen concentration in the inner membrane space
Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration?
glucose → NADH → electron transport chain → oxygen – correct
glucose → pyruvate → ATP → oxygen
glucose → pyruvate → electron transport chain → NADH → ATP
food → glycolysis → citric acid cycle → NADH → ATP
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the production of which of the following sets of molecules?
ATP, CO2, and ethanol (ethyl alcohol) – correct
ATP, CO2, and lactate
ATP, NADH, and ethanol
ATP, CO2, and acetyl CoA
Match the following to label the diagram of the chloroplast.
In a plant, which of the following reactions produce molecular oxygen (O2)?
the light reactions alone- correct
the Calvin cycle alone
the light reactions and the Calvin cycle
neither the light reactions nor the Calvin cycle
Plants containing only chlorophyll b are exposed to radiation with the following wavelengths: 10nm (x-rays), 450nm (blue light), 670nm (red light), and 800nm (infrared light). Which plants harness the most energy for photosynthesis?
X-ray irradiated plants
Blue light irradiated plants- correct
Red light irradiated plants
Infrared irradiated plants
Match the following to label the diagram.
Light Harvesting Complex
Primary Electron Acceptor
Pigment Molecules (e.g. chlorophyll a, chlorophyll b, beta-carotene)
From which component of the light-dependent reactions does NADPH form most directly?
photosystem I – correct
What happens to the free energy released as electrons are passed from photosystem II to photosystem I through a series of electron carriers?
It excites electrons of the reaction center in photosystem I.
It is used to establish and maintain a proton gradient. – correct
It is used to synthesize ATP through substrate-level phosphorylation.
It is used to phosphorylate NAD+ to NADPH.
Which of the following events accompanies absorption of energy by pigment molecules of the light harvesting complex?
ATP is synthesized from the energy absorbed.
An electron is excited. – correct
NADP+ is reduced to NADPH.
A molecule of water is split.
Which complex is not involved in the establishment of conditions for ATP synthesis?
photosystem I – correct
Which order of molecular conversions is correct for the Calvin cycle?
RuBP + G3P → 3-PGA → sugar
RuBisCO → CO2 → RuBP → G3P
RuBP + CO2 → [RuBisCO] 3-PGA → G3P- correct
CO2 → 3-PGA → RuBP → G3P
Which molecule must enter the Calvin cycle continually for the light-independent reactions to take place?
Which of the following processes occurs during the Calvin cycle?
oxidation of NADPH- correct
release of oxygen
production of CO2
production of ATP
CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they ________.
fix CO2 into organic acids during the night- correct
fix CO2 into sugars in the bundle-sheath cells
fix CO2 into pyruvate in the mesophyll cells
use photosystem I and photosystem II at night
When an enzyme catalyzes a chemical reaction, it will lower the:
activation energy needed for the reaction to occur. – correct
free energy stored in the products.
change in free energy of the reaction.
free energy stored in the reactants.
energy present in the system.
During the light-dependent reactions of photosynthesis (PS = Photosystem):
Water is split to supply electrons to PS II. – correct
NADP+ reductase functions right after PS II.
Electrons originally in water end up in ATP.
Electrons from the electron transport chain get transferred to oxygen.
Light energy is used to pump protons inside PS I.
Electron transport chains (ETCs) are used to make ATP in both chloroplasts and mitochondria. Which of the following is correct?
In mitochondria, protons are pumped across a membrane, but in chloroplasts, electrons are pumped.
In the mitochondria, electrons from the ETC end up in ATP.
The mitochondrial ETC is in an inner membrane, but the chloroplast ETC is in the outer membrane.
In chloroplast ETCs, the electrons originally come from water. – correct
In chloroplasts, electrons end up in water after the ETC, but in mitochondria, they end up in oxygen.
Which of the following will increase the fluidity of a phospholipid bilayer at low temperature?
Replacing carbon atoms with a heavier isotope of carbon.
Adding trans double bonds to the phospholipids.
Reducing the amount of cholesterol in the membrane.
Exposing both sides of the bilayer to different concentrations of a polar solvent.
Adding cis double bonds to the phospholipids. – correct
Small particles and liquids are taken into cells by:
Two different systems are shown for transporting solutes across membranes. In the first system, sodium and potassium ions (Na+ and K+) are moved up their concentration gradients, in opposite directions, using energy from ATP hydrolysis. In the second, protons move from high to low concentration, which allows transport of sucrose in the same direction, up its concentration gradient. Which is a correct statement?
System 2 uses a channel protein.
Systems 1 and 2 are both examples of active transport- correct
System 1 is active transport, and system 2 is passive transport.
System 1 is exocytosis, and system 2 is endocytosis.
System 2 is an example of facilitated diffusion.