Final Exam Flashcards
You are a pathologist in training. You look at a slide that contains a skin lesion. There are many abnormal cells that have a diameter of approximately 3 um.
You predict these are:
invading prokaryotic cells causing an infection
What is true of electron microscopes?
they require that samples be treated with solutions that contain metal before imaging
Which is true about eukaryotes and prokaryotes?
eukaryotes CONTAIN mitochondria, but prokaryotes do NOT
In water, polar covalent bonds are found:
between a hydrogen atom and an oxygen atom WITHIN a water molecule
Condensation reactions _____________.
create new water molecules
What is the correct expression that accurately describes the calculation of pH?
pH = -log10[H+]
How does the chemical structure of phospholipids suit their function in the cell membrane?
-self assemble so that polar head groups associate with water molecules through hydrogen bonding
-polar molecules cannot easily cross as the interior of the membrane bilayer is hydrophobic
-self assemble so that water is excluded from the interior of the bilayer (hydrophobic exclusion
-aqueous solution within a cell is mostly separated from the external environment because the phospholipids form a bilayer
Your temperature is 100 F, give or take a few degrees.
What is true of this observation?
the heat released from your body contributes to the increasing disorder in the universe
A cell breaks down molecules to obtain energy.
What is a characteristic most likely associated with this process?
exergonic, catabolism, hydrolysis reactions
Imagine you are studying acetylcholinesterase activity isolated from rat brains. You determine that an acetylcholinesterase-catalyzed reaction has a deltaG = -80 kcal/mol. You decide to REPEAT the experiment and add TWICE as much of the enzyme.
What do you predict the deltaG to be?
-80 kcal/mol
*STAYS THE SAME!
A drug (Lisinopril) sits directly in the active site of an enzyme so that the normal substrate cannot bind.
What is this type of enzymatic inhibition called?
Competetive inhibition
What do protein alpha helices involve?
hydrogen bonding between carboxyl (carbonyl) and amino groups of different amino acids
What are proteins that are allosteric?
their activity is regulated by shifting between 2 or more confirmations (shapes)
Disulfide bridges on the same polypeptide chain are examples of a protein’s ______________.
HINT: structure
tertiary
A protein such as hemoglobin, which is composed of more than one polypeptide chain has ______________ structure.
quaternary
Within the subunits of hemoglobin, there is specific coordination of a heme (iron-containing) groups that are part of the proteins O2-binding ______________.
domain
Does a Kinase add or remove a phosphate group. What does Phosphatase do?
Kinase ADDS phosphate
Phosphatase REMOVES phosphate
TRUE/FALSE: Protein domains are only found in proteins with quaternary structure
False
Consider a 3-letter sequence of DNA that is transcribed to mRNA and eventually translated to become an amino acid.
When would a mutation in this DNA be LEAST likely to cause a problem?
if both the mutant and original amino acids are both non-polar
In the test zone of an ELISA Assay (e.g. pregnancy test), what is NOT present?
polyclonal antibodies that are specific to monoclonal antibodies
TRUE/FALSE: Spontaneous reactions occur rapidly even when no enzyme is present
False
TRUE/FALSE: If a molecule if reduced, the molecule has acquired more electrons
True
TRUE/FALSE: A biological example of the first law of thermodynamics is the proton gradient in mitochondria driving ATP synthesis in oxidative phosphorylation
True
TRUE/FALSE: Enzymes may denature when the salt concentration of a solution is changed
True
What contains most of the “dry weight” of a cell?
proteins
What are non-polar, made of carbon ring structures or long hydrocarbon chains?
lipids
What is made of carbon, hydrogen, and oxygen, and used for structural support and a ready energy source
polysaccharides
What is a polymer that contains phosphorus?
DNA
Give 3 examples of how ATP is used in a living cell.
- For proteins in the membrane to open up for molecules (e.g. Na/K pump)
- To allow an enzyme to add a phosphate group to a protein (turning it into and active/inactive state)
- Allow for the “power stroke” to occur within a myosin filament (contraction)
Name an example of an integral membrane protein
Bacteriorhodopsin
What cell types would you expect to have the HIGHEST relative amount of saturated phospholipids in its plasma membrane?
an extremophilic bacterium that lives in boiling, sulfuric pools
Within the cell membrane, a protein that is attached to a sugar group is called a ____________
glycoprotein
What is true regarding the carbohydrate later of glycolipids, glycoproteins, and proteoglycans?
