We are all aware that children resemble their parents more than unrelated persons. Inheritance, often known as heredity, is the transmission of qualities from one generation to the next (from the Latin word, heir). Sons and daughters, on the other hand, are not exact replicas of their parents or siblings.

There is variety in addition to inherited similarities. The scientific study of heredity and inherited variation is known as genetics. This course will teach you about genetics at many levels, from animals to cells to molecules.

The processes of meiosis (a kind of cell division) and fertilization (the union of sperm and egg, as shown in the tiny photo) keep a species' chromosomes in place.

• The term genes refer to parents that endow their offspring with coded information in the form of hereditary units. The genes we inherit from our mothers and fathers are our genetic link to our parents, and they account for family resemblances such as shared eye color or freckles. Our genes program-specific traits that emerge as we develop from fertilized eggs into adults

The genetic code is written in DNA, a polymer made up of four distinct nucleotides. Inherited information is handed down in the form of each gene's unique sequence of DNA nucleotides, much how printed information is transmitted through meaningful letter sequences. The language is symbolic in both situations.

Cells convert DNA into freckles and other characteristics in the same way that your brain translates the word apple into a mental image of the fruit. Most genes instruct cells to create certain enzymes and other proteins, the cumulative effect of which results in an organism's hereditary characteristics.

One of biology's unifying themes is the encoding of these characteristics in the form of DNA.

The replication of DNA, which generates copies of genes that may be handed down from parents to children, is the molecular foundation for the transfer of genetic characteristics.

Gametes, which are reproductive cells in animals and plants, are the vehicles that carry genes from one generation to the next. Male and female gametes (sperm and eggs) combine during fertilization, passing on genes from both parents to their offspring.

The ability of sexual reproduction to create genetic variety is the most frequently offered reason for this process's evolutionary survival.

Consider the particular instance of the bdelloid rotifer (as shown in the image attached).

A bdelloid rotifer, an animal that reproduces only asexually.

It appears that this group did not reproduce sexually for more than 50 million years of its evolutionary history, a theory backed by the current genetic sequence study of its genome. Is this to say that genetic variation isn't beneficial in this species? Bdelloid rotifers, it turns out, are an exception to the norm that sex alone creates genetic diversity: Other than sexual reproduction, bdelloids have ways for creating genetic diversity.

Karyotypes are created by isolating somatic cells. They are then developed after being injected with a medication to induce mitosis for a few days in culture Cells are halted when the chromosomes are disrupted. are stained when they are most condensed—during metaphase—and then seen via a microscope using a digital camera.

On a computer monitor, a picture of the chromosomes is presented and computerized software is used to group them into pairs based on their physical looks.

This karyotype depicts a human's chromosomes man (as indicated by the existence of an XY chromosomal pair), colored to draw attention to their chromosomal banding patterns

The size of the chromosome, the position of the centromere, and the pattern of stained bands all contribute to the identification of individual chromosomes.

Each metaphase chromosome is made up of two closely connected sister chromatids, which are difficult to see in the karyotype (see the figure of the first pair of homologous duplicated chromosomes).

Every sexually reproducing species has a unique diploid and haploid number. The fruit fly Drosophila melanogaster, for example, has a diploid number (2n) of 8 and a haploid number (n) of 4, whereas dogs have 2n of 78 and n of 39.

The number of chromosomes does not typically correspond with the size or complexity of a species' genome; it merely represents how many linear bits of DNA make up the genome, which is a result of the species' evolutionary history (as shown in the image attached above).

Following chromosomal duplication and condensation, a cell from an organism with a diploid number of 6 (2n = 6) is illustrated below. Each of the six duplicated chromosomes is made up of two sister chromatids that are tightly linked along their lengths. Each homologous pair is made up of one chromosome from the maternal set (red) and one from the paternal set (yellow) (blue).

In this example, each set consists of three chromosomes (long, medium, and short). Nonsister chromatids are one maternal and one paternal chromatid in a pair of homologous chromosomes.

The term fertilization refers to the union of gametes, culminating infusion of their nuclei. The resulting fertilized egg, or zygote, is diploid because it contains two haploid sets of chromosome-bearing genes representing the maternal and paternal family lines.