Cell Biology 1.b., FINAL EXAM FOR HIST

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A hungry yeast cell lands in a vat of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process: C6H12O6 + 2ADP + 2Pi + H+ 2CO2 + 2CH3CH2OH + 2ATP + 2H2O Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeast cell membrane, and the yeast cell dies. Which of the following could account for the yeast cell's demise? (a) toxic buildup of carbon dioxide inside the cell (b) toxic buildup of ethanol inside the cell (c) diffusion of ATP out of the cell (d) inability to import sugar into the cell

Below is a list of molecules with different chemical characteristics. Knowing that all molecules will eventually diffuse across a phospholipid bilayer, select the option below that most accurately predicts the relative rates of diffusion of these molecules (fastest to slowest). alanine estrogen propanol sodium (a) alanine > propanol > sodium > estrogen (b) sodium > propanol > alanine > estrogen (c) estrogen > propanol > sodium > alanine (d) estrogen > propanol > alanine > sodium

Cells make use of H+ electrochemical gradients in many ways. Which of the following proton transporters is used to regulate pH in animal cells? (a) light-driven pump (b) H+ ATPase (c) H+ symporter (d) Na+-H+ exchanger

Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________. (a) active transport (b) free diffusion (c) facilitated diffusion (d) passive transport

(a) active transport

Transporters, in contrast to channels, work by ________________. (a) specific binding to solutes (b) a gating mechanism (c) filtering solutes by charge (d) filtering solutes by size

(a) specific binding to solutes

We can test the relative permeability of a phospholipid bilayer by using a synthetic membrane that does not contain any protein components. Some uncharged, polar molecules are found to diffuse freely across these membranes, to varying degrees. Which of the following has the lowest rate of diffusion across an artificial membrane? Why? (a) glucose (b) water (c) glycerol (d) ethanol

(a). Glucose will have a negligible degree of diffusion across the synthetic bilayer. Not only is it polar, it is also larger than other molecules that are able to diffuse across the membrane.

Voltage-gated channels contain charged protein domains, which are sensitive to changes in membrane potential. By responding to a threshold in the membrane potential, these voltage sensors trigger the opening of the channels. Which of the following best describes the behavior of a population of channels exposed to such a threshold? (a) Some channels remain closed and some open completely. (b) All channels open completely. (c) All channels open partly, to the same degree. (d) All channels open partly, each to a different degree.

(a). Individual channels are either completely open or completely closed. However, in a given population there will be a mixture of open and closed channels.

Although the extracellular environment has a high sodium ion concentration and the intracellular environment has a high potassium ion concentration, both must be neutralized by negatively charged molecules. In the extracellular case, what is the principal anion? (a) HCO3- (b) Cl- (c) PO43- (d) OH-

(b) Cl-

Active transport requires the input of energy into a system so as to move solutes against their electro chemical and concentration gradients. Which of the following is not one of the common ways to perform active transport? (a) Na+-coupled (b) K+-coupled (c) ATP-driven (d) light-driven

(b). Because K+ is a positively charged ion and the outside of the plasma membrane is positively charged, K+ has a very small electrochemical gradient across the membrane even though its concentration gradient is large. Because there is little net movement across the membrane for K+, it would not make a good source of energy to drive the transport of other molecules against their respective gradients.

Ion channels are classified as membrane transport proteins. Channels discriminate by size and charge. In addition to Na+, which one of the following ions would you expect to be able to freely diffuse through a Na+ channel? Explain your answer. (a) Mg2+ (b) H+ (c) K+ (d) Cl-

(b). If an ion channel is open, it will allow any ion that is under a certain size and that has the correct charge to pass through. H+ is the only ion listed that is both smaller and has the same charge of +1.

You have generated antibodies that recognize the extracellular domain of the Ca2+ pump. Adding these antibodies to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+? (a) Ca2+ pumps in vesicles membranes keep cystosolic calcium levels low. (b) Ca2+ pumps in the ER membrane keep cystosolic calcium levels low. (c) Ca2+ pumps in the Golgi apparatus keep cystosolic calcium levels low. (d) Ca2+ concentrations in the cytosol increase at a steady rate.

(b). In addition to the Ca2+ pumps in the plasma membrane, they are also found in the membrane of the endoplasmic reticulum. Those in the ER membrane will continue to remove calcium ions from the cytosol, keeping calcium levels low.

A hungry yeast cell lands in a vat of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process: C6H12O6 + 2ADP + 2Pi + H+ ® 2CO2 + 2CH3CH2OH + 2ATP + 2H2O Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeast cell membrane, and the yeast cell dies. Which of the following could account for the yeast cell's demise? (a) toxic buildup of carbon dioxide inside the cell (b) toxic buildup of ethanol inside the cell (c) diffusion of ATP out of the cell (d) inability to import sugar into the cell

(d) inability to import sugar into the cell

what does active transport by ATPase do?

-Maintain extracellular ionic composition -move solutes against an electrochemical gradient

what is the role of the carrier protein in active transport?

-against a concentration gradient -harness energy from ATP

how are antibodies able to specfically target bacterial infections in humans?

-bind to region of bacterial ribosomes -block initiation of transcription by binding to RNA polymearse

what are the binding sites of the glucose carrier/transport? How does the glucose transporter work?

-binding site of glucose is to the transmembrane segments - one conformation exposes the binding site to the outside of the cell and the other to the inside of the cell. (refer to figure 1.1

what is the role of channels in passive transport?

-down a concentration gradient -no expenditure of energy

Describe the glucose carrier/transporter?

-have 2 conformations -switch back and forth to open and close on each side

what is the function of the intermediate filaments?

-provide tensile strength -increase cells ability to withstand mechanical stress

Why does the Plasma Membrane and its inserted proteins work to maintain the concentration of ions inside and outside of the cell? and why

-to develop membrane potential -to drive cellular response to stimuli

why does the cell membrane and its inserted proteins work to matain membrane potential

-to drive ceullar respones to stimuli -to keep the ions in the cell balance

the process of gene amplification is important when a cell requires enhanced protein synthessi. Explain in what two ways can this process be facilliated

-transcription there can be muptile identical mRNA =translation elevatuate production of proteins

what type of energy do the channel use for ions? Also what type of channel is this?

-use diffusion to move across -ion channel when only ion moved

how many molecules of ATP needed for the NA/k pump

list the three covalent post transcptional modicfication that are made to RNA

1) 5' capping with a 7-methylguanosine protects the 5' 2)3' polyadenylation-protect and mark 3)intron splicing prodcue the final set of instrutrions for the protein

what are the steps of shirking a microtubule?

1) Protofilaments containing GDP tubulin peel away from the microtubule wall 2) GDP tubulin is released to the cytosl

What are the 5 purposes of the cytoskeleton

1) adapt shape of the cell 2) organize interior of the cell 3)interact mechanically with enviroment 4)carry out movement 5)support the cytoplasma

what are the two classes of membrane proteins

1) carrier protein (transporter/pump? 2)channels

What is the purpose of the membrane transport?

1) exchange of molecules 2) use of membrane transport proteins 3) maintain internal ion composition 4) control biological process

how does the calcium pump keep extracellular calcium low?

1)ATP binds and then 2 Ca2+ bind 2)aspartic acid is phosphorylated 3)Trigger conformational change Nucleotide binding domain and activator domains get close Leads to rearrangement of transmembrane helices 4)Disrupts Ca2+ binding sights 5)Ca2+ is released into lumen of SR or extracellular space (figure 1.3

How does the Na/K pump works?

1)Pump binds ATP then 3 Na+ ions 2)ATP is hydrolyzed leading to Phosphorylation of pump 3)Conformational change exposes Na To outside (P-pump has low affinity For Na and Na is released) 4)Pump binds 2 K+ ions. Causes Dephosphorylation of pump 5)Pump revert to previous Coformation (deP-pump has higher Affinity for NA than K, so K is Released) 6)Cycle starts again

The tRNA is structually folded into a coverleaf. If tRNA was mutated what would happen

1)anticdon region: recongize of the the condon 2) 3' end: site of covalently bound amino acid tRNA carry amino acids to the ribosomes

what are the steps of the formation of the microtublues?

1)gamma tubulin rings are on the surface of centrosome 2)alpha and beta tubulin dimers are added to gamma tubulin via noncovalent bonds *thus making an individual protofilament that has polarity 3) 13 protofilament will then organize into a hollow cylindrical microtubule

what are the 3 types of cytoskeletal filaments

1)intermediate filaments 2) microtubules 3) actin filaments

What is the function of the sodium/ potassium pump?

1)moves K in while moving Na out 2)maintains high (Na) outside the cell becasue Na leaks back in thru other channels or carriers

there are 4 domains of the DNA polymerase. Describe them

1)palm- dna bound here when enzyme active and catalyze transfer of phosphoryl group 2)finger-binds and postion nucleotide triphosphate with template base 3)thumb involved in translocation posistion of the dna 5exonuclease- proofreading

what are the difference between passive vs. active transport?

1)passive -down the concentration gradient -no energy required by channels and transporters 2)active -against the concentration gradient -energy required by transporters ------ This is for small hydrophillic molecules

why does the glucose use _____ transport?

1)passive transport -glucose moves according to the concentration gradient across the membrane

what is the 3 step process of movement of the cell?

1. push out the protruding leading edge of the cell 2. protrusion adhere to new surface 3. drag the rest of the cell forward by traction

what is the structure of the sodium/posstum pump?

