The passing of traits from parents to their offspring was probably one of the first scientific observations about the natural world, and may have been used to initiate domestication of livestock by encouraging particular traits to be more prevalent, and others to be less so. However, the mechanism by which this transmission occurs was not known until relatively recently, largely because the technology to observe and prove it didn't exist.
As with many other pseudo-scientific theories in human history, heredity was at times hypothesized to be due to a "life force" that was transmitted from parent to child, or some variation on this that suggested they were made from literally similar materials. This explained not only the obvious phylogenetic similarities, but afforded for some of the natural variations that were present as well. However, not being scientifically grounded, there was no understanding of the underlying genetic causes and relationships that produced the phenotypic effects.
Traits are passed from parent to offspring because the traits are the product of specific genes. Each parent has two copies of almost every gene, and those genes are each located on the two copies of every chromosome. During reproduction, these chromosomes are shuffled and then distributed into gametes (sperm and eggs) with a random combination of genes selected from the parent's available options.
So, out of the two copies of every gene, the child is ensured of receiving one. This may or may not be the same gene responsible for the dominant, visible trait in the parent, which accounts for how children can look more similar to one parent than the other, but usually resemble some combination of both, and only rarely do they resemble neither parent.
Further Reading
How are characteristics traits passed from parents to offspring?
Characteristics or traits are passed from parents to offspring at the genetic level. Sex cells which include sperm and oocytes each contain 23 chromosomes. Each chromosome within the sperm has a corresponding homologous chromosome within the oocyte. When the sperm and oocyte unite during fertilization, the result is an egg containing 46 chromosomes. In other words, the egg contains 23 homologous chromosomes. Each chromosome contains double stranded DNA (deoxyribonucleic acid). Within each strand of DNA, one finds specific genes which code for characteristics or traits associated from each parent. For instance, consider homologous chromosome 5 out of 23 homologous chromosomes. The fertilized egg will contain one chromosome 5 from the sperm and the other homologous chromosome 5 from the oocyte. This chromosome will contain a collection of genes which code for specific traits from each parent. Through a complex genetic process, some of these genes are turned on whereas some of these genes are turned off. Depending upon which ones are on and which ones are off, one observes specific characteristics or traits from each parent.
As an aside, the characteristics or traits that are being referred to above are those which can be biologically linked to observable ones (e.g., eye color, height, Sickle Cell Anemia, etc.). There are some characteristics or traits which are not directly observable...
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that may be the result of learning or experience rather than genetics (e.g., temperament, likes and dislikes, personality, etc.).
Can you explain briefly how traits are passed from parents to their offspring?
DNA is the chemical of heredity and is found in the chromosomes of our cells. The instructions of the DNA are used to synthesize various proteins needed by the body to function optimally. Distinct segments of DNA are known as genes. Genes are inherited by offspring from their parents. In sexually reproducing organisms, fifty percent of the genes come from the mother and fifty percent from the father. Meiotic cell division produces haploid gametes or sex cells, with half the chromosomes the organism will need. At fertilization, the two haploid sex cells form a diploid zygote(fertilized egg). It is at that moment, that all of the organism's genes are established that they will have in their body. From that fertilized egg, mitotic divisions take place until a mature offspring is formed. All the cells of the body have the chromosome complement that was present in that first fertilized egg cell. In asexually reproducing organisms, whatever chromosomes the parent cell has are passed down to the offspring due to mitosis.
Can you explain briefly how traits are passed from parents to their offspring?
Most traits of any organism are genetic, that is they are present in the DNA codes that make up the organism's genes. Genes are passed down from parent to offspring in all living things. A bacterium that has a gene that protects it from pencillin will inevitably leave that gene to the two daughter bacteria when it undergoes mitosis passing that trait (pencillin resistance) to its offspring. The same happens in sexually reproducing animals. You've probably heard relatives say over a baby, "she has her mother's eyes." They usually mean that the baby has the same eye color as her mother. The mother has brown eyes, and carries the genetic code for brown eyes. Her egg (which became the baby) received the code for brown eyes during meiosis and didn't have a "blue eyes" counter from dad's sperm, so the trait of brown eyes was passed down to the baby.
How are traits passed from parent to their offspring?
DNA is the molecule that makes up our chromosomes, which in turn contain thousands of genes. Genes direct the production of proteins according to the genetic code and these proteins are needed for life processes to occur, building the body's structure, are components of cell membranes, muscles, hormones and enzymes.
Organisms inherit traits via the process of fertilization. At that moment, a haploid sperm nucleus and an egg nucleus also haploid, fuse together creating a diploid fertilized egg or zygote. It is from this cell that the genetic blueprint for all the cells to follow within the organism has been determined.
Our genes are found in pairs because each parent has supplied a set to the offspring. Specific laws based on the work of Gregor Mendel can be applied to the gene pairs to determine the traits seen in the phenotype of an offspring. Different versions of a gene are called alleles. If for example, an offspring inherits a dominant allele and a recessive allele, although both are present in the organism, the dominant one will be expressed in the phenotype.
Sometimes, incomplete dominance is seen in a specific trait where two different genes blend together. For example, in Japanese four o clock flowers, if a plant inherits a red allele and a white, they blend to form a pink offspring.
Sometimes, traits can be co --dominant where they are both fully expressed in the offspring. Hence, a person with the gene for type A and the gene for type B blood will have type AB where the blood cells contain both the A and B antigens.
Traits may be linked to the X chromosome. Males have one X and are hemizygous for genes on that chromosome. Females have two X chromosomes. Many times, males inherit X linked traits from their mothers who are carriers.
By using the information and rules discovered by Mendel and others in the field of genetics, we can apply that information to make predictions of what type of offspring a pair will produce, provided that their genetic makeup is known.