Exam 2 Flashcards
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is best know as
Feedback inhibition
A strand of DNA is 30% A. What percentage of it is made up of thymine?
30%
What is a passive process in which molecules move from a region of higher concentration to a region of lower concentration
Diffusion
What types of bonds form between the monomers that make up carbohydrates?
Glycosidic
What type of bonds form between the monomers that make up lipids?
Ester
Proteins are polymers made up of monomers known as
Amino acids
How do enzymes increase the speed of certain biological chemical reactions?
By bringing reactants into physical contact with one another
The kinds of molecules that pass through a cell membrane most easily are
Small and hydrophobic
The type of bond that forms between two nucleotides is known as a
Phosphodiester bonds
What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
Catabolic pathways
What is NAD+ reduced to and when?
To NADH during glycolysis, pyruvate oxidation, and the citric avid cycle
What kind of metabolic poison (toxin) would most directly interfere with glycolysis?
An agent that closely mimics the structure of glucose but is not metabolized
In glycolysis, for each molecule of glucose oxidized to pyruvate ________ molecules of ATP are used and ________ molecules of ATP are produced
2
4
The glucose molecule has a large quantity of energy in its _______
C-H bonds
Why might adding inorganic phosphorus to a reaction mixture where glycolysis is rapidly proceeding help sustain the metabolic pathway?
The metabolic intermediates of glycolysis are phosphorylated
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _________
Loses electrons and loses potential energy
Why is glycolysis described as having an investment phase and a payoff phase?
It uses stored ATP and then forms a net increase in ATP
In addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
A strand of DNA is 12% C. What percentage of it is made up of T?
38%
Using only single bonds, how many hydrogen atoms would it take to covalently bond to one carbon atom before molecule would become most stable?
4
A cellular membrane that has no cholesterol molecules dispersed throughout phospholipids. If you were to place this organism in an extremely hot environment, what would you expect to see change in regard to cell membrane permeability?
The membrane would become more permeable to glycerol
What kind of reactions link monosaccharides together to form carbohydrates?
Dehydration/condensation
Product A binds to the enzyme that converts X to Y at a position remote from its activation site. The binding decreases the activity of the enzyme. What is the substance A?
An allosteric inhibitor
What two molecules are the major structural components of the cell membrane?
Phospholipids and Proteins
What do prokaryotes include?
Ribosomes
Simple cytoskeleton
Specialized membranes for photosynthesis and the storage of ions or enzymes
What does a prokaryote have instead of a nucleus?
Nucleoid
What is the shape of chromosomes in prokaryotes?
Circular
What are prokaryote’s cell walls made of?
Peptidoglycan
What do prokaryotes contain?
Nucleoid
Plasmids
Circular chromosomes
What do eukaryotes contain?
Nucleus
Complex organelles
What do prokaryotes and eukaryotes both contain?
Ribosomes
DNA
Cell Wall
Plasma Membrane
You have found that an unknown cell type contains DNA, ribosomes, and circular plasmids. Based off this information you know that….
That it is a prokaryote
What are bacterial cells walls made of?
Peptidoglycan
If you are observing a prokaryotic cell under a microscope, which would you expect to find?
A circular chromosome
And ribosomes
What happens if the surface area to volume ratio is too small?
Then the cell can’t get rid of waste or take up nutrients fast enough
Which is the most ideal set of conditions for a cell?
Small volume and large surface area
What does the endomembrane system include?
Cell membrane Endoplasmic reticulum (rough and smooth) Golgi apparatus Lysosomes Peroxisomes Vesicles
What do ribosomes help with?
Protein synthesis
Where do ribosomes start out?
Free-floating in the cytoplasm
Where are the two places ribosomes can go form the cytoplasm?
- stay in the cytoplasm
- dock with the ER if the protein they are making requires it
What is a ribosome dock based on?
Signal sequence
What does the signal sequence allow a ribosome to do?
