Bio 3 - Exam 2 Flashcards
Interphase
In the cell cycle, the phase during which the cell grows and functions; during this phase, replication of DNA occurs in preparation for cell division
Mitosis
The division of a nucleus into two genetically identical nuclei that, along with cytokinesis, leads to the formation of two identical daughter cells
Meiosis
In sexually reproducing organisms, a process of nucleus division in the gonads that along with cytokinesis, produces reproductive cells that have half as much generic material as the parent cell and that all differ from each other genetically
Cytokinesis
In the cell cycle, the stage following mitosis in which cytoplasm and organelles duplicate and are divided into approximately equal parts and the cell separates into two daughter cells. In meiosis, two diploid daughter cells are formed in cytokinesis following telophase I and found haploid daughter cells are formed in cytokinesis following telophase II.
Prophase
The first phase of mitosis, in which the nuclear membrane breaks down, sister chromatids condense, and the spindle forms. In meiosis, homologous paris of sister chromatids come together and cross over in prophase I, and the chromosomes in daughter cells condense in prophase II.
Metaphase
The second phase of mitosis, in which the sister chromatids line up at the center of the cell; in meiosis, the homologues line up at the center of the cell in metaphase I and the sister chromatids line up in metaphase II.
Anaphase
A phase in mitosis and meiosis in which chromosomes separate. In mitosis it is the third phase, in which the sister chromatids are pulled apart by the spindle fibers, with a full set of chromosomes going to opposite sides of the cell. In meiosis, the homologues separate in anaphase I and sister chromatids separate in anaphase II.
Telophase
The fourth and last phase of mitosis, in which the chromosomes begin to uncoil and the nuclear membrane is reassembled around them. In meiosis, the sister chromatids arrive at the cell poles and the nuclear membrane reassembles around them in telophase I’ in telophase II, the sister chromatids have pulled apart and the nuclear membrane reassembles around haploid numbers of chromosomes.
Chromosome
A linear or circular strand of DNA on which are found specific sequences of base pairs. The human genome consists of two copies of each 23 unique chromosomes, one from the mother and one from the father.
Chromatid
One of the two strands of a replicated chromosome.
Centromere
After replication, the region of contact between sister chromatids, which occurs near the center of two strands.
Crossing Over
The exchange of some genetic material between a paternal homologous chromosome and a maternal homologous chromosome, leading to a chromosome carrying genetic material from each; also referred to as recombination.
Spindles
A part of the cytoskeleton of a cell, formed in prophase (in mitosis) or in prophase I (in meiosis), from which extend the fibers that organize and separate the sister chromatids.
Homologous Chromosome Pair
The maternal and parental copies of a chromosome.
Meiosis I
Reduction division; separation of homologous chromosomes into two different nuclei; chromosome numbers reduced to haploid.
Meiosis II
Equal division; duplicated chromosomes separate; no change in chromosome numbers.
Haploid
Describes cells that have a single copy of each chromosome (in many species, including humans, gametes are haploid).
Diploid
Describes cells that have two copies of each chromosome (in many organisms, including humans, somatic cells are diploids).
Sister Chromatids
The two identical strands of a replicated chromosome.
Non-Sister Chromatids
Two non-identical strands of a replicated chromosomes that represent different but homologous chromosomes. The non-sister chromatid will carry the same type of genetic information, but not exactly the same information.
Synapsis
The pairing of two homologous chromosomes that occurs during meiosis during prophase I. This allows matching up of homologous pairs prior to their segregation, and possible chromosomal crossover between them.
Chiasma
The point where two homologous non-sister chromatids exchange genetic material during chromosomal crossover during meiosis.
