unit 2 term rev

• What is the term for the number of chromosomes if only one partner from each pair is present?

  Haploid
• How many chromosomes are present in a haploid cell in humans?

  22 autosomes + 1 sex chromosome
• What is the term for the number of chromosomes if two partners from each pair are present?

  Diploid
• How many chromosomes are present in a diploid cell in humans?

  44 autosomes + 2 sex chromosomes
• What type of cells are somatic cells?

  Body cells produced by mitosis
• What is the chromosome number in somatic cells?

  Diploid number of chromosomes
• What are gametes?

  Reproductive cells produced by meiosis
• What is the chromosome number in gametes?

  Haploid number of chromosomes
• What is mitosis?

  The nuclear division that produces two identical diploid cells
• What is meiosis?

  The nuclear division that produces four different haploid cells
• What is the purpose of mitosis?

  For growth, repair, and development
• What is the purpose of meiosis?

  To make gametes for sexual reproduction
• When does crossing over occur?

  During meiosis (Prophase 1)
• What is crossing over?

  Exchange of genetic material between homologous chromosomes
• What does independent assortment refer to?

  The arrangement of one pair of chromosomes not influencing others
• When does independent assortment occur?

  During meiosis (Metaphase 1)
• What does it mean for genes to be linked?

  They are found on the same chromosome
• How does linkage affect inheritance?

  Inheritance of one gene influences the inheritance of another
• What is a gene?

  A sequence of nucleotides that codes for a specific polypeptide
• What is an allele?

  Different versions of a gene
• What are autosomes?

  Homologous pairs of chromosomes found in both males and females
• What are sex chromosomes?

  Chromosomes responsible for determining an individual's sex
• What are homologous chromosomes?

  Chromosomes that contain the same gene loci
• What is a genotype?

  Combination of alleles for a given gene
• What is a phenotype?

  Visible expression of a genotype
• What does heterozygous mean?

  Genotype containing two different alleles
• What does homozygous mean?

  Genotype containing two identical alleles
• What is a dominant trait?

  Requires one copy of an allele for expression
• What is a recessive trait?

  Requires two copies of an allele for expression
• What is complete dominance?

  Where one dominant trait is expressed in a heterozygous individual
• What is co-dominance?

  Where both alleles are expressed in a heterozygous individual
• What are continuous phenotypes?

  Phenotypes that display measurable variation in a population
• What are discontinuous phenotypes?

  Phenotypes that belong in discrete categories
• What are polygenic traits?

  Traits caused by the action of two or more genes
• What are monogenic traits?

  Traits caused by the action of one gene
• What is a test cross?

  A breeding experiment with a known homozygous recessive individual
• What is the purpose of a test cross?

  To determine the unknown genotype of an individual with a dominant trait