Question

You are given a metaphase chromosome preparation (a slide) from an unknown organism that contains 12 chromosomes. Two that are clearly smaller than the rest appear identical in length and centromere placement. Describe all that you can about these chromosomes.

Short answer

Answer: The two smaller homologous chromosomes are identical in length and centromere placement, suggesting that they are inherited from each parent. Some characteristics of these chromosomes include their smaller length, same centromere position, and being part of an organism with a diploid chromosome number of 12 (2n = 12). Although we cannot confirm their specific function, they may carry genes responsible for certain traits or be involved in cellular processes. Homologous chromosomes are important in inheritance, as they carry genetic information from the parents and contribute to genetic diversity in the offspring through crossing over during meiosis.

Step-by-step solution

Identifying the homologous chromosomes

The two smaller chromosomes with identical length and centromere placement are called homologous chromosomes. Homologous chromosomes are similar in length, gene location, and centromere position. They are inherited from the parent organisms, one from each parent.

Identifying the main characteristics of the chromosomes

Some of the main characteristics to describe about these homologous chromosomes are: 1. Length: They are smaller than the rest of the chromosomes in the organism. 2. Centromere placement: The position of the centromere seems to be in the same location for both of these chromosomes. 3. Number: Since there are 12 chromosomes in total, we can say that the organism has a diploid chromosome number of 12 (2n = 12).

Predicting the possible function of these chromosomes

Based on their appearance, we cannot definitively identify the function of these chromosomes, but we can speculate about their possible functions. For example, they might carry genes responsible for certain traits in the organism, or they might be involved in the regulation of other important cellular processes.

Explaining the importance of homologous chromosomes in inheritance

Homologous chromosomes are significant in the inheritance process because they carry the genetic information passed down from the parents to the offspring. During meiosis, homologous chromosomes pair up and exchange genetic material through the process of crossing over, which contributes to genetic diversity in the offspring.