Saturday, May 5, 2012

About chromosomes?

1. where do you find them in body?



2. how do the chromosomes in human sperm cells differ from those ova?



3. in humans most cells contain 23 pairs of chromosomes. in which parts of the body would you find cells with 23 single chromosomes?



4. cosmo said to his friend." i inherited my red hair from my grandmother". what does he mean by this?



Thanks for helping :]



About chromosomes?

1) in the nucleus of each cell in the body



2) human sperm cells have 22 + X or 22 + Y



whereas human ova cells have only 22 + X



3) we can't say which part of the body because only the human sperm(in the testes) and ova(in the ovary) cells have 23 single chromosomes



testes and ovary are organs, which contains 23 pairs of chromosomes



4) both parents may not have red hair but can still carry the gene for red hair.



the gene for red hair is not expressed in both the parents because it's a recessive gene, which only can be expressed when both recessive are together



you'll learn more about dominant and recessive genes when you study genetics and heredity



About chromosomes?

1)in your cells



2)sperms cells contain the y chromosone and 1 x chromosone. The ova cells contain 2 x chromosones



3)i think.........um......hmmm..........i think idon't know...............i think its nowhere i'll ask my bio teacher i got an exam 4 bio today :(



4) his grama gave his father a recessive trait and his mother also had the rececive trait. So both parents could have the dominate gene for blonde fair and the rececive for red........which they got from grama.....who is red headed so cosmo and his grama are redheads(like me!)



About chromosomes?

1) they are found in every cell with a nucleus.



2) there are no substantial differences



3) in gametes ( egg and sperm) there are, due to meiosis, unpaired chromosomes



4) Cosmo likely inferred by phenotype ( trait seen) that his grandmother's genotype ( genetic material) included genes for red hair. He then deduced that the lineage for his hair color passed through his grandmother.



About chromosomes?

1. They are found in the nucleus of cells.



2. Sperm cells have X and Y gamates whilst ova cells have 2 X gamates.



3. The sperm cells and the ova



4.His granmother has red hair and has passed on the recessive trait to one of his parents who also passed it to him



About chromosomes?

1. Chromosomes are darkly stained thread like bodies present in the nucleus of all cells and is easily observed during the metaphase stage of a cell division.



2. The allosomes ( sex chromosomes) in humans are of two types X and Y chromosomes. The X chromosome is found to look bigger than the Y chromosome. The female cells have two XX chrosomes, hence their sex cells, the gametes ova has X chromosomes each. But in the case of males, the diploid body cells have XY chromosmes. And that is why the half of the sperm cells produced in them have X chromosome and the other half has Y chromosome. And that is why the male and female gametes differ in their chromosomes, especially the allosomes.



3 The 23 single chromosomes are found in the haploid sex cells, gametes , ova and sperm, due to the reductional division, meiosis.



4. Cosmo means that the genes expressing the red hair color phenotype in him was transfered from his grandmother to him through his parents. This well known phenomena is termed as inheritance.



About chromosomes?

In most higher plants and animals, including humans, chromosomes from the body cells can be matched up in pairs. The two chromosomes of a pair are called homologous chromosomes. The members of most homologous pairs of chromosomes look alike. They are the same length, their centromeres are in the same position, they show the same pattern of light and dark bands when stained, and they carry genes for the same inherited characteristics, line up on the chromosome in the same order.



The occurrence of pairs of chromosomes in our karyotype is a result of our sexual origins. We inherit one member of each chromosome pair from each parent. So the 46 chromosomes in our somatic cells are actually two sets of 23 chromosomes鈥攁 maternal set (from our mother) and a paternal set (from our father.) A cell with two of each kind of chromosome is called a diploid cell and is said to contain a diploid, or 2n, number of chromosomes.



In humans, the homologous pairs are defined and numbered and carry the genes for the same trait in each person. For example, human chromosome #1 contains, along with many others, the genes for the Rh blood protein and for a starch-digesting enzyme in the saliva. However, the corresponding genes on the two homologous chromosomes are not necessarily identical. For instance, some chromosomes have a gene for the protein that makes a person Rh-positive, and some have a gene coding for a different version of this protein (Rh-negative) at the Rh location. Different versions of the same gene are referred to as alleles. An individual with two genes the same for a trait is said to be homozygous for that trait. A person with two different alleles for the same trait is heterozygous for that trait.



In human males, the partners of 22 of the pairs of chromosomes look similar, but the twenty-third pair is mismatched with two unlike chromosomes, called X and Y (see the far right chromosome pair in the bottom row of the male karyotype above.) In the cells of a female, both members of homologous pair #23 are X chromosomes (far right pair of chromosomes in the bottom row in the female karyotype.) The X and Y chromosomes are called the sex chromosomes, because they differ between the sexes and because they carry the genes that determine the sex of the individual. The other 22 chromosomes are called autosomal chromosmes or simply autosomes.



It is the Y chromosome that is of major interest to the genealogist because, as it is handed from father to son, virtually unchanged, it becomes a signature or fingerprint for the surname which is passed down in the same way in many cultures

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