Genetics - Mitosis & Meiosis

Asexual Reproduction

Is natural “cloning.” Parts of the plant, such as leaves or stems, produce roots and become an independent plant.

Sexual Reproduction

Requires fusion of male cells in the pollen grain with female cells in the ovule.

Sporophyte

Diploid, produce haploid spores by meiosis.

Gametophyte

Haploid, produce gametes by mitosis.

Genetics

Is the scientific study of heredity and variation.

Heredity

Is the transmission of traits from one generation to the next.

Variation

Is demonstrated by the differences in appearance that offspring show from parents and siblings.

Genes

Are the units of heredity and are made up of segments of DNA.

Locus

Each gene has a specific location called a _____ on a certain chromosome.

Clone

Is a group of genetically identical individuals from the same parent.

Life Cycle

Is the generation-to-generation sequence of stages in the reproductive history of an organism.

Somatic Cells

(any cell other than a gamete) have 23 pairs of chromosomes.

Homologous Chromosomes

The two chromosomes in each pair are called _____, or homologs.

sex chromosomes

called X and Y

Autosomes

The 22 pairs of chromosomes that do not determine sex are called _____

Fertilization

is the union of gametes (the sperm and the egg)

Zygote

The fertilized egg is called a _____ and has one set of chromosomes from each parent.

Meiosis

Gametes are the only types of human cells produced by _____, rather than mitosis

Gametophyte

Each spore grows by mitosis into a haploid organism called a

synapsis

homologous chromosomes loosely pair up, aligned gene by gene.

crossing over

nonsister chromatids exchange DNA segments

chiasmata

X-shaped regions where crossing over occurred

Unicellular organisms

Reproduce by cell division

mitotic phase

Is made up of mitosis and cytokinesis

mitotic spindle

Is an apparatus of microtubules that controls chromosome movement during mitosis

Leptotene

chromosomes appear as “string of beads” (nucleosomes); DNA double-strand breaks begin.

Zygotene

homologous chromosomes pair via the synaptonemal complex, forming a tetrad/bivalent.

Pachytene

crossing over occurs at chiasmata, producing recombination.

Diplotene

synaptonemal complex breaks down; homologs begin to separate but remain attached at chiasmata.

Diakinesis

chiasmata move to chromosome ends (terminalization); chromosomes condense; nucleolus and nuclear envelope break down; spindle forms.