2 alpha and 2 beta subunits

3___ for 2____

3 Na for 2 K. removing 1 positive charge carrier from the intracellular space

Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant outside a typical mammalian cell? (a) Na+ (b) K+ (c) Ca2+ (d) Cl-

Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________. (a) active transport. (b) free diffusion. (c) facilitated diffusion. (d) passive transport.

Transporters, in contrast to channels, work by ________________. (a) specific binding to solutes. (b) a gating mechanism. (c) filtering solutes by charge. (d) filtering solutes by size.

Which of the following channels would not be expected to generate a change in voltage by movement of its substrate across the membrane where it is found? (a) an aquaporin (b) a sodium channel (c) a calcium channel (d) a proton channel

____ is a region of protein folded in to compact, stable structure with specific function or activity.

A Domain

K+ leak channels are found in the plasma membrane. These channels open and close in an unregulated, random fashion. What do they accomplish in a resting cell? (a) They set the K+ concentration gradient to zero. (b) They set the membrane potential to zero. (c) They disrupt the resting membrane potential. (d) They keep the electrochemical gradient for K+ at zero.

Negatively charged ions are required to balance the net positive charge from metal ions such as K+, Na+, and Ca2+. Which of the following negatively charged ions is the most abundant outside the cell and which ion does most often neutralize (written in parentheses)? (a) Cl- (Ca2+) (b) PO43- (K+) (c) PO43- (Ca2+) (d) Cl- (Na+)

A chromosome is very ______ during the life cycle of a cell.

Dynamic

The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content. -True -False

False

Transporters are similar to channels, except that they are larger, allowing folded proteins as well as smaller organic molecules to pass through them. -True -False

False

The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content.

False. The primary difference between cell membranes and artificial membranes is that cell membranes have proteins responsible for creating a selective permeability, which varies with the location and function of the membrane.

Transporters are similar to channels, except that they are larger, allowing folded proteins as well as smaller organic molecules to pass through them.

False. Transporters work by changing conformation after specific binding of the solute to be transported. Channels exclude molecules on the basis of size and charge, but do not depend on specific recognition of the molecules moving through.

For an uncharged molecule, the direction of passive transport across a membrane is determined solely by its __________________ gradient. On the other hand, for a charged molecule, the __________________ must also be considered. The net driving force for a charged molecule across a membrane therefore has two components and is referred to as the __________________ gradient. Active transport allows the movement of solutes against this gradient. The transporter proteins called __________________ transporters use the movement of one solute down its gradient to provide the energy to drive the uphill transport of a second gradient. When this transporter moves both ions in the same direction across the membrane, it is considered a(n) __________________; if the ions move in opposite directions, the transporter is considered a(n) __________________. antiport coupled

For an uncharged molecule, the direction of passive transport across a membrane is determined solely by its concentration gradient. On the other hand, for a charged molecule, an additional force called the membrane potential must also be considered. The net driving force for a charged molecule across a membrane therefore has two components and is referred to as the electrochemical gradient. Active transport allows the movement of solutes against this gradient. The transporter proteins called coupled transporters use the movement of one solute down its gradient to provide the energy to drive the uphill transport of a second gradient. When this transporter moves both ions in the same direction across the membrane, it is considered a(n) symport; if the ions move in opposite directions, the transporter is considered a(n) antiport.

Glucose

what happens when you eat a meal and increase circulating blood sugar?

Glucose is high outside the cell so the conformation is open to take in glucose and move it to the cytosol where the concentration is low (at beta cell and other cell types)

once transcription is complese the stpry of the LDL receptor begin where inside the cell and why?

LDL receptors are translated by ribosomes on the er and are motdified by the golgo before traveling in vesicle to cell surface

If ATP production is blocked in an animal cell, the cell will swell up. Explain this observation.

ATP is required to power the Na+-K+ pump, which is necessary for maintaining osmotic balance. The pump requires ATP hydrolysis to drive its pumping cycle. So, in the absence of ATP production, the Na+ concentration inside the cell will increase. This is followed by passive diffusion of water across the membrane, causing the cell to swell.

Which of the following statements about the cytoskeleton is true? A. All eukaryotic cells have actin, microtubules, and intermediate filaments in their cytoplasm. B. Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end. C. The three cytoskeletal filaments perform distinct tasks in the cell and act completely independently of one another. D. The cytoskeleton provides a rigid and unchangeable structure important for the shape of the cell.

Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end

Compared to the normal situation, in which actin monomers carry ATP, what do you predict would happen if actin monomers that bind a nonhydrolyzable form of ATP were incorporated into actin filaments? A. Actin filaments would grow shorter because depolymerization would be enhanced. B. Actin filaments would grow longer. C. No change, as addition of monomers binding nonhydrolyzable ATP would not affect actin filament length. D. Actin filaments would grow shorter because new monomers could not be added to the filaments.

Actin filaments would grow longer.

It is thought that the glucose transporter switches between two conformational states in a completely random fashion. How is it possible for such a system to move glucose across the membrane efficiently in a single direction?

Although the opening of the glucose transporter on one side of the membrane or the other is random, the binding of glucose into the binding site of the transporter is not a random event. The affinity between the glucose molecule and the transporter governs the binding event: transporter + glucose Û transporter-glucose At high glucose concentrations the complex formation is favored; at low glucose concentrations dissociation of glucose from the transporter is favored. So, as long as there is a large concentration gradient, efficient transport can occur by the simple rules of binding equilibria.

You have generated antibodies that recognize the extracellular domain of the Ca2+-pump. Adding these antibodies to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+? (a) Ca2+-pumps in vesicle membranes keep cytosolic calcium levels low. (b) Ca2+-pumps in the endoplasmic reticulum membrane keep cytosolic calcium levels low. (c) Ca2+-pumps in the Golgi apparatus keep cytosolic calcium levels low. (d) Ca2+ concentrations in the cytosol increase at a steady rate.

The Na+-K+ ATPase is also known as the Na+-K+ pump. It is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. What happens immediately after the pump hydrolyzes ATP? (a) Na+ is bound (b) ADP is bound (c) the pump is phosphorylated (d) the pump changes conformation

When the net charge on either side of the plasma membrane is zero, what else is true? (a) There is an equal number of K+ ions on each side of the plasma membrane. (b) The K+ leak channels are open. (c) The electrochemical potential across the membrane is zero. (d) The resting membrane potential is between -20 mV and -200 mV.

Which of the following statements about resting membrane potential is not true? (a) The resting membrane potential for most animal cells is 0 mV, because the positive and negative ions are in balance. (b) The resting membrane potential for most animal cells is positive, because Na+ ions are so plentiful inside cells. (c) The resting membrane potential for most animal cells is negative, because the inside of the cell is more negatively charged than the outside of the cell. (d) At the resting membrane potential, no ions enter or exit the cell.

You have generated antibodies that recognize the extracellular domain of the Ca2+ pump. Adding these antibodies to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+? Select one: a. Ca2+ pumps in vesicles membranes keep cystosolic calcium levels low. b. Ca2+ pumps in the ER membrane keep cystosolic calcium levels low. c. Ca2+ pumps in the Golgi apparatus keep cystosolic calcium levels low. d. Ca2+ concentrations in the cytosol increase at a steady rate.

Ca2+ pumps in the ER membrane to keep cytosolic calcium levels low

how does calcium release from it concentration gradients interacts with vesicles?

Calcium activates SNARE Proteins expressed on vesicle and membrane surfaces (and other bud related proteins) Mediate docking and fusion of vesicle to membrane this is the exocytosis of insulin

It becomes dispersed DNA-protein complex know as _______ in nondividing cells.

Chromatin

Cl-

Which of the following statements about the cytoskeleton is false? A. The cytoskeleton is made up of three types of protein filaments. B. Covalent bonds between protein monomers hold together cytoskeletal filaments. C. The cytoskeleton controls the location of organelles in eukaryotic cells. D. The cytoskeleton of a cell can change in response to the environment.

Covalent bonds between protein monomers hold together cytoskeletal filaments.

Which of the following statements about the function of the centrosome is false? A. Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome. B. Centrosomes typically contain a pair of centrioles, which is made up of a cylindrical array of short microtubules. C. Centrosomes are the major microtubule-organizing center in animal cells. D. Centrosomes contain hundreds of copies of the g-tubulin ring complex important for microtubule nucleation.

Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome.

where is calcium located at?

Mitocohdria ER cytoplasma

Which of the following statements about microtubules is true? A. Motor proteins move in a directional fashion along microtubules by using the inherent structural polarity of a protofilament. B. Because microtubules are subject to dynamic instability, they are used only for transient structures in a cell. C. The centromere nucleates the microtubules of the mitotic spindle. D. ATP hydrolysis by a tubulin heterodimer is important for controlling the growth of a microtubule.

Motor proteins move in a directional fashion along microtubules by using the inherent structural polarity of a protofilament.

describe how the carrier protein works?

Move the solute across the membrane by binding it one side and transporting it to the other side.

You discover a protein, MtA, and find that it binds to the plus ends of microtubules in cells. The hypothesis that best explains this localization is ________________. A. MtA is important for the interaction of microtubules with the centrosome. B. MtA binds to GTP-bound tubulin on microtubules. C. MtA will not bind to purified microtubules in a test tube. D. MtA is involved in stabilizing microtubules.

