Cell Bio Exam 3

unfolded

unfolded

Proteins that are transported into the chloroplasts or mitochondria are ______ as they are being transported.

expression of gene regulatory proteins within the cytosol

The following occurs when the unfolded protein response (UPR) is activated in the ER:

1) detection of misfolded proteins by receptors in the membrane of the ER

2) production of more ER membrane and chaperone proteins

3) ?

Asn-X-Ser/Thr

N-linked oligosaccharides on secreted glycoproteins are attached to the asparagine in the sequence

The core oligosaccharide side chain

Located in the ER, this contains N-acetyl glucosamine, mannose, and glucose

False

True or false: disulfide bonds form under reducing environments (i.e. in the cytosol)

cis Golgi network

Vesicles from the endoplasmic reticulum enter the Golgi at the _________

translation; cytoplasmic

Ribosomes that don't anchor on the surface of the rough ER during _______ are possibly synthesizing ______ proteins or proteins destined for organelles outside of the endomembrane system

N-glycosylated

A protein that is _________ is expected to be secreted from the cell

stop/start transfer sequences

Proteins that become embedded in the membrane of the ER have _________________, which stop and start translocation of a polypeptide through the ER membrane, resulting in transmembrane proteins

Endoplasmic Reticulum (ER)

Glycosylation of proteins starts in the

Endoplasmic Reticulum

This is a site for N-linked glycosylation of polypeptides

secreted from the cell

A protein that is N-glycosylated is expected to be

Protein Disulfide Isomerase (PDI)

This enzyme localizes to the ER and facilitates the formation of disulfide bonds in the ER.

oxidative

The ER has an _________ environment

True

True or false: disulfide bonds do not form under reducing environments (i.e. in the cytosol)

stabilizes

Disulfide bonding ______ the structure of proteins

the oxidation of pairs of cysteine side chains on the protein

Disulfide bonding occurs by...

Chaperone proteins help misfolded proteins fold properly

What is the purpose of chaperone proteins within the endoplasmic reticulum?

proper assembly

What must protein complexes (or multimeric) be checked for before they can exit the ER?

proteasomes; cytosol

Proteins that are misfolded are degraded by ________ in the __________

endoplasmic reticulum; Golgi apparatus, plasma membrane

A newly synthesized protein destined for the plasma membrane travels through the _____, the _____, followed by the ______

membrane-spanning domain length

A membrane protein that is concentrated in the cis-Golgi apparatus has a _____________ that equals the thickness of the cis-Golgi apparatus

Adaptins functions

(1) Bind to and select the cargo molecules that will be transported in vesicles that are produced by the trans Golgi network (TGN).

(2) interact with clathrin at the cytosolic surface of the Golgi membrane. Once vesicle budding occurs, clathrin molecules are released from the vesicle.

(3) select the molecules that will be packed into vesicles for transport from the Golgi apparatus and plasma membrane.

Clathrin

This protein plays a major role in the formation of coated vesicles. It organizes a coat and form vesicles on the trans-Golgi network (TGN) and the plasma membrane.

large protein aggregates

The sorting of secretory proteins into regulated secretory vesicles in the trans-Golgi network involves the formation of?

the continuous release of mucus by the epithelial cells lining the respiratory tract

What is an example of constitutive secretion?

To direct transport vesicles to their target membranes.

What is the function of v-SNARES, t-SNARES, Rabs, and tethering proteins?

True

True or false: an individual transport vesicle will fuse with only one type of target membrane

False

True or false: an individual transport vesicle will fuse with multiple types of target membranes

Vesicle recognition and fusion

v-SNARE, t-SNARE, Rab GTPase, and tethering complex are involved in:

Pinocytosis

Cell drinking

Phagocytosis

Cell eating

Autophagy

Self-eating of the cell

devlier material to the lysosome

Pinocytosis, phagocytosis, and autophagy ________

endocytosis

Pinocytosis (cell drinking) is a form of ______ in which fluid is up taken by the cell

fluid intake activity

Exocytosis balance out the _________ of pinocytosis to keep the cell's volume relatively constant over time

lumen of the endosome

When a cargo molecule is brought into a cell via receptor-mediated endocytosis, the acidic pH of the lumen in the endosome causes the receptor to release its cargo molecule into the

The plasma membrane

Clathrin forms the coat during receptor-mediated endocytosis-coated pit formation on/at

receptors and/or vesicle content

In receptor-mediated endocytosis, recycling to the plasma membrane, transcytosis, or digestion in a lysosome can be a fate for the

