Technology 

How are eukaryotic genes usually controlled?

Joe Ford

How are eukaryotic genes usually controlled?

Gene expression in eukaryotic cells is regulated by repressors as well as by transcriptional activators. Like their prokaryotic counterparts, eukaryotic repressors bind to specific DNA sequences and inhibit transcription. Other repressors compete with activators for binding to specific regulatory sequences.

How is gene expression controlled?

Gene expression is primarily controlled at the level of transcription, largely as a result of binding of proteins to specific sites on DNA. Regulation of protein production is largely achieved by modulating access of RNA polymerase to the structural gene being transcribed.

What are three ways in which eukaryotic cells can control gene expression?

Eukaryotic gene expression can be regulated at many stages

  • Chromatin accessibility. The structure of chromatin (DNA and its organizing proteins) can be regulated.
  • Transcription. Transcription is a key regulatory point for many genes.
  • RNA processing.

What is the most common form of gene expression regulation in both bacteria and eukaryotes?

Transcriptional control is the primary means of regulating gene expression in eukaryotes, as it is in bacteria. In eukaryotic genomes, cis-acting control elements that regulate transcription from a promoter often are located many kilobases away from the start site.

Which of the following is unique to eukaryotes?

Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes. However, unlike prokaryotic cells, eukaryotic cells have: a membrane-bound nucleus. numerous membrane-bound organelles (including the endoplasmic reticulum, Golgi apparatus, chloroplasts, and mitochondria)

Why shouldn’t every cell express all of its genes?

Cells would have to be enormous if every protein were expressed in every cell all the time. The control of gene expression is extremely complex. Malfunctions in this process are detrimental to the cell and can lead to the development of many diseases, including cancer.

Does all DNA encode genes?

The genes of bacteria are tightly packed together; virtually all the DNA encodes proteins. However, experiments done in the 1960s, showed that a large proportion of eukaryotic DNA is composed of repeated sequences that do not encode proteins.

How are genes activated?

Gene regulation can occur at any point during gene expression, but most commonly occurs at the level of transcription (when the information in a gene’s DNA is passed to mRNA). Signals from the environment or from other cells activate proteins called transcription factors.

What does DNA contain the instructions for making?

DNA contains the instructions needed for an organism to develop, survive and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies.

Miscellaneous 

How are eukaryotic genes usually controlled?

Joe Ford

How are eukaryotic genes usually controlled?

Gene expression in eukaryotic cells is regulated by repressors as well as by transcriptional activators. Like their prokaryotic counterparts, eukaryotic repressors bind to specific DNA sequences and inhibit transcription. Other repressors compete with activators for binding to specific regulatory sequences.

What is unique about eukaryotic gene regulation?

Unlike prokaryotic cells, eukaryotic cells can regulate gene expression at many different levels. Eukaryotic gene expression begins with control of access to the DNA. This form of regulation, called epigenetic regulation, occurs even before transcription is initiated.

What are homeotic genes and what do they do?

homeotic gene, any of a group of genes that control the pattern of body formation during early embryonic development of organisms. These genes encode proteins called transcription factors that direct cells to form various parts of the body.

Why are most eukaryotic genes off?

Genes can’t control an organism on their own; rather, they must interact with and respond to the organism’s environment. It turns out that the regulation of such genes differs between prokaryotes and eukaryotes. For prokaryotes, most regulatory proteins are negative and therefore turn genes off.

Why do eukaryotes have a more complex system of gene regulation?

Eukaryotes have a more complex system of gene regulation than prokaryotes because eukaryotic gene expression requires more steps. Each level of gene expression—transcription, post-transcription, translation, and post-translation—has its own regulation.

How does the process that stops transcription differ between prokaryotes and eukaryotes?

mRNAs in prokaryotes tend to contain many different genes on a single mRNA meaning they are polycystronic. Termination in prokaryotes is done by either rho-dependent or rho-independent mechanisms. In eukaryotes transcription is terminated by two elements: a poly(A) signal and a downstream terminator sequence (7).

What is significant about the homeotic genes in many different organisms?

Homeotic genes are responsible for determining the identity of particular segments or structures of the body. So, when homeotic genes are inactivated or expressed in unusual locations due to mutations, they may cause body segments to take on new—and sometimes startling!

How do homeotic genes regulate development?

Homeotic genes often encode transcription factor proteins, and these proteins affect development by regulating downstream gene networks involved in body patterning. Mutations in homeotic genes cause displaced body parts (homeosis), such as antennae growing at the posterior of the fly instead of at the head.

How do homeotic genes regulate the expression of other genes?

Most animal homeotic genes encode transcription factor proteins that contain a region called the homeodomain and are called Hox genes. Hox genes are turned on by a cascade of regulatory genes; the proteins encoded by early genes regulate the expression of later genes.

Homeotic genes control development of whole body segments or structures. When they are overactive or missing, weird things can happen! Homeotic genes are master regulator genes that direct the development of particular body segments or structures.

What happens when homeotic genes are overactivated or inactivated?

Homeotic genes are master regulator genes that direct the development of particular body segments or structures. When homeotic genes are overactivated or inactivated by mutations, body structures may develop in the wrong place—sometimes dramatically so!

Where are the homeotic genes located in the fly?

Another fly homeotic gene with dramatic effects is the Ultrabithorax gene. This gene is expressed strongly in the third segment of the thorax, which bears the fly’s rearmost pair of legs. Ultrabithorax expression in this region of the fly starts early in development and continues throughout the fly’s life.

How are genes expressed in the development of a fly?

As it turns out, a set of master regulator genes are expressed in different regions of a fly’s body during development. These genes turn on the right genetic “program” for development of each section of the body. They make sure, for example, that the fly’s thorax carries legs while its head does not.