MtA binds to GTP-bound tubulin on microtubules.

give an example of a voltage gated ion channel

Na+, K+, Ca2+

Fill in Table Q12-15. In the "type of transport" column, designate whether the transporter works by uniport, symport, or antiport mechanisms. Na+-K+ pump Na-glucose Ca2+ pump bacteriarhopdosin

Na+-K+ pump is antiport that requires ATP the main function is to maintain the gradients of Na n K ion across plasma membrane Na-glucose symport energy source Na gradient the import of glucose across plama membrane Ca pump uniport requires ATP function is to export CA ion from the cytosol bacteriarhopdosin is a uniport energy source light exporting H ions from the cell

There are several reasons why the primase used to make the RNA primer for DNA replication is not suitable for gene transcription. Which of the statements bleow is NOT one of those reasons? a) Primase initiates RNA synthesis on a single stranded DNA template b) Primase can initiate RNA synthesis without the need for a base-paired primer c) primase synthesizes only RNA's of about 5-20 nucleotides in length d) The RNA synthesized by primase remains base-paired to the DNA template

Primase can initiate RNA synthesis without the need for a base-paired primer

what happens to cause the release of Ca into the ER

Pump has four domains ATP binds and then 2 Ca2+ bind aspartic acid is phosphorylated Trigger conformational change Nucleotide binding domain and activator domains get close Leads to rearrangement of transmembrane helices Disrupts Ca2+ binding sights Ca2+ is released into lumen of SR or extracellular space

If a protein, such as hemoglobin, is composed of more than one polypeptide, it will has _______ structure.

Quaternary

The key enzymes involved in the synthesis of RNAs are ______

RNA polymerases

On the removal of urea, an unfolded protein can become ______.

Renatured

The a helices and b sheets are examples of protein _______ structure.

Secondary

It is concluded that all the information required to determine a protein's conformation is contained in its amino acid _______ and that the conformation of protein is also affected by ________.

Sequence Environmental conditions

How do small nonpolar molecules pass through?

Simple diffusion

Voltage-gated channels contain charged protein domains, which are sensitive to changes in membrane potential. By responding to a threshold in the membrane potential, these voltage sensors trigger the opening of the channels. Which of the following best describes the behavior of a population of channels exposed to such a threshold? Select one: a. Some channels remain closed and some open completely. b. All channels open completely. c. All channels open partly, to the same degree. d. All channels open partly, each to a different degree.

Some channels remain closed and some open completely.

In this case, each polypeptide is called a _______.

Subunit

The overall three-dimensional conformation of protein is its_____ structure.

Tertiary

Which of the following statements is true? Select one: a. Amoebae have transporter proteins that actively pump water molecules from the cytoplasm to the cell exterior. b. Bacteria and animal cells rely on the Na+-K+ pump in the plasma membrane to prevent lysis resulting from osmotic imbalances. c. The Na+-K+ pump allows animal cells to thrive under conditions of very low ionic strength. d. The Na+-K+ pump helps to keep both Na+ and Cl- ions out of the cell.

The Na+-K+ pump helps to keep both Na+ and Cl- ions out of the cell.

The movement of glucose into the cell, against its concentration gradient, can be powered by the co-transport of Na+ into the cell. Explain this movement with respect to the net entropy of the system (i.e. thermodynamics).

The movement of Na+ ions from an area that has a high Na+ concentration to a new area of low Na+ concentration is energetically favorable because the net entropy in the system is increasing. As long as the difference in Na+ ion concentration across the membrane is large, the entropic factor will be sufficient to drive the import of glucose into the cell, which represents a decrease in entropy with respect to the population of glucose molecules inside the cell.

Which of the following statements regarding dynamic instability is false? A. GTP hydrolysis by the tubulin dimer promotes microtubule shrinking. B. The newly freed tubulin dimers from a shrinking microtubule can be immediately captured by growing microtubules and added to their plus end. C. The GTP cap helps protect a growing microtubule from depolymerization. D. Each microtubule filament grows and shrinks independently of its neighbors.

The newly freed tubulin dimers from a shrinking microtubule can be immediately captured by growing microtubules and added to their plus end.

There are multiple proteins involved in the transport of proteins into the er. describe the steps pf this process

The signal sequence binds to a cytosolic SRP that also binds to ribosome Translation slows down until SRP binds the ER membrane SRP receptor SRP released Receptor passes ribosome to translocator in ER membrane-Translation continues -Signal functions to open the translocator channel -it stays bound to translocator channel Peptide continues threading through translocator, the signal is cleaved by peptidase 6. The sequence is released from channel into membrane and degraded Once synthesis is complete, soluble protein released into ER lumen Translocator channel closes

describe how hexokinase enzymatic activity is regulated

Their activities are regulated by the reversible binding of allosteric effectors or by covalent modification

what are the alpha subunits of the Na/K pump?

They are catalytic portion ----sit of ATP binds, binds Na and K, and P sites

what does the GLUT 4 do in adipose and muscle cells?

They are insulin regulated transporter -Facilitate glucose storage -when there is low insulin, glut 4 are in vesicles (figure 1.2)

K+ leak channels are found in the plasma membrane. These channels open and close in an unregulated, random fashion. What do they accomplish in a resting cell? Select one: a. They set the K+ concentration gradient to zero. b. They set the membrane potential to zero. c. They disrupt the resting membrane potential. d. They keep the electrochemical gradient for K+ at zero.

They keep the electrochemical gradient for K+

In order for a cell's genetic material to be utilized, the information is first copied from the DNA into the nucleotide sequence of RNA in a process called ________

Transcription

Cells expend energy in the form of ATP hydrolysis so as to maintain ion concentrations that differ from those found outside the cell.

True

Cells expend energy in the form of ATP hydrolysis so as to maintain ion concentrations that differ from those found outside the cell. -True -False

True

CO2 and O2 are water-soluble molecules that diffuse freely across cell membranes.

True.

What is an electrochemical gradient?

Voltage across the membrane created by charge ions

All intermediate filaments are of similar diameter because ____________. (a) the central rod domains are similar in size and amino acid sequence. (b) the globular domains are similar in size and amino acid sequence. (c) covalent bonds among tetramers allow them to pack together in a similar fashion. (d) there is only a single type of intermediate filament in every organism.

Compared to the normal situation, in which actin monomers carry ATP, what do you predict would happen if actin monomers that bind a nonhydrolyzable form of ATP were incorporated into actin filaments? (a) Actin filaments would grow longer. (b) Actin filaments would grow shorter because depolymerization would be enhanced. (c) Actin filaments would grow shorter because new monomers could not be added to the filaments. (d) No change, as addition of monomers binding nonhydrolyzable ATP would not affect actin filament length.

Which of the following does not occur before a eukaryotic mRNA is exported from the nucleus? a) the ribosome binds to the mRNA b) the mRNA is polyadenylated at its 3'end c) 7-methyl-G is added in a 5' to 5' linkage to the mRNA d) RNA polymerase dissosciates

Which of the following items is not important for flagellar movement? (a) sarcoplasmic reticulum (b) ATP (c) dynein (d) microtubules

Which of the following organelles has both an outer and an inner membrane? a) endoplasmic reticulum b) mitochondrion c) lysosome d) peroxisome

Which of the following statements about microtubules is true? (a) Motor proteins move in a directional fashion along microtubules by using the inherent structural polarity of a protofilament. (b) The centromere nucleates the microtubules of the mitotic spindle. (c) Because microtubules are subject to dynamic instability, they are used only for transient structures in a cell. (d) ATP hydrolysis by a tubulin heterodimer is important for controlling the growth of a microtubule.

Which of the following statements about the function of the centrosome is false? (a) Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome. (b) Centrosomes contain hundreds of copies of the γ-tubulin ring complex important for microtubule nucleation. (c) Centrosomes typically contain a pair of centrioles, which is made up of a cylindrical array of short microtubules. (d) Centrosomes are the major microtubule-organizing center in animal cells.

Which of the situations below will enhance microtubule shrinkage? (a) addition of a drug that inhibits GTP exchange on free tubulin dimers (b) addition of a drug that inhibits hydrolysis of the GTP carried by tubulin dimers (c) addition of a drug that increases the affinity of tubulin molecules carrying GDP for other tubulin molecules (d) addition of a drug that blocks the ability of a tubulin dimer to bind to γ-tubulin

Which of the following statements about the structure of microtubules is false? A. Within a microtubule, all protofilaments are arranged in the same orientation, giving the microtubule structural polarity. B. a-Tubulin and b-tubulin are covalently bound to make the tubulin dimer that then assembles into protofilaments. C. Microtubules are built from protofilaments that come together to make a hollow structure. D. The two ends of a protofilament are chemically distinct, with a-tubulin exposed at one end and b-tubulin exposed at the other end.

a-Tubulin and b-tubulin are covalently bound to make the tubulin dimer that then assembles into protofilaments.

what is consider the hallmark of cell invasion

ability of one cell to break away from tumor and move

concentrated under pm in are called cell coretx

actin

important for formation of the lamellipodia

actin

monomer that binds ATP

actin

Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________. Select one: a. active transport b. free diffusion c. facilitated diffusion d. passive transport

active transport

What type of transport is the carrier protein?

active transport

pumps are transporters that are able to harness energy provided by other components in cells to drive movement of solutes across membranes, against their concentration gradient. this type of transport is called

active transport

what does Calcium act as

acts as 2nd messenger to trigger events: contraction and release of insulin

Which of the situations below will enhance microtubule shrinkage? A. addition of a drug that inhibits hydrolysis of the GTP carried by tubulin dimers B. addition of a drug that blocks the ability of a tubulin dimer to bind to g-tubulin C. addition of a drug that inhibits GTP exchange on free tubulin dimers D. addition of a drug that increases the affinity of tubulin molecules carrying GDP for other tubulin molecules

addition of a drug that inhibits GTP exchange on free tubulin dimers

The hydrolysis of GTP to GDP carried out by tubulin molecules ________________. A. allows the behavior of microtubules called dynamic instability. B. tips the balance in favor of microtubule assembly. C. occurs because the pool of free GDP has run out. D. provides the energy needed for tubulin to polymerize.

allows the behavior of microtubules called dynamic instability.

