Section 1
Gametes Split Chromosomes in Half
Gametes are reproductive cells containing half the normal number of chromosomes. Human eggs and sperm each have 23 chromosomes, combining during fertilization to create a cell with 46 chromosomes.
In this Grade 7 Life Science lesson from Chapter 4: Patterns of Heredity, students learn how meiosis produces haploid (1n) gametes — egg and sperm cells — that each contain half the normal number of chromosomes found in diploid (2n) body cells. Students explore how meiosis differs from mitosis by involving two sequential divisions (meiosis I and meiosis II) that result in four haploid cells, and how fertilization combines two 1n gametes to restore the full 2n chromosome count in offspring. The lesson also introduces key vocabulary including gamete, diploid, haploid, homologs, and fertilization within the context of sexual reproduction.
Section 1
Gametes Split Chromosomes in Half
Gametes are reproductive cells containing half the normal number of chromosomes. Human eggs and sperm each have 23 chromosomes, combining during fertilization to create a cell with 46 chromosomes.
Section 2
Meiosis Produces Four Unique Cells
Unlike mitosis, meiosis involves two cell divisions that reduce chromosome numbers by half. This special process creates haploid gametes with different genetic combinations for sexual reproduction.
Section 3
Fertilization Combines Genetic Material
During fertilization, a sperm cell joins with an egg cell, combining their genetic material. This process creates a fertilized egg with a complete set of chromosomes that develops into offspring.
Section 4
Genes Determine Inherited Traits
Dominant and recessive alleles (forms of genes) control how traits appear in offspring. The complete set of genes forms your genotype, while observable characteristics make up your phenotype.
Section 5
Scientists Map Chromosomes to Track Inheritance
Researchers discovered genes have specific locations on chromosomes. By studying how these genes travel together during reproduction, scientists can map chromosomes and predict patterns of inheritance.
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Section 1
Gametes Split Chromosomes in Half
Gametes are reproductive cells containing half the normal number of chromosomes. Human eggs and sperm each have 23 chromosomes, combining during fertilization to create a cell with 46 chromosomes.
Section 2
Meiosis Produces Four Unique Cells
Unlike mitosis, meiosis involves two cell divisions that reduce chromosome numbers by half. This special process creates haploid gametes with different genetic combinations for sexual reproduction.
Section 3
Fertilization Combines Genetic Material
During fertilization, a sperm cell joins with an egg cell, combining their genetic material. This process creates a fertilized egg with a complete set of chromosomes that develops into offspring.
Section 4
Genes Determine Inherited Traits
Dominant and recessive alleles (forms of genes) control how traits appear in offspring. The complete set of genes forms your genotype, while observable characteristics make up your phenotype.
Section 5
Scientists Map Chromosomes to Track Inheritance
Researchers discovered genes have specific locations on chromosomes. By studying how these genes travel together during reproduction, scientists can map chromosomes and predict patterns of inheritance.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter