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2021-05-15

What phenomenon occurs in females as a result of X chromosome inactivation quizlet?

What phenomenon occurs in females as a result of X chromosome inactivation quizlet?

X inactivation in heterozygous females produces a mosaic pattern of gene expression. During early embryonic development, some cells have the maternal X chromosome inactivated and other cells have the paternal X chromosome inactivated; these embryonic cells will divide and produce billions of cells.

What happens during X inactivation in females?

X-inactivation (also called Lyonization, after English geneticist Mary Lyon) is a process by which one of the copies of the X chromosome is inactivated in therian female mammals. The inactive X chromosome is silenced by it being packaged into a transcriptionally inactive structure called heterochromatin.

What occurs during X chromosome inactivation?

X-chromosome inactivation occurs randomly for one of the two X chromosomes in female cells during development. Inactivation occurs when RNA transcribed from the Xist gene on the X chromosome from which it is expressed spreads to coat the whole X chromosome.

What happens to X chromosomes that are inactivated quizlet?

X-Chromosome inactivation is a product of the DNA being highly methylated, which puts it in an increased heterochromatic state, the DNA stored is called a Barr body. Making the DNA on the X chromosome more heterochromatic, decreasing the accessibility and thus preventing expression. You just studied 2 terms!

What does Barr body mean?

: a densely staining inactivated condensed X chromosome that is present in each somatic cell of most female mammals and is used as a test of genetic femaleness (as in a fetus)

What is the role of transcription factors quizlet?

What is the role of transcription factors? Transcription factors are required for RNA pol II binding to promoter. TFs are DNA binding proteins, but can also bind other TFs. They assist in bringing RNA pol II in close proximity of the promoter.

What is the main function of transcription factors?

Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA. Transcription factors include a wide number of proteins, excluding RNA polymerase, that initiate and regulate the transcription of genes.

What are the roles of transcription factors?

Transcription factors are proteins that regulate the transcription of genes—that is, their copying into RNA, on the way to making a protein. The human body contains many transcription factors. Transcription factors help ensure that the right genes are expressed in the right cells of the body, at the right time.

What is the role of regulatory sequence?

A regulatory sequence is a segment of a nucleic acid molecule which is capable of increasing or decreasing the expression of specific genes within an organism. Regulation of gene expression is an essential feature of all living organisms and viruses.

What is the function of Tfiid?

TFIID is the first protein to bind to DNA during the formation of the pre-initiation transcription complex of RNA polymerase II (RNA Pol II). Binding of TFIID to the TATA box in the promoter region of the gene initiates the recruitment of other factors required for RNA Pol II to begin transcription.

What is a TATA box and what does it do?

The TATA box is the binding site of the TATA-binding protein (TBP) and other transcription factors in some eukaryotic genes. Gene transcription by RNA polymerase II depends on the regulation of the core promoter by long-range regulatory elements such as enhancers and silencers.

How does TBP bind to DNA?

TBP binds with the negatively charged phosphates in the DNA backbone through positively charged lysine and arginine amino acid residues. The sharp bend in the DNA is produced through projection of four bulky phenylalanine residues into the minor groove.

Is Tfiid a transcriptional activator protein?

Recently, TFIID was shown to be a multisubunit complex containing a TATA box-binding polypeptide (TBP) and several tightly associated polypeptides (TAFs), which are required for transcriptional stimulation by activator proteins. Electrophoretic mobility-shift analysis demonstrated a single major DNA-protein complex.

Is Tfiid a promoter?

TFIID was shown to co-exist in two distinct structural states while the presence of both TFIIA and promoter DNA stabilizes a rearranged state of TFIID that enables promoter recognition and binding.

Does Tfiih bind to TATA box?

Many viral and cellular promoters transcribed in higher eukaryotes by RNA polymerase II lack obvious A+T-rich sequences, called “TATA” boxes, that bind the transcription factor TFIID.

How many domains does the TATA binding protein have?

two domains

Why is TBP the universal transcription factor?

The TATA binding protein (TBP) is a subunit of several macromolecular complexes required for transcription by the three nuclear RNA polymerases. This observation led to the idea that TBP is a “universal” transcription factor.

What is the main function of the TATA binding protein quizlet?

What is the main function of the TATA-binding protein? The TATA-binding protein is a subunit of RNA polymerase II that helps initiate transcription. When the TATA-binding protein binds to the TATA sequence in DNA, the protein causes the DNA helix to bend.

Which biochemical reaction is catalyzed by a ribozyme?

In addition, numerous artificial ribozymes were developed by in vitro evolution in the past years. All natural ribozymes fall into two major groups which are the small and large ribozymes. Ribozymes catalyze reactions such as RNA splicing, RNA cleavage and protein synthesis.

How may an enhancer sequence facilitate transcription?

Enhancer regions are binding sequences, or sites, for specific transcription factors. When a protein transcription factor binds to its enhancer sequence, the shape of the protein changes, allowing it to interact with proteins at the promoter site.

What property of DNA allows the TATA box binding protein to recognize the DNA helix?

The combination of the unusual flexibility of TATA DNA sequences and these specific hydrogen bonds allows TATA-binding protein to recognize the proper sequence.

Does TATA binding protein bind to DNA as a monomer?

Abstract. The TATA binding protein (TBP) is a central component of all eukaryotic transcription machineries. TBP dimers do not bind DNA, but they must dissociate into monomers before stably binding to the TATA box.

How does RNA polymerase bind to the DNA?

To begin transcribing a gene, RNA polymerase binds to the DNA of the gene at a region called the promoter. Each gene (or, in bacteria, each group of genes transcribed together) has its own promoter. A promoter contains DNA sequences that let RNA polymerase or its helper proteins attach to the DNA.