The address information for protein sorting in eukaryotic cell is contained in the ___ of the proteins. Proteins that remain the cytosol do not contains_____. Proteins enter the nucleus in thier____ form while proteins entering the mitochondria are in thier___ form. the proteins transported into the ER by____in thier ____ form. Proteins are transported in the golgi appararturs via_____. Proteins are transported out of the cell via____ pathayway. Fluids and macromoleucles are transported into the cell via____ pathway. THe formation of____in ____ stabilizes protein structure

amino acids sorting signal folded unfolded translocation unfolded transport vesicles secetary endocytics disulfide bonds er

What can pass through the membrane that are large uncharged polar molecules? easy or no?

amino acids, glucose, and nucleotides not easy

How is the intermediated filaments anchored

anchored to plasma membrane by cell-cell junction called DESMosomes -allowing neighboring cell to be link

Na+ - K+ pump - name type of transport, energy source and function

antiport, atp, maintain gradients of sodium and K ions across membrane

what type of structure do the channel have?

aqueous pore

what amino acid in regards to the calcium pump is phosphlayted?

aspartic acid

what is the purpose of dynamin

assemble around necl of bud to pinch off vesicle

Consider the mechanism by which actin and tubulin polymerize. Which of the items below does not describe something similar about the polymerization mechanisms of actin and microtubules? (a) Although both filaments can grow from both ends, the growth rate is faster at the plus ends. (b) Depolymerization initiates at the plus ends of filaments. (c) Nucleotide hydrolysis promotes depolymerization of filaments. (d) Free subunits (actin and tubulin) carry nucleoside triphosphates.

Which of the following statements about organellar movement in the cell is false? (a) Organelles undergo saltatory movement in the cell. (b) Only the microtubule cytoskeleton is involved in organellar movement. (c) Motor proteins involved in organellar movement use ATP hydrolysis for energy. (d) Organelles are attached to the tail domain of motor proteins.

Which of the following statements is false? (a) Cytochalasins prevent actin polymerization. (b) Actin filaments are usually excluded from the cell cortex. (c) Integrins are transmembrane proteins that can bind to the extracellular matrix. (d) ARPs can promote the formation of branched actin filaments.

Which of the following statements is false? a)DNA molecules, like proteins, consist of a single, long polymeric chain that is assembled from small monomeric subunits b)The polarity of a DNA strand results from the polarity of the nucleotide subunits c)There are five different nucleotides that become incorporated into a DNA strand d)Hydrogen bonds between each nucleotide hold individual DNA strands together

You discover a protein, MtA, and find that it binds to the plus ends of microtubules in cells. The hypothesis that best explains this localization is ________________. (a) MtA is involved in stabilizing microtubules. (b) MtA binds to GTP-bound tubulin on microtubules. (c) MtA is important for the interaction of microtubules with the centrosome. (d) MtA will not bind to purified microtubules in a test tube.

ion channels are classified as membrane transport proteins. channels discriminate by size and charge. in addition to Na+, which of following ions would you expect to be able to freely diffuse through a Na+ channel. explain

b b/c its positively charged and small enough to fit through channel

Which of the following best describes the behavior of a gated channel? (a) It stays open continuously when stimulated. (b) It opens more frequently in response to a given stimulus. (c) It opens more widely as the stimulus becomes stronger. (d) It remains closed if unstimulated.

b) It opens more frequently in response to a given stimulus.

why does the membrane block most water-soluble molecules from passing

becuase interior of lipid bilayer is hydrophobic

Which molecule is more likely to diffuse through the lipid bilayer? -amino acids -benzene

benzene

what cause the dephoshplylation of the pump?

binding of pottassium

how does calcium faciltate insulin relase

by interacting with the insulin vesicles which in turn cause the insuln to relase from activating SNARE

The microtubules in a cell form a structural framework that can have all the following functions except which one? (a) holding internal organelles such as the Golgi apparatus in particular positions in the cell (b) creating long, thin cytoplasmic extensions that protrude from one side of the cell (c) strengthening the plasma membrane (d) moving materials from one place to another inside a cell

Which of the following statements about the cytoskeleton is false? (a) The cytoskeleton is made up of three types of protein filaments. (b) The cytoskeleton controls the location of organelles in eukaryotic cells. (c) Covalent bonds between protein monomers hold together cytoskeletal filaments. (d) The cytoskeleton of a cell can change in response to the environment.

Which of the following statements is correct? Kinesins and dyneins ____________________. (a) have tails that bind to the filaments. (b) move along both microtubules and actin filaments. (c) often move in opposite directions to each other. (d) derive their energy from GTP hydrolysis.

Which of the following statements regarding DNA replication are TRUE? a) primase is only needed to initiate DNA replication on the lagging strand b) The sliding clamp is loaded multiple timeson each DNA strand c) Telomerase is a DNA polymerase that carries its own RNA molecule to use as a primer at the end of the lagging strand d) primase requires a proofreading function that ensure there are no errors in the RNA primers used for DNA replication

You are examining a cell line in which activation of the Rho family member Rac promotes lamellipodia formation. Which of the following statements is most likely to be true? (a) Cells carrying a Rac mutation that makes Rac act as if it is always bound to GTP will polymerize more unbranched actin filaments than normal cells. (b) Cells carrying a Rac mutation that makes Rac unable to exchange GDP for GTP will polymerize more unbranched actin filaments than normal cells. (c) Cells carrying a Rac mutation that makes Rac act as if it is always bound to GTP will polymerize more branched actin filaments than normal cells. (d) Cells carrying a Rac mutation that makes Rac unable to exchange GDP for GTP will polymerize more branched actin filaments than normal cells.

For both actin and microtubule polymerization, nucleotide hydrolysis is important for ______. (a) stabilizing the filaments once they are formed. (b) increasing the rate at which subunits are added to the filaments. (c) promoting nucleation of filaments. (d) decreasing the binding strength between subunits on filaments.

Keratins, neurofilaments, and vimentins are all categories of intermediate filaments. Which of the following properties is not true of these types of intermediate filaments? (a) They strengthen cells against mechanical stress. (b) Dimers associate by noncovalent bonding to form a tetramer. (c) They are found in the cytoplasm. (d) Phosphorylation causes disassembly during every mitotic cycle.

The hydrolysis of GTP to GDP carried out by tubulin molecules ________________. (a) provides the energy needed for tubulin to polymerize. (b) occurs because the pool of free GDP has run out. (c) tips the balance in favor of microtubule assembly. (d) allows the behavior of microtubules called dynamic instability.

Which of the following statements about actin is false? (a) ATP hydrolysis decreases actin filament stability. (b) Actin at the cell cortex helps govern the shape of the plasma membrane. (c) Actin filaments are nucleated at the side of existing actin filaments in lamellipodia. (d) The dynamic instability of actin filaments is important for cell movement.

Which of the following statements about the cytoskeleton is true? (a) All eukaryotic cells have actin, microtubules, and intermediate filaments in their cytoplasm. (b) The cytoskeleton provides a rigid and unchangeable structure important for the shape of the cell. (c) The three cytoskeletal filaments perform distinct tasks in the cell and act completely independently of one another. (d) Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end.

Which of the following statements about the structure of microtubules is false? (a) Microtubules are built from protofilaments that come together to make a hollow structure. (b) The two ends of a protofilament are chemically distinct, with α-tubulin exposed at one end and β-tubulin exposed at the other end. (c) Within a microtubule, all protofilaments are arranged in the same orientation, giving the microtubule structural polarity. (d) α-Tubulin and β-tubulin are covalently bound to make the tubulin dimer that then assembles into protofilaments.

Which of the following statements regarding dynamic instability is false? (a) Each microtubule filament grows and shrinks independently of its neighbors. (b) The GTP cap helps protect a growing microtubule from depolymerization. (c) GTP hydrolysis by the tubulin dimer promotes microtubule shrinking. (d) The newly freed tubulin dimers from a shrinking microtubule can be immediately captured by growing microtubules and added to their plus end.

