Cell Bio Exam 3- Torres

What could be defined as an organized network of extracellular materials found beyond the immediate vicinity of the plasma membrane?

extracellular matrix

All of the following are components of the extracellular matrix except for ______.

a. laminin

b. collagen

c. peptidoglycan

d. proteoglycan

c. peptidoglycan

laminin and fibronectin play an important role during embryonic development, mainly by directing cell migration

True or False

True

Which of the following statements about the basement membrane is true?

a. it is the place where most metabolic enzymes are found in epithelial cells

b. it is rich in sodium and potassium channels

c. it is one of the layers of the ecm

d. it provides mechanical support for attached cells

d. it provides mechanical support for attached cells

The components of the ECM are subject to continual degradation and reconstruction. These processes are important during tissue remodeling, embryonic cell migration and wound healing, and are accomplished by a family of enzymes known as

A. Extracellular proteinases

B. Matrix dehydrogenases

C. ECM-desaturases

D. Matrix metalloproteinases

E. Endotheliases

d. mmps

Enzymatic digestion of the ECM surrounding the cartilage cells would

A. Do nothing

B. Get the scientist fired

C. Set the scientist on fire

D. Decrease their synthetic and secretory activities

D. Decrease their synthetic and secretory activities

The ____ is a type of extracellular matrix that forms the supporting structure on which epithelial and endothelial cells grow

A. Laminin

B. Fibronectin

C. Hyaluronidase

D. Matrix metalloprotease

E. Basement membrane

e. basement membrane

Vitamin C deficiency is associated with important skin functions, particularly wound healing. Vitamin C is required for hydroxylation of amino acids that stabilize _____

A. Glycosaminoglycan

B. Collagen

C. Fibroblasts

D. Fibronectin

E. Integrins

b. collagen

Collagen contains large amounts of hydroxylated amino acids. These amino acids use the OH group to form _________ between the different chains, to enhance protein stability

A. Van der Waals forces

B. Hydrophobic interactions

C. Hydrogen bonds

D. Covalent bonds

c. hydrogen bonds

Which of the components of the ECM would be affected if cells were treated with hyaluronidase?

A. Collagen

B. Proteoglycans

C. Laminin

D. Fibronectin

E. B, C and D

b. proteoglycans

Cartilage is made up of cells imbedded in an ECM mainly composed of

A. Collagen and proteoglycans

B. Collagen and Integrins

C. Collagen and fibronectin

D. Proteoglycans and laminin

E. Hyaluronic acid and Integrins

A. Collagen and proteoglycans

An extracellular matrix protein that binds to cell-surface integrins to promote adhesion of cells to the matrix and to provide guidance to migrating cells in developing tissues, best describes

A. Collagen

B. Proteoglycan

C. Fibronectin

D. Focal Adhesion

C. Fibronectin

Which of the following statements about integrins is/are true?

A. They anchor cells to the substrate.

B. They are found in both animal and plant cells.

C. Different cell types are restricted to just one type of integrin

D. All of the above are true

A. They anchor cells to the substrate.

The basal membrane normally provides an impenetrable barrier to cells, but lymphocytes and macrophages are able to cross it by digesting components of the basal membrane. This process involves the activation of a family of enzymes known as ____

mmp's

The specialized adhesive structure that facilitates the stable adhesion of epithelial cells to the underlying basement membrane is called

A. Focal adhesion

B. Hemidesmosome

C. Gap junction

D. Adherens junction

B. Hemidesmosome

What would be the effect of exposing an embryo to laminin-specific neutralizing antibodies?

A. All the processes of cell migration would stop

B. Migration of primordial germ cells would stop

C. Migration of neural crest cells out of the neural plate would stop.

D. Migration of all lymphoid cells would stop.

B. Migration of primordial germ cells would stop

The ______ activation of integrins is triggered by a cytoplasmic signal and leads to increased affinity of the integrin extracellular domain for a ligand

A. Inside-out

B. Outside -in

A. Inside-out

Unlike malignant cells, normal cells ____ grow unless they are cultured on a solid substratum. The type of signaling involved in this process is an example of ___

A. Can; Inside-out signaling

B. Can; Outside-in signaling

C. Cannot; Inside-out signaling

D. Cannot; Outside-in signaling

D. Cannot; Outside-in signaling

In this figure, why aren't blood clots being formed?

A. Platelets lost their integrin proteins

B. Fibrinogen lost their integrin proteins

C. Fibrinogen lost their RGD sequences

D. Fibrinogen can't bind integrin proteins

D. Fibrinogen can't bind integrin proteins

In this interaction, which component(s) has/have the RGD sequence?

