4.1 Genes, Chromosomes, Mutations

In the 20th century, Morgan a geneticist, discovered that a group of genes that were all located on the X chromosome of a Drosophila (a fruit fly). Carefully crossing experiments lead to showing that genes were arranged in a linear sequence along the X chromosome. This same pattern has been found in other organisms and species, and they are found in a particular position on one chromosome type. Locus: the particular position on homologous chromosomes of a gene. Homologous: is when two chromosomes have the same sequence of genes. Homologous chromosomes are not usually identical to each other because of some genes on them, alleles will be different. Allele: one of a number of different types of gene. Genome: the whole of the genetic information of an organism.
The chromosomes of eukaryotes are large enough to be seen with a microscope, because the chromosomes are condensed (thick, dense), by the coiling process. Eukaryote chromosomes: DNA molecules associated with protein.  Histone protein: involved with coiling of the chromosomes, and also in control of the gene transcription. Diploid: two homologous chromosomes, a nucleus that has two sets of chromosomes, and so has two chromosomes of each type. The parent passes on only one copy of each gene onto the offspring, because a gamete only consists of one chromosome of each type. Diploid: gamete,  a nucleus that has one set of chromosomes, and so has one chromosome of each type.

Data- Based Questions (pg 155)
1) Any of the species do not have 13 chromosomes because it is an odd number, meaning it is undergoing meiosis.
2) The dog may not be more complex than the American black bear, but it only has more chromosomes.
3) The size of the genome of species cannot be determined from the number of chromosomes because the state of chromosomes may be altered, changing shape/size, condensing, and being separated.
4) Evolutions shows that chimpanzees are ancestors of humans, yet they have more chromosomes. The chromosomes of the chimpanzees may have altered, where two chromosomes became one.