Dynamin

requires GTP for vesicle scission during receptor-mediated endocytosis

Phagocytosis

During ________, large particles are ingested

pseudopods

Phagocytosis involves the projection of

ingest food

Phagocytosis is used by amoebae to

ingest bacteria

Phagocytosis is used by macrophages and neutrophils to

endoplasmic reticulum; Golgi apparatus

Lysosomal enzymes are synthesized in the ______ and routed through the ____________

A mannose-6-phosphate sugar

When this is added to lysosomal enzymes in the Gogli, these proteins are diverted out of the secretory pathway so they can reach the lysosome

ATP-dependent proton pumps

The low pH of lysosomes is established by

The nucleus, mitochondria, chloroplasts, and peroxisomes

These organelles receive proteins by posttranslational import of proteins synthesized on cytoplasmic ribosomes

Cytosolic proteins/polypeptides

This type of protein/polypeptide (which are completely translated in the cytosol) are transported to a target organelle by posttranslational import

inner membrane, intermembrane space, outer membrane

What are the components of the nuclear envelope?

serves as a selective barrier that separates nuclear and cytoplasmic elements

the nuclear envelope has three functions

1. ?

2. localizes chromosomes within the cell

3. sequesters many of the mRNA processing activities from the cytosol

localizes chromosomes within the cell

the nuclear envelope has three functions

1. serves as a selective barrier that separates nuclear and cytoplasmic elements

2. ?

3. sequesters many of the mRNA processing activities from the cytosol

sequesters many of the mRNA processing activities from the cytosol

the nuclear envelope has three functions

1. serves as a selective barrier that separates nuclear and cytoplasmic elements

2. localizes chromosomes within the cell

3. ?

endoplasmic reticulum

This is the major site for new membrane synthesis in the cell

rough ER; smooth ER

Where in the ER are these molecules synthesized?

- Proteins to be delivered to the ER lumen:

- Steroid hormones:

the endoplasmic reticulum (smooth and rough), Golgi apparatus, endosomes, and lysosomes

What are the components of the endomembrane system?

Nuclear localization signal (NLS)

This type of signaling in nuclear proteins is bound by cytoplasmic proteins called importins, or nuclear import receptors, that direct the nuclear protein to the nucleus. These proteins will enter through the nuclear pores

Genes that encode for nuclear proteins have DNA that encodes for this sequence

lysine and arginine

For large nuclear proteins that pass through the nuclear pore, it's important to have an appropriate nuclear localization sequence, which typically contains which positively charged amino acids?

Heat shock proteins or chaperone proteins

These proteins, located in the mitochondria matrix, facilitate the movement of proteins across the outer and inner mitochondrial membranes

outer membrane

The signal sequence located at the N-terminus of proteins destined for the chloroplasts or mitochondria are recognized by receptor proteins in the ________ of these organelles

signal peptidase (transit peptidase)

What is the name of the protein that will remove the signal sequence of proteins that have been imported into the chloroplasts or mitochondria?

still being synthesized

Cotranslational import describes the crossing of proteins across an organelle's membrane while ______-

as they are being synthesized

An example of cotranslational import is proteins entering the endomembrane system. Newly synthesized proteins are inserted into the system through a pore complex _________

cotranslational import

Most proteins destined to enter the endoplasmic reticulum being to cross the membrane while still being synthesized. This is an example of what? (also occurs in the transfer of polypeptides to the ER)

cytosolic; translation

Proteins destined for the ER are translated by ________ ribosomes and are targeted to the ER when their signal sequences emerge from the ribosomes during which process?

the ER

A protein destined to be secreted from a cell will be first found in which organelle?

the addition of carbohydrates to proteins (through glycosylation) to make glycoproteins

The endoplasmic reticulum is the site for many important processes:

1) ?

2) protein folding

3) recognition and removal of misfolded proteins

4) assembly of multimeric proteins

protein folding

The endoplasmic reticulum is the site for many important processes:

1) the addition of carbohydrates to proteins (through glycosylation) to make glycoproteins

2) ?

3) recognition and removal of misfolded proteins

4) assembly of multimeric proteins

detection and removal of misfolded proteins

The endoplasmic reticulum is the site for many important processes:

1) the addition of carbohydrates to proteins (through glycosylation) to make glycoproteins

2) protein folding

3) ?

