exam two Flashcards
Long noncoding RNA (IncRNA) can function as a(n)
protein scaffold
RNA polymerase
transcriptional regulator
telomerase
protein scaffold
Which protein complex mediates the RNAi silencing process by inhibiting RNA polymerase via histone methylation and heterochromatin formation?
mediator
RITS
RISC
RNase
RITS
MicroRNAs block the expression of a specific gene product by binding to the _____ and inhibiting ______.
mRNA; translation
DNA; transcription
protein; activity
ribosome; translation
mRNA; translation
The control of a gene product’s levels or activity after transcription has taken place is called
post-transcriptional control
cell memory
combinatorial control
epigenetic inheritance
post-transcriptional control
The figure below depicts which of the following mechanisms that cells use to maintain their identity through cell divisions?
positive feedback
DNA methylation
histone modification
differentiation
positive feedback
A transcriptional regulator that activates expression of additional transcriptional regulators that induce production of a particular cell type or organ is called a
master regulator
reprogramming regulator
feedback activator
terminal differentiator
master regulator
In eukaryotes, multiple genes can be expressed simultaneously by
the arrangement of multiple genes into an operon
the binding of a specific transcriptional regulator to several genes
the binding of a mediator complex to several genes at once
a repressor protein binding to multiple operators
the binding of a specific transcriptional regulator to several genes
In the cell, enhancer sequence functions are limited in their range of action by the formation of _______ that hold specific genes and enhancers in close proximity.
loops
chromatin
helics
operons
loops
Eukaryotic repressor proteins can decrease transcription using which of the following mechanisms?
binding an operon and preventing polymerase binding
recruiting a histone acetyltrasferase complex to modify histones
preventing the assembly of the transcription initiation complex
attracting a chromatin remodeling complex to open chromatin at the site
preventing the assembly of the transcription initiation complex
Excess amounts of the amino acid tryptophan result in down regulation of the expression of the enzymes required for its synthesis due to ______
the repressor binding to the operator
inactivation of the repressor protein
the inability of the repressor to bind to the operator
the inactivation of RNA polymerase
the repressor binding to the operator
Which of the following is the main point of control for regulating gene expression levels?
translation
transcription
protein degradation
mRNA degradation
transcription
A housekeeping gene is a gene whose cellular function is
involved in removal of waste product from cells
turned off periodically for maintenance
important for processes found in all cell types
critical for specialized activities in a specific cell type
important for processes found in all cell types
Transplanting the nucleus of an epithelial cell into an egg cell lacking genetic information leads to the formation of
another epithelial cell
a dead cell
a normally developing embryo
a hybrid cell that has characteristics of both embryonic cells and epithelial cells
a normally developing embryo
The following image shows two triacylglycerol molecules with different fatty acid chains. If these fatty acids were in a phospholipid molecule, which of the two would form the most fluid membrane?
saturated
unsaturated
both would form very fluid membranes
both would form very stiff membranes
unsaturated
______ of ATP creates an irreversible step of a motor protein to move it in one direction
oxidation
hydrolysis
reduction
dehydration
hydrolysis
Arrange the cellular respiration events in order
glycolysis
citric acid cycle
electron transport chain
digestion
digestion
glycolysis
citric acid cycle
electron transport chain
Where does glycolysis take place?
cytosol
endoplasmic reticulum
mitochondrial inter-membrane space
mitochondrial matrix
cytosol
which of the following requires energy?
simple diffusion
osmosis
active transport
passive transport
active transport
catabolic metabolism pathways (select all that apply)
require energy
add chemical bonds
produce heat
remove chemical bonds
produce heat
remove chemical bonds
which of the following are considered energy carriers? (select all that apply)
H2O
O2
ATP
FADH2
ATP AND FADH2
Which of these are produced in the citric acid cycle (select all that apply)
NADH
GTP
Pyruvate
FADH2
NADH
GTP
FADH2
The following occur during the electron transport chain (select all that apply)
acetyl CoA is combined with oxaloacetate to form citrate
carbon atoms are stripped of fatty acid chains
high energy electrons are transferred through protein complexes in the inner mitochondrial matrix
protons are pumped into the mitochondrial intermembrane space
high energy electrons are transferred through protein complexes in the inner mitochondrial membrane
protons are pumped into the mitochondrial intermembrane space
which of the following are sub-units of ATP synthase (select all that apply)
heavy chain
stationary head (F1)
rotating ring (F0)
light chain
stationary head (F1)
rotating ring (F0)
Mitochondria and chloroplasts are thought to have arisen from bacterial ancestors because they still possess which of the following features?
lysosomes
DNA and ribosomes
endoplasmic reticulum
a nucleus
DNA and ribosomes
Which of the following molecules require transporters to enter a cell (select all that apply)
O2
CO2
glucose
H+
glucose
H+
What 4C compound is used in the Citric Acid Cycle?
