Sexual Reproduction and Meiosis

Haploid Cells

(n) One copy of each chromosome

three non-homologous chromosomes

gametes

result from dipolid cells via meiosis

Diploid Cells

(2n) Two copies of each chromosome

three pairs of homologous chromosomes

somatic cells

undergo mitosis

created through fusion of two haploid cells

Homologous Chromosomes

chromosomes with the same gene in the same order

One homolog is inherited from each parent.

Non-Homologous Chromosomes

carry different sets of genes

Alleles

different versions of the same gene

chromosome composition of human cells

46 chromosomes, organized into 23 pairs.

diplontic organisms

The adult is a diploid

Gametes are the only haploid cells: don’t divide following meiosis

male gamete= sperm female gamete=egg

germ cells: produce gametes

all other cells: somatic cells

Haplontic organisms

Haploid cells divide by mitosis

The fusion of haploid cells creates a diploid zygote

diploid zygote (fertilized egg) —> hapolid cells via meiosis

Asexual reproduction key factors

• only one parent

• Offspring are clones: genetically identical to each other and parent cell

• rare mutations are the only source of genetic variation

Sexual reproduction key factors

• two parents

• Both parents contribute genetic material to offspring

• offspring have unique combination of genes

• lots of genetic variation, even without mutation

Explain how independent assortment and recombination contribute to genetic diversity

shuffling and recombining genetic material, leading to unique combinations of alleles in gametes