4) assembly of multimeric proteins

assembly of multimeric proteins

The endoplasmic reticulum is the site for many important processes:

1) the addition of carbohydrates to proteins (through glycosylation) to make glycoproteins

2) protein folding

3) recognition and removal of misfolded proteins

4) ?

unfolded protein response (UPR)

The __________ slow down the production of the majority of proteins and increases the production of chaperones (proteins required for folding) and the E1-E2-E3 ubiquitination cascade (proteins required for degradation)

detection of misfolded proteins by receptors in the membrane of the ER

The following occurs when the unfolded protein response (UPR) is activated in the ER:

1) ?

2) production of more ER membrane and chaperone proteins

3) expression of gene regulatory proteins within the cytosol

production of more ER membrane and chaperone proteins

The following occurs when the unfolded protein response (UPR) is activated in the ER:

1) detection of misfolded proteins by receptors in the membrane of the ER

2) ?

3) expression of gene regulatory proteins within the cytosol

rough ER

Cells synthesizing secretory proteins would have more?

smooth ER

Cells synthesizing steroid hormones would have more

KDEL; R-X-R

To make a protein accumulate in the ER, the protein would have to have either a _____ sequence (ER retrieval sequence) located near the protein's C-terminus, or an _______ sequence (ER retention)

Juxtacrine signaling

This type of signaling is contact dependent, meaning that it requires physical contact between cells

Autocrine

this is the reception of a signal released by the same cell

Hormone

This is a signal that is used when a signal is sent to most of the cells throughout a multicellular organism

small, hydrophobic ligands

Estrogen, testosterone, and cortisol are all types of

cytosolic steroid receptors

Small, hydrophobic ligands diffuse into the cell cytoplasm and interacts with?

Hydrophilic primary messenger

Extracellular signal molecules and ligands serve what role for signal transduction?

on the outer surface of the plasma membrane

A hydrophilic primary messenger for a signal transduction will bind its receptor where?

the synthesis of hormones by endocrine tissue cells

Characteristics of endocrine signaling:

1) ?

2) secretion of endocrine hormones directly into the bloodstream

3) having a hormone-specific lifespan in the blood ranging from seconds to hours

4) interacting with specific receptors on cells in target tissues throughout the body

secretion of endocrine hormones directly into the bloodstream

Characteristics of endocrine signaling:

1) the synthesis of hormones by endocrine tissue cells

2) ?

3) having a hormone-specific lifespan in the blood ranging from seconds to hours

4) interacting with specific receptors on cells in target tissues throughout the body

having a hormone-specific lifespan in the blood ranging from seconds to hours

Characteristics of endocrine signaling:

1) the synthesis of hormones by endocrine tissue cells

2) secretion of endocrine hormones directly into the bloodstream

3) ?

4) interacting with specific receptors on cells in target tissues throughout the body

interacting with specific receptors on cells in target tissues throughout the body

Characteristics of endocrine signaling:

1) the synthesis of hormones by endocrine tissue cells

2) secretion of endocrine hormones directly into the bloodstream

3) having a hormone-specific lifespan in the blood ranging from seconds to hours

4) ?

they directly turn proteins on and off or activate and inactivate proteins through changes in phosphorylation status

Why are kinases and phosphatases essential in the cell?

removes

Phosphatases ______ phosphate groups, which inactivates signaling proteins

add

Kinases _____ phosphate groups, which activates signaling proteins

serine and threonine

These are the most common types of protein kinase

terminal

Protein kinases transfer the ______ phosphate from ATP onto a protein.

become activated

In phosphorylation, a GTP-binding protein exchanges its bound GDP for GTP to:

integrating device

A protein kinase can act as an ____________ in signaling if it is activated by two or more proteins in different signaling pathways

Calcium ions, IP3, DAG, and cAMP

These are all examples of intracellular messengers

secondary messengers

Cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3), diacylglycerol (DAG), and calcium ions (Ca2+) are what kind of intracellular messengers specifically?

ligand binding

Steps for the Epinephrine - GPCR signaling pathway

1) ?

2) G-protein activation

3) adenylyl cyclase activation

4) cAMP production

5) protein kinase A activation

G-protein activation

Steps for the Epinephrine - GPCR signaling pathway

1) ligand binding

2) ?

3) adenylyl cyclase activation

4) cAMP production

5) protein kinase A activation

adenylyl cyclase activation

Steps for the Epinephrine - GPCR signaling pathway

1) ligand binding

2) G-protein activation

3) ?

4) cAMP production

5) protein kinase A activation

cAMP production

Steps for the Epinephrine - GPCR signaling pathway

1) ligand binding

2) G-protein activation

3) adenylyl cyclase activation

4) ?

5) protein kinase A activation