NADH
acetyl CoA
Glucose
Pyruvate
acetyl CoA
which of the following are ways that an enzyme catalyzes reactions (select all that apply)
acting over large distances
aligning substrates
rearranging chemical bonds
rearranging charges in a substrate
aligning substrates
rearranging chemical bonds
rearranging charges in a substrate
scramblases are enzymes that _______
catalyze transfer of specific phospholipids to the cytosolic monolayer in the Golgi
catalyze transfer of specific phospholipids to the cytosolic monolayer in the ER
catalyze random transfer of phospholipid monolayers in the ER
catalyze random transfer of phospholipid monolayers in the Golgi
catalyze random transfer of phospholipid monolayers in the ER
Foods are broken down into simple molecular subunits for distribution and use throughout the body. Which type of simple subunits, listed below, is used preferentially as an energy source?
simple sugars
proteins
glycerol
free fatty acids
simple sugars
The final metabolite produced by glycolysis is
glutamate
acetyl CoA
3-phosphoglycerate
pyruvate
pyruvate
Which of the following is NOT a way that cells restrict the lateral movement of membrane proteins?
anchoring to internal cell components like actin or other proteins
tethering to external cell components like the extracellular matrix or adjacent cells
establishing diffusion barriers in the membrane
reducing the temperature of the membrane
reducing the temperature of the membrane
In a FRAP experiment, a fluorescently tagged membrane protein, A, shows very little recovery of fluorescence ten minutes after photobleaching, while membrane protein B shows a rapid increase in fluorescence after bleaching, recovering nearly 80% of its original fluorescent signal by ten minutes. Based on this information, which of the following statements can be made?
Protein A has faster mobility in the membrane
Protein B is diffusing in a more fluid membrane
Proteins A and B interact with each other in a complex
Protein A is easily denatured
Protein B is diffusing in a more fluid membrane
In a famous experiment, mouse cells and human cells were fused into hybrid cells and the membrane proteins of human origin and mouse origin were specifically tagged and examined. After cell fusion and incubation, what was observed by investigators?
the mouse and human proteins remained separated from each other on opposite sides of the hybrid cell
The mouse proteins mixed throughout the membrane of the hybrid cell, whereas the human proteins remained in half of the membrane, in their original location
the human proteins mixed throughout the membrane of the hybrid cell, whereas the mouse proteins remained in half of the membrane, in their original location
the mouse and human proteins mixed evenly throughout the membrane of the hybrid cell
the mouse and human proteins mixed evenly throughout the membrane of the hybrid cell
detergent molecules are _______ in nature and bind with membrane proteins and membrane lipids to disrupt their interactions and release the proteins from the membrane
amphipathic
hydrophobic
hydrophilic
polar
amphipathic
Which of the following is a common transmembrane protein structure that can traverse the membrane to form a pore or channel by alternating hydrophobic and hydrophilic amino acids?
single-pass alpha helix
multipass alpha helix
beta barrel
beta sheet
beta barrel
If the backbone of a polypeptide is hydrophilic, how can a transmembrane alpha helix span the hydrophobic portion of the lipid bilayer?
because amino acid side chains in a transmembrane helix are hydrophobic and interact with the hydrophobic interior of the bilayer
because the membrane bends in such a way that the polar heads of the lipids contact the transmembrane helix
because the hydrophilic backbone makes a hole in the membrane
because many transmembrane alpha helices must come together in a way that neutralizes the hydrophilic backbone
because amino acid side chains in a transmembrane helix are hydrophobic and interact with the hydrophobic interior of the bilayer
Proteins that are associate with the membrane by non-covalent interactions with other membrane proteins are called ______ proteins
integral membrane
peripheral membrane
monolayer-associated
lipid-linked
peripheral membrane
How is the protein shown in the diagram associated with the plasma membrane?
it is associated with one layer of the lipid bilayer
it is a membrane-spanning protein (transmembrane)
it is linked to lipids in the bilayer
it is attached to another protein that is a transmembrane protein
it is associated with one layer of the lipid bilayer
plasma membrane proteins that move ions in and out of cells using active transport are called
transporters
channels
anchors
receptors
transporters
______ are the most abundant molecules in the animal cell membrane, whereas ______ make up 50% of the membrane by mass
lipids, proteins
proteins, lipids
lipids, carbohydrates
carbohydrates, lipids
lipids, proteins
If a phospholipid is located in the outer layer of the bilayer in a vesicle, where will it end up when the vesicle fuses with the plasma membrane?
the cytosolic face of the bilayer
the extracellular face of the bilayer
randomly on one side or another
vesicles cannot fuse with the plasma membrane
the cytosolic face of the bilayer
a phospholipid is inserted into the cytosolic side of the ER membrane. Which of the following could randomly reposition this phospholipid to the other (lumen) side of the ER membrane?
flippase
scramblase
glycolipids
golgi apparatus
scramblase
where are new phospholipids made?
endoplasmic reticulum
golgi apparatus
mitochondria
nucleus
endoplasmic reticulum
why do cells regulate their membrane fluidity?