A. The surface of the platelets

B. The integrins

C. The blood protein fibrinogen

D. A and B

E. B and C

F. A, B and C

C. the blood protein fibrinogen

In a third experiment, you combine the cells, fibronectin, proteoglycan and one of the two following peptides:

1. Experiment A: T-A-R-R-G-G-T-A

2. Experiment B: D-A-V-R-G-D-P-T

In which experiment do you expect cells will attach?

A. Cells in Experiment A will attach

B. Cells in Experiment B will attach

C. Cells in both experiments will attach

D. Cells will not attach in any experiment

B. Cells in Experiment B will attach

What are the three major proteins that are involved in cell-cell adhesion/ interactions?

A. Cadherins, Immunoglobulins and Selectins

B. Integrins, Cadherins and Proteoglycans

C. Selectins, Cadherins and Cell plate

D. Intermediate filaments, Laminin and Selectins

A. Cadherins, Immunoglobulins and Selectins

What are the two types of structures that mediate intercellular (between cells) communication?

A. ECM and ICAM

B. Integrins and plasmodesmata

C. Gap junctions and plasmodesmata

D. P-selectins and gap junctions

C. Gap junctions and plasmodesmata

What biological process occurs by presence of selectins and immunoglobulins as a primary response to infection?

A. Apoptosis

B. Leukocytosis

C. Meiosis

D. Embryogenesis

E. Inflammation

E. Inflammation

According to the assigned reading, the ability to feel "lumps" during a breast exam is associated with

A. Increased activity of metalloproteases in the ECM

B. Altered cross-linking and organization of collagen in the ECM

C. Increased migration of neutrophils to the breast tissue

D. Increased presence of fibrinogen and integrins in the ECM of the tumor cells

B. Altered cross-linking and organization of collagen in the ECM

When cells from different parts of an embryo are dissociated and then intermixed, the cells initially aggregate and then sort out by associating with other cells of the same type. This recognition is mediated by ___

A. Immunoglobulins

B. Integrins

C. Selectins

D. Cadherins

E. Fibronectin

D. Cadherins

The symptoms observed in these blistering diseases are the result of:

A. Abnormal attachment of the actin filaments

B. Loss of cell viability by inactivation of signaling kinases such as FAK

C. Weak attachment of the epidermis to the dermis

C. Weak attachment of the epidermis to the dermis

During one of your cell bio labs, you treat cells with an agent that sequesters calcium from the medium. Which of the following proteins would MOST likely be affected in their cell-to-cell adhesion?

A. Collagen

B. Fibronectin

C. Integrins

D. Immunoglobulins

E. Cadherins

E. Cadherins

One of the most important roles of selectins is to_____

A. Mediate adhesive contacts to construct tissues and organs in the embryo

B. Slow down and recruit leukocytes during inflammation

C. Mediate adhesion between non-immune cells during neural development

B. Slow down and recruit leukocytes during inflammation

LAD 1 is caused by mutations in gene that encoded by an integrin subunit (ITGB2), which is essential for_____

A. Closing neural connections during embryogenesis

B. Leading migrating neural crest cells

C. Adhesion of leukocytes at sites of infection

D. Recognizing glycoproteins on the surface of cells

C. Adhesion of leukocytes at sites of infection

In 1, the cells in orange are expressing E-cadherins. In 2, some cells stop expressing E-cadherins and start expressing N-cadherins. What do you expect will happen during step 3?

A. Cells expressing E-cadherin will undergo apoptosis

B. Cells expressing E-cadherins will migrate to another organ

C. Cells expressing N-cadherins will form gap junctions with the cells expressing E-cadherins

D. Cells expressing N-cadherins will separate from cells expressing E-cadherin

D. Cells expressing N-cadherins will separate from cells expressing E-cadherin

Which of the following phenotypes would you expect to be associated with a malignant cell phenotype?

A. More adhesive than normal cells

B. Lower migration rates

C. Higher expression of matrix metalloproteases (MMP)

D. Higher expression of E-cadherins

E. C and D

C. Higher expression of matrix metalloproteases (MMP)

The correct order of passage of materials produced in a biosynthetic pathway is :

A. ER, Golgi complex, plasma membrane, secretory vesicle.

B. ER, lysosome, secretory vesicle, plasma membrane.

C. ER, Golgi complex, secretory vesicle, plasma membrane.

D. Nucleus, Golgi complex, ER plasma membrane.

C. ER, Golgi complex, secretory vesicle, plasma membrane.

A tissue has been briefly labeled with radiolabeled amino acids. It is then transferred to a medium containing unlabeled amino acids. This can be done several times with different tissue samples for varying periods of time. What is the entire procedure called ?

