3B Sexual reproduction and meiosis Flashcards
diploid (2n)
a cell with a nucleus containing two full sets of chromosomes
haploid (n)
a cell with a nucleus containing one complete set of chromosomes
zygote
the cell formed when two haploid gametes fuse at fertilisation
fertilisation
the fusing of the haploid nuclei form two gametes to form a diploid zygote in sexual reproduction
polyploidy
a cell or an organism with more than two sets of chromosomes
gonads
the sex organs in animals
anthers
male sex organs in plants that produce the male gametes contained in the pollen
ovules
the haploid female gametes in plants
testes
the male sex organs in animals that produce the male gametes - sperm
pollen
the spore which contains the haploid male gametes of plants
spermatozoa
the haploid male gametes in animals
ova
the haploid female gametes in animals (singular =ovum)
microspores
the result of meiosis in plants that develop into the spore (pollen) containing the male gametes
megaspores
the result of meiosis in plants that develop into the female gametes, ovules
homologous pairs
matching pairs of chromosomes in an individual which both carry the same genes, although they may have different alleles
crossing over (recombination)
the process by which large multi-enzyme complexes cut and re-join parts of the maternal and parental chromatids at the end of prophase I, introducing genetic variation
chiasmata
the points where the chromatids break during recombination
mutation
a permanent change in the DNA of an organism
independent assortment
the process by which the chromosomes derived form the male and female parent are distributed into the gametes at random
gametogenesis
the formation of the gametes by meiosis in the sex organs
oocyte
a cell in an ovary which may form an ovum if it undergoes meiotic division
acrosome
the region at the head of the sperm that contains enzymes to break down the protective layers around the ovum
sporophyte generation
the diploid generation in plants that produces spores by meiosis
zona pellucida
a layer of protective jelly around the unfertilised ovum
sporophyte generation
the diploid generation in plants that produces spores by meiosis
gametophyte generation
the haploid generation in plants that gives rise to the gametes by mitosis
microgametes
the male gametes produced in plants, the pollen grains
tube nucleus
the male nucleus that will control the production of the pollen tube in fertilisation
generative nucleus
the male nucleus that will fuse with the female nucleus
pollen tube
a tube that grows out of a pollen grain down the style, into the ovary and through the micropyle of the ovule to carry the generative nucleus (which divides to form two male nuclei) to the ovule
placenta (plant)
placenta (plant) the pad of special tissue that attaches the plant ovule to the ovary wall
placenta (plant)
placenta (plant) the pad of special tissue that attaches the plant ovule to the ovary wall
megagamete
the female gamete, the egg cell, in plants
pollination
the transfer of pollen from the anther to the stigma, often from one flower to another
external fertilisation
the process of fertilisation in which the female and male gametes are released outside of the parental bodies to meet and fuse in the environment
internal fertilisation
the fertilisation of the female gamete by the male gamete, which takes place inside the body of the female
mating
the process by which a male animal transfers sperm from his body directly into the body of the female
acrosome reaction
the reaction seen when the sperm reach the oocyte and enzymes are released from the acrosome and digest the follicle cells and the zona pellucida
polyspermy
the fertilisation of an egg by more than one sperm
cortical reaction
the reaction seen when cortical granules in the cytoplasm of the ovum release enzymes into the zona pellucida; these enzymes destroy the sperm-binding sites and also thicken and harden the jelly of the zona pellucida
fertilisation membrane
the tough layer that forms around the fertilised ovum to prevent the entry of other sperm
conception
the term used for fertilisation of the ovum in humans
germinate
(of pollen) the process by which a pollen tube starts to grow out of the pollen grain to transfer the male nuclei to the ovule
double fertilisation
the process that occurs in plants in which one male nucleus fuses with the two polar nuclei to form the triploid endosperm nucleus and the other fuses with the egg cell to form the diploid zygote
sporophyte
the diploid main body of the plant
ovaries
the female sex organs in both animals and plants; they produce the female gametes called ovules in plants and ova in animals