Which of the statements below about intermediate filaments is false? (a) They can stay intact in cells treated with concentrated salt solutions. (b) They can be found in the cytoplasm and the nucleus. (c) They can be anchored to the plasma membrane at a cell-cell junction. (d) Each filament is about 10 μm in diameter.

where is K+

inside cell

includes keratin and neurofilaments

intermediate

supports and strenthen the nuclear enbole

intermediate

can be connected through desmosomes

intermediated

Is calcium high or low in the cell?

intracellular calcium concentrations must be low

intergrin

involemnt in focal contacts

what is the hallmark of cancer cell invasion?

is the ability of one cell to break away and away from tumor and move

why are microtublues unstable?

it allows the assembly and dissassembly in different locations

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

what does the morpholgical changes of the cell show?

lead to detachment of cell from tumor -promote formation of lamellopodia

ldl

lipoprotein carries the cholesterol

Various kinds of RNAs are produced, each with different functions. _____ molecules codes proteins, _____ molecules act as transporters for protein synthesis.

mRNA tRNA

calcium is involved in which of the 3 parts of vesicle transport

medicate docking and fushion of vescile to membrane

centrosomes involved in organzation theb formation

micor

major property is dynamic instability

micro

Another organelle found in essentially all eukaryotic cells is the ______ which generates the chemical energy for the cell.

mitochondria

Following _____ for the purpose of cell divison the instructions specified by the DNA will specify the production of proteins needed by that cell. For a cells genetic material to be used the information is first copied from _____ into the nucleotide sequece of____ in a process called_____ that is confined to the ____. Various kinds of RNA ar e produced each with different functions.____ molecules code for proteins____moleucles act as adaptors for protein sysnthessi___ molecules areintergal compoments of the ribosomes. Next proteins are synthesized using the RNA molecule on a ____that is located in the___or on____ in process called _______

mitosis dna rna transcrption nucleus mrna trna rrna ribosomes cytoplasma er translaction

uncharged polar molecules

molecules with an uneven distribution of charge diffuse reapidly if small enough. H20 (18 daltons passes), ehtanol (46 daltons), glycerol (92 daltons) is less rapid and glucose (180 daltons) bare crosses

after a pasta meal b cell release insule. ATP generated from glycolysis cause ATP senstive K channels to close. How is membrane affected

more posistive

where are the intermediate filaments of neurofilaments located at? (cytoplasmic)

nerve cells

what would happen to resting membrane potential if inner channel of K+ leak channel decreased in size by half?

no K+ would be able to leak out and resting membrane potential would become more positive

ions and charged molecules

no matter hw smal, highly impermeable. molecules' charge and strong electrical attraction to water molecules inhibit them from entering hydrocarbon phase of bilayer

Splicing of exons is ________ a covalent modifcation that can be made to an RNA molecule in eukaryotic cells before the RNA molecule becomes a mature mRNA

not

The _________ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum.

nuclear envlope

where are the itermediated filaments of the nuclear located at? and what are they called

nuclear lamins and in all animal cells

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 thier cargo in the nucleus

Eukaryotic cells are bigger and more elaborate than prokaryotic cells. By definition, all eukaryotic cells have a ______________, usually the most prominent organelle.

nucleus

The process of making a new strand of DNA is confined to the ____and take place in____ phase of_______in the cell cycle. During____ replication the_____strand is copied in the 5-3 direction while the____ strand is copied in the 3-5 direction. The____ is responsible for unwinding the two DNA strands at the____ thus creating two____ this allows for greatter efficiencey and timing of replication

nucleus s phase interphase semi consertive lagging leading helicase orgin strands

Which of the following statements is correct? Kinesins and dyneins ____________________. A. have tails that bind to the filaments. B. derive their energy from GTP hydrolysis. C. move along both microtubules and actin filaments. D. often move in opposite directions to each other.

often move in opposite directions to each other.

it is thought glucose transporter switches btwn two conformational states in completely random fashion. how is it possible for such a system to move glucose across membrane efficiently in single direction

opening of glucose transporter on one side of membrane or other is random, but binding of glucose into binding site of transporter is not random. affinity between glucose molecule and transporter governs binding event: at high glucose concentrations complex formation is favored, at low concentrations, dissociation of glucose from transporter is favored. as long as there is a large concentration gradient, efficient transport can occur by rules of binding equilibria

where is Na+

outside cell

What type of transport is the channel?

passive transport

DNA is a linear polymer of nucleotides linked by ________

phosphodiester bonds

what happens immediately after the pump hydrolyzes ATP-na/k

phosphoylation of pump

Ca2+ pumps in the plasma membrane and endoplasmic reticulum are important for _____________. Select one: a. maintaining osmotic balance b. preventing Ca2+ from altering the activity of molecules in the cytosol c. providing enzymes in the endoplasmic reticulum with Ca2+ ions that are necessary for their catalytic activity d. maintaining a negative membrane potential

preventing Ca2+ from altering the activity of molecules in the cytosol

how many domains do the calcium pump contains?

pump has 4 domains

na+-K+ atpase also known as Na+-K+ pump. it is responsible for maintaining high extracellular sodium ion concentration and high intracellular potassium ion concentration. what happens immediately after pump hydrolyzes ATP

pump is phosphorylated

what must happen for a cell not to be torn apar

quantity of positivie charge inside must be balanced almost equally by external negative charge

_____ molecules are integral components of the ribosomes.

rRNA

which two proteins are involved in docking the vesicle to the target membrane

rabgtoase SNARE

how does the tumor cell show morphological changes

rearrangement of actin in the cytoskeleton decrease interaction of the cell to neighboring tumor cells.

what is the purpose of chromatin remodeling

rearrangment of chromtin for a condense state to a transcptionally one. allowing transcriptiion factors to acess dna and control it in gene expression

what does the NA/K ATPase pump require?

requires ATP hydrolysis and therefore pump is also an ATPase enzyme

what does the carrier protein require?

requires that the solute fit in the specific binding site (selective) -turnstile-like

Which of the following items is not important for flagellar movement? A. ATP B. dynein C. microtubules D. sarcoplasmic reticulum

sarcoplasmic reticulum

what does the rate of diffusion depend on

size of molecule and its solubility properties, generally smaller the molecule and more soluble, rate of diffusion is faster

What does the rate of diffusion pass the plasma membrane depend on?

size of molecule and solubility

describe how the channel membrane protein work?

small hydrophillic pores that allow for solutes to pass through

what can pass through the membrane easily that are small hydrophobic ? easy or no?

small hydrophobic molecules O2, CO2, N2 and benzene easy

what are the smaller beta subunits of the Na/K pump?

smaller beta subunits are glyvoproteins for plasma membrane localization

where are K+, Ca2+, Cl- and H+ most plentiful

solute's in a cell's environment

what type of structure do the carrier protein have?

solute-binding site

what kind of molecules can pass via transporter

solutes that are either small organic molecules or inorganic ions

After isolating the rough er from the rest of the cytoplasm you purfy the rna attacted to it. Which of the following proteins do you expect the RNA from the rough er to encode

souble secreted proteins er membrane proteins plasma membrane proteins

Transporters, in contrast to channels, work by ________________. Select one: a. specific binding to solutes b. a gating mechanism c. filtering solutes by charge d. filtering solutes by size

specific binding to solutes

transporters, in contrast to channels, work by

specific binding to solutes

The microtubules in a cell form a structural framework that can have all the following functions except which one? A. strengthening the plasma membrane B. holding internal organelles such as the Golgi apparatus in particular positions in the cell C. moving materials from one place to another inside a cell D. creating long, thin cytoplasmic extensions that protrude from one side of the cell

strengthening the plasma membrane

The stimulation of auditory nerves depends on the opening and closing of channels in the auditory hair cells. Which type of gating mechanism

stress-gated

_______ ion channels are found in the hair cells of the mammalian cochlea. Select one: a. Ligand gated b. Stress gated c. Voltage gated

stress-gated

what problems do ppl with Cystic fibrosis suffer

suffer with a higher then normal thick mucos. a device can be insted into them to break up the mucous. or the use of dubfrim can be used which open up an altertive Cl- channel

Na+ - glucose -name type of transport, energy source and function

symport, Na+ gradient, import glucose into cell against its gradient

All intermediate filaments are of similar diameter because ____________. A. the central rod domains are similar in size and amino acid sequence. B. the globular domains are similar in size and amino acid sequence. C. covalent bonds among tetramers allow them to pack together in a similar fashion. D. there is only a single type of intermediate filament in every organism.

the central rod domains are similar in size and amino acid sequence.

All intermediate filaments are of similar diameter because ____________. A. covalent bonds among tetramers allow them to pack together in a similar fashion. B. there is only a single type of intermediate filament in every organism. C. the globular domains are similar in size and amino acid sequence. D. the central rod domains are similar in size and amino acid sequence.

the central rod domains are similar in size and amino acid sequence.

describe cell movement?

the meshwork cell cortex allows rearrangement of actin filaments to allow change in cell shape and locomotion (crawling)

what is the cell cortex?

the meshwork cortex supports plasma membrane and gives mechanical strength it interacts with acting binding proteins

what is dynamic instability?

the polymerization and depolymerization of microtubules

The Na+-K+ ATPase is also known as the Na+-K+ pump. It is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. What happens immediately after the pump hydrolyzes ATP? Select one: a. Na+ is bound. b. ADP is bound. c. The pump is phosphorylated. d. The pump changes conformation.

the pump is phosphorylated

How is the movement of the cell dependent on?

the response is dependent on a chemical signal or stimuli

before fushion can occur how are the water molecules between the two hydrophillic surface displaced

the squeexing of the snares foces water out of the interactions

What drives calcium into the cell?

there is a large electrochemical gradient driving Ca into the cell

Once the actin monomer ATP binding site has hydrolyzed to ADP what happens to the stability?

this will decrease stability of the filament (which will later promote the de-polymerization of filament

ion channels

tiny hydrophilic pores which only allow inorganic molecules to diffuse

What is the purpose of the calcium ATPase pump

to keep intracellular (cytosolic) calcium low

what is the ldl receptor

translocated to cell surface via vesicls

proteins that are fully translated i the cytosol do not end up in

transport vesicles

what are the two main classes that mediate transfer of molecules across membrane

transporter, channel

Most ion channels are gated, which allow them to open and close in response to a specific stimulus rather than allowing the constant, unregulated flow of ions. Select one: True False

true

T or F a channel can only mediate passive/facilitate diffusion

true

T or F transports can mediate active transport

true

The electrochemical gradient for K+ across the plasma membrane is small. Therefore, any movement of K+ from the inside to the outside of the cell is driven solely by its concentration gradient. Select one: True False

true

Transporters undergo transitions between different conformations, depending on whether the substrate-binding pocket is empty or occupied. Select one: True False

true

chromatin is the most condensed structure of DNA

true

histones bind to dna in a sequence specific manner

true

t or f K+ leak channel allows potassium to flow down concentration gradient

true

the core histone is subject to covalent modification

true

negative dna is wrapped around posistively charged histones

trye.

