Sexual reproduction

sexuallysexualreproduce sexuallysexually reproducingreproduces sexuallyreproductionreproductivesexually reproducesexually reproductivebreeding
Sexual reproduction is a type of life cycle where generations alternate between cells with a single set of chromosomes (haploid) and cells with a double set of chromosomes (diploid).wikipedia
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Biological life cycle

life cyclelifecyclelife history
Sexual reproduction is a type of life cycle where generations alternate between cells with a single set of chromosomes (haploid) and cells with a double set of chromosomes (diploid).
Transitions of form may involve growth, asexual reproduction, or sexual reproduction.

Chromosome

chromosomeschromosomalChromosomal number
Sexual reproduction is a type of life cycle where generations alternate between cells with a single set of chromosomes (haploid) and cells with a double set of chromosomes (diploid).
Chromosomal recombination during meiosis and subsequent sexual reproduction play a significant role in genetic diversity.

Fertilisation

fertilizationconceptionfertilized
Two haploid cells combine into one diploid cell in a process called fertilisation.
This cycle of fertilisation and development of new individuals is called sexual reproduction.

Meiosis

meioticsyzygymeiosis I
Diploid cells divide into haploid cells in a process called meiosis.
This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi.

Ploidy

diploidhaploid2n
Sexual reproduction is a type of life cycle where generations alternate between cells with a single set of chromosomes (haploid) and cells with a double set of chromosomes (diploid).
Virtually all sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different organisms, between different tissues within the same organism, and at different stages in an organism's life cycle.

Human reproduction

reproductionbegetbegat
For instance, in human reproduction each human cell contains 46 chromosomes in 23 pairs.
Human reproduction is any form of sexual reproduction resulting in human fertilization.

Sexual intercourse

sexcopulationintercourse
When the gametes are combined via sexual intercourse to form a fertilized egg, the resulting child will have 23 chromosomes from each parent genetically recombined into 23 chromosome pairs or 46 total.
Copulation, by contrast, more often denotes the mating process, especially for non-human animals; it can mean a variety of sexual activities between opposite-sex or same-sex pairings, but generally means the sexually reproductive act of transferring sperm from a male to a female or sexual procreation between a man and a woman.

Animal

Animaliaanimalsmetazoa
Cell division mitosis then initiates the development of a new individual organism in multicellular organisms, including animals and plants, for the vast majority of whom this is the primary method of reproduction.
With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.

Plant

Plantaeplantsflora
Cell division mitosis then initiates the development of a new individual organism in multicellular organisms, including animals and plants, for the vast majority of whom this is the primary method of reproduction.
Plants are characterized by sexual reproduction and alternation of generations, although asexual reproduction is also common.

Mating

matematescopulation
Sexual selection is a mode of natural selection in which some individuals out-reproduce others of a population because they are better at securing mates for sexual reproduction.
In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms, usually for the purposes of sexual reproduction.

Asexual reproduction

asexualasexuallyreproduce asexually
The evolution of sexual reproduction is a major puzzle because asexual reproduction should be able to outperform it as every young organism created can bear its own young.
While all prokaryotes reproduce without the formation and fusion of gametes, mechanisms for lateral gene transfer such as conjugation, transformation and transduction can be likened to sexual reproduction in the sense of genetic recombination in meiosis.

Evolution of sexual reproduction

evolution of sexsexual reproductiondeterministic mutation hypothesis
The evolution of sexual reproduction is a major puzzle because asexual reproduction should be able to outperform it as every young organism created can bear its own young. These reasons include reducing the likelihood of the accumulation of deleterious mutations, increasing rate of adaptation to changing environments, dealing with competition, DNA repair and masking deleterious mutations.
The evolution of sexual reproduction describes how sexually reproducing animals, plants, fungi and protists could have evolved from a common ancestor that was a single-celled eukaryotic species.

Bacterial conjugation

conjugationconjugativeExconjugant
Prokaryotes, whose initial cell has additional or transformed genetic material, reproduce through asexual reproduction but may, in lateral gene transfer, display processes such as bacterial conjugation, transformation and transduction, which are similar to sexual reproduction although they do not lead to reproduction.
coli'' bacterial conjugation is often regarded as the bacterial equivalent of sexual reproduction or mating since it involves the exchange of genetic material.