To bind to an SRP (signal sequence receptor) which binds to a receptor on the ER
Where does a ribosome go after the ER?
(Phagocytosis)
- packaged into transport vesicles
- sent to the Golgi apparatus
- can then be packaged into lysosomes
What are necessary for the endomembrane system to function properly?
Vesicles
What do vesicles do?
They help transport the products from the ER to the Golgi apparatus and so on
How do vesicles move around the cell so easily?
Motor proteins such as kinesins
What are kinesins made of?
2 subunits twisted together
What is the structure of kinesins?
Has a head, a stall, and a tail
What do the tails of kinesins do?
Bind to the vesicle while the heads bind to the microtuble “highways” throughout the cell
What do the heads of kinesins?
“Walk” along the microtubles, moving the vesicle around the cell
What does each “step” of kinesins require?
ATP
A free floating ribosome attaches to a piece of mRNA in the cytoplasm. When protein synthesis begins, no ER signal sequence is present. What is the final destination of this protein?
It will remain within the cell’s cytoplasm
A protein has been packaged into vesicle to be to be secreted. What signal sequences did the mRNA contain that were integrated into the final protein?
ER signal
A cell acquires a mutation to its DNA that causes the Zip Code and Transmembrane sequences to become unreadable in the final protein? Where is the most likely destination for this protein?
It will be secreted to the outside of cell
Which organelle is NOT directly involved in the Endomembrane system?
Mitochondria
What is the order of events of a protein that has an ER and Zip code signal sequence?
- Protein translation beings with a ribosome
- Protein is synthesized in the rough ER
- Protein is transported in vesicle to the Golgi apparatus
- Protein is transported in vesicle to a lysosome
what is substance that resides within the cell’s plasma membrane, but outside of all other cellular organelles and/or compartments?
cytoplasm
What is cytoplasm thickened with?
with ions, salts, and dissolved polar biomolecules
Which cells so not have a nucleus?
prokaryotic
What resides in the nucleoid?
circular DNA chromosome of these cells compacts with the help of some associated proteins for prokaryotes
What is the nucleus?
Organelle that encapsulates the DNA of eukaryotic cells
What is the nuclear envelope?
the double-phospholipid bilayer on the surface of the nucleus
What is the nucleolus?
darkly stained region within the nucleus
Where can molecules pass through the bilayers of the nucleus’s surface?
nuclear pores
What is a combination of proteins and rRNA that does not have membrane?
ribosome
What do ribosomes do?
Takes information from mRNA and assembles amino acids into a protein (translation)
What is rough endoplasmic reticulum?
Organelle attached to the nucleus that is composed of stacks of flattened, circular membranes that are much like the outer cell membrane
Why is rough ER considered rough?
because the surface of these membranes are studded with ribosomes
What is the function of the rough ER?
the synthesis and packaging of proteins for export to outside of the cell
What is smooth endoplasmic reticulum?
Organelle found directly outside of the rough ER that is also composed of stacks of flattened, circular membranes that are much like the outer cell membrane
Why is smooth ER considered smooth?
because the surface of these membranes are NOT studded with ribosomes
What does smooth ER contain?
enzymes for carbohydrate and lipid synthesis and/or degradation
What is the golgi apparatus?
Organelle found directly outside of the ER that is also composed of stacks of flattened, circular membranes much like the outer cell membrane
What is the function of the golgi apparatus?
receiving vesicles, sorting the contents, and re-packaging the contents into a new vesicle to be shipped to a new location
What are the two sides of the golgi?
cis side and the trans side
What does the cis side of the golgi do?
receives vesicles. Because the membranes are similar to the ER, the vesicles fuse with the golgi and dump their contents inside
What is a lysosome?
Organelle that is a product of the golgi
What makes mitochondria and chloroplasts different from other organelles?
Both have 2 membranes
Have their own DNA
“Reproduce” through binary fusion
Very similar to the traits of prokaryotes
What is outside the plasma membrane?