What are microtubles made from?

tubulin

where are actin filaments most concentrated at?

under plasma membrane in area called cell cortex

describe the mechanism by which post-translational histone modification facilitates chromtin remodeling

undergoes reversible covalent chemical modifcations to control local structure allowing acess to DNA

Ca2+ pump - name type of transport, energy source and function

uniport, ATP, pumps Ca2+ out of cytosol

bacteriorhodopsin - name type of transport, energy source and function

uniport, light, pumps protons out of cell

berfiely explain why the mitochondria is not concerned with damage dna

unique repair feature: degrade excessibly damage mtDNA followed by replication(fussion) of intact mtDNA

the addition of cholesterol between ____ hydrocarbon tails can ___ membrane fuldity

unsaturated decrease

what is ATP-driven pumps?

use ATP hydrolysis to go against gradient (often two metabolites are coupled together to maintain cell membrane potential

describe the mechanism by which the chromatin remodeling complex facilitates chromatin remodeling

use ATP hydrolysis to phyically push and slide the DNA as it moves along, loosening the strand from the histone whihc in turn gains acces to DNA

what is K+ balance by

variety of negatively charged intracellular ions (anions)

______ ion channels respond to changes in membrane potential. Select one: a. Ligand gated b. Stress gated c. Voltage gated

voltage-gated

What characteristic can a molecule pass through that need help passing?

water soluble large uncharged charged ion-use active transport

You are interested in understanding the regulation of nuclear lamina assembly. To create an in vitro system for studying this process you start with partly purified nuclear lamina subunits to which you will add back purified cellular components to drive nuclear lamina assembly. Before you start doing experiments, your instructor suggests that you consider what type of conditions would be most amenable to the assembly of the nuclear lamina from its individual subunits in vitro. Which of the following conditions do you predict would be most likely to enhance the assembly of the nuclear lamina? (a) addition of phosphatase inhibitors (b) addition of ATP (c) addition of a concentrated salt solution that is 10 times the concentration normally found in the nucleoplasm (d) addition of protein kinase inhibitors

The helical structure of DNA is quite stable. List and describe the 3 properties related to the bases that for stablity.

weak noncovalent forces of h nonpolar,heterocyclic aromatic GC (3 h bonds) and AT (2 h bonds)

what is the purpose of apo B

wraps around the LDL molecule

Your friend works in a biotech company that has just discovered a drug that seems to promote lamellipodia formation in cells. Which of the following molecules is unlikely to be involved in the pathway that this drug affects? (a) Rac (b) ARP (c) actin (d) myosin

d) They keep the electrochemical gradient for K+ at zero.

Facilitated diffusion can be described as the favorable movement of one solute down its concentration gradient being coupled with the unfavorable movement of a second solute up its concentration gradient. Select one: True False

false

Gap junctions are large pores that connect the cytosol to the extracellular space. Select one: True False

false

T or F a transporter can only mediate passive/facilitated diffusion

false

The ion selectivity of a channel completely depends solely on the charge of the amino acids lining the pore inside the channel. Select one: True False

false

The net negative charge on the cytosolic side of the membrane enhances the rate of glucose import into the cell by a uniporter. Select one: True False

false

What characteristic can a molecule pass through easily without help?

fay soluble small nonpolar uncharged polar: small -use simple diffusion

Describe the polarity structure of the actin filament?

filament has structural polarity with minus ends and plus ends

what is the actin filament made of?

filament is a twisted chain of actin monomers

A hungry yeast cell lands in a vat of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process: C6H12O6 + 2ADP + 2Pi + H+ → 2CO2 + 2CH3CH2OH + 2ATP + 2H2O Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeast cell membrane, and the yeast cell dies. Which of the following could account for the yeast cell's demise? -toxic buildup of carbon dioxide inside the cell -toxic buildup of ethanol inside the cell -diffusion of ATP out of the cell -inability to import sugar into the cell

inability to import sugar into the cell

what is the fucntion of actin filaments

essential for cell movements by creating tempoary structures

Which molecule is more likely to diffuse through the lipid bilayer? -Cl- -ethanol

ethanol

what is Na+ mostly balanced by

extracellular Cl-

Aquaporin channels are found in the plasma membrane, allowing the rapid passage of water molecules and small ions in and out of cells. Select one: True False

false

Ca2+ pumps in the plasma membrane and endoplasmic reticulum are important for _____________. (a) maintaining osmotic balance (b) preventing Ca2+ from altering the activity of molecules in the cytosol (c) providing enzymes in the endoplasmic reticulum with Ca2+ ions that are necessary for their catalytic activity (d) maintaining a negative membrane potential

(b). The major purpose of the Ca2+ pumps is to keep the cytosolic concentration of Ca2+ low. When Ca2+ does move into the cytosol, it alters the activity of many proteins; hence Ca2+ is a powerful signaling molecule. It is not involved in the catalytic activity of ER enzymes (choice (c)). Because the levels of Ca2+ are very low relative to the levels of K+ and Na+, the Ca2+ gradient does not have a significant effect on the osmotic balance of the cell (choice (a)) or the membrane potential (choice (d)).

If Na+ channels are opened in a cell that was previously at rest, how will the resting membrane potential be affected? (a) The membrane potential is not affected by Na+. (b) It becomes more negative. (c) It becomes more positive. (d) It is permanently reset.

(c). As Na+ ions move into the cell, the net charge becomes more positive (less negative) and the membrane potential changes to reflect the Co/Ci for both Na+ and K+ ions.

The Na+-K+ ATPase is also known as the Na+-K+ pump. It is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. What happens immediately after the pump hydrolyzes ATP? (a) Na+ is bound. (b) ADP is bound. (c) The pump is phosphorylated. (d) The pump changes conformation.

(c). The phosphorylation of the pump causes the conformational change, and it occurs after the binding of Na+.

Which of the following statements is true? (a) Amoebae have transporter proteins that actively pump water molecules from the cytoplasm to the cell exterior. (b) Bacteria and animal cells rely on the Na+-K+ pump in the plasma membrane to prevent lysis resulting from osmotic imbalances. (c) The Na+-K+ pump allows animal cells to thrive under conditions of very low ionic strength. (d) The Na+-K+ pump helps to keep both Na+ and Cl- ions out of the cell.

(d). The Na+-K+ pump keeps Na+ out directly by pumping it out and keeps Cl- out indirectly by helping to maintain the negative membrane potential. Cells do not have pumps for moving water molecules across the membrane (choice (a)), since the lipid bilayer is permeable to water. Bacteria do not have Na+-K+ pumps in their plasma membranes (choice (b)). The Na+-K+ pump cannot directly remove water molecules from the cell; it helps maintain osmotic balance by pumping out the Na+ that leaks in, which would not help if the cell were in a solution of very low ionic strength (choice (c)).

(d). The high extracellular concentration of Na+ is employed by a transporter that pumps protons out of animal cells as Na+ is brought into the cell. The other transporters are found only in bacterial cells.

3. drag the rest of the cell forward by traction

*The cell using this anchor to drag the rest of the cell body forward via contraction *Myosin motor proteins aid in the contraction

step 1 push out the protruding leading edge of the cell

*driven by actin polymerization *leading edge now called a lamellipodia

2. protrusion adhere to new surface

*lamellipodia touch down and stick with the help of integrins *integrins are transmembrane proteins -do the adhering to the new surface *integrins capture actin filaments in the cell cortex creating an anchor

A molecule moves down its concentration gradient by __________________ transport, but requires __________________ transport to move up its concentration gradient. Transporter proteins and ion channels function in membrane transport by providing a __________________ pathway through the membrane for specific polar solutes or inorganic ions. __________________ are highly selective in the solutes they transport, binding the solute at a specific site and changing its conformation so as to transport the solute across the membrane. On the other hand, __________________ discriminate between solutes mainly on the basis of size and electrical charge.

A molecule moves down its concentration gradient by passive transport, but requires active transport to move up its concentration gradient. Transporter proteins and ion channels function in membrane transport by providing a hydrophilic pathway through the membrane for specific polar solutes or inorganic ions. Transporter proteins are highly selective in the solutes they transport, binding the solute at a specific site and changing its conformation so as to transport the solute across the membrane. On the other hand, ion channels discriminate between solutes mainly on the basis of size and electrical charge.

A. Gap junctions are large pores that connect the cytosol to the extracellular space. B. Aquaporin channels are found in the plasma membrane, allowing the rapid passage of water molecules and small ions in and out of cells. C. The ion selectivity of a channel completely depends solely on the charge of the amino acids liningthe pore inside the channel. D. Most ion channels are gated, which allow them to open and close in response to a specific stimulus rather than allowing the constant, unregulated flow of ions.

A. False. Gap junctions are used to connect the cytosol of adjacent cells, allowing the sharing of ions and small metabolites. Because gap junctions are large channels, if they were open while facing the extracellular environment, the ability of the plasma membrane to serve as a permeability barrier would be greatly reduced. B. False. Charged molecules (even protons, which are very small), are not able to pass through aquaporins. C. False. Selectivity depends on three parameters: the diameter, shape and charge of the ion trying to pass through the pore of the channel. D. True.

A. Facilitated diffusion can be described as the favorable movement of one solute down its concentration gradient being coupled with the unfavorable movement of a second solute up its concentration gradient. B. Transporters undergo transitions between different conformations, depending on whether the substrate-binding pocket is empty or occupied. C. The electrochemical gradient for K+ across the plasma membrane is small. Therefore, any movement of K+ from the inside to the outside of the cell is driven solely by its concentration gradient. D. The net negative charge on the cytosolic side of the membrane enhances the rate of glucose import into the cell by a uniporter.

