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  1. ... 000 genes. Every person has two copies of each gene, one inherited from each parent. Most genes are the same in all ... of DNA bases. These small differences contribute to each person’s unique physical features. Scientists keep track ...
  2. In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled ...
  3. Each person’s fingerprints are unique, which is why they have long been used as a way ... the details of the patterns are specific to each individual. Dermatoglyphs develop before birth and remain the ...
  4. ... humans have the same number of chromosomes in each generation. It is a two-step process that ... the sperm and egg cells unite at conception, each contributes 23 chromosomes so the resulting embryo will ...
  5. In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called ...
  6. Each cell expresses, or turns on, only a fraction of its genes at any given time. The ...
  7. ... dominant One altered copy of the gene in each cell is sufficient for a person to be ... occur in both copies of the gene in each cell. The parents of an individual with an ...
  8. ... percent chance of passing the altered gene to each child. The chance that a child will not ... children. Autosomal recessive inheritance: Two unaffected people who each carry one copy of the altered gene for ...
  9. ... words and sentences. DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule ...
  10. ... proteins in cells. This regulation helps ensure that each cell produces only proteins that are necessary for ... attachment of small chemical groups called methyl groups (each consisting of one carbon atom and three hydrogen ...
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