BCMB 311 Final

What is the smallest distance two points can be separated and still resolved using light microscopy?

0.2 um

What are the three major membrane lipid groups?

1. phospholipids 2. sterols 3. glycolipids

Which of the following would yield the most highly mobile phospholipid (listed as number of carbons and number of double bonds, respectively)?

15 carbons with two double bonds

Glycolysis generates more stored energy than it expends. What is the net number of activated carrier molecules produced in this process (number and type of molecules produced minus the number of those molecules used as input)?

2 ATP, 2 NADH

If you are looking through the eye piece of a conventional light microscope with an eyepiece with 10X magnification and the objective lens you are using is 60X, what is the total magnification of the image?

600X

Red blood cells expressing fluorescent sceptrin were used in a FRAP experiment. Which of the following results would you expect when a high-intensity laser bleaches a region with the fluorescently tagged spectrin?

Almost no regain in fluorescence signal in bleached area

Sort the following events to reflect the normal order in which they occur in G-protein-coupled receptor signaling. Your answer would be a four-letter string composed of letters A to D only, e.g. ACBD. (A) α subunit releases its GDP and binds a GTP and becomes dissociated from βγ dimer (B) Ligand binds to receptor (C) Receptor conformational changes and receptor interacts with G-protein (D) α subunit binds and activates other effector proteins

BCAD

Acetylcholine acts at a GPCR on heart muscle to make the heart beat more slowly. It does so by ultimately opening K+ channels in the plasma membrane, which decreases the cell's excitability by making it harder to depolarize the plasma membrane. (See Image below) In a mutant cell, the receptor does not recognize or bind to acetylcholine on the cell surface. Indicate whether this mutation would increase or decrease the effect of acetylcholine.

decrease

Which of the following substances is most commonly used to help purify a membrane protein?

detergent

The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted by-products back out. Which term describes the process by which external materials are captured inside transport vesicles and brought into the cell?

endocytosis

The advantage to the cell of the gradual oxidation of glucose during cellular respiration compared with its combustion to CO2 and H2O in a single step is that

energy can be extracted in usable amounts

Cells that are specialized for the secretion of proteins are likely to have which of the following features?

enlarged endoplasmic reticulum

____ requires the use of two sets of filters. The first filter narrows the wavelength range that reaches the specimen and the second blocks out all wavelengths that pass back up to the eyepiece except for those emitted by the dye in the sample.

fluorescence

Cholesterol makes membranes _______ permeable to water and small solutes and ______ rigid

less, more

What unit of length would you generally use to measure a typical plant or animal cell?

micrometers

Which of the following organelles has both an outer and an inner membrane?

mitochondrion

Indicate by writing "yes" or "no" whether amplification of a signal could occur at the particular steps described below. Explain your answers. An extracellular signaling molecule binds and activates a GPCR. Adenylyl cyclase produces cyclic AMP. Protein kinase A phosphorylates target proteins.

no, yes, yes

Which of the following stages in metabolism generates the most amount of ATP?

oxidative phosphorylation

____ uses a light microscope with an optical component to take advantage of the different refractive indices of light passing through different regions of the cell.

phase-contrast

The central dogma provides a framework for thinking about how genetic information is copied and used to produce structural and catalytic components of the cell. From the choices below, select the order of biochemical processes that best correlates with the tenets of the central dogma.

replication, transcription, translation

____ requires coating a sample with a thin layer of a heavy metal to produce three- dimensional images of the sample surface.

scanning electron

Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of the material "burned" and the form of energy produced during cellular respiration?

sugar, ATP

____ has the ability to resolve cellular components as small as 2 nm.

transmission electron

Which of the following lipid is the most hydrophobic?

triacylglycerol

Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell. Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a fluorescent microscope is still limited by the __________ of visible light.

wavelength

Biological systems __________ hydrocarbons in stepwise __________ reactions. Glucose is the preferred energy source in eukaryotes, and must be converted into __________ before it can be transported across the __________ mitochondrial membrane for use in the citric acid cycle. The citric acid cycle is critical for the mitochondrion's subsequent production of __________.

Biological systems OXIDIZE hydrocarbons in stepwise CATABOLIC reactions. Glucose is the preferred energy source in eukaryotes, and must be converted into PYRUVATE before it can be transported across the INNER mitochondrial membrane for further oxidation in the citric acid cycle. The citric acid cycle is critical for the mitochondrion's subsequent production of ATP.

Ras is activated by a Ras-activating protein (Ras-GEF) that does what?

Causes Ras to exchange GDP for GTP

Which part of the cell is made up of a network of filaments that maintains the cell shape and structure?

Cytoskeleton

Glucose transport into the cells from the blood stream requires all of the following, EXCEPT:

Energy in the form of ATP

The lateral mobility of plasma membrane proteins cannot be restricted in cells.

False

What is the role of the nuclear localization sequence in a nuclear protein?

It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.

Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran to exchange GDP for GTP. What is the most likely effect of this drug on nuclear transport?

Nuclear transport receptors would be unable to release their cargo in the nucleus.

State one of the main 2 main features of a confocal microscope discussed in class that reduce photo-bleaching and chemical damage of the sample imaged generating thin optical sections?

One of the two ways is to reduce the light to a pin like amount and the other would be the use a mirror to reflect the light so that it's not directly on the sample.

Lipid synthesis is largely catalyzed by enzymes at the cytosolic side of the smooth ER. These lipids cannot sustainably be added to just one leaflet; they must be able to get to the inner leaflet as well. What is primarily responsible for this movement between leaflets?

Scramblase

With regards to phospholipids, what are two factors that have an effect on membrane fluidity?

The two factors that affect membrane fluidity is the amount of double bonds and that tail length.