A. False. This describes coupled transport, which is one type of active transport. Facilitated diffusion can also be called passive transport, in which a solute always moves down its concentration gradient. B. True. C True. D. False. Glucose is an uncharged molecule, and its import is not directly affected by the voltage difference across the membrane if glucose is being transported alone. If the example given were the Na/glucose symporter, we would have to consider the charge difference across the membrane.

You have prepared lipid vesicles (spherical lipid bilayers) that contain Na+-K+ pumps as the sole membrane protein. All of the Na+-K+ pumps are oriented in such a way that the portion of the molecule that normally faces the cytosol is on the inside of the vesicle and the portion of the molecule that normally faces the extracellular space is on the outside of the vesicle. Assume that each pump transports one Na+ ion in one direction and one K+ ion in the other direction during each pumping cycle (see Figure Q12-16 for how the Na+-K+ pump normally functions in the plasma membrane).

A. Without any ATP to provide energy for the Na+-K+ pumps, no ions will be pumped. B. The pumps will use the energy from ATP hydrolysis to transport Na+ out of the vesicles and K+ into the vesicles. (The pumps will stop working either when the amount of ATP inside the vesicle is depleted or when the K+ outside the vesicles is depleted.) C. The pump will bind a molecule of Na+, causing the ATPase activity to hydrolyze ATP and transfer the phosphate group onto the pump. A conformational change will occur, leading to the release of Na+ from the vesicle. However, because there is no K+ outside the vesicle, the pump will get stuck at that step and subsequent steps of the cycle will not occur.

Circle the molecule in each pair that is more likely to diffuse through the lipid bilayer. A. amino acids or benzene B. Cl- or ethanol C. glycerol or RNA D. H2O or O2 E. adenosine or ATP

A. benzene (small nonpolar versus larger uncharged) B. ethanol (polar versus charged) C. glycerol (small polar versus very large, highly charged) D. O2 (nonpolar versus polar) E. adenosine (polar versus highly charged)

For each missing section of the paragraph, select the best word or phrase from the pull-down menus below. For an uncharged molecule, the direction of passive transport across a membrane is determined solely by its ___A___ gradient. On the other hand, for a charged molecule, the ___B___ must also be considered. The net driving force for a charged molecule across a membrane therefore has two components and is referred to as the ___C___ gradient. Active transport allows the movement of solutes against this gradient. The transporter proteins called ___D___ transporters use the movement of one solute down its gradient to provide the energy to drive the uphill transport of a second gradient. When this transporter moves both ions in the same direction across the membrane, it is considered a ___E___; if the ions move in opposite directions, the transporter is considered a ___F___.

A. concentration B. membrane potential C. electrochemical D. coupled E. symport F. antiport

A molecule moves down its concentration gradient by ___A___ transport, but requires ___B___ transport to move up its concentration gradient. Transporter proteins and ion channels function in membrane transport by providing a ___C___ pathway through the membrane for specific polar solutes or inorganic ions. ___D___ are highly selective in the solutes they transport, binding the solute at a specific site and changing its conformation so as to transport the solute across the membrane. On the other hand, ___E___ discriminate between solutes mainly on the basis of size and electrical charge.

A. passive B. active C. hydrophilic D. transporter proteins E. ion channels

Active transport requires the input of energy into a system so as to move solutes against their electrochemical and concentration gradients. Which of the following is not one of the common ways to perform active transport? (a) Na+-coupled (b) K+-coupled (c) ATP-driven (d) light-driven

Ca2+-pumps in the plasma membrane and endoplasmic reticulum are important for _____________. (a) maintaining osmotic balance. (b) preventing Ca2+ from altering the activity of molecules in the cytosol. (c) providing enzymes in the endoplasmic reticulum with Ca2+ ions that are necessary for their catalytic activity. (d) maintaining a negative membrane potential.

Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell? (a) Na+ (b) K+ (c) Ca2+ (d) Cl-

Which of the following occur without coupling transport of the solute to the movement of a second solute? (a) import of glucose into gut epithelial cells (b) export of Ca2+ from the cytosol (c) export of H+ from animal cells for pH regulation (d) the export of Na+ from cells to maintain resting membrane potential

what is the purpose of the S1P/S2p and SREBP

enzymes that are activated by SCAP when cholestrol levels are low -cleaved SREBP migrates to nucleus and ads as a transcrption factor

what does the GLUT 2 beta cells and liver cells do in regards to glucose?

Bidirectional 1)Uptake glucose for glycolysis And 2)Release glucose from liver during Gluconeogensis And 3)Free flow beta cell to gauge Serum glc levels

Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following negatively charged ions is not primarily used to buffer positive charges inside the cell? (a) PO43- (b) OH- (c) Cl- (d) HCO3-

Some cells have aquaporins—channels that facilitate the flow of water molecules through the plasma membrane. For these cells, what regulates the rate and direction of water diffusion across the membrane? (a) aquaporin conformation (b) resting membrane potential (c) solute concentrations on either side of the membrane (d) availability of ATP

Active transport requires the input of energy into a system so as to move solutes against their electrochemical and concentration gradients. Which of the following is not one of the common ways to perform active transport? Select one: a. Na+-coupled b. K+-coupled c. ATP-driven d. light-driven

K+-coupled

The stimulation of auditory nerves depends on the opening and closing of channels in the auditory hair cells. Which type of gating mechanism do these cells use? (a) voltage-gated (b) extracellular ligand-gated (c) intracellular ligand-gated (d) stress-gated

Consider the mechanism by which actin and tubulin polymerize. Which of the items below does not describe something similar about the polymerization mechanisms of actin and microtubules? A. Although both filaments can grow from both ends, the growth rate is faster at the plus ends. B. Nucleotide hydrolysis promotes depolymerization of filaments. C. Free subunits (actin and tubulin) carry nucleoside triphosphates. D. Depolymerization initiates at the plus ends of filaments.

D. Depolymerization initiates at the plus ends of filaments.

Each chromosome has a single molecule of _____ who extraordinarily long length can be highly compacted during _____ of the cell cycle.

DNA, mitosis

A newly synthesized protein generally folds up into a stable conformation with lowest energy. When exposed to urea, a protein will become ______ due to breakage of ______ bonds.

Denatured Noncovalent

Consider the mechanism by which actin and tubulin polymerize. Which of the items below does not describe something similar about the polymerization mechanisms of actin and microtubules? A. Free subunits (actin and tubulin) carry nucleoside triphosphates. B. Nucleotide hydrolysis promotes depolymerization of filaments. C. Depolymerization initiates at the plus ends of filaments. D. Although both filaments can grow from both ends, the growth rate is faster at the plus ends.

Depolymerization initiates at the plus ends of filaments.

Cell movement involves the coordination of many events in the cell. Which of the following phenomena is not required for cell motility? (a) Myosin-mediated contraction at the rear of the moving cell. (b) Integrin association with the extracellular environment. (c) Nucleation of new actin filaments. (d) Release of Ca2+ from the sarcoplasmic reticulum.

H+

what ions can pass through the membrane? easy or not?

H, Na, HCo3, K, Ca2, Cl,Mg Not

what can pass through the membrane that are small uncharged polar molecules? easy or no?

H2O, glycerol, and ethanol easy

This is accomplished by binding to a group of small basic proteins known as ______, which interact with _______ charged DNA double helix.

Histones Negatively

They are mainly stabilized by _____

Hydrogen Bonds

If Na+ channels are opened in a cell that was previously at rest, how will the resting membrane potential be affected? Select one: a. The membrane potential is not affected by Na+. b. It becomes more negative. c. It becomes more positive. d. It is permanently reset.

It becomes more positive.

Which of the following best describes the behavior of a gated channel? Select one: a. It stays open continuously when stimulated. b. It opens more frequently in response to a given stimulus. c. It opens more widely as the stimulus becomes stronger. d. It remains closed if unstimulated.

It opens more frequently in response to a given stimulus.

what type of filaments are in the cytoplasmic that are keratin located at? (cytoplasmic)

epithelail cells

The bead-like DNA protein complex, called _______, is the basic unit of chromosomes.

Nucleosomes

Which molecule is more likely to diffuse through the lipid bilayer? -H2O -O2

What are water soluble molecules that diffuse freely cross cell membranes?

O2 and CO2

Which of the following statements about organellar movement in the cell is false? A. Organelles are attached to the tail domain of motor proteins. B. Motor proteins involved in organellar movement use ATP hydrolysis for energy. C. Organelles undergo saltatory movement in the cell. D. Only the microtubule cytoskeleton is involved in organellar movement.

Only the microtubule cytoskeleton is involved in organellar movement.

Which of the following statements about organellar movement in the cell is false? A. Organelles undergo saltatory movement in the cell. B. Only the microtubule cytoskeleton is involved in organellar movement. C. Organelles are attached to the tail domain of motor proteins. D. Motor proteins involved in organellar movement use ATP hydrolysis for energy.

Only the microtubule cytoskeleton is involved in organellar movement.

Keratins, neurofilaments, and vimentins are all categories of intermediate filaments. Which of the following properties is not true of these types of intermediate filaments? A. Dimers associate by noncovalent bonding to form a tetramer. B. Phosphorylation causes disassembly during every mitotic cycle. C. They strengthen cells against mechanical stress. D. They are found in the cytoplasm.

Phosphorylation causes disassembly during every mitotic cycle.

