Cell & Molecular Bio

Front 1

Name 4 basic properties of cells

Back 1

-carry out a variety of chemical reactions
-engage in numerous mechanical activities
-able to respond to stimuli
-capable of self-regulation

Front 2

Name technique often used to predict transmembrane segments of integral proteins

Back 2

hydropathy plot

Front 3

Which protein is expressed only in the cytoplasmic side of the membrane?

Back 3

Protein Z

Front 4

You are working with some mutant cyanobacteria that lack some lipid desaturases. At 34 deg C the mutant and wild type cyanobacteria exhibit similar growth rates. At 22 deg C mutant doubling time rises to 59 hours compared to 22 hours for a wild type cyanobacteria. What happens if the gene for lipid desaturase is inserted into mutant cells? (a desaturase makes double bonds in the carbon chain of fatty acids)

Back 4

There was a dramatic drop in doubling time.

Front 5

Carbohydrates are composed of _____

Back 5

polysaccharides

Front 6

Assume that a red blood cell with an internal osmolarity equivalent to 0.15 M NaCl is placed in a solution with a concentration of 0.35 M NaCl. What happens to the cell?

Back 6

It shrinks

Front 7

From what is the lipid-containing outer envelope surrounding the viral capsid of many animal viruses derived?

Back 7

the cell membrane

Front 8

A solution containing a viroid that affects potatoes is treated with an enzyme and then exposed to a potato plant. The plant is unaffected by the solution. To what enzyme is the solution likely to have been exposed?

Back 8

RNAse

Front 9

What kind of transport will be necessary to remove urine from the kidney cells

Back 9

Active transport

Front 10

If a protein was linked to a framesyl or geeranylgeranyl fatty acid it would be located

Back 10

on the cytoplasmic side of the lipid bilayer

Front 11

Which is a branched chain carbohydrate

Back 11

Glycogen

Front 12

In equilibrium density gradient centrifugation

Back 12

During high speed centrifugation each particle migrates through a gradient of sucrose or glycerol to the position in the gradient where the density of the surrounding media is the same as the particle density

Front 13

What happens to the phospholipid mobility when the cell is treated with agents that disrupt the underlying membrane skeleton?

Back 13

Their mobility is increased because the fences that normally restrict their diffusion are removed.

Front 14

Membrane protein found entirely outside bilayer on extracellular or cytoplasmic surface? These proteins are associated with the membrane surface by noncovalent bonds.

Back 14

Peripheral proteins

Front 15

Which part of a microscope is responsible for collecting light rays previously focused on the specimen? It collects two kinds of light rays, those passing through the slide and the specimen.

Back 15

objective lens

Front 16

How are integral membrane proteins isolated from membranes for study?

Back 16

They are extracted with ionic or nonionic detergents.

Front 17

An N-linked carbohydrate on a glycoprotein would be found on a _____ while an O linked carbohydrate would be found on a _______

Back 17

aspargine, threonine

Front 18

The following are properties of cancerously transformed cells

Back 18

-immortal
-can be grown in suspension culture
-do not display contact inhibited growth
-form tumors when injected into mice

Front 19

Which is a technique used to isolate a particular organelle in bulk so that its function can be studied or so that an enzyme can be isolated from it

Back 19

differential centrifugation

Front 20

What kind of membrane protein penetrates into the hydrophobic part of the lipid bilayer?

Back 20

integral protein

Front 21

Due to its resolving power, 2D-gel electrophoresis is ideally suited to detect changes in proteins found

Back 21

-in cell under different conditions
-at different developmental stages
-at different cell cycle stages
-in different organisms

Front 22

Which of the following processes could be studied using fluorescence resonance energy transfer?

Back 22

-shape changes in a molecule when it binds to a specific ligand
-protein folding
-association of components within a membrane
-dissociation of components within a membrane

Front 23

Assume that a red blood cell with an internal osmolarity equivalent to 0.15 M NaCl is placed in a solution with a concentration of 0.35 M NaCl. What word describes the solution surrounding the red blood cell relative to its internal concentration?

Back 23

Hypertonic

Front 24

Which of the following is NOT true of membrane phsophoglycerides

Back 24

They include collagen, glycogen, and cholesterol among others.

Front 25

Which proteins move the farthest during SDS polyacrylamide gel electrophoresis?

Back 25

the smallest

Front 26

Substance X is a charged molecule of small molecular weight. It is found at higher concentration outside of the cell than inside. The charge on the molecule is positive and the environment inside the cell is negatively charged. How might substance X enter the cell?

Back 26

Diffusion through a channel

Front 27

Which of the following conditions would result in the best resolution?

Back 27

blue light and 0.95 N.A.

Front 28

In a proviral infection, the virus does which of the following

Back 28

-does not immediately kill the host cell
-integrates its DNA into the host cell's DNA

Front 29

Why do electron microscopes provide much greater resolving power than light microscopes?

Back 29

because electron wavelength is much lower than that of visible light.

Front 30

Lipids contain a hydrophilic head group with two hydrophobic polysaccharide chains

Back 30

FALSE

Front 31

A relatively small number of cells is added to a dish so that each cell resides at some distance from its neighbors. Under these conditions, each surviving cell proliferates to form a separate colony whose members are all derived from the same original cell. What kind of culture does this describe?

Back 31

a clonal culture

Front 32

Which is more important to microscopy and why?

Back 32

resolution, because it allows you to distinguish separate objects

Front 33

The energy to transport substance A into the cell against a concentration gradient is provided by the energy generated by cotransport of substance B into the cell. This is an example of what kind of coupled transport?

Back 33

symport

Front 34

The chloride ion transporter whose mutation is associated with cystic fibrosis and the multi drug resistance transport proteins are members of what super family of transporters.

Back 34

ABC transporters

Front 35

If Gorter and Grendel, extracted lipids from the membranes of red blood cells and determined that they covered 96 mm^2 of water, what would you estimate as the surface area of the red blood cells from which the lipids were extracted based on your knowledge of cell membrane structure

Back 35

48 mm sq

Front 36

Which of the following tenets is NOT considered to be part of the Cell Theory?

Back 36

Cells can arise independently.

Front 37

Substance A is found to have a partition coefficient of 0.3 while substance B has a partition coefficient of 300. Both substances A and B are small uncharged polar molecules. These properties mean that

Back 37

Substance B will penetrate the membrane by passive diffusion much faster than substance A.

Front 38

What enzyme was instrumental in the discovery of GPI-anchored proteins? It was found that this enzyme would release certain membrane proteins from a membrane.

Back 38

phospholipase

Front 39

Which light microscope technique delivers an image that has an apparent 3-D quality?

Back 39

Differential interference contrast microscopy

Front 40

What technique is best for determining the location of radioactive isotope in a tissue or cell?

Back 40

autoradiography

Front 41

What light microscopy technique is based on the fact that excitation energy can be transfered from one fluorescent group (a donor) to another fluorescent group (an acceptor), as long as the two groups are very close together (1-10 nm)?

Back 41

fluorescence resonance energy transfer

Front 42

By using FRAP (fluorescence recovery after photobleaching) you can determine

Back 42

how rapidly and to what extent the bulk of proteins in the membrane move

Front 43

How many carbons from 13 original glucose molecules enter the Krebs cycle in the presence of oxygen?

Back 43

13 x 4 = 52

Front 44

Which region of the sarcomere represents the region of overlap between the two types of filaments in the sarcomere?

Back 44

the part of the A band on either side of the H zone.

Front 45

Microscopic beads are coated with kinesin and subjected to an in vitro mobility assay. In which direction and along what cytoskeletal element are they seen to move?

Back 45

toward the plus end of the microtubule

Front 46

All of the following are functions of the cytoskeleton EXCEPT

Back 46

it functions as an energy storage site in the cell

Front 47

In order for muscle relaxation to take place which of the following molecules must have the highest affinity for Ca++

Back 47

sarcoplasmic reticulum Ca++ ATPase

Front 48

The following statement about Focal adhesions is FALSE.

Back 48

Focal adhesions form at the + end of microtubules anchoring and stabilizing them at the cell periphery

Front 49

Which is not a function of either cilium or a flagellum?

Back 49

moving vesicles down the nerve cell axon

Front 50

Which type of cytoskeletal element is characterized as a hollow, rigid cylindrical tube with walls composed of tubulin subunits?

Back 50

microtubules

Front 51

Which of the following is an electron transporter that carries electrons from one complex to another directly through the lipid bilayer

Back 51

ubiquinone

Front 52

Acetyl CoA adds the carbons from the acetate group to oxaloacetate at the start of the Krebs cycle to form

Back 52

citrate

Front 53

Which of the following observations suggest that there must be cellular factors (or proteins) that control actin polymerization

Back 53

the fact that there exists a concentration of actin monomers in the cell that is much higher than the critical concentration of actin monomers needed to initiate actin polymerization

Front 54

A signal is sent and binds to a receptor to initiate the extension of a pseudopod. Which is the next step in the process of pseudopod extension?

Back 54

the wasp/scar protein recruits the Arp2/3 complex

Front 55

All of the following are true of the proton motive force EXCEPT

Back 55

it involves transfer of phosphate to ADP

Front 56

The following statements are true of microtubules

Back 56

-They are involved in transport of materials between different compartments in the cell
-They play a role in determining cell shape
-Treatment with drugs that disrupt them causes cellular organization to be disrupted

Front 57

Assembly of intermediate filaments differs from the assembly of actin or tubulin because

Back 57

subunits self assemble adding to the interior of the growing filament

Front 58

Which of the following organelles is essentially equal in structure to basal bodies?

Back 58

centrioles

Front 59

What advantages do the cristae confer on the mitochondria?

Back 59

They greatly increase the surface area for aerobic respiration machinery.

Front 60

The drug cytochalasin binds to the ____ of F-actin ________ the addition of actin subunits and stimulating ______ from the ________

Back 60

plus end, blocking, depolymerization, minus end

Front 61

All of the following are true of molecular motors EXCEPT

Back 61

can move in both forward and reverse directions

Front 62

If microtubules are inherently unstable when GTP on its dimer subunits has been hydrolyzed to GDP, why do they sometimes persist?

Back 62

MAPs can bind and, act like stabilizing factors that prevent microtubule disassembly.

Front 63

What happens to the carbons of pyruvate that do not enter the Krebs cycle?

Back 63

they are converted to CO2.

Front 64

A mutation in which of the following is responsible for cells undergoing multiple rounds of nuclear division but not dividing the cytoplasm because they can not carryout cytokinesis.

Back 64

myosin II

Front 65

List the four events occurring during cell locomotion

Back 65

1. A part of the cell surface protrudes in the direction of cell movement.
2. Lower surface of cell protrusion attaches to substratum, forming temporary anchorage sites.
3. The bulk of the cell is pulled forward over adhesive contacts.
4. The cell breaks its rear contacts with the substratum, retracting its trailing edge.

Front 66

A minus end actin capping protein would

Back 66

cause elongation of actin filaments

Front 67

Mitochondria are organelles where

Back 67

oxygen plays a role in energy generation and synthesis of ATP

Front 68

The F0 base of ATP synthase serves as a(n)

Back 68

channel that conducts protons from the intermembrane space back to the matrix.

Front 69

You inject radioactively labeled keratin subunits into cultured skin cells. What happens a few minutes later?

Back 69

Filaments initially become labeled at scattered sites along their length.

Front 70

A protein that blocks myosin from interacting with actin preventing muscle contraction is

Back 70

tropomycin

Front 71

Which property is most characteristic of intermediate filaments?

Back 71

highly resistant to tensile forces

Front 72

A lipid present in the inner membrane of the mitochondria that decreases the permeability of this membrane to protons is

Back 72

cardolipin

Front 73

What protein is responsible for intraflagellar transport of kinesin-II molecules and recycled axonemal proteins toward the basal body?

Back 73

2 headed cytoplasmic dynein

Front 74

Oxidation involves

Back 74

loss of electrons

Front 75

What motor is associated with microfilaments?

Back 75

myosin

Front 76

The polarity of microtubules is established at the MTOC because

Back 76

alpha tubulin can bind to gamma tubulin and beta tubulin can't

Front 77

Which type of cytoskeletal element is described as tough, ropelike fibers composed of a variety of related proteins like keratin and is responsible for providing tensile strength?

Back 77

intermediate filaments

Front 78

You want to study the cytoskeleton and so you need to isolate the cytoskeleton from cells. Which of the actions would you do to isolate the cytoskeleton

Back 78

Isolate the material that is left behind as a pellet after lysing the cells in triton x 100

Front 79

F-actin is

Back 79

a flexible filament composed of two strands of actin molecules wound around each other in a double helix.

Front 80

What is the final electron acceptor in the electron transport chain?

Back 80

Oxygen

Front 81

When a microtubule is growing, the plus end is present as an open sheet to which GTP-dimers are added. A cap of GTP-dimers can often form on the growing microtubules during rapid growth periods. How does this cap form?

