3B Cell Cycle, Fertilisation Flashcards
cell cycle
a regulated process of three stages (interphase, mitosis and cytokinesis) in which cells divide into two genetically identical daughter cells
interphase
the period between active cell divisions when cells increase their size and mass, replicate their DNA and carry out normal metabolic activities
mitosis
the process by which a cell divides to produce tow genetically identical daughter cells
meiosis
a form of cell division in which the chromosome number of the original cell is halved, leading to the formation of the gametes
asexual reproduction
the production of genetically identical offspring form a single parent or organism
histones
positively charged proteins involved in the coiling of DNA to form dense chromosomes in cell division
nucleosomes
dense clusters of DNA wound around histones
karyotype
a way of displaying an image of the chromosomes of a cell to show the pairs of autosomes and sex chromosomes
chromatid
one strand of the replicated chromosome pair that is joined to the other chromatid at the centromere
cyclins
small proteins that build up during interphase and are involved in the control of the cell cycle by phosphorylating other proteins, activated by attachment to cyclins
cyclin - dependent kinases CDKs
enzymes involved in the control of the cell cycle by phosphorylating other proteins, activated by attachment to cyclins
prophase
- the first stage of active cell division
- the chromosomes are coiled up and consist of two daughter chromatids joined by the centromere
- the nucleolus breaks down
metaphase
- the second stage of active cell division
- a spindle of overlapping protein microtubules forms
- the chromatids line up on the metaphase plate
centromere
the region where a pair of chromatids are joined and which attaches to a single strand of the spindle structure at metaphase
telophase
- fourth stage of active cell division
- a nuclear membrane forms around the two sets of chromosomes
- the chromosome
clones
genetically identical individuals resulting from asexual reproduction in a single parent
mitotic index
the ratio between the number of cells in a tissue sample that are in mitosis and the total number of cells in the sample
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
gonads
the sex organs in animals
ovaries
the female sex organs in both animals and plants; they produce the female gametes called ovules in plants and ova in animals
pollen
the spore which contains the haploid male gametes of plants