A protein's amino acid sequence is known as its ________ structure.

Primary

Which of the following statements about actin is false? A. Actin at the cell cortex helps govern the shape of the plasma membrane. B. The dynamic instability of actin filaments is important for cell movement. C. ATP hydrolysis decreases actin filament stability. D. Actin filaments are nucleated at the side of existing actin filaments in lamellipodia.

The dynamic instability of actin filaments is important for cell movement.

You are studying nuclear lamins in yeast. Using recombinant DNA technology, you alter the coding sequence of a nuclear lamin gene such that the gene now codes for a nuclear lamin protein that can no longer be phosphorylated when the nuclear envelope is broken down during mitosis. What do you predict would happen if the yeast cell only had the altered nuclear lamin gene (and not the unaltered version)? (a) Mitosis should proceed as usual because the dephosphorylation of the lamin is what is important for nuclear lamina assembly during mitosis, so phosphorylation will not be necessary. (b) Disassembly of the nuclear lamins will occur prematurely because the lamins cannot be phosphorylated. (c) Nuclear lamins will no longer disassemble properly during mitosis. (d) Nuclear lamins will be unable to produce dimers, as coiled-coil formation will be disrupted.

what class of membrane requires a conformation change?

carrier protein

what reactions does hexoikanase carry out on the ligand and what product is produced

catayse the reaction of adding a "p" ti glucose thus charging the glucose

for a cancer cell to migrate to a new locartion what three things are required

cell cooordination polarity cytoskelton activity reaarament of extracellyar matrix

Eukaryotic cells are bigger and more elaboarte than prokaryotic cells. Prokaryotic cells have a _______ that eukaryotic cells do not have. In contrast, eukaryotic cells have________ that are necessary for compartmentalization. Eukaryote cells also uniquely have a_______that stores _____. The _____ is continuous with the outer membrane of the______and is often studded with____ and is the location of____bond formation. ANother orgallen the, ___is resonble for chemical energy formation via a process of____

cell wall internal membranes nucleus dna nuclear envlope er ribosomes protein mitochodria cellular respiration

growth factors

chemically signal tumor cells

In contrast, the _________ is a type of organelle found only in the cells of plants and algae, and performs photosynthesis.

choloplast

The nucleus, an organelle found in eukaryotic cells, confines the ______, keeping them separated from other components of the cell.

chormosomes

What are the two movements the membrane is under

concentraion gradient voltage across the membrane

where are the intermediate filaments that are vimentin and vimentin-related located?(cytoplasmic)

connective tissue cells, muscle cells, and glial cells

insulin secretion from the pancreas is an important step in glucose metabolism. list the 9 steps in insulin secretion

consume a meal, glucose high in circulation, pancreas responds 1)high carb food- glucose uptake 2)GLUT2-facilitated diffusion 3)glucokinase 4)glycoysis respiration 5) ATP and ADP increases 6)ATP- senstive potassium channels closes 7)depolarization 8) voltage-gated calcium channels open 9)insulin is resleased

The purpose of the plasma membrane is to act as ____ to hold___and ____. Membrane lipids are _____ molecules composed of a hydrophillic portion and a hyrdophobic portion. All cell mebranes have the same____ structure with the____ of the phospholi[ids facing into the interior of the membrane and teh_____on the outside. The most common lipids in most cell membrane are the____that can often have fewer_____molecules and more___ causing the membrane to be highly____. The specilazed function of plasma membrane largely determng by the___it contains. Memvrabe proteins that span the lipid bilayer are called____proteins and hae sequence of____ in a alpha helix that exposed to the interior of the bilayer trhough___ interactions

container cytoplasm organelles amphatic bilayer tail head fatty acids carbon double bonds fulidity protein transmembrane amino acids covelntly

myosin

contracting the rear of the cell

actin polymerization

contributes to protrusion of the leading edge

what does the movements of the cancer cell require?

coordinated cell polarity (leading edge and trailing back edge) cytoskeletal activity (action of actin filaments, along with myosin ) rearrangement of extracellular matrix that surrounds cell to create a path for cell figure 1.4

Discuss how glucose metabolism would be affected if cysteines where depleted

cysteines bond wit itseld to hold the insulin protein -supplement lowers blood glucose

where are the intermediate filaments located?

cytoplasm and nucleus

1) singal recongtion particle 2)protein translocator 3)mRNA 4)SRP receptor

cytosol cytosol cytosol er membrane

If we were to strip away the plasma membrane from a eukaryotic cell and remove all of its membrane-enclosed organelles, we would be left with the __________, which contains many long, fine filaments of protein that are responsible for cell shape and structure and thereby form the cell's _____________.

cytosol, cytoskeleton

name the organelles involved in intraceullar signaling

er, golgi apparatus nucleus

d). If the pump is mechanistically similar to the Na+-K+ pump, then the transport of ions is driven by ATP hydrolysis and the pump is transiently phosphorylated; phosphorylation is stimulated by one ion and dephosphorylation is stimulated by the other ion. Because all of the protein is in the phosphorylated form in the absence of Zn2+ (lane F), Zn2+ is probably required for dephosphorylation. K+, then, probably binds to the dephosphorylated form and stimulates the ATPase/autophosphorylation. So, if Zn2+ is added to the phosphorylated pump, Zn2+ will stimulate dephosphorylation, trigger a conformational change, and be injected into the vesicle. K+ will stimulate the kinase activity of the pump, but because there is no ATP to be hydrolyzed in the interior of the vesicle, no phosphorylation and hence no movement of K+ will occur.

For both actin and microtubule polymerization, nucleotide hydrolysis is important for ______. A. increasing the rate at which subunits are added to the filaments. B. stabilizing the filaments once they are formed. C. decreasing the binding strength between subunits on filaments. D. promoting nucleation of filaments.

decreasing the binding strength between subunits on filaments.

For both actin and microtubule polymerization, nucleotide hydrolysis is important for ______. A. stabilizing the filaments once they are formed. B. decreasing the binding strength between subunits on filaments. C. increasing the rate at which subunits are added to the filaments. D. promoting nucleation of filaments.

decreasing the binding strength between subunits on filaments.

lysosome

digestive the lipoprotein

what is Dynamic instability driven by?

driven by the binding of GTP to tubulin dimers that is hydrolyzed after dimer is added to the prtpfilament

what does each free actin monomer contains?

each free actin monomer has a binding site for 1 ATP - once incorporated into the filament (polymerization), the ATP is hydrolyzed to ADP

endosome

endorses the ldl molecule and transports

Intermediate filaments help protect animal cells from mechanical stress because ____________. Answers: A. filaments make up the desmosome junctions that connect cells; these junctions are more important than the internal network of filaments for protecting cells against mechanical stress. B. filaments remain independent of other cytoskeletal elements and keep the mechanical stress away from other cellular components. C. filaments in each cell are indirectly connected to the filaments of a neighboring cell through the desmosome, creating a continuous mechanical link between cells. D. filaments directly extend from the interior of the cell to the extracellular space and into the next cell, linking one cell to the next, helping to distribute locally applied forces.

filaments in each cell are indirectly connected to the filaments of a neighboring cell through the desmosome, creating a continuous mechanical link between cells.

channels are summial are to transportes expect they binf the molecule to a specific binding site

flase

posistive DNA is wrapped around negatively charged histones

flase

transporters and channels are similar because they are both selective

flase

what are the purpose of microtubules? examples?

for cellular cytoplasmic organization ------ -anchor membrane bound organelles -create a track for vesicles movement between membrane

channels

form tiny hydrophilic pores which solutes pass through diffusion

When does the formation of microtubules began?

formation stats at organizing center called centrosome

why do eukaryotics cells have both free and bound ribosomes?

free proteins used within cell 2 bound protein insterd into er then transported

what happens when the glucose levels are low in the blood and you have not eaten?

glucagon (hormone) triggers the breakdown of glycogen in the liver, glucose levels are high in the cell and then the conformation moves the glucose out of the cell to the blood stream---to make it to other cells that need it

compare the function of the three transmembrane involved in insulin secretion

glut2 glucose uptake atp senstive pottassium channels- prevent ATP and k from leaving the cell -volatage gated channels- uptake calcium

Which molecule is more likely to diffuse through the lipid bilayer? -glycerol -RNA

glycerol

what is passive transport base on electrochemical gradient?

gradient determines the direction of the charged solute during passive transport

what type of chemical signals do a tumor cell recevies?

growth factor

atp

has binding site on actin monomer

transporter

has moving parts, can shift small molecules from one side to the other by chaning its shape

what is the purpose of clathrin

help shape membrane into bud aid in capturing cargo for transport

Currently Belinostat is a new thearpy in Phase II clincal trail for oviran cancer. How does it aid transcription

histone deacctylase inhibitor -help keep histones acetylated to aid in transcription

The synthessi of cholestrol is a long process. the activity of ______ is the rate-limiting step in cholestrol synthesis, it is located in teh ____ and is turned off by the binding of______

hmg reducatase er chlosteral

in detail describe a phospholipid

hydrophillic head made up of choline glycerine and phosphate hydrophobic tail that is made up of hydrocarbons

what would happen to a cell if you placed it in a hypertonic solution? hypotonic?

hypertonic means high salt outside, water would rush out of cell and shrivel. hypotonic means low salt outside, water would rush in and swell

smal nonpolar molecules

i.e. O2, CO2, readily dissolve in lipid bilayers and rapidly diffuse

What does the channel protein require?

if open, will let solutes pass if they have the right size and charge -trapdoor like

Cell Biology 1.b., FINAL EXAM FOR HIST

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