Back 81

Tubulin dimers are added to the microtubule faster than the GTP is hyrolyzed.

Front 82

Which suggests that actin polymerization itself can be a force generating mechanism

Back 82

-the sperm acrosomal reaction
-the movement of listeria monocytogenes

Front 83

An important characteristic of the nuclear envelope is that

Back 83

it is made up of two membranes which contact each other at specific locations

Front 84

The shape of an eukaryotic nucleus is largely determined by

Back 84

the nuclear lamina located on the nucleoplasmic side of the nuclear envelope

Front 85

The movement of different types of molecules and macromolecules across the nuclear envelope is characeterized by

Back 85

both small molecules and large molecules moving through the nuclear pore complexes.

Front 86

The activity of MPF ("mitosis promoting factor") and probably the other cell cycle stage "promoting factors" is determined or regulated by:

Back 86

the amount of the catalytic subunit, the amount of the regulatory (stimulatory) subunit, the amount of an inhibitory protein, the activity of specific protein kinases, and the amount of a specific phosphatase.

Front 87

In metaphase human cells, how many pieces of DNA would you expect to find in each chromosome?

Back 87

two

Front 88

The inheritance of genes in human mitochondria

Back 88

is strictly "maternal" in that genes that are inherited come from the mother's egg.

Front 89

What is the intracellular secondary "messenger" that affects cytoplasmic [Ca++]; and where is the binding site of its specific receptor found

Back 89

IP3; ion channels in the ER

Front 90

Human cells with a doubling/generation time of 24 hours were pulse labeled for 20 minutes with H3-thymidine, and then the percentage of cells in mitosis that were radioactively labeled was determined at various times in samples taken during the next 24 hours. Which of the following experimental observations/data might you expect to find?

Back 90

The first few hours had no labeled mitotic cells, then most of the cells were labeled for the next several hours, followed by a decline in labeled cells until about the 24 hour time point.

Front 91

In puberty, mammals (such as humans) develop various secondary steroid-dependent phenotypic characteristics such as beards or underarm hair for men. In certain diseases/syndromes, these secondary sexual characteristics don't develop. What is/are the possible causes/defects/mutations in various components that might cause this result?

Back 91

-the sER in the liver is no longer able to metabolize inactive precursors to active forms of the hormone
-lipid-carriers in the blood have lost their affinity for the hormone, or are no longer made.
-no hormone is synthesized in the body

Front 92

In chromatin nucleosomes are made up of

Back 92

two turns of DNA coiled around a protein core made of pairs of 4 different histones.

Front 93

The function of a kinetochore is to:

Back 93

serve as the binding site for the mitotic spindle fibers.

Front 94

For MPF (mitosis promoting factor), what can be said about the concentration of its catalytic protein subunit during the cell cycle and what can be said about the concentration of its regulatory protein subunit?

Back 94

no change in concentration during interphase; gradual increase in concentration during interphase

Front 95

Barr bodies or the chromosome with the gene determining the coat color of calico cats are examples of

Back 95

specific heterochromatin state of an entire chromosomes in interphase cells.

Front 96

An example of a common strategy that eukaryotic cells use to "activate" or "switch on" a protein in signal transduction pathways is

Back 96

the binding of GTP

Front 97

What is known about the domain structure of steroid hormone receptors?

Back 97

there are at least 3 domains: one for binding the hormone, one for binding DNA and one for interacting with other transcription factors and/or RNA polymerase.

Front 98

The concept of "Editing" in cell biology at the molecular level refers to:

Back 98

the addition to or removal of nucleotides from certain initially transcribed messenger RNAs.

Front 99

You would expect to find "active" or transcribing genes in:

Back 99

euchromatin

Front 100

A very important signal transduction pathway involves a receptor with enzymatic activity. Where is this receptor located, and what is the nature of its enzymatic activity

Back 100

plasma membrane; it kinases a specific protein at a specific tyrosine amino acid

Front 101

The relationship between the 30 nm chromatin fiber and the nucleosome is

Back 101

the nucleosomes coil up in a helix or a zig-zag to form the fiber.

Front 102

Which of the following experimental procedures would you predict would result in DNA synthesis occurring/continuing/beginning?

Back 102

transplanting a G1 phase nucleus into S phase cytoplasm

Front 103

Histones play an important role in the structure of chromatin because

Back 103

their net charge helps to neutralize the charge of naked DNA and so allow it to be compacted more easily.

