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Can mRNA travel back into the nucleus?

Due to this physical separation, messenger RNAs (mRNAs) must be exported to the cytoplasm where they direct protein synthesis, whereas proteins participate in the nuclear activities are imported into the nucleus. In addition, some types of RNAs reenter to the nucleus after being exported to the cytoplasm [1]….

What does mRNA carry from the nucleus?

mRNA is a single-stranded molecule that carries genetic code from DNA in a cell’s nucleus to ribosomes, the cell’s protein-making machinery.

How are proteins transported to the nucleus?

Nuclear proteins are transported actively through nuclear pores by a selective, mediated process. The process is mediated by a nuclear localization signal (NLS), and can be divided into at least two steps, (a) targeting to the pores and (b) translocation through the pores.

What proteins are found in the nucleus?

In order to organize the large amount of DNA within the nucleus, proteins called histones are attached to chromosomes; the DNA is wrapped around these histones to form a structure resembling beads on a string. These protein-chromosome complexes are called chromatin. Figure 4.3C….

Does DNA travel out of the nucleus?

Eukaryotic DNA never leaves the nucleus; instead, it’s transcribed (copied) into RNA molecules, which may then travel out of the nucleus.

Why is unfolding unnecessary for nuclear protein import?

Protein transport into the endoplasmic reticulum (ER) or mitochondria requires unfolding the protein and threading the amino acid chain through a channel or pore into the organelle. For this reason, it is unnecessary to unfold the protein, which can pass through the pore in its native state.

Do proteins unfold during nuclear transport?

For example, proteins going into the nucleus are transported through pores in the nuclear membranes with the help of nuclear transporter proteins. In this case, the proteins must enter in an unfolded form, since the dimensions of the translocator will not allow a folded protein to pass through.

What is a nuclear basket?

The nuclear envelope (NE) is a bilayer membrane that separates the DNA-containing nucleoplasm from the cytoplasm. The nucleoplasmic filaments are organized in a basket-like structure that projects from the NPC towards the nuclear interior called “Nuclear Basket”….

Why does the nucleus have an envelope around it?

The nuclear envelope keeps the contents of the nucleus, called the nucleoplasm, separate from the cytoplasm of the cell. The all-important genetic material, mainly the DNA is kept separate and relatively safe from the chemical reactions taking place in the cytoplasm.

What is the main function of nuclear envelope?

A nuclear membrane is a double membrane that encloses the cell nucleus. It serves to separate the chromosomes from the rest of the cell. The nuclear membrane includes an array of small holes or pores that permit the passage of certain materials, such as nucleic acids and proteins, between the nucleus and cytoplasm.

Do plant cells have an envelope surrounding the nucleus?

Plant cells have an envelope surrounding the nucleus. Animal cells do not. They act as the powerhouse for the cell. They are involved in the separation of chromosomes during cell division.

Which structure is found in all but not plants?

Some (but not all) plant cells – mostly those in the middle of leaves – have chloroplasts – green structures which contain the pigment chlorophyll….Approximate sizes:

cell/component size / ┬Ám
chloroplast length 3