Mitosis and Meiosis Flashcards
Polar microtubules
Overlap in the midline and are responsible for pushing the poles of the spindle apparatus apart
Bilvalent
A pair of homologs held together by chiasmata
Chiasmata
Positions where chromosomes touch and crossing over occurs
Pseudoautosomal region
Matching sequence on the X and Y chromosome that allows for crossing over
Kinetochore microtubules
Responsible for pulling the sister chromatids of each chromosome apart
Sister chromatids
Two identical strands of a replicated chromosome joined by the centromere
2 forms of genetic reassortment
Crossing over
Independent assortment
Mendel’s law of Segregation
Gametes contain only one homologous chromosome and therefore one gene for each trait
Chromosomes
Rod shaped structures of condensed nucleic acid material
Nondisjunction
Failure of two chromosomes in a pair to disjoin during anaphase of cell division (both go into 1 daughter cells)
Karyotype
Organized picture of chromosomes
Centrioles
Located in the centrosome and produces the microtubules
4 genetic counsequences of meiosis
Reduction in chromosome number
Segregation
Independent assortment
Crossing over
Spindle apparatus
Network of filaments overall responsible for separating chromosomes during cell division
Stages of cell cycle
G1 > S > G2 > M
Centrosome
Organelle that is the primary microtubular organizing center that splits and forms the spindle apparatus
Mendel’s law of Independent Assortment
Chromosomes are inherited independently from other chromosomes
Homologous Chromosomes
A pair of chromosomes inherited from different parents and generally carry the same genes in the same order but do not have the same DNA sequence
Centromere
Constriction on a chromosome at which the sister chromatids are held together
Kinetochore
Protein structure on the centromere to which the spindle fibers attach
Astral microtubules
Radiate in all directions and aid in the spindle orientation immediately before mitosis
4 important steps of prophase
- Chromosome condensation