- makes up the extracellular (non-cytosolic) side of the plasma membrane
-helps to protect the cell from friction and mechanical abrasion
-allows cell-cell recognition
-allows cell-cell adhesion
What is true about voltage-sensing ion channels?
their voltage sensor domain contains positively charged amino acids
What is true of experiments described in the Caterina et al. paper that described the discovery of VR1 (known now as TRPV1)?
researchers discovered that VR1 is activated by HOT TEMPERATURES
What is true of the experimental strategy used in the Caterina et al. paper that descrived the discovery of VR1 (known now as TRPV1)?
VR1 DNA was expressed in HEK293 cells and electrical responses were measured
Compared to the cytosol, the extracellular fluid in animals generally ________________.
has more glucose, more sodium, and more calcium
The non-cytosolic face of the cell membrane ___________
- contains glycolipids
-contains sphingomyelin
-is found on the inside of the intracellular vesicles
-faces the ER lumen during membrane synthesis
Ouabain is a toxin from the foxglove plant that inhibits the Na/K pump.
What would be the most reasonable prediction of the effects of this toxin on a neuron?
resting membrane potential becomes depolarized (moves closer to 0mV)
Defects in peripheral membrane proteins, such as spectrin, may lead to:
-problems with red blood cells
-cells that cannot withstand mechanical stress
-defects in cell shape
-anemia
Imagine the inside of a cell contains 0.95 mM glycine and outside of the cell contains 0.60 mM glycine. The cell membrane is impermeable to glycine
In this example, you would expect WATER to _______ the cell.
Enter
What channel would NOT be expected to generate a change in voltage by movement of its substrate/solute across the membrane?
-aquaporin
-sodium channel
-calcium channel
proton (H+) channel
aquaporin
TRUE/FALSE: Adding cholesterol to a cell membrane will generally make it more rigid
True
*Sometimes in high temps
TRUE/FALSE: Osmosis is an example of active transport
False
TRUE/FALSE: Flippase activity is generally required for phospholipids that assume a final position in the extracellular face of the cell membrane
False
*Cytosolic Face
During the RISING PHASE of an action potential, what is occurring?
voltage-gated sodium channels open, allowing sodium to enter the cell
During the PEAK of an action potential, what is occurring?
equilibrium potential of sodium is reached
During the FALLING PHASE of an action potential, what is occurring?
voltage-gated potassium channels open, allowing potassium to exit the cell
During the LOWEST POINT of an action potential, what is occurring?
equilibrium potential of potassium is reached
During the RETURN TO RESTING MEMBRANE POTENTIAL of an action potential, what is occurring?
potassium flows through leaky channels, membrane potential is becoming more depolarized
During the RESTING MEMBRANE POTENTIAL of an action potential, what is occurring?
voltage-gated channels are closed, membrane potential is constant
What has a delayed activation in response to a depolarizing stimulus?
Voltage-gated potassium cahnnel
What actively transports calcium ions out of the cell?
Calcium ATPase
What transports sodium AGAINST its concentration gradient?
Sodium-potassium ATPase (Na/K pump)
What transports glucose AGAINST its concentration gradient?
Sodium-glucose transporter 1
The ___________ is made of actin, spectrin, and other proteins. It is a structure that is important for membrane integrity. It is found on the ____________ side of the cell membrane
Cell Cortex
Intracellular
New phospholipids are added in the ______________ to the __________ face of the pre-existing membrane
Endoplasmic Reticulum
Cytosolic
What is the result of the transition step in aerobic respiration (pyruvate oxidized to acetyl CoA)?
NADH is produced
Which protein is involved in the active pumping of protons across the inner membrane of the mitochondria?
cytochrome c oxidase
Redox reactions happen in many metabolic pathways.
As a molecule is oxidized, what is a possible effect on that molecule?