Fitness (biology)

fitnessbiological fitnessreproductive fitness
This 50% cost is a fitness disadvantage of sexual reproduction.
With sexual reproduction, genotypes are scrambled every generation.

Red Queen hypothesis

Red QueenRed Queen's Hypothesisred queen effect
These reasons include reducing the likelihood of the accumulation of deleterious mutations, increasing rate of adaptation to changing environments, dealing with competition, DNA repair and masking deleterious mutations.
The hypothesis intends to explain two different phenomena: the constant extinction rates as observed in the paleontological record caused by co-evolution between competing species, and the advantage of sexual reproduction (as opposed to asexual reproduction) at the level of individuals.

Sex organ

genitaliagenitalsgenital
Dimorphism is found in both sex organs and in secondary sex characteristics, body size, physical strength and morphology, biological ornamentation, behavior and other bodily traits.
A sex organ (or reproductive organ) is any part of an animal's body that is involved in sexual reproduction.

Species

specificspecific epithetspecific name
Sexual dimorphism is where the basic phenotypic traits vary between males and females of the same species.
A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction.

Eukaryote

Eukaryotaeukaryoticeukaryotes
Sexual reproduction is by far the most common life cycle in eukaryotes, for example animals and plants.
Most eukaryotes also have a life cycle that involves sexual reproduction, alternating between a haploid phase, where only one copy of each chromosome is present in each cell and a diploid phase, wherein two copies of each chromosome are present in each cell.

Muller's ratchet

accumulationMueller's ratchetMüller’s ratchet
These reasons include reducing the likelihood of the accumulation of deleterious mutations, increasing rate of adaptation to changing environments, dealing with competition, DNA repair and masking deleterious mutations.
Muller proposed this mechanism as one reason why sexual reproduction may be favored over asexual reproduction, as sexual organisms benefit from recombination.

Evolution

evolvedtheory of evolutionevolutionary
Biologists studying evolution propose several explanations for why sexual reproduction developed and why it is maintained.
Variation comes from mutations in the genome, reshuffling of genes through sexual reproduction and migration between populations (gene flow).

Fisher's principle

Fisher's theoryFisher's prediction of a 1:1 male to female sex ratioFisher's theory of sex ratio selection
The English statistician and biologist Ronald Fisher outlined why this is so in what has come to be known as Fisher's principle.
Fisher's principle is an evolutionary model that explains why the sex ratio of most species that produce offspring through sexual reproduction is approximately 1:1 between males and females.

DNA

deoxyribonucleic aciddouble-stranded DNAdsDNA
In a process called genetic recombination, genetic material (DNA) joins up so that homologous chromosome sequences are aligned with each other, and this is followed by exchange of genetic information.
This physical separation of different chromosomes is important for the ability of DNA to function as a stable repository for information, as one of the few times chromosomes interact is in chromosomal crossover which occurs during sexual reproduction, when genetic recombination occurs.

Mutation

mutationsgenetic mutationmutated
One definite advantage of sexual reproduction is that it impedes the accumulation of genetic mutations.
DFE, as used to determine the relative abundance of different types of mutations (i.e., strongly deleterious, nearly neutral or advantageous), is relevant to many evolutionary questions, such as the maintenance of genetic variation, the rate of genomic decay, the maintenance of outcrossing sexual reproduction as opposed to inbreeding and the evolution of sex and genetic recombination.

Sex

biological sexsexesanatomical sex
After the pollen tube grows through the carpel's style, the sex cell nuclei from the pollen grain migrate into the ovule to fertilize the egg cell and endosperm nuclei within the female gametophyte in a process termed double fertilization.
Sexual reproduction involves the combining and mixing of genetic traits: specialized cells known as gametes combine to form offspring that inherit traits from each parent.

Spore

sporessporulationsporulate
Ferns mostly produce large diploid sporophytes with rhizomes, roots and leaves; and on fertile leaves called sporangium, spores are produced.
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions.