Question 1

Hox genes, one class of ____ genes, contain a conserved ____ region and encode transcription factors.  These encoded transcription factors contain a _____ that corresponds to the conserved region in the Hox genes and binds to the regulatory sequences of the target genes whose transcription they regulate.

Accepted Answer

Hox genes are a class of homeobox genes, which contain a conserved homeobox region and encode transcription factors with a homeodomain that binds to the regulatory sequences of target genes.

Question 2

A cell that is totipotent ____.

Accepted Answer

Totipotent cells have the potential to differentiate into any cell type, including both somatic and placental cells, making them capable of developing into a complete organism.

Question 3

Which process sets the developmental fate of an embryonic cell?

Accepted Answer

Determination is the process by which a cell becomes committed to a specific fate, setting its developmental path.

Question 4

Which statement accurately describes the relationship between RNAi, small interfering RNA (siRNA), and miRNA?

Accepted Answer

RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. This process can occur in two main ways: through microRNAs (miRNAs) or small interfering RNAs (siRNAs). Both miRNAs and siRNAs play crucial roles in gene silencing, but they originate from different types of RNA precursors and have slightly different mechanisms of action.

Question 5

The anterior-posterior orientation of Drosophila embryos is initially controlled and determined by ____.

Accepted Answer

Maternal-effect genes are responsible for establishing the anterior-posterior orientation in Drosophila embryos. These genes are expressed by the mother and their products are deposited in the egg, setting up the initial gradients that determine the embryo's body plan.

Question 6

In RNAi, imperfect pairing of miRNA to target mRNA results in ____ or ____, while perfect pairing of miRNA to target mRNA causes ____.

Accepted Answer

Imperfect pairing of miRNA to target mRNA typically results in blocking translation or a shorter half-life for the mRNA, while perfect pairing often leads to mRNA degradation.

Question 7

Experiments with mouse cells indicate that long noncoding RNAs ____.

Accepted Answer

Long noncoding RNAs have been found to play a significant role in the differentiation of cardiac cells, guiding their development from stem cells into specialized cardiac cells.

Question 8

The expression of any gene can be _______ using ____.

Accepted Answer

RNA interference (RNAi) is a biological process where RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules, leading to a reduction (knockdown) in gene expression levels rather than a complete knockout.

Question 9

A tumor comprised of cells that invade and disrupt surrounding tissues is called a(n) ____ tumor.

Accepted Answer

Malignant tumors are characterized by their ability to invade and disrupt surrounding tissues, distinguishing them from benign tumors, which do not spread or invade nearby tissues.

Question 10

Why is ubiquitin nicknamed the "doom tag"?

Accepted Answer

Ubiquitin is referred to as the "doom tag" because when it binds to a target protein, that complex is recognized by the proteasome, which then degrades the tagged protein. This process is a key regulatory mechanism to control the levels of various proteins within the cell, ensuring damaged or unneeded proteins are broken down.

Question 11

Micro RNAs (miRNAs) are important in ____.

Accepted Answer

Micro RNAs (miRNAs) are primarily involved in RNA interference (RNAi), a biological process where RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules.

Question 12

Increases in poly(A) tail length result in increased ____.

Accepted Answer

Increases in poly(A) tail length generally result in increased translation efficiency. The poly(A) tail, found at the 3' end of mRNA molecules, aids in the stability and translation of mRNA by interacting with proteins involved in the initiation of translation.

Question 13

When cells differentiate, they ____.

Accepted Answer

During differentiation, cells do not lose or gain DNA, nor do they remain totipotent (capable of developing into any type of cell). Instead, they express a specific subset of genes that define their function, structure, and role in the organism. This process does not necessarily mean they stop growing, as growth can occur in differentiated cells depending on their type and function.

Question 14

Transcription factors that control genes for developmental events are encoded by ____ genes.

Accepted Answer

Master regulatory genes encode transcription factors that control the expression of genes involved in developmental events, guiding the development and differentiation of cells and tissues in an organism.

Question 15

Posttranslational modification includes ____.

Accepted Answer

Posttranslational modification refers to the chemical modification, processing, and degradation of proteins after they have been synthesized. This can include the addition of functional groups, cleavage of signal peptides, and the formation of disulfide bridges, among other modifications.

Question 16

Sporadic cancers ____.

Accepted Answer

Sporadic cancers are those that occur due to mutations or changes in the DNA that happen over a person's lifetime, rather than being inherited through the family line. These are the most common type of cancers, contrasting with familial or hereditary cancers, which are passed down genetically.

Question 17

Pepsin, a digestive enzyme that degrades proteins in the stomach, is synthesized as pepsinogen and converted to active pepsin in the stomach by the removal of several amino acids. The activation of pepsin is an example of ____.

Accepted Answer

The activation of pepsin from pepsinogen involves the removal of several amino acids from the pepsinogen molecule, which occurs after the protein has been synthesized. This process is a form of posttranslational modification, where the protein's function is altered after translation.

Question 18

A small molecule of RNA is transcribed in the nucleus. It is folded, cleaved by the Dicer enzyme, forms a complex with proteins, which then binds to a target molecule of mRNA. This molecule of RNA must be ____.

Accepted Answer

miRNA (microRNA) is transcribed in the nucleus, processed by Dicer, forms a complex with proteins, and binds to target mRNA to regulate gene expression.

Question 19

One function of the 3' UTR (untranslated region) of mRNA is to ____.

Accepted Answer

The 3' UTR of mRNA plays a crucial role in controlling the stability and half-life of the mRNA molecule, influencing how long the mRNA is available for translation before it is degraded.

Question 20

Cytoplasmic determinants are ____.

Accepted Answer

Cytoplasmic determinants are key mRNAs and proteins stored in the egg cytoplasm that direct the early stages of development. These determinants are not found in the sperm cytoplasm but are instead provided by the egg and play a crucial role in the early patterning and development of the embryo.

Quiz 16: Regulation of Gene Expression

Hox genes, one class of genes, contain a conserved region and encode transcription factors. These encoded transcription factors contain a _ that corresponds to the conserved region in the Hox genes and binds to the regulatory sequences of the target genes whose transcription they regulate.