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 #31 : Rna, Transcription, And Translation

In prokaryotes what site on the mRNA does the ribosome bind to initiate translation?

Possible Answers:

The operator

The poly adenine tail

The Shine-Dalgarno sequence

The promoter

The 3' untranslated region

Correct answer:

The Shine-Dalgarno sequence

Explanation:

The Shine-Dalgarno sequence is the ribosomal binding site in in prokaryotic mRNA that is located around 8 bases upstream of the start codon.

Example Question #471 : Gre Subject Test: Biochemistry, Cell, And Molecular Biology

Which of the level of protein structure is incorrectly matched to its description?

Possible Answers:

Secondary structure is determined by hydrogen bonding of the amino acid backbone

Primary structure is the linear amino acid sequence of a protein

Quaternary structure is the three-dimensional structure of a multi-subunit protein

Tertiary structure is the two-dimensional structure of a protein

Correct answer:

Tertiary structure is the two-dimensional structure of a protein

Explanation:

Primary structure of a protein is determined by covalent peptide bonds, and corresponds to the linear sequence of amino acids before structures begin to form. Secondary structure results from hydrogen bonding between the amino acid backbones to form alpha-helices and beta-sheets. Tertiary structure is formed when functional groups of the amino acids interact, either by hydrogen bonding, hydrophobic interactions, or disulfide bridge formation. Tertiary structure is associated with the three-dimensional structure of a single polypeptide chain. Quaternary structure forms when multiple polypeptide chains interact to build a multi-subunit structure.

Example Question #32 : Rna, Transcription, And Translation

Which of the following proteins are likely to contain leucine zipper domains?

Possible Answers:

Transcription factors

Transmembrane proteins

Lipases

Proteases

Correct answer:

Transcription factors

Explanation:

Leucine zippers are domains that allow for the binding of DNA. The question is essentially asking, "which of these proteins are capable of binding DNA?"

Proteases cleave proteins, lipases hydrolyze lipids, and transmembrane proteins interact with membranes. Transcription factors are the only given proteins that bind DNA and, therefore, are much more likely to contain leucine zipper domains than the other options. 

Example Question #1 : Help With Protein Structures

Which protein structure involves the binding of multiple polypeptides?

Possible Answers:

Primary structure

Tertiary structure

Quaternary structure

Secondary structure

Correct answer:

Quaternary structure

Explanation:

The structures of a protein increase in complexity all the way up to quaternary structure. Primary structure is based on the amino acid sequence of the protein, while secondary and tertiary structures are based on intermolecular attractions between the amino acids in the polypeptide. Quaternary structure is only seen when a functional protein complex is composed of two or more polypeptides bound together.

Example Question #42 : Rna, Transcription, And Translation

Disulfide bonds in proteins are categorized under which structure class? 

Possible Answers:

More than one of these

Quaternary structure

Tertiary structure

Primary structure

Secondary structure

Correct answer:

More than one of these

Explanation:

The correct answer is more than one of these. Primary structure is defined as a succession of amino acids joined by peptide bonds. Secondary structure introduces dimensionality to a protein via hydrogen bonding to produce two predominant structures, alpha helices and beta-pleated sheets. Tertiary structures cause further protein folding by disulfide bonds between cysteines, Van der Waal interactions, and hydrophobic interactions. Quaternary structures involve multiple amino acid chains folding together, and utilize the same types of bonds as tertiary structures. 

Example Question #43 : Rna, Transcription, And Translation

The 5' cap on eukaryotic mRNA molecules is recognized by which of the following proteins?

Possible Answers:

RNA polymerase

PABP

eIF4e

40s ribosomal subunit

Correct answer:

eIF4e

Explanation:

The 5' cap is recognized by the important translation factor eIF4e. Once bound, eIF4e helps transport the mRNA molecule to the ribosome and facilitates bonding to the ribosomal machinery.

The 3' poly-A tail is recognized by PABP. RNA polymerase is involved in transcription, not translation. The 40s ribosomal subunit is recruited by the initiation complex (including eIF4e, PABP, and various other translation factors).

Example Question #11 : Translation And Proteins

When conducting a stain of chromosomes, certain regions along the chromosome will stain more darkly than the rest. This is due to the fact that these regions are more tightly condensed. What is the functional outcome of having one region more condensed (heterochromatin) than the rest (euchromatin)?

Possible Answers:

Heterochromatin is typically not transcribed/transcribed at a lower rate because the tight packing limits accessibility to polymerases.

Heterochromatin does not contain any genes and is a structural component of the chromosome. 

Heterochromatin is not transcribed/is transcribed at a lower rate because euchromatin saturates all available polymerase. 

Heterochromatin is transcribed at a high frequency because there are a high number of genes in a small area. 

Heterochromatin unpacking requires many ATP and is energetically expensive. 

Correct answer:

Heterochromatin is typically not transcribed/transcribed at a lower rate because the tight packing limits accessibility to polymerases.

Explanation:

Heterochromatin often contains simple, repetitive sequences, and although it cannot be said that it is completely void of coding sequences, it is not typically transcribed. The tight wrapping prevents polymerase from accessing the strand, and euchromatin typically contains the regions that get transcribed. Thus, heterochromatin is though to contain repressed or inactive genes. 

Example Question #45 : Rna, Transcription, And Translation

Small GTPases are important molecular switches and signaling pathways. What proteins are responsible for promoting the activation of these small GTPases?

Possible Answers:

Kinases 

Nicotinamide adenine dinucleotide

Guanine triphosphate

Phosphatases

Guanine nucleotide exchange factors 

Correct answer:

Guanine nucleotide exchange factors 

Explanation:

The correct answer is guanine nucleotide exchange factors. In order to activate small GTPases and subsequently stimulate downstream pathways, guanine nucleotide exchange factors bind inactive GTPases and cause the release of guanine diphosphate (GDP). This allows guanine triphosphate (GTP) to bind and active the GTPase. 

Example Question #46 : Rna, Transcription, And Translation

Which of the following is not an example of post-translational modification?

Possible Answers:

Ubiquitination 

Alkylation

Polyadenylation

Myristoylation

Correct answer:

Polyadenylation

Explanation:

Polyadenylation is an example of post-transcriptional modification. This process involves adding large repeats of adenine bases to the 3' end of mRNA molecules, known as the poly-A tail.

Myristoylation is the process of adding myristate (a fatty acid) to a protein, alkylation is the process of adding an alkyl group, and ubiquination is the process of adding a molecule of ubiquitin (a small protein often used to signal degradation). 

Example Question #47 : Rna, Transcription, And Translation

In which of the following organelles does the initial linkage of a sugar for post-translation modification N-linked glycosylation most commonly occur?

Possible Answers:

Mitochondria

Nucleus

Golgi apparatus

Endoplasmic reticulum

Correct answer:

Endoplasmic reticulum

Explanation:

Two of the more common types of glycosylation, N-linked and O-linked, occur at different points and in different places in the cell. N-linked glycosylation takes place in the lumen of the endoplasmic reticulum, while O-linked glycosylation takes place in the Golgi body.

The other options, the mitochondria and the nucleus, are not involved in these post-translational modifications.

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

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