A. Pulse

B. Chase

C. Pulse-Chase

D. GFP-Chase

E. RACE

C. Pulse-Chase

The process of co-translational translocation involves

A. Translocation of fully synthesized proteins into the ER

B. Translocation of proteins to the ER while they are still being synthesized

C. Translocation of ribosomes to the membrane of the Golgi complex

D. Translocation of ribosomes to the plasma membrane

E. Induced transcription of extracellular proteins

B. Translocation of proteins to the ER while they are still being synthesized

Membrane-bound ribosomes produce many proteins that are ________, while free ribosomes produce many proteins that are _____

A. Exported from the cell; Used inside the cell

B. Used inside the cell; Exported from the cell

C. Used in the cytoplasm; Destined for the plasma membrane

D. Used in the nucleus; Used in the cytoplasm

A. Exported from the cell; Used inside the cell

Membrane-bound ribosomes are bound to the ________, and synthesize proteins that contain a signal sequence in the ______

A. Plasma membrane; Plasma membrane

B. ER membrane; Last amino acid

C. Golgi membrane; C-terminus

D. Plasma membrane; Transmembrane domain

E. ER membrane; N-terminus

E. ER membrane; N-terminus

Which of the following organelles are part of the endomembrane system?

1. Lysosomes

2. Golgi complex

3. Nucleus

4. Plasma Membrane

5. Mitochondria

A. 1, 2 and 3

B. 1, 2 and 4

C. 1, 2, 3 and 4

D. All except the plasma membrane

E. All except the nucleus

B. 1, 2 and 4

A scientist wishes to visualize movement of a protein in a living cell. Which procedure would work best?

A. Pulse-chase

B. Fusion of the green fluorescent protein gene to the gene encoding the protein to be tracked through the cell

C. Fusion of the green fluorescent protein gene to a membrane-bound ribosome

D. Pulse-chase using fluorescent antibodies

B. Fusion of the green fluorescent protein gene to the gene encoding the protein to be tracked through the cell

During the "pulse" of a pulse-chase experiment:

A. The cell is incubated with radioactive amino acids, which are incorporated into the proteins

B. The cell is incubated with unlabeled amino acids, and allowed to continue regular cellular activities

A. The cell is incubated with radioactive amino acids, which are incorporated into the proteins

In a pulse-chase procedure, if the chase is longer, which statement below correctly describes the location of the radioactively labeled proteins in the cell?

A. Closer to the synthesis site

B. Farther from the nucleus

C. Farther from the synthesis site

D. Closer to the nucleus

C. Farther from the synthesis site

Why are viruses useful in the study of protein movement through the biosynthetic pathway?

A. Viruses can be seen in electron microscopy, specifically colonizing the ER

B. Viruses can deliver radioactive amino acids into the cell, which allows to track protein movement

C. Viruses specifically colonize ER-bound ribosomes, which are secreted via the biosynthetic pathway

D. Viruses force cells to synthesize and secrete large amounts of viral proteins

D. Viruses force cells to synthesize and secrete large amounts of viral proteins

Protein A is synthesized in ER-bound (membrane bound) ribosomes. Protein A could be a ________ protein

A. Golgi complex

B. ER

C. Mitochondria

D. Plasma membrane

E. A, B and D

E. A, B and D

Succinate dehydrogenase is most likely synthesized by

A. Free ribosomes

B. ER-bound ribosomes

A. Free ribosomes

Eukaryotic cells contain two different types of ribosomes: cytosolic (free) ribosomes are chemically and structurally different from ER-bound ribosomes.

True or False

False

A stretch of 6-15 hydrophobic amino acids known as ______, is usually located in the _____ of _______

A. Transmembrane domain; C-terminus; Secretory proteins

B. Translocon; C-terminus; cytosolic proteins

C. Signal sequence; N-terminus; Secretory proteins

D. Signal peptide; N-terminus; Mitochondrial proteins

E. Ribozyme; C-terminus; Chloroplastic proteins

C. Signal sequence; N-terminus; Secretory proteins

Synthesis of all proteins starts in free ribosomes. A signal sequence in the N-terminus, signals the ribosome to temporarily halt synthesis of this peptide and relocate to the ER membrane, where synthesis of this protein continues. This process is known as

A. Co-translational translocation

B. Co-transcriptional translocation

C. Collaborative translocation

D. Ribosomal translocation

A. Co-translational translocation

The Signal Recognition Particle (SRP) is an abundant protein that targets specific proteins to the ER. Would this protein itself contain a signal sequence on its N-terminus?

