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Flashcards in Quiz 3 Deck (31)
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1
Q

Which of these is true for lipid molecules that move from one leaflet to another?

A

The process requires energy and the flippase enzyme.

2
Q

The rate of diffusion of a molecule across a membrane will be inversely proportional to:

A

Thickness of the membrane.

3
Q

By which process do oxygen molecules cross membranes?

A

Diffusion across the lipid bilayer.

4
Q

If there is a rise in sodium concentration outside of a cell with open chloride channels, in what direction are the chloride ions and water expected to move across the plasma membrane?

A

Both chloride ions and water will move out of the cell.

5
Q

The inhibition of the enzyme phosphofructo kinase-1 by citrate is an example of

A

allosteric regulation.

6
Q

uses an organic molecule as a final electron acceptor.

A

fermentation

7
Q

What is the purpose of CoA?

A

To form an unstable molecule Acetyl-CoA that readily donates its 2C-acetyl group to oxaloacetate.

8
Q

Which of these produces carbon dioxide?

A

TCA cycle

9
Q

_____________ is a small vesicle that is derived from fragmented ER produced when cells are homogenized.

A

Microsome

10
Q

The Sec61 complex forms _____________ within the ER membrane.

A

translocon

11
Q

Precursor proteins destined for this organelle retain their targeting signal after transport across the organelle’s two membranes:

A

nucleus

12
Q

Posttranslational glycosylation of proteins is inhibited specifically by:

A

tunicamycin.

13
Q

Perioxisomal matrix proteins

A

undergo post-translational import into perioxisomes

14
Q

Transmembrane proteins of which of these organelles is synthesized on cytosolic ribosomes:

A

peroxisome

15
Q

The _________ protein forms general import pore which is a large passive channel through the outer mitochondrial membrane.

A

Tom 40

16
Q

Plastocyanin is a thylakoid lumen protein. Consider a scenario wherein, through genetic engineering, you replace the first 40 resides of Plastocyanin with a stretch of 40 Alanines. What can you predict about targeting or localization of this newly synthesized mutated protein?1

A

It will remain in the cytoplasm

17
Q

Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?

A

Tyrosine, serine and threonine

18
Q

Calcium ion

A

concentration in the cytosol is increased by activation of phospholipase C.
concentration in the cytosol is increased by activation of membrane calcium channels.
release from the endoplasmic reticulum may trigger influx of calcium ions from the extracellular fluid.

19
Q

What type of signaling occurs when insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake?

A

Endocrine signaling

20
Q

Which of the following statements is true of signal molecules?

A

Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors.

21
Q

A ligand for a membrane-bound receptor is chemically linked to beads that form an affinity chromatography column. When a solubilized preparation of membrane proteins is passed over this column, only the receptor binds to the beads. Later, an excess of the ligand is poured through the column after the receptor binding step. What do you expect will occur?

A

The ligand will cause the receptor to be displaced from the beads and eluted out.

22
Q

Which of the following are common means by which binding of a chemical messenger to a cell’s receptor brings about an intracellular response?

A

Opening or closing of specific ionic channels in the plasma membrane
Activation of an intracellular second-messenger system
Promoting or inhibiting the transcription of genes that code for the synthesis of cellular proteins

23
Q

Activation of a receptor that is coupled by G proteins to adenylyl cyclase

A

may increase the intracellular concentration of cyclic AMP.
may decrease the intracellular concentration of cyclic AMP.
may result in stimulation or inhibition of DNA transcription.

24
Q

Activation of a receptor by a chemical messenger

A

occurs when the messenger binds to the ligand-binding site of the receptor
is the first step leading to the ultimate response of a cell to the messenger.
requires a change in receptor conformation.

25
Q

Oxytocin is a peptide hormone that causes the smooth muscle of the uterus to contract, but it has no effect on the smooth muscle cells of the small intestine. This difference in responsiveness exists because

A

uterine smooth muscle cells contain specific receptors for oxytocin

26
Q

Amplification during a second messenger cascade is beneficial because amplification

A

allows small amounts of hormones to produce large responses in target cells.

27
Q

Nuclear pore complex is made up of multiple copies of some 30 different proteins called ______________.

A

nucleoporin

28
Q

TCA cycle occurs in the ______________ region of the mitochondria.

A

matrix

29
Q

Chemicals such as DNP uncouple ______________________ from electron transport.

A

oxidative phosphorylation

30
Q

In the technique of _______________, cell surface molecules are labeled with a fluorescent tag and then a portion of them are bleached with a laser beam followed by quantification of the lateral movement of proteins and lipids within the membrane.

A

Florescence Recovery After Photobleaching

FRAP

31
Q

The anaerobic catabolism of glucose called _________________ is the basis of beer and wine production.

A

fermentation