Skip to main content
Back

Anatomy Unit 6

Control buttons has been changed to "navigation" mode.
1/21

Terms in this set (21)

  • What is genetics?

    Genetics is the study of heredity and how traits and genetic information are passed from one generation to the next.

  • What is a gene?

    A gene is a unit of hereditary information located at a specific position on a chromosome that contains instructions for producing functional products like proteins.

  • Define allele.

    An allele is a particular version of a gene. Individuals usually have two alleles for each gene, one from each parent.

  • What is the difference between genotype and phenotype?

    Genotype is the genetic makeup (the alleles an individual has), while phenotype is the observable trait resulting from the genotype and environment.

  • What does homozygous mean?

    Homozygous means having two identical alleles for a gene, e.g., BB (homozygous dominant) or bb (homozygous recessive).

  • What does heterozygous mean?

    Heterozygous means having two different alleles for a gene, e.g., Bb.

  • Explain dominant and recessive alleles.

    A dominant allele is expressed in the phenotype if at least one copy is present. A recessive allele is expressed only when two copies are present.

  • What is Mendelian inheritance?

    Mendelian inheritance describes how alleles separate during gamete formation and combine at fertilization to determine offspring genotypes.

  • What is a Punnett square used for?

    A Punnett square is a diagram used to predict possible genotypes and phenotypes of offspring from parental genotypes.

  • What are the genotype probabilities for a Bb × Bb cross?

    Genotype probabilities are 25% BB, 50% Bb, and 25% bb.

  • What are the phenotype probabilities for a Bb × Bb cross under complete dominance?

    Phenotype probabilities are 75% dominant (BB or Bb) and 25% recessive (bb).

  • Why can siblings have different traits despite having the same parents?

    Because offspring receive different combinations of alleles from each parent, leading to genetic variation.

  • What is continuous variation?

    Continuous variation refers to traits influenced by multiple genes and environment, showing a range of phenotypes, e.g., height.

  • What are sex chromosomes in humans?

    Humans have 23 pairs of chromosomes; one pair are sex chromosomes: XX typically female, XY typically male.

  • What is X-linked inheritance?

    X-linked inheritance involves genes on the X chromosome, where males (XY) have only one copy, affecting expression of recessive traits.

  • How are X-linked recessive traits expressed in males and females?

    Males (XY) with a recessive allele on X are affected; females (XX) can be unaffected, carriers, or affected depending on their two X alleles.

  • How do you set up an X-linked Punnett square?

    Include sex chromosomes in gametes (X or Y) and track alleles on the X chromosome separately from autosomal alleles.

  • What is a key point about affected XY fathers in X-linked recessive inheritance?

    An affected XY father passes his Y chromosome to sons and his X chromosome to daughters, so sons do not inherit his X-linked allele.

  • Difference between autosomal and X-linked inheritance?

    Autosomal genes are on non-sex chromosomes; X-linked genes are on the X chromosome and require tracking sex chromosomes in inheritance.

  • What are common mistakes to avoid in genetics problems?

    Confusing genotype with phenotype, homozygous with heterozygous, assuming dominant means more common, and forgetting to include sex chromosomes in X-linked traits.

  • Summarize key genetics terms: gene, allele, genotype, phenotype.

    Gene: hereditary instruction; Allele: version of a gene; Genotype: genetic combination; Phenotype: observable trait.