A. Yes, of course it would

B. No, of course it would not

B. No, of course it would not

The process of co-translational translocation is important for

A. All proteins synthesized in a cell

B. All proteins that start and finalize synthesis in free-ribosomes

C. All proteins synthesized in ER-bound ribosomes

D. All proteins that need to be secreted from a cell

E. C and D

E. C and D

A mitochondrial membrane protein, like succinate dehydrogenase, will contain a signal sequence on the N-terminus

A. False, the signal is on the C-terminus

B. True, since it is an integral membrane protein

C. False, since it is mitochondrial bound

D. True, the signal is on the N terminus

E. Both B and D are correct

C. False, since it is mitochondrial bound

Protein glycosylation is the process by which

A. More amino acids are added to some proteins in the Golgi complex

B. Carbohydrate molecules are added to some proteins

C. Lipid molecules are added to some proteins in the Golgi complex

D. Proteins are properly folded in the ER

B. Carbohydrate molecules are added to some proteins

UGGT and calnexin are proteins involved specifically in the cellular process known as

A. The Unfolded Protein Response (UPR)

B. Protein Ubiquitination

C. The biosynthetic pathway

D. The endomembrane system

E. Quality control

E. Quality control

Which is the main purpose of the unfolded protein response (UPR)?

A. To synthesize new proteins

B. To alleviate stress in the ER after an accumulation of misfolded proteins

C. To ensure that glycoproteins are properly folded before movement to the Golgi complex

D. To stop all protein synthesis in the cell

E. To transfer sugar residues onto a nascent polypeptide

B. To alleviate stress in the ER after an accumulation of misfolded proteins

Which of the following is/are correct about the Signal Recognition Particle (SRP)?

A. It is a protein that resides within the ER (ER lumen)

B. It is a protein that resides in the cytoplasm

C. It binds to an ER-bound ribosome after it has attached to the ER membrane

D. It temporarily stops synthesis of proteins that contain a signal peptide on the C-terminus

B. It is a protein that resides in the cytoplasm

Which proteins will be synthesized in ER-bound ribosomes?

A. Proteins that need to end up as part of any compartment of the endomembrane system, including the plasma membrane or the extracellular space

B. Proteins that need to end up in the nucleus, the cytoplasm, the mitochondria or the chloroplast

A. Proteins that need to end up as part of any compartment of the endomembrane system, including the plasma membrane or the extracellular space

How are plasma membrane proteins embedded in the membrane?

A. A ribosome travels to the plasma membrane during protein synthesis and a protein complex helps insert the protein directly in the PM

B. A ribosome travels to the ER membrane during protein synthesis and a translocon helps insert the protein in the ER membrane

B. A ribosome travels to the ER membrane during protein synthesis and a translocon helps insert the protein in the ER membrane

The process of protein glycosylation involves adding ______. This process starts in the ________

A. More amino acids to carbohydrates; Cytoplasm

B. More amino acids to proteins; ER lumen

C. Carbohydrates to proteins; Cytoplasm

D. Carbohydrates to proteins; ER lumen

D. Carbohydrates to proteins; ER lumen

Which of the following is correct about the process of quality control?

A. It is activated in response to the presence of abundant misfolded proteins

B. Verifies that integral membrane proteins are properly embedded in the membrane.

C. Occurs in the Golgi Complex

D. Ensures that glycoproteins are properly folded

D. Ensures that glycoproteins are properly folded

When a mannose (carbohydrate) is removed from a glycoprotein during quality control, the protein ____

A. Is recognized by calnexin (a chaperone), which tries to fold it again

B. Is recognized by the conformation-sensing enzyme UGGT

C. Cannot be recycled anymore and is degraded

D. Is now properly folded and can leave the ER

C. Cannot be recycled anymore and is degraded

If you sequenced the genes that encode different components of the process of quality control, which would you expect would encode a peptide on their N-terminus of the protein?