-electrons are lost from the molecules
-single covalent bonds become less common and double-covalent bonds become more common
-the molecule will contain fewer numbers of atoms
Each molecule of NADH in the mitochondria can provide enough energy to produce up to how many molecules of ATP?
2.5
By the end of the Krebs Cycle, most of the energy remaining from the original glucose will eventually be used to power the cell is stored as ______________.
NADH
During the oxidation of pyruvate to acetyl CoA, what is produced?
NADH and CO2
Several different classes of enzymes are needed for the catabolism of carbohydrates.
What best describes the functions of an ISOMERASE, an enzyme that catalyzes _____________.
the rearrangement of bonds within a single molecule
What is true of glycolysis?
it results in the net creation of 2 molecules of ATP per molecule of glucose
What process generates the most ATP?
Electron Transport Chain followed by ATP synthase
What is true of NADH that is produced in the cytosol?
-requires 1 molecule of ATP to transport these NADH into the mitochindira
-can be used during fermentation
-can be used in the ETC
For a single molecule of pyruvate imported into the mitochondria, what is directly produced by the Krebs Cycle?
1 GTP
3 NADH
1 FADH2
How many molecules of ATP can be produced during oxidative phosphorylation from 4 NADH (assuming that the NADH is produced in the mitochondria)?
10 ATP
4 x 2.5 = 10 ATP
Normally, if a person is eating a strictly keto diet (very low carbs) what is happening to their circulating insulin and glucose levels?
Both would be LOW
Under conditions where a person is eating a strict keto diet, what describes alterations to their metabolism?
acetyl CoA is converted to ketones
What is true regarding the changes to metabolism that occur on a strict keto diet?
ketones are produced by the liver to provide energy to other tissues
TRUE/FALSE: NADH is more reduced than NAD+
True
TRUE/FALSE: Glycolysis occurs in the mitochondrial matrix
False
*occurs in cytosol
TRUE/FALSE: Oxygen is more electronegative than any of the proteins in the ETC
True
*it is the final acceptor
What is the appropriate statement for the following enzyme:
Phosphofructokinase
glycolytic enzyme that adds a phosphate group
What is the appropriate statement for the following enzyme:
NADH dehydrogenase
ETC enzyme that moves protons into the intermembrane space of mitochondria
What is the appropriate statement for the following enzyme:
Hexokinase
glycolytic enzyme that traps glucose inside the cell
What is the appropriate statement for the following enzyme:
Lipase
breaks down fatty acids
What is the appropriate statement for the following enzyme:
Pyruvate Dehydrogenase
converts pyruvate to acetyl CoA
What is the appropriate statement for the following enzyme:
Glycogen Phosphorylase
breaks down glycogen
What is the appropriate statement for the following enzyme:
Fatty Acid Synthase
builds fatty acids
What is the appropriate statement for the following enzyme:
HMG CoA Reductase
part of the cholesterol synthesis pathway
What is the appropriate statement for the following enzyme:
Acetyl CoA Carboxylase
builds precursors to fatty acids from acetyl CoA
List the following proteins of the ETC proteins by the order that electrons from NADH encounter them
Cytochrome c oxidase
Cytochrome c
Ubinquinone
NADH dehydrogenase
Cytochrome b-c1
- NADH dehydrogenase
- Ubiquinone
- Cytochrome b-c1
- Cytochrome c
- Cytochrome c oxidase
Under ________ conditions, cells use glycolysis to break down glucose and essentially “burn sugar using molecular oxygen.
aerobic
_____________ combines with oxaloacetate to form the 6-carbon molecule Citrate in the Krebs Cycle.
Acetyl-CoA
As Citrate is oxidized, NADH is generated and the NADH in turn is used to provide electrons to the ____________
ETC
Electron transfers protons to be pumped against their gradient and eventually these electrons reduced oxygen to ___________
H2O
Why is it essential that fermentation occurs?
-Glycolysis still occurs in this condition and results in the formation fo NADH
-This cannot be used in the ETC as oxygen isn’t present, so it may be converted back to NAD+ so that glycolysis may continue
-Basically an “ATP Backup” - net 2 ATP per glucose
