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Genetic Inheritance in Anatomy & Physiology

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Terms in this set (20)

  • What is a gene?

    A gene is a factor that controls a heritable characteristic, located on a chromosome, storing information in a DNA segment that encodes for protein synthesis.

  • Define allele.

    An allele is an alternate form of a gene coding for the same trait, with one allele on each homologous chromosome.

  • What is genotype vs phenotype?

    Genotype is the genetic composition (e.g., Bb), while phenotype is the physical expression of a gene (e.g., brown eyes).

  • Difference between dominant and recessive alleles?

    Dominant alleles are expressed alone or in pairs (capital letter), while recessive alleles are expressed only without a dominant allele (lowercase letter).

  • What does homozygous mean?

    Homozygous means having two identical alleles: either dominant (BB) or recessive (bb).

  • What does heterozygous mean?

    Heterozygous means having two different alleles (Bb).

  • What is a mutation?

    A mutation is a permanent change in the nucleotide sequence of a gene, often altering the amino acid sequence of the protein.

  • What causes Phenylketonuria (PKU)?

    PKU is caused by a mutation in the gene for phenylalanine hydroxylase, leading to a non-functional enzyme and inability to break down phenylalanine.

  • Explain dominant-recessive inheritance.

    In dominant-recessive inheritance, the phenotype reflects the dominant allele if present, masking the recessive allele.

  • What is a Punnett square used for?

    A Punnett square predicts possible genotypes and phenotypes of offspring from parental allele combinations.

  • What is incomplete dominance?

    Incomplete dominance occurs when neither allele is dominant, and heterozygotes show a blended phenotype.

  • Describe sickle cell disease inheritance.

    Sickle cell disease results from a mutation in hemoglobin gene; heterozygotes have sickle cell trait, homozygous recessive have anemia.

  • Why does the sickle cell allele persist in populations?

    The sickle cell allele persists because it confers resistance to malaria in heterozygous carriers.

  • What is multiple-allele inheritance?

    Multiple-allele inheritance involves genes with more than two alleles, such as ABO blood types with IA, IB, and i alleles.

  • Explain ABO blood group inheritance.

    Blood types A and B are co-dominant; O is recessive. Genotypes determine blood type phenotype (e.g., IAIB = AB blood).

  • What is polygenic inheritance?

    Polygenic inheritance involves traits controlled by multiple genes, producing a range of phenotypes often in a bell curve distribution.

  • What is complex inheritance?

    Complex inheritance involves multiple genes and environmental factors influencing traits like skin color and height.

  • What is a karyotype?

    A karyotype is the complete set of chromosomes arranged by size, shape, and centromere position.

  • How is chromosomal sex determined?

    Sex is determined by 23 pairs of chromosomes; 22 autosomes and 1 pair of sex chromosomes (XX female, XY male).

  • What is sex-linked inheritance?

    Sex-linked inheritance involves genes on the X chromosome, such as red-green color blindness, affecting mostly males.