A. Calnexin

B. UGGT

C. The proteasome

D. A and B

E. A, B and C

D. A and B

You are following a protein that is being transported backwards, from the golgi complex to the ER. How do you think this protein will reach its final destination?

a. it will arrive in a clathrin-coated vesicle

b. it will arrive in an ER-bound ribosome

c. it will arrive in a free-ribosome

d. it will arrive in a COPI-coated vesicle

e. it will arrive in a COPII-coated vesicle

d. it will arrive in a COPI-coated vesicle

Which of the following proteins will most likely contain a KDEL sequence?

a. a selectin

b. an integrin

c. an enzyme that synthesizes phospholipids

d. a protein of the Krebs cycle

e. a lysosomal enzyme

c. an enzyme that synthesizes phospholipids

lysosomal enzymes are synthesized in ____ ribosomes and are transported in _____

a. free ; COPI-coated vesicles

b. free ; COPII-coated vesicles

c. ER-bound ; COPI-coated vesicles

d. ER-bound ; clathrin-coated vesicles

d. ER-bound ; clathrin-coated vesicles

How is the process of quality control different from the unfolded protein response?

a. only quality control occurs in the ER

b. only the UPR occurs in the ER

c. only quality control involves the use of chaperones

d. only the UPR is activated in response to accumulation of misfolded proteins

d. only the UPR is activated in response to accumulation of misfolded proteins

synthesis of proteins ______

a. always starts in free ribosomes

b. always starts in ER-bound ribosomes

c. it depends on the presence/absence of a signal sequence on the N-terminus

d. it depends on the presence/absence of a signal sequence on the C-terminus

a. always starts in free ribosomes

A protein that has a signal sequence on the N-terminus

a. could represent a protein that will be fully synthesized in free-ribosomes

b. could represent a protein that will be processed by co-translational translocation

c. could only represent a plasma-membrane protein

b. could represent a protein that will be processed by co-translational translocation

what is responsible for temporarily halting the process of translation in free-ribosomes, and directing the ribosome-mRNA-synthesizing peptide to the ER membrane?

a. the ribosome receives a signal from the nucleus, indicating it should translocate to the ER

b. the nascent peptide binds to a chaperone that sends it to the ER

c. the recognition of the signal sequence by the signal recognition particle (SRP)

c. the recognition of the signal sequence by the SRP

If a protein needs to end up in the plasma membrane, it will

a. become embedded in the membrane after it is glycosylated

b. become embedded in the membrane after being released by the UPR

c. become embedded in the ER membrane during translation

d. become embedded in the membrane by a plasma membrane bound ribosome

c. become embedded in the ER membrane during translation

The process of quality control takes place in

a. the cytoplasm

b. the golgi

c. the ER

d. the nucleus

e. the plasma membrane

c. the ER

What kind of proteins could act as "helpers" to alleviate stress caused by misfolded proteins?

a. chaperones

b. quality control proteins

c. clathrin-coat proteins

d. a and b

e. all of the above

d. a and b

which of the following proteins are transported by COPII-coated vesicles?

a. enzymes involved in glycosylation process in the golgi

b. proteins involved in the process of quality control

c. ion channels in the plasma membrane

d. a and c

e. all of the above

d. a and c

what happens if some essential ER-proteins escaped by accident?

a. the cell will automatically undergo apoptosis

b. the cell will synthesize an entire new ER to recover them

c. the UPR will be activated

d. they can be retrieved, if they have a special signal in the C-terminus

e. they can reach the ER if they have a signal sequence in the N-terminus

d. they can be retrieved, if they have a special signal in the C-terminus

An ER-resident protein like disulfide isomerase contains a KDEL signal sequence on the C-terminus and a signal peptide sequence on the N-terminus

True or False

True

Lysosomal enzymes carrying a _____ are recognized by specific receptors and transported from the trans golgi network to the lysosomes in ____ coated vesicles

a. KDEL seq ; COPI

b. G6P ; clathrin

c. RGD seq ; COPII

d. signal peptide ; COPI

e. mannose 6-phosphate ; clathrin

e. mannose 6-phosphate ; clathrin

Mannose is a type of _____. If the sorting signal for lysosomal enzymes is the presence of a phosphorylated mannose, that means that most lysosomal enzymes are ______

a. monosaccharide ; glycosylated

b. polysaccharide ; synthesized in free ribosomes

c. lipid ; hydrophobic

d. amino acid ; hydrolyzed in the golgi

e. sugar ; very sweet

a. monosaccharide ; glycosylated

which of the following happen in the golgi complex?

a. proteins are sorted to their final destination

b. more amino acids are added to proteins

c. more sugars are added to glycoproteins

d. escaped proteins are retrieved if they have an N-terminus signal sequence

A and C

Assume a plasma membrane glycoprotein has a very specific and distinct arrangement of sugars, some of which needs to be phosphorylated. which of the following best describes this protein?

a. this protein was glycosylated only in the ER and further modified in the golgi complex

b. this protein was initially glycosylated in the ER and further modified in the golgi complex

c. this protein never passed the process of quality control

d. this protein was glycosylated only in the ER

b. this protein was initially glycosylated in the ER and further modified in the golgi complex