Each gamete contains a single copy of every chromosome, and each chromosome contains one allele for every gene. Therefore, each allele for a given gene is packaged into a separate gamete. For example, a fly with the genotype Bb will produce two types of gametes: B and b.
What chromosomes carry genes for the same traits?
The two chromosomes in a homologous pair are very similar to one another and have the same size and shape. Most importantly, they carry the same type of genetic information: that is, they have the same genes in the same locations.
Do chromosomes have the same alleles?
An allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome. Humans are called diploid organisms because they have two alleles at each genetic locus, with one allele inherited from each parent.
Do different chromosomes carry different genes?
Different chromosomes contain different genes. That is, each chromosome contains a specific chunk of the genome. For example, in humans the gene for alpha globin, a part of the hemoglobin protein that carries oxygen in red blood cells, is found on chromosome 16.
Do the alleles have to be the same for each trait?
When genes mutate, they can take on multiple forms, with each form differing slightly in the sequence of their base DNA. These gene variants still code for the same trait (i.e. hair color), but they differ in how the trait is expressed (i.e. brown vs blonde hair). Different versions of the same gene are called alleles.
What is the main difference between Chromatin and Chromosomes?
Chromatin is a complex formed by histones packaging the DNA double helix. Chromosomes are structures of proteins and nucleic acids found in the living cells and carry genetic material. Chromatin is composed of nucleosomes. Chromosomes are composed of condensed chromatin fibers.
Where do alleles come from?
One allele for every gene in an organism is inherited from each of that organism’s parents. In some cases, both parents provide the same allele of a given gene, and the offspring is referred to as homozygous (“homo” meaning “same”) for that allele.
How many genes are in a chromosome?
Chromosome 1 likely contains 2,000 to 2,100 genes that provide instructions for making proteins.
What if a person has 47 chromosomes?
A trisomy is a chromosomal condition characterised by an additional chromosome. A person with a trisomy has 47 chromosomes instead of 46. Down syndrome, Edward syndrome and Patau syndrome are the most common forms of trisomy.