Question

Crossing-Over in Meiosis Meiosis is a process of nuclear division that reduces the number of chromosomes in new cells to half the number in the original cell. The parent cell is diploid (2n), and it begins meiosis with a replicated set of chromosomes. During meiosis, this parent cell Homologou will divide twice to create four haploid (1n) cells. pairs During prophase I of meiosis I, homologous pairs of chromosomes pair up and stick together to form tetrads through the process called synapsis. During synapsis, the Prophase I chromatids within a homologous pair twist around one another. Portions of chromatids may break off and attach to adjacent chromatids on the homologous chromosome - a process called crossing-over. This process permits the exchange of genetic material between the parent cell's maternal and paternal chromosomes. Thus, crossing-over results in genetic recombination by producing a new mixture of genetic material. CD-MODDODD This picture above shows the results of meiosis when there are no crossing over events. Notice that all four daughter cells at the end of meiosis have chromosomes that match the parent cells chromosomes. C0--DODO This second picture shows the results of meiosis when crossing over has occurred. Notice that the daughter on the far left and far right are just like the parent cell's chromosomes, but the two in the middle contain chromosomes that are part checkered and part blank. 1. Label each of the features in the image below. . XX-M-M-XX

Answer 1

As per the honor code, we are obliged to answer only one question at a time. Therefore, we are answering question number 1 listed here.

1.

Meiosis is a type of cell division that includes two cycles of division, the formation of four daughter cells and the reduction of the ploidy level. A cell undergoes S-phase, during which the DNA is replicated, and two copies are formed of every DNA molecule. A DNA condenses to form chromosome molecules. Out of the replicated copies of a chromosome, one is known as chromatid and both (have the identical set of gene segments) are termed as sister chromatids. Chromosomes that have corresponding loci of a gene and are quite similar in structure and arrangement of genes are known as the homologous chromosomes. A diploid organism has a pair of homologous chromosomes.

During meiosis, another event of an exchange of gene segments between two non-sister chromatids (chromatids of two homologous chromosomes lying next to each other) occurs, known as crossing over. The point at which segments of two non-sister chromatids are connected for crossing over is known as chiasma.

A. Chromatids - SE C B. Sister chromatids D. Chiasma . Homologous chromosome