DNA structure & replication

• What are genes?


  Segments of DNA that contain instructions for making specific proteins
• What is a genetic disorder?


  A health condition caused by changes in one or more genes or chromosomal alterations
• What is an allele?


  Alternative forms of a gene that occupy the same position on a chromosome
• How do alleles affect traits in humans?

  Different alleles can result in different traits, such as eye color
• What is an example of alleles in humans?

  The gene for eye color has alleles for blue, brown, and green
• How many alleles does an individual inherit for each gene?


  Two alleles, one from each parent
• What is the definition of dominant alleles?


  Alleles that are expressed in the phenotype when present
• What is the definition of recessive alleles?


  Alleles that are expressed in the phenotype only when two copies are inherited
• If an individual has one brown allele and one blue allele, what color eyes will they have?

  Brown eyes, because the brown allele is dominant
• What is a homozygous genotype?

  A genotype with two identical alleles
• What is a heterozygous genotype?

  A genotype with two different alleles
• How do homozygous genotypes express traits?


  They always express the same phenotype
• How do heterozygous genotypes express traits?


  They can express either the dominant or recessive trait
• What is the definition of phenotype?


  The observable characteristic or trait of an organism
• In a plant species with codominance, what would the phenotype be for a plant with genotype Rr if R is red and r is white?


  Red and white patches
• In a plant species with incomplete dominance, what color would a plant with genotype Rr have if R is red and r is white?


  Pink petals, as a blend of red and white
• What does DNA stand for?


  Deoxyribonucleic Acid
• How is DNA often described in relation to life?


  As a blueprint for life
• What are the repeating units that make up DNA called?

  Nucleotides
• What shape does the DNA molecule form?


  A twisted ladder or spiral
• How many hydrogen bonds are between A-T pairs?


  Two hydrogen bonds
• How many hydrogen bonds are between G-C pairs?


  Three hydrogen bonds
• If one strand of DNA has the sequence ATCG, what would be the complementary sequence on the other strand?


  TAGC
• If one strand of DNA has the sequence GCAT, what would be the complementary sequence on the other strand?


  CGTA
• What is the term for the process by which DNA makes a copy of itself?


  DNA replication
• In rapidly dividing cancer cells, which process is likely to be occurring at a higher rate?


  DNA replication