genetics

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  • Genetic variation: Individuals of a species have similar characteristics but they are rarely identical, the difference between them is called variation. Genetic variation is a result of subtle differences in our DNA.
  • 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. Deoxyribonucleic acid is shaped like a tightly coiled ladder, called a double helix. The two ladder rails are called backbones, and the rungs are pairs of four building blocks (adenine, thymine, guanine, and cytosine) called bases. The sequences of these bases provide the instructions for building molecules, most of which are proteins. It has a pentose sugar bonds and phosphate backbone
  • In humans, there are 46 chromosomes arranged in 23 pairs. One member of each pair comes from your mother; the other comes from your father. Chromosomes contain thousands of genes and are located in the nucleus. Chromosomes hold DNA. 22 pairs are for somatic cells, and 1 pair is for sex cells. 2 sister chromatids make a chromosome and their arms are called telomeres (p = long, q = short). Their bumpy texture holds DNA. Females have XX chromosomes and men have XY chromosomes.
  • DNA replication occurs during cell division. Before cells divide, they make exact copies of all of their chromosomes so that each daughter cell receives a complete set of chromosomes. Each strand of the original DNA molecule serves as a template for making a complementary copy of itself. As a result, each new DNA molecule consists of one old strand and one newly synthesized strand.