Membrane-forming phospholipids have all of these properties except:

They have 1, 2 or 3 fatty acid tails

What do the phosphorylated tyrosines on activated RTKs do?

They serve as binding sites and activation for a variety of intracellular signaling proteins

We can estimate the relative mobility of a population of molecules along the surface of a living cell by fluorescently labeling the molecules of interest, bleaching the label in one small area, and then measuring the speed of signal recovery as molecules migrate back into the bleached area. What is this method called? What does the abbreviation stand for?

This method is called FRAP and it stands for fluorescence recovery after photobleaching.

MAP kinase kinase kinase (MAPKKK) phosphorylates and activates MAPKK, which does the same for MAPK

True

The Na+ K+ pump, pumps 3 sodium ions out of the cell and 2 potassium ions into the cell, and is powered by ATP.

True

Which of the following scientists coined the term "mitosis"?

Walther Flemming

Cyclic AMP (cAMP) and Cyclic GMP (cGMP) are second messengers that activate downstream signaling of different cellular responses. What are the precursors of each? Name the enzymes that catalyze the formation of cAMP and cGMP?

cAMP: ATP cGMP: GTP

Which of the following choices BEST describes the role of the lysosome?

clean-up, recycling, and disposal of macromolecules

____ scans the specimen with a focused laser beam to obtain a series of two- dimensional optical sections. The laser excites a fluorescent dye molecule, and the emitted light from each illuminated point is captured through a pinhole and recorded by a detector.

confocal

____ employs a light microscope and requires that samples be fixed and stained in order to reveal cellular details.

conventional light/ bright field

Which of the following steps or processes in aerobic respiration include the production of carbon dioxide?

conversion of pyruvate to acetyl CoA

When levels of insulin are high in the blood stream

Hormone Sensitive Lipases (HSL) are inhibited

Which of the following would you NOT expect to find in a bacterial cell?

ATP production in mitochondria

G-protein-coupled receptors (GPCRs) all have a similar structure with __________ transmembrane domains. When a GPCR binds an extracellular signal, an intracellular G protein, composed of __________ subunits, becomes activated. __________ of the G-protein subunits are tethered to the plasma membrane by short lipid tails. When unstimulated, the α subunit is bound to __________ which is exchanged for __________ on stimulation. The __________ activity of the αsubunit is important for inactivating the G protein. __________inhibits this activity of the α subunit, thereby keeping the subunit in an active state.

G-protein-coupled receptors (GPCRs) all have a similar structure with SEVEN transmembrane domains. When a GPCR binds an extracellular signal, an intracellular G protein, composed of THREE subunits, becomes activated. TWO of the G-protein subunits are tethered to the plasma membrane by short lipid tails. When unstimulated, the α subunit is bound to GDP which is exchanged for GTP on stimulation. The GTPASE activity of the α subunit is important for inactivating the G protein. CHOLERA TOXIN inhibits this activity of the αsubunit, thereby keeping the subunit in an active state.

Your friend has purified a membrane associated protein that contains a seven transmembrane helices, with a width of approx. 40 Å. Knowing that you are studying similar topics in your Cell Biology course, your friend asks if you can help identify to which class of proteins this one might belong. What would you suggest?

GPCRs

High-energy electrons are transferred through a series of molecules, and the energy released during these transfers is used to generate a gradient of __________, or __________. Because their concentration is __________ outside than inside the mitochondria, the flow of __________, or __________, down the concentration gradient is energetically very __________ and can thus be coupled to the production of ATP from ADP. Thus, oxidative phosphorylation refers to the oxidation of __________ and __________ molecules and the phosphorylation of __________. Without this process, the yield of ATP from each glucose molecule would be __________ decreased.

High-energy electrons are transferred through a series of molecules, and the energy released during these transfers is used to generate a gradient of PROTONS, or H+. Because their concentration is HIGHER outside than inside the mitochondria, the flow of PROTONS, or H+, down the concentration gradient is energetically very FAVORABLE and can thus be coupled to the production of ATP from ADP. Thus, oxidative phosphorylation refers to the oxidation of NADH and FADH2 molecules and the phosphorylation of ADP. Without this process, the yield of ATP from each glucose molecule would be SEVERELY decreased.

Gq family of heterotrimeric G proteins, hydrolyzes the inner membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP2), what are the two second messengers produced from this reaction?

IP3 and diacylglycerol

Akt promotes the survival of many cells by affecting the activity of Bad and Bcl2, as diagrammed in the Figure provided. Which of the following statements is FALSE?

In the absence of a survival signal, Bad is phosphorylated.

All of the following processes take place in the mitochondria, EXCEPT:

The conversion of glucose to pyruvate

Molecules to be packaged into vesicles for transport are selected by

adaptins

Which of the following protein families are NOT involved in directing transport vesicles to the target membrane?

adaptins

When adrenaline binds to adrenergic receptors on the surface of a muscle cell, it activates a G protein, initiating an intracellular signaling pathway in which the activated α subunit activates adenylyl cyclase, thereby increasing cAMP levels in the cell. The cAMP molecules then activate a cAMP-dependent kinase (PKA) that, in turn, activates enzymes that result in the breakdown of muscle glycogen, thus lowering glycogen levels. You obtain muscle cells that are defective in various components of the signaling pathway. Referring to the Figure provided below, indicate how glycogen levels would be affected in the presence of adrenaline in the following cells. Would they be higher or lower than in normal cells treated with adrenaline? cells that lack adenylyl cyclase cells that lack the GPCR cells that lack cAMP phosphodiesterase cells that have an α subunit that cannot hydrolyze GTP but can interact properly with the β and γ subunit

higher, higher, lower & lower

Where does most new membrane synthesis take place in a eukaryotic cell?

in the endoplasmic reticulum