Test 3: Sexual Reproduction Flashcards
Asexual reproduction
A method of reproduction where genetically identical clones are produced through a single parent without the involvement of gametes.
Sexual reproduction
A method of reproduction involving the fusion of two haploid cells to form a genetically unique diploid organism, introducing variation into offspring.
Meiosis
A type of cell division that produces haploid cells as part of the sexual reproductive cycle, reducing the chromosome number by half.
Fertilization
The process of uniting two haploid cells to form a diploid zygote, restoring the diploid condition.
Diploid
Organisms with two sets of chromosomes per somatic cell, where each chromosome type has two copies that are homologous to each other.
Haploid
Cells containing one set of chromosomes, which is half the diploid number.
Germ cells
Specialized diploid cells in animals that give rise to haploid gametes through meiosis.
Alternation of generations
A life cycle in plants where multicellular haploid and diploid organisms alternate, such as in ferns.
Gametes
Specialized cells involved in sexual reproduction, each containing one set of chromosomes.
Sporophyte
The diploid multicellular plant in plants with alternation of generations, producing haploid spores through meiosis.
Gametophyte
The haploid multicellular plant in plants with alternation of generations, producing gametes.
Zygospore
The diploid cell formed by the fusion of specialized haploid cells in fungi, undergoing meiosis to produce haploid spores.
Meiosis I
Separates homologous chromosomes into haploid daughter cells
Interphase
Precedes meiosis, includes G1, S, G2 phases for cell growth and DNA replication
Chromosome replication
Produces identical sister chromatids held at centromere until anaphase II
Prophase I
Homologous chromosomes pair, undergo crossing over
Crossing over
Exchange of genetic material between homologous chromosomes
Chiasma
Visual evidence of crossing over events
Prometaphase I
Spindle fibers attach to kinetochores of homologous chromosomes
Metaphase I
Homologous chromosomes align at metaphase plate randomly
Independent assortment
Random alignment of homologous chromosomes at metaphase plate
Genetic recombination
Occurs during prophase I, introduces genetic variation
Random fertilization
Contributes to unique gene combinations in offspring
Haploid Cells
Result from the first meiotic division, containing one set of chromosomes
Chiasmata
Break in anaphase I, where homologous chromosomes are pulled apart
Telophase I
Stage where separated chromosomes reach opposite poles in meiosis I
Cytokinesis
Physical separation of cytoplasmic components into daughter cells
Interkinesis
Brief phase between meiosis I and II, lacking S phase
Aneuploidy
Abnormal chromosome number, including monosomy or trisomy
Euploid
Individual with a complete set of chromosomes
Nondisjunction
Failure of homologous chromosomes or sister chromatids to separate
Barr Body
Inactive X chromosome structure in females to compensate for double X dose
Klinefelter Syndrome
Genetic disorder in males with XXY genotype, leading to infertility
Turner Syndrome
Genetic disorder in females with X0 genotype, causing various symptoms
Trisomy
Possessing an extra chromosome of a particular type
Monosomy
Missing one chromosome of a particular type
Autosome
Any chromosome that is not a sex chromosome
Synapsis
Pairing of homologous chromosomes during meiosis
Triploid
Individual with three sets of chromosomes
Tetraploid
Individual with four sets of chromosomes
Trisomic
Individual with an extra chromosome of a particular type
Monosomic
Individual missing one chromosome of a particular type
Chromosome Number Abnormalities
Disorders caused by duplicating or losing entire chromosomes
Meiosis and fertilization produce unique combinations of genetic material by three mechanisms
genetic recombination during prophase I, independent assortment during metaphase I, and random fertilization.
Sexual genetic variation comes from
Crossover, independent assortment, random fertilization
