You can see that the parents have two different alleles on the same chromosome, and when the gametes fuse, the offspring will receive one of the two alleles from each parent.So the offspring will have two different alleles on the same chromosome, which makes them genetically different from both of their parents.This is why siblings can look different from each other and why children can look similar but also very different from their parents.So that’s it for this video.We talked about sexual reproduction, how it produces genetic variation, and how it’s responsible for the diversity of traits that we see in biological families and in populations all around the world.
Have you ever wondered why children often look a little similar but also very different from their biological parents, or even how biological siblings tend to share some common features but still have different traits from each other? To answer this question, we have to go beyond the physical traits that we see in family portraits and dive into genetic inheritance.
In this video, we’re going to see that it’s sexual reproduction, a mechanism used by many organisms to produce offspring, that creates the diversity of traits that exist in biological families and in animal and plant populations all around the world.
Let’s start from the beginning. All life comes from other life through the process of reproduction. Parents reproduce to form offspring, and during this process, they pass on their genetic information to their offspring. During sexual reproduction, two parents produce offspring. So each offspring gets a mixture of genetic information from two parents.
Parents pass this genetic information to their offspring via chromosomes, the coiled up DNA molecules found inside cells that contain genes. Sexually reproducing organisms often have many different chromosomes, each containing specific genes. For example, humans have 23 different chromosomes assigned numbers one through 23. However, there are two copies of each chromosome, so that there are 23 chromosome pairs instead of 23 single chromosomes. Each chromosome pair is a homologous pair, which means that the two chromosomes are the same size and contain the same genes in the same order.
However, the alleles on the two homologous chromosomes may be different, meaning that the chromosomes may not exactly have the same genetic information. During fertilization, cells called gametes, which are egg and sperm cells, fuse to form a new organism. Each parent contributes one gamete.
So you might be wondering, if each of the parents’ organism cells are diploid, and offspring result from the fusion of cells from two parents, how do the offspring of sexual reproduction maintain the same number of chromosomes? Well, diploid organisms form gametes that are haploid, meaning that they only contain one set of chromosomes. When gametes fuse during fertilization, that brings the total number of chromosomes back to 46, or 23 homologous pairs.
So why is sexual reproduction so important? Well, not only does it allow organisms to produce offspring, but it also creates genetic variation and diversity. The reason that offspring have different traits compared to their parents, and that one sibling looks different from another, can be attributed to sexual reproduction.
This diagram helps illustrate how sexual reproduction creates genetic variation. The diagram shows a cross between two hypothetical parents. It shows the chromosomes and the possible gametes that the parents can form, and the possible chromosome combinations in the offspring. You can see that the parents have two different alleles on the same chromosome, and when the gametes fuse, the offspring will receive one of the two alleles from each parent. So the offspring will have two different alleles on the same chromosome, which makes them genetically different from both of their parents. This is why siblings can look different from each other and why children can look similar but also very different from their parents.
So that’s it for this video. We talked about sexual reproduction, how it produces genetic variation, and how it’s responsible for the diversity of traits that we see in biological families and in populations all around the world. During sexual reproduction, gametes from each parent fuse together to create a diploid offspring with homologous chromosome pairs. This diagram shows that each parent passes on only one chromosome from each homologous pair, resulting in multiple combinations of chromosomes that can occur in the offspring. This is why siblings can look alike, but aren’t identical. Furthermore, there are other genetic processes that occur during fertilization that increase variation even more, resulting in trillions of possible allele combinations for each offspring. This is why no two people, except monozygotic twins, are genetically alike. In conclusion, the patterns of chromosome inheritance during sexual reproduction lead to genetic variation in families and populations, making each and every one of us one of a kind.