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.
How do you know if a chromosome is Unreplicated?
a unreplicated chromosome has one DNA molecule; a replicated chromosome has two identical DNA molecules (sister chromatids) attached at the centromere. eg., In humans, the haploid sperm has 23 chromosomes; haploid egg has 23; diploid embryo has 46 chromosomes. HOMOLOGOUS chromosomes are chromosomes of the same type.
What is a Unreplicated chromosome called?
A homologous pair of chromosomes consists of one chromosome from each parent. During most of the cell cycle, homologous chromosome pairs are unreplicated. When the chromosomes replicate, each chromosome of the pair becomes doubled; each “half” of the doubled chromosomes is called a chromatid.
What is a duplicated chromosome?
Chromosome duplication: Part of a chromosome in duplicate. A particular kind of mutation involving the production of one or more copies of any piece of DNA, including sometimes a gene or even an entire chromosome. A duplication is the opposite of a deletion.
What does N and 2N stand for in genetics?
– Genomic (X) number is a set of different chromosomes 2N = number of chromosomes in somatic cells (somatic chromosome number) N = number of chromosomes in gametic cells (gametic chromosome number) X = Number of chromosomes in a genome complement (genomic chromosome number) 4.
Is a chromosome a single strand of DNA?
Each chromosome contains a single double-stranded piece of DNA along with the aforementioned packaging proteins. … This condensed form is approximately 10,000 times shorter than the linear DNA strand would be if it was devoid of proteins and pulled taut.
What are the four stages of mitosis?
These phases are prophase, prometaphase, metaphase, anaphase, and telophase.