GRE Subject Test: Biochemistry, Cell, and Molecular Biology : GRE Subject Test: Biochemistry, Cell, and Molecular Biology

Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology

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All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

1 Diagnostic Test 201 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #11 : Cellular Structures And Functions

Which of the following transport mechanisms requires ATP hydrolysis to move a molecule against its concentration gradient?

Possible Answers:

Secondary active transport

Facilitated diffusion

Cotransport

Active transport

Passive diffusion

Correct answer:

Active transport

Explanation:

Secondary active transport and cotransport are the same thing, and while solutes can be moved against their concentration gradient, ATP is not used. Passive and facilitated diffusion do not require ATP either. Active transport is the only transport mechanism that uses ATP to move molecules against their concentration gradient. 

Example Question #11 : Cell Membrane And Cell Wall

Which of the following is not a method used to transport substances into a cell?

Possible Answers:

Exocytosis

Phagocytosis

Pinocytosis

Receptor-mediated endocytosis

Correct answer:

Exocytosis

Explanation:

Endocytosis is the process by which substances from the external environment are encapsulated in vesicles and brought into the cell. Receptor-mediated endocytosis uses membrane receptors to help localize the formation of the trasnport vesicle. Pinocytosis uses vesicles to transport fluids into the cell, while phagocytosis uses vesicles to bring pathogenic debris into the cell for digestion.

Exocytosis, in contrast, is the expulsion of substances from the cell via a transport vesicle.

Example Question #221 : Gre Subject Test: Biochemistry, Cell, And Molecular Biology

Every cell membrane has protein channels that allow certain molecules to pass through.

Which acronym is used to explain the concentration gradient of sodium (Na+) and potassium (K+) inside and outside the cell membrane?

Possible Answers:

I'm A People Person

SOAP

HIKIN'

KADE

TIRE

Correct answer:

HIKIN'

Explanation:

"HIKIN'" represents the statements "there is a HIgh K concentration INside the cell."

"KADE" is used to remember the vitamins that are fat soluble: vitamins K, A, D, and E. "I'm A People Person" refers to the four-point physical assessment of a disease: Inspection, Auscultation, Percussion, Palpation. SOAP is the acronym for Subjective, Objective, Assessment, and Plan—a way to organize patient examination information. TIRE is an mnemonic for remembering the four abdominal muscles: transversus abdominis, internal abdominal oblique, rectus abdominis, external abdominal oblique.

Example Question #1 : Nucleus And Ribosomes

What is the main function of the nucleolus in eukaryotic cells?

Possible Answers:

To facilitate nuclear transport of proteins and mRNA from the nucleus to the cytoplasm

The site of microtubule assembly during mitosis

To promote the transcription, processing, and assembly of rRNA genes into ribosomes

Eukaryotic cells do not have a nucleolus

Storage site for transcription factors, RNA polymerases, DNA polymerases, and other transcriptional machinery until transcription occurs

Correct answer:

To promote the transcription, processing, and assembly of rRNA genes into ribosomes

Explanation:

The correct answer is that the nucleolus is the site of ribsome synthesis and assembly. Chromosomes containing rRNA (ribosomal RNA genes) are clustered within the nucleolus, which facilitates rapid transcription and processing of rRNA genes and assembly of rRNA subunits into ribosomes. 

Example Question #2 : Nucleus And Ribosomes

The nuclear lamina is generally associated with __________.

Possible Answers:

ribosome synthesis and assembly 

heterochromatin and transcriptionally active genes

chromatin containing transcriptionally inactive genes

chromatin containing transcriptionally active genes

euchromatin and transcriptionally inactive genes

Correct answer:

chromatin containing transcriptionally inactive genes

Explanation:

The correct answer is chromatin and transcriptionally inactive genes. The nuclear lamina provides support and structure to the nucleus and binds transcriptionally inactive regions. Euchromatin is loosely packed chromatin and is, therefore, associated with transcriptionally active genes. Alternatively, heterochromatin is densely packed chromatin and implies inactive genes. Ribosome synthesis and assembly occurs in the nucleolus.

Example Question #3 : Nucleus And Ribosomes

What is the function of RanGAP in relation to nuclear import and export?

Possible Answers:

Bind cargo proteins

Bind importins/exportins and bring them through the nuclear pore complex

Attach GTP to Ran

Maintain a gradient of GTP/GDP bound Ran 

Correct answer:

Maintain a gradient of GTP/GDP bound Ran 

Explanation:

RanGAP is notable for its ability to activate the GTPase function of the Ran protein. This allows for the hydrolysis of the third phosphate of GTP-bound Ran and the maintenance of a Ran-GDP/Ran-GTP gradient that is used to control nuclear import and export. RanGAP does not directly associate with cargo proteins or importins/exportins.

Example Question #4 : Nucleus And Ribosomes

Which of the following choices would have the biggest effect on nuclear transport?

Possible Answers:

An inhibitor that globally targets exportins at their cargo binding sites

A mutated, non-functional copy of RanGAP

An inhibitor that globally targets importins at their cargo binding sites

A non-functional copy of the gene that encodes CRM1

Correct answer:

A mutated, non-functional copy of RanGAP

Explanation:

Because the question is asking which will have the largest effect, it makes sense that the answer should affect import and export globally.

Importins and exportins only work in one direction. While mutations to either of these protein classes would greatly affect nuclear transport, each is only responsible for "half" or the transport across the membrane. CRM1 is a well characterized exportin.

RanGAP, however, is responsible for helping maintain the gradient of Ran bound to GTP or GDP. The gradient of RanGTP/GDP is what provides global directionality to nuclear import and export. Loss of RanGAP would affect both import and export, having the largest detrimental effect on nuclear transport.

Example Question #3 : Nucleus And Ribosomes

What is the site of ribosomal subunit synthesis in the cell?

Possible Answers:

Smooth endoplasmic reticulum

Nucleolus

Nucleus

Golgi apparatus

Correct answer:

Nucleolus

Explanation:

Ribosomal subunits are created in the nucleolus, a small area found inside of the nucleus.

Example Question #1 : Help With Ribosome Structure

How many RNA molecules are found in the small ribosomal subunit.

Possible Answers:

1

6

0

3

2

Correct answer:

1

Explanation:

The small subunit of the ribosome contains only one RNA molecule; the 16S rRNA in prokaryotes and the 18S rRNA in eukaryotes.

Example Question #1 : Help With Mitochondria Structure

What is the primary purpose of cristae in the mitochondria?

Possible Answers:

Protect the mitochondrial genome

Prevent the mitochondria from folding in on itself

Provide a large surface area for chemical reactions

No purpose has yet been identified; they are likely an evolutionary remnant 

Correct answer:

Provide a large surface area for chemical reactions

Explanation:

The importance of the cristae comes from the fact that they greatly increase the surface area of the inner membrane of the mitochondria. This is important because this membrane houses the electron transport chain proteins. A larger surface area allows reactions to occur at a higher rate and, thus, more ATP can be generated. The cristae are not essential to protecting the mitochondrial genome or maintaining shape.

All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

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