The extracellular matrix
What does the the extracellular matrix help with?
Cell-cell communication, cell-type identity, self-identify (like in the immune system)
What is the extracellular matrix made up of?
Integrins, microfilaments of the cytoskeleton, collagen fibers, proteoglycan molecules, polysaccharide molecules and proteoglycan complex
How do plant cells communicate?
Channels between cells through cell walls: plasmodesmata
How do animal cells communicate?
Gap junctions: span the space between cells to form a channel, directly connecting the cytoplasm of adjacent cells, allows molecules to pass in between
What do tight junctions do?
Holds the membrane of 2 cells together to prevent anything from leaking in between them
What is lipid soluble signaling?
Lipid soluble signals are able to pass through the membrane
They bind with a receptor inside the cytosol of the cell and can bind directly to the targeted gene on DNA
What are lipid insoluble signals?
Unable to pass through the membrane
Bonds with a receptor protein on the outside of the cell
—signal must be transducers into the cytoplasm where it is amplified so it can bind to the DNA
How do plant cells communicate with each other?
Plasmodesmata
If an animal cell wanted to send molecules to an adjacent cell, which type of a cell-cell communication would it use?
Gap junctions
If a signaling molecule is hydrophobic (like a steroid) how would you expect the signal to interact with the cell?
Passes through the membrane and bonds directly to the DNA
What are the uses of food in the body?
Used for cellular respiration
Used for biosynthesis
How is NAD+ like a rechargeable battery?
Stores energy
Can be used over and over again
Do plants still need to perform cellular respiration?
Yes
Which type of macromolecules are broken down to ultimately make ATP?
All of them
What enzyme splits glucose?
aldolase
Is the majority of the energy from glucose harvested during glycolysis?
No
What is the “ATP math” of glycolysis?
2 used + 4 gained = +2
In what organisms does alcoholic fermentation occur?
yeast and some types of bacteria
What is the product of alcoholic fermentation that is toxic to cells?
ethanol
In what organisms does lactic acid fermentation occur?
animals
What is the product of pyruvte processing?
Acetyl CoA
How many times will the Krebs cycle turn when 1 glucose is used?
Twice
What does the citric acid cycle do?
finishes oxidizing glucose
Are the citric acid cycle and the Kreb’s cycle the same thing?
yes
What does the Krebs cycle start and end with?
Citrate
oxalocetate
What does one spin of the citric acid cycle produce?
2 CO2
3 NADH
1 ATP
1 FADH2
How many of each electron carrier is made by one glucose during aerobic cellular respiration?
10 NADH, 2 FADH2
What part of cellular respiration requires O2?
ETC and Oxidative Phosphorylation
What does the ETC and oxidative phosphorylation use from previous processes?
NADH and FADH2
What is Oxidative Phosphorylation?
the biggest contributor to ATP production
Where does ETC and Oxidative phosphorylation?
across inner membrane of mitochondria
Electrons _____ energy as they’re passed through the ETC
lose
Where does the energy that the electrons lose throughout the ETC go towards?
powering proton pumps, causing H+ ions to pass through the membrane into the inner membrane space
What does the movement of H+ out of the matrix create?
a concentration gradient
H+ _______ through the ATP synthase
passively diffuses
What is phosphorylation?
adding of phosphate group (s)
What does the potential energy created by the gradient become?
kinetic energy
How does the shift of energy happen?
spinning of ATP synthase’s rotor
what does kinetic energy facilitate?
the phosphorylation of ADP
How many H+ ions enter ATP synthase to make 1 ATP?
3
About how many ATP does oxidative phosphorylation create?
34
What other macromolecules does cellular respiration use besides glucose?
larger sugars, lipids, and proteins
During which stage of cellular respiration is O2 used?
Oxidative phosphorylation
Which stage of aerobic respiration does NOT take place in the mitochondria?
Glycolysis
Which stage of cellular respiration produces the most ATP?
Oxidative phosphorylation
What is the summary the cellular respiration?
Glucose -> NADH -> ETC -> proton motive force -> ATP -> cellular work
What are the outputs of cell respiration?
CO2 and H2O
Do animals and plants have mitochondria?
yes
Which consumer will gain the most energy from their meal?
primary consumer
What are the elements of the chloroplasts?
thylakoid and stroma
What is in the thylakoid?
pigments and ETC
What is in the stroma?
liquid and Enzymes for CO2
What reaction occurs in the chloroplast?
Calvin cycle and the ETC
What gives plants their characteristic green coloration?
Chlorophyll
What part of the chloroplast is the primary location of the ETC ?
thylakoid membrane
What are the pigments involved in photosynthesis?
Chlorophyll a
Chlororphyll b
Carentenoids
Why don’t albino plants tend to survive for long?
They reflect all light waves and the ETC can not proceed
What would likely happen if you grew a plant under a green light?
The plant will not grow much at all
Which wavelength/ color of light would provide more energy to the Light-Dependent reactions?
blue
Which would be the most likely result if the ETC in Photosystem I did not fully transport the electrons?
There would not be enough NADPH fro reverse glycolysis to optimally occur
What are the inputs of the Light-Dependent reactions?
ADP, Pi, NADP+, H+, Water
Which processes of the calvin cycle require energy?
Reduction/Reverse Glycolysis
Regeneration of RuBP
What are the inputs of the Light-Independent Reactions?
**
What would be the most likely effect of Rubisco fixing to O2 rather than Carbon in CO2?
No glucose would be produced because of the reduced amount of G3P produced
What are the three experiments relevant to DNA?
- The Griffith Experiments
- The Hershey-Chase Experiment
- The Meselson-Stahl Experiments
Where the rough strain cells able to resurrect the heat-killed smooth strain cells?
no, they did not resurrect the dead cells
What was the difference between the Rough Strain and Smooth strain bacteria?
The Smooth Strain Bacteria had a capsule that protected the bacteria from the immune responses
What was the main idea of the Griffith Experiments?
R cells obtained information from the Heat-killed S cells which allowed the R cells to become living S cells
What is the process of bacteria obtaining foreign DNA from other bacteria?
Transduction
What is the best definition of a bacteriophage?
A type of virus that attack bacteria cells in a parasitic manner
What was the main idea of the Hershey-Chase Experiment?
Capsid portion of bacteriophage stayed on outside of the cell (as seen with the radioactive protein)
Virus DNA was injected into the cell (as seen with the radioactive DNA)
During the Meselson-Stahl experiments, what was the significance of growing bacteria in various mediums containing nitrogen isotopes such as 14N or 15N?
Bacteria will inevitably use the isotopes while synthesizing DNA; therefore placing an identifiable “marker” in the DNA
What was the order of events of the Meselson-Stahl Experiments?
1) Start with bacteria with 15N DNA (Gen 0)
2) Allow Gen 0 to replicate in 14N medium (Gen 1)
3) Allow Gen 1 to replicate in 14N medium (Gen 2)
4) Each generation was centrifuged and DNA was analyzed
What type of bonds hold complementary base pairs together?
hydrogen
Which direction is DNA synthesized?
5’ -> 3’
How do nucleic acids polymerize?
by adding at the 3 carbon
Where will the RNA primer be placed in order to synthesize the other strand?
3’ end
What why do strands run?
anti-parallel
Which protein primes the 3’ end?
primase
Does DNA replication begin at the very end of the strand?