so they don’t freeze in cold temperatures
to allow membrane proteins to diffuse to where they are needed for their function
so that large, charged molecules can easily pass through the membrane
to keep two neighboring cells from easily fusing
to allow membrane proteins to diffuse to where they are needed for their function
a less permeable membrane is likely to have
more cholesterol
less cholesterol
many unsaturated fatty acids
shorter fatty acid tails
more cholesterol
a cell membrane made up primarily of lipids with which characteristics would be the least fluid?
short, unsaturated fatty acid tails
long, saturated fatty acids tails
long, unsaturated fatty acid tails
short, saturated fatty acid tails
long, saturated fatty acid tails
which type of movement is the least common for lipids in a bilayer?
flip-flop
lateral diffusion
flexion
rotation
flip-flop
What kind of lipid molecule is represented in this figure?
phospholipid
glycolipid
cholesterol
triacylglycerol
phospholipid
phospholipids assemble into a membrane using
enzymes
hydrophobic forces
assembly proteins
covalent bonds
hydrophobic forces
Which of the following is not commonly found in the plasma membrane?
carbohydrates
proteins
nucleic acids
fatty acids
nucleic acids
a transcriptional regulator that activates expression of additional transcriptional regulators that induce production of a particular cell type or organ is called a
master regulator
reprogramming regulator
feedback activator
terminal differentiator
master regulator
A reporter gene is an experimentally engineered regulatory DNA sequence from a gene of interest that has been fused to a gene that encodes a protein that is easily observed experimentally. Why is this approach useful?
it can provide information as to where a gene is expressed
it can provide information as to when a gene is expressed
it provides information into where and when a gene is expressed
it provides information on the binding interactions of the gene product
it provides information into where and when a gene is expressed
In eukaryotes, multiple genes can be expressed simultaneously by
the arrangement of multiple genes into an operon
the binding of a specific transcriptional regulator to several genes
the binding of a mediator complex to several genes at once
a repressor protein binding to multiple operators
the binding of a specific transcriptional regulator to several genes
many transcriptional regulators function together to decide the expression level of a particular gene. this describes the concept of
operons
repression
combinatorial control
activation
combinatorial control
Which of the following mechanisms describes how eukaryotic activator proteins can regulate chromatin packaging to enhance transcription?
binding to enhancer regions to promote formation of the transcription initiation complex
activating polymerase binding through contacts made in the activation region
recruiting histone deacetylase complexes to remove acetyl groups from histones
recruiting chromatin-remodeling complexes to eject or slide nearby nucleosomes
recruiting chromatin-remodeling complexes to eject or slide nearby nucleosomes
Generally, bacterial promoters that are regulated by transcriptional activators bind _______ to RNA polymerase on their own, but promoters that are regulated with transcriptional repressors bind ________ to RNA polymerase
weakly; strongly
strongly; weakly
weakly; weakly
strongly; strongly
weakly; strongly
Mutations in which of the following elements would abrogate RNA polymerase’s ability to activate gene expression?
regulatory DNA sequence region
promoter
transcription termination site
major groove
promoter
Which enzyme class is involved with randomly distributing phospholipids in the membrane?
ion channels
ATPases
Scramblases
Flippases
Scramblasaes
Which class of enzyme is involved with transfer of phospholipids to create asymmetric distribution in a membrane?
Flippases
ATPases
Lipases
Scramblases
Flippases
Which of these are functions of membrane associated proteins? (select all that apply)
anchoring to the extracellular matrix
ion transport across a membrane
transcription
translation
anchoring to the extracellular matrix
ion transport across a membrane
what method do protozoans use to prevent osmotic swelling?
contractile vacuoles
cell wall
ion transport
none of these
contractile vacuoles
Which of the following contribute to the net driving force needed to move a solute across a membrane (select all that apply)
the membrane potential
the solute concentration
the charge of the solute
the electrochemical gradient
all of the above
Which of the following are areas where gene expression can be regulated? (select all that apply)
transcriptional control at gene locus
mRNA transport and localization
translational control
RNA processing
all of the above
Which of the regulatory RNA protein complex is involved in the cells’ protection from viral or bacterial DNA
lnRNA RITS
miRNA DICER
siRNA RITS
miRNA RITS
siRNA RITS
Which of the following would be considered reporter genes? (select all that apply)
LacZ
GFP
RFP
mCherry
all of the above
Transporters, in contrast to channels, work by
filtering solutes by size
filtering solutes by charge
a gating mechanism
specific recognition of transport substrates
specific recognition of transport substrates
The figure below illustrates charges in membrane potential in the axon of a neuron. What membrane characteristic or measurement is indicated by the arrow?
threshold potential
resting membrane potential
action potential
stimulation potential
action potential
What gives rise to a membrane potential
the distribution of ions across the membrane electrical charges from the environment
the distribution of uncharged molecules across the membrane
the amount of glucose in a cell
the distribution of ions across the membrane
aquaporins are channels that primarily allow passage of _____ through bilipid membranes
water
electrons
ions
protons
water
What is the byproduct of aerobic respiration in yeast?
methanol and O2
ethanol and O2
methanol and CO2
ethanol and CO2
ethanol and CO2
what is the final byproduct of aerobic glycolysis
pyruvate
FADH2
Citrate
lactate
pyruvate