Front 104

Upon exposure to specific hormones, the overall amount of protein kinase-A (PKA) activity in responding cell increases. What is the mechanism for this?

Back 104

The hormone causes an increase in the number of cAMP molecules which bind to and thus "remove" a protein which inhibits the PKA catalytic protein.

Front 105

The rate of DNA replication (base pairs synthesized/minute) in a human replication complex is 25 times slower than that in E. coli, yet human S-phase is only 5-6 hours for a genome that is 1000 times larger.(Replicaiton in E. coli takes about 20 minutes.) How would you explain this?

Back 105

the human genome has many replicons that can replicate simultaneously.

Front 106

What does the initial enzymatic "effector" in the G-protein linked phosphoinositol signal transduction system do?

Back 106

it causes the breakdown of a specific membrane lipid molecule.

Front 107

An important consequence of having signal transduction "cascades" is:

Back 107

the effect of a "weak" signal (or very low concentration of hormone) can be amplified

Front 108

In plant cells, you would expect to find DNA replication in:

Back 108

the nucleus, mitochondria, and chloroplasts

Front 109

An unusual feature of the synthesis of messenger RNA in human mitochondria is that

Back 109

it initially involves the total transcription of both strands of the mitochondria DNA.

Front 110

Which of the following statements best describes the macromolecular composition of a metaphase chromosome?

Back 110

Its major constituents are just protein and DNA, with much more protein than DNA.

Front 111

A common strategy that cells use to reduce their sensitivity to a given hormone and so "adapt" to varying levels of the hormone signal is:

Back 111

to change the number of receptor molecules accessible to being bound by the hormone.

Front 112

The hormones changing the concentration of cAMP in the cytoplasm do so by:

Back 112

increasing the rate of synthesis of cAMP without affecting the rate of destruction of cAMP.

Front 113

Telomerase is an unusual enzyme because it

Back 113

has a protein catalytic subunit as well as a RNA molecule specifying the sequence of the synthesized DNA.

Front 114

Visually can you distinguish the cytoplasmic side of the nuclear pore complex from the nucleoplasmic side?

Back 114

Yes, because the cytoplasmic side has filaments extending into the cytoplasm whereas the nucleoplasmic side has a "cage-like" structure.

Front 115

Which proteins would you expect to be preferentially synthesized during the S phase of human cells and during the M phase?

Back 115

histones; no proteins

Front 116

The actual enzymatic activity of the various "promoting factors" that are required for cells to move into their next cell cycle stage is:

Back 116

a specific protein kinase

Front 117

What type of mutation in RAS will tend to "transform" normal human cells into cancerous cells that continuously progress through the cell cycle because their MAP pathway is continually stimulated?

Back 117

a mutation that eliminates its ability to hydrolyze GTP.

Front 118

Enzymotology of DNA replication and types of required enzymes in eukaryotic human cells are quite different from prokaryotic bacterial cells

Back 118

NO, since both types of cells actually have analogous or similar enzymes for DNA replication.

Front 119

The concept of "Convergence" in signal transduction pathways means that

Back 119

different types of hormones with different types of receptors can all affect the same or a common "effector" or signalling cascade.

Front 120

If there were a mutation in the RAN protein that inhibited its ability to bind GTP, what would you predict might be the resulting effect on the movement of material into and out of the nucleus?

Back 120

Movement of material both into and out of the nucleus would be inhibited.

Front 121

Methylation of DNA is one way eukaryotic cells apparently can use to:

Back 121

cause repression of specific gene expression.

Front 122

What would happen if the gene coding for CDI (or p21 or p27) that binds to MPF was "knocked out" or destroyed in a human cell?

Back 122

it would speed up the entry of cells into M phase.

Front 123

The concept of the "Histone Code" refers to the hypothesis that

Back 123

the N-terminal regions of specific core histones can be reversibly modified with groups such as methyl and acetate.

Front 124

What determines whether a given big protein will move into or out of the nucleus, or remain in the cytoplasm?

Back 124

Whether or not it has a specific amino acid sequence.

Front 125

The initial steps in the cAMP signal transuction pathway have the equivalent of a "GEF". What component in the pathway has this function?

Back 125

the receptor when it has the hormone bound to it.

Front 126

An important similarity between steroid hormone recpetors and receptors involved in the cAMP signal transduction pathway is:

Back 126

both are proteins

Front 127

The shape of the nucleosome is ____ , and its approximate diameter is about ____

Back 127

flattened disk like; 11 nm