NO
Why does the DNA replication not start at the very end?
it would take too long to replicate the entire genome with just one set of proteins
_________ sites are far more efficient
multiple replicating
What does helicase do?
catalyzes the breaking of hydrogen bonds between base pairs to open the double helix
what do single-strand DNA binding proteins do?
stabilizes single-stranded DNA
What does topoisomerase do?
breaks and rejoins the DNA double helix to relieve twisting forces caused by the opening of the helix
What does the primase do?
catalyzes the synthesis of the RNA primer
What does the DNA polymerase III do?
extends the leading strand
what does the sliding clamp do?
holds DNA polymerase in place during strand extension
If primes failed to place the RNA primer during leading strand synthesis. how will DNA Polymerase III be affected?
fail to synthesize the leading strand properly since it does not have a starting place
What does polymerase I do?
removes the RNA primer and replaces it with DNA
What does DNA ligase do?
catalyzes the joining of Okazaki fragments into a continuous strand
What does telomerase do?
it elongates the end of the lagging strand so a DNA Polymerase can finish its replication
What is a reasonable explanation fro the apparent bending between the mismatched nucleotides?
do not properly form hydrogen bonds with each other
What protein would fix the mistake of the bending between mismatched nucleotides?
DNA Polymerase I
In addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
Inside an active mitochondrion, most electrons follow which pathway?
citric acid cycle → NADH → electron transport chain → oxygen
Which electron carrier(s) function in the citric acid cycle?
NADH and FADH2
Which of the following factors would tend to increase membrane fluidity?
a greater proportion of unsaturated phospholipids
The enzyme that joins the small fragments of the lagging strand together into a continuous strand is called _______.
DNA ligase
What structures have a circular chromosome?
Mitochondria
Chloroplasts
Prokaryotic Cells
During exercise, the body is starving for oxygen which causes multiple changes in the way our cells function. What is/are the possible consequence(s) of this lack of oxygen?
- Pyruvate will be converted to lactic acid causing immediate muscle “burn”
- The electron transport chain begins to stall leaving the cell starving for energy
The light-independent reactions of plants function to make organic molecules using carbon dioxide as a carbon source. What is the electron source that helps reduce carbon dioxide to sugars and other organic molecules?
NADPH
A medical scientist is designing an experiment to test a new anti-cancer drug that she hypothesizes will greatly reduce and possibly eliminate adverse side effects compared to the current treatment. If this experiment is to be set up correctly, she must
Divide the patients into two groups and give one group the new drug and the other group a placebo (or sugar pill)
Replication moves outward from the origin in ________ direction(s) and is said to be ________.
both, bidirectional
An explanation of a fundamental principle developed through extensive and reproducible observations is a
Theory
About twenty-five of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96 percent of living matter?
carbon, hydrogen, nitrogen, oxygen
Although there are three different types of fibers that make up the cytoskeleton, all have the same function inside the cell.
false
You’ve found an unknown substance that you’ve designated Substance X. This substance dissolves in water. Based on this fact, you know that the majority of the bonds in the molecules that make up Substance X can NOT be.
non-polar covalent
Bipasha is studying a new drug, Calcigro, that is suspected to improve bone density. The drug has made it through animal testing and into human trials. Two groups of females have been matched for age, race and health status. Group A is given a pill containing starch and 1000 mg of Calcigro while Group B is given a pill containing starch only. Both groups are following a diet regimen with an intake of 1000 mg of calcium daily.
What is the independent variable?
Contents of the pill
What are the molecules that go into (are the “inputs” for) the electron transport chain and chemiosmosis?
ADP + P
Oxygen
Electrons from FADH2
Electrons from NADH
What are the molecules that go into (are the “inputs” for) glycolysis?
Glucose
ADP + P
NAD+
What are the molecules that go into (are the “inputs” for) the Citric Acid Cycle?
NAD+
Acetyl CoA
ADP (or GDP) + P
FAD+
What statements pertaining to lipid-soluble cells signals are true?
Lipid-soluble signals usually bind to an internal receptor in the cytosol to cause an effect.
Lipid-soluble signals can usually be transported directly through the cellular membrane.
Semiconservative replication involves a template. What is the template?
one strand of the DNA molecule
In an analysis of the nucleotide composition of DNA, which of the following will be found?
A + C = G + T
Which of the following reactions is the correct description of the beginning of the Citric Acid (Kreb’s) Cycle?
Acetyl CoA + oxaloacetate → citrate
Where does Glycolosis take place in eukaryotic cells?
Cytoplasm (Cytosol)
What are the final products (or “outputs”) of the Citric Acid Cycle?
CO2
ATP
FADH2
NADH
What are the final products (or “outputs”) of the Electron Transport Chain and Chemiosmosis?
Water
ATP
FAD+
NAD+
What are the final products (or “outputs”) of glycolysis?
ATP
NADH
Pyruvate
Dihydrofolate reductase catalyzes the reaction that breaks down folic acid into cofactors to create nucleotides. The reaction is inhibited by methotrexate (which resembles folic acid, but cannot be catalyzed by dihydrofolate reductase). Increasing the ratio of folic acid to methotrexate reduces the inhibitory effect of methotrexate.
Dihydrofolate reductase is the enzyme and folic acid is the substrate.
What will be able to cross the phospholipid bilayer of a cell membrane without the assistance of a membrane protein?
A small nonpolar molecule (e.g. CO2)
Which polysaccharide has the main function of energy storage in plants?
Starch
A cell, after undergoing glycolysis, takes the products from these reactions and immediately begins alcoholic fermentation. Which of the following cell types could achieve the above scenario?
A yeast cell
A prokaryotic cell
The DNA strand growing toward the replication fork grows ______ in a 5’—>3’ direction as the replication fork advances and is called the ________.
continuously, leading strand
What are the “outputs”, or products, of the light-dependent reactions of photosynthesis?
NADPH
Oxygen
ATP
What are the final products (or “outputs”) of the light-dependent reactions of photosynthesis?
O2
ATP
NADPH
How are the light-dependent and light-independent reactions of photosynthesis related?
The products of light-dependent reactions are used in light-independent reactions.
The electron carrier NAD+ undergoes _____ to form ____.
reduction
NADH
Chitin is a major component of the ________.
exoskeleton of insects
What are the differences between DNA and RNA?
- The sugars differ between the nucleotides found in each.
- One is most often double-stranded, while the other is usually single-stranded.
- There are differences in the nitrogenous bases found in the nucleotides of each
What organelle contains enzymes for the synthesis of lipids?
Smooth ER
Which of the following characteristics, structures, or processes is common to bacteria and viruses?
genetic material composed of nucleic acid
Put the following steps of DNA replication in chronological order.
- Hydrogen bonds between base pairs of antiparallel strands are broken
- Single-stranded binding proteins attach to DNA strands
- Primase binds to the site of origin
- An RNA primer is created
- DNA polymerase binds to the template strand
Bonds between two atoms that are equally electronegative are ________
nonpolar covalent bonds
What are the molecules that go into (are the “inputs” for) pyruvate processing?
NAD+
Pyruvate
Which of the following is TRUE of osmosis?
In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration
A cell, after undergoing glycolysis, takes the products from these reactions and immediately shuttles them to the mitochondria for processing. Which of the following cell types could achieve the above scenario?
A human muscle cell
A prokaryotic cell
In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the ________.
stroma to the thylakoid space
Cellulose is ________.
a major structural component of plant cell walls
Bacteria are grown in a medium containing 15NH4Cl for a number of generations so that all of the DNA is made of fully “heavy” DNA. The bacteria are moved to a new medium and grown in 14NH4Cl so that all new DNA will be “light”. If replication were dispersive, what would the DNA look like after one generation time.
Each strand is made of a mixture of “heavy” and “light” DNA with each strand being about 50% “light”.
What statement best represents the relationships between the light reactions and the Calvin cycle?
The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, P, and NADP+ to the light reactions.
A bacterial cell suddenly stops creating protein, even though the DNA is still present and in working order. Which organelle’s malfunction would be responsible for this result?
Ribosomes
