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Nuclear Changes in Prophase Later, chromosome condense into two threads termed sister chromatids that are closely paired along their entire lengths.
- What are condensed strands of DNA?
- What is a thread of DNA called?
- What happens when DNA is condensed?
- What is a condensed unit of DNA?
- What are the loose threads in interphase?
- Why is DNA condensed?
- What is chromatin packaging?
- How is histone octamer formed?
- What is packaging of DNA?
- Why is DNA condensed during cell cycle?
- What is DNA called when it is not condensed?
- Why are chromosomes condensed during mitosis?
- What is the function of nucleolus?
- What is Euchromatic nucleus?
- What is condensation and Decondensation?
What are condensed strands of DNA?
Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. Nuclear DNA does not appear in free linear strands; it is highly condensed and wrapped around nuclear proteins in order to fit inside the nucleus. Chromatin exists in two forms.
What is a thread of DNA called?
In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.
What happens when DNA is condensed?
DNA condenses into chromosomes. When the time is right for the cell to divide, the nuclear membrane disassembles, and chromosomes are on the move. The structure of a chromosome has everything to do with what the purpose of each phase of the cell cycle.
What is a condensed unit of DNA?
In most eukaryotes, DNA is arranged in the cell nucleus with the help of histones. In this case, the basic level of DNA compaction is the nucleosome, where the double helix is wrapped around the histone octamer containing two copies of each histone H2A, H2B, H3 and H4.
What are the loose threads in interphase?
While in interphase, the DNA is shaped like uncoiled strands that look like spaghetti. When it is in this shape, it is called chromatin. When DNA is loosely packed like this it is much easier for the cell's machinery to copy.
Why is DNA condensed?
DNA is tightly packed up to fit in the nucleus of every cell. As shown in the animation, a DNA molecule wraps around histone proteins to form tight loops called nucleosomes. ... Condensing DNA into chromosomes prevents DNA tangling and damage during cell division.
What is chromatin packaging?
Chromatin is the material that makes up a chromosome that consists of DNA and protein. The major proteins in chromatin are proteins called histones. They act as packaging elements for the DNA. The reason that chromatin is important is that it's a pretty good packing trick to get all the DNA inside a cell.
How is histone octamer formed?
A histone octamer is the eight protein complex found at the center of a nucleosome core particle. ... The octamer assembles when a tetramer, containing two copies of both H3 and H4, complexes with two H2A/H2B dimers. Each histone has both an N-terminal tail and a C-terminal histone-fold.
What is packaging of DNA?
Chromosomal DNA is packaged inside microscopic nuclei with the help of histones. These are positively-charged proteins that strongly adhere to negatively-charged DNA and form complexes called nucleosomes. Each nuclesome is composed of DNA wound 1.65 times around eight histone proteins.
Why is DNA condensed during cell cycle?
During mitosis, the chromosomes condense so that each chromosome is a distinct unit. Prior to mitosis, the cell copies its DNA so that it contains two copies of each chromosome. ... Condensing the DNA into tightly packed chromosomes makes the process of chromosome alignment and separation during mitosis more efficient.
What is DNA called when it is not condensed?
During interphase, the cell's DNA is not condensed and is loosely distributed. A stain for heterochromatin (which indicates the position of chromosomes) shows this broad distribution of chromatin in a mouse cell (upper left).
Why are chromosomes condensed during mitosis?
Chromatin, a substance that contains genetic material such as DNA, is normally found in a loose bundle inside a cell's nucleus. During the prophase of mitosis, the chromatin in a cell compacts to form condensed chromosomes; this condensation is required in order for the cell to divide properly.
What is the function of nucleolus?
The nucleolus is a region found within the cell nucleus that is concerned with producing and assembling the cell's ribosomes. Following assembly, ribosomes are transported to the cell cytoplasm where they serve as the sites for protein synthesis.
What is Euchromatic nucleus?
Euchromatin is a lightly packed form of chromatin (DNA, RNA, and protein) that is enriched in genes, and is often (but not always) under active transcription. ... In eukaryotes, euchromatin comprises the most active portion of the genome within the cell nucleus.
What is condensation and Decondensation?
Chromatin condensation is driven by condensins and interactions between histones. ... Once segregated by the spindle, chromatin decondenses to re-establish its interphase structure competent for DNA replication and transcription.
