Genetics is the study of heredity, which means the study of genes and factors related to all aspects of genes. The scientific history of genetics began with the works of Gregor Mendel in the mid-19th century.

Gregor Mendel

Modern genetics began with the work of the Augustinian friar Gregor Johann Mendel. His work on pea plants, published in 1866, established the theory of Mendelian inheritance. With the basic patterns of genetic inheritance established, many biologists turned to investigations of the physical nature of the gene.

​What is genetics? Genetics is the scientific study of genes and heredity—of how certain qualities or traits are passed from parents to offspring as a result of changes in DNA sequence. A gene is a segment of DNA that contains instructions for building one or more molecules that help the body work.

“Humans have 23 pairs of chromosomes, while all other great apes (chimpanzees, bonobos, gorillas and orangutans) have 24 pairs of chromosomes,” Belen Hurle, Ph.D., says via email.

​Chromosome Different organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes–22 pairs of numbered chromosomes, called autosomes, and one pair of sex chromosomes, X and Y.

The Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes.

For example, if a human egg and sperm each contained 46 chromosomes, then the resulting embryo would contain 92 chromosomes– a chromosome number not compatible with normal development or survival. The two sperm cells split again producing four sperm cells, each with 23 or n chromosomes.

Each sperm cell contains half the father’s DNA. But it’s not identical from sperm to sperm because each man is a mixture of the genetic material from his parents, and each time a slightly different assortment of that full DNA set gets divided to go into a sperm.

The resounding answer is yes. Because the baby’s DNA will only come from the egg donor and the sperm provider, many women using egg donation worry that they will not share any genetic information with their child.

The female egg cell is bigger than you think Compared to the other human cells, egg cells are huge. They are 100 microns in diameter (that’s a millionth of a metre) and are about as wide of a strand of hair. That may sound small, but no other cell comes close to being that large.

A mother’s egg contains a copy of her own DNA — 23 chromosomes — as well as DNA for her mitochondria. A fertilised egg usually contains two pronuclei — genetic material from the egg and sperm — as well as mitochondria.

DNA is the molecule that is the hereditary material in all living cells. Genes are made of DNA, and so is the genome itself. A gene consists of enough DNA to code for one protein, and a genome is simply the sum total of an organism’s DNA.

On 6 May 1952, at King´s College London in London, England, Rosalind Franklin photographed her fifty-first X-ray diffraction pattern of deoxyribosenucleic acid, or DNA.

An international research effort called the Human Genome Project, which worked to determine the sequence of the human genome and identify the genes that it contains, estimated that humans have between 20,000 and 25,000 genes.

The chemicals come in four types A, C, T and G. A gene is a section of DNA made up of a sequence of As, Cs, Ts and Gs. Your genes are so tiny you have around 20,000 of them inside every cell in your body! Human genes vary in size from a few hundred bases to over a million bases.

ApoE-e3 is the most common allele (a variant of the gene) and is found in more than 50% of the general population….According Kerpedjiev, the top-10 most-studied genes are:

• EGFR;
• VEGFA;
• APOE;
• IL6;
• TGFBI;
• MTHFR;
• ESR1; and,
• AKT1.

There are 22 homologous pairs and two sex chromosomes (the X and Y chromosomes). One chromosome in each pair is inherited from one’s mother and one from one’s father. Each chromosome is a single molecule of DNA.

Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. Each nucleosome is composed of DNA wrapped around eight proteins called histones. …

A. Deoxyribonucleic acid extracted from cells has been variously described as looking like strands of mucus; limp, thin, white noodles; or a network of delicate, limp fibers. Under a microscope, the familiar double-helix molecule of DNA can be seen.

Figure 2: The four nitrogenous bases that compose DNA nucleotides are shown in bright colors: adenine (A, green), thymine (T, red), cytosine (C, orange), and guanine (G, blue).