what are chromosomes?

Answer 1

A threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries the genes and functions in the transmission of hereditary information.
A circular strand of DNA in bacteria that contains the hereditary information necessary for cell life.

Answer 2

Definition and description

A chromosome is the visible state of genetic material during a phase of the division of the cell (metaphase). Humans have 23 pairs of chromosomes, which makes the diploid number 46. The diploid number is the number of chromosomes of a normal cell. The haploid number is the number of chromosomes in a gamete. Usually, the diploid number is twice the haploid number. The number of chromosomes varies depending on the species.

Just before mitosis, DNA, which contains the genetic information, is replicated. Now there are two identical copies of all the DNA in this cell. The cell is ready to divide.
chromosome fibre...
The DNA molecule is twisted onto itself, and the supercoiled molecule is wrapped around proteins which maintain its shape. These proteins have a special name - histone proteins. The fibre has the structure of a spring (a solenoid, to be technical), as shown in the illustration on the right. The DNA is wrapped around the protein, and then, twisted together again in the shape of a spring. The complex DNA protein is called chromatin, while the structure formed by two turns of DNA around one histone is called a nucleosome.
From DNA to chromosome
Loop

The LOOP, drawn on the right, is a well packed chromosome fibre. The chromosome fibre is coiled around a protein scaffold. The string of little packets is then wrapped around another protein structure to form a chromatid.
chromosome A model of a chromosome during metaphase is displayed on the left: Click on it to see the legend (don't forget to come back).

A chromosome like this one is made of two identical molecules of DNA efficiently packed into chromatids. As can be seen in the illustration, a chromatid is made of a protein frame, and loops around it.

The efficiency of this packing is pretty impressive! Human chromosome 1 is hardly 10 micrometers long. But it contains 7 centimetres of DNA!

Answer 3

A chromosome is a single large macromolecule of DNA, and is the basic 'unit' of DNA in a cell. It is a very long, continuous piece of DNA (a single DNA molecule), which contains many genes, regulatory elements and other intervening nucleotide sequences. A broader definition of "chromosome" also includes the DNA-bound proteins which serve to package and manage the DNA. The word chromosome comes from the Greek χρώμα (chroma, color) and σώμα (soma, body) due to its capacity to be stained very strongly with vital and supravital dyes.

Chromosomes vary extensively between different organisms. The DNA molecule may be circular or linear, and can contain anything from tens of kilobase pairs to hundreds of megabase pairs. Typically eukaryotic cells have large linear chromosomes and prokaryotic cells smaller circular chromosomes; although there are many exceptions to this rule. Furthermore, cells may contain more than one type of chromosome; for example mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosome in addition to the nuclear chromosomes.

In eukaryotes nuclear chromosomes are packaged by proteins (particularly histones) into chromatin to fit the massive molecules into the nucleus. The structure of chromatin varies through the cell cycle, and is responsible for the compaction of DNA into the classic four-arm structure during mitosis and meiosis. Prokaryotes do not form chromatin, the cells lack proteins required and the circular configuration of the molecule prevents this.

"Chromosome" is a rather loosely defined term. In eukaryotes a small circular DNA molecule may be called either a plasmid or a small chromosome. In viruses, mitochondria, and chloroplasts their DNA molecules are commonly referred to as chromosomes, despite being naked molecules, as they constitute the complete genome of the organism or organelle.

Answer 4

chromosomes are units of human genetic make up.
that carry the human genetic informations from parrents to offspring.
each human cell nucleus contains 46 chromosomes including all genetic characterstics like eye color,physical stature,blood group,etc....
we recieve 23 chromosome from each parent(father&mother) which sums up to 46

Answer 5

Chromosomes are either x or y & determine the gender (sex) of the child. Two x's = a girl, an x & a y = a boy. You can't get two y's.

Answer 6

chromosomes are, essentially, strands of DNA found inside eukaryotic cells. 50% of one's chromosomes are inherited from one's mother, while the other 50% are inherited from one's father.

Answer 7

they contain DNA

Answer 8

something in the blood