Problem 11 - Biology of Humans: Concepts, Applications, and Issues

Question

_____________ is the pairing of chromosomes during meiosis.

Step-by-Step Solution

Answer

Synapsis

Step 1: Understand the Question

The question is asking for the term that describes the pairing of chromosomes during meiosis. This process is key to sexual reproduction.

Step 2: Recall the Meiosis Process

Meiosis involves two rounds of cell division: meiosis I and meiosis II. The pairing of chromosomes occurs during meiosis I.

Step 3: Identify the Pairing Stage

During meiosis I, specifically in prophase I, homologous chromosomes pair up. This pairing is known as synapsis.

Step 4: Provide the Specific Term

The term for the pairing of homologous chromosomes during meiosis is 'synapsis'.

Key Concepts

meiosis

Meiosis is a special type of cell division that reduces the number of chromosomes by half. This process is essential for sexual reproduction in eukaryotic organisms. Meiosis consists of two main stages: meiosis I and meiosis II.
During meiosis I, homologous chromosomes are separated, resulting in two haploid cells. Meiosis II is similar to mitosis, where the sister chromatids are separated, ultimately forming four distinct haploid cells.
Important aspects to remember about meiosis include:

• It results in genetic variation due to crossing over and random assortment of chromosomes.
• It ensures that offspring have the same number of chromosomes as their parents.

Overall, meiosis is a crucial biological process that allows for diversity and proper chromosome distribution in sexually reproducing organisms.

homologous chromosomes

Homologous chromosomes are pairs of chromosomes in a diploid organism that are similar in shape, size, and genetic content. One chromosome of each pair is inherited from the mother, and the other from the father.
These chromosomes carry genes for the same traits, although they may have different alleles for those traits.

• For example, chromosome 1 from the mother and chromosome 1 from the father form a homologous pair.

During meiosis I, specifically in prophase I, homologous chromosomes pair up in a process known as synapsis. This pairing is crucial because it allows crossing over to occur, where segments of genetic material are exchanged between chromatids, leading to genetic diversity in the offspring.

prophase I

Prophase I of meiosis is one of the most critical stages of the entire process. During this phase, several key events occur:

• Chromosomes condense and become visible under a microscope.
• Homologous chromosomes pair up in a process known as synapsis.
• The paired homologous chromosomes form structures called tetrads, which consist of four chromatids.
• Genetic recombination or crossing over takes place, where segments of DNA are swapped between chromatids of homologous chromosomes.

This exchange of genetic material increases genetic variation among offspring, which is essential for evolution and adaptation.
As prophase I progresses, the nuclear envelope breaks down, and spindle fibers begin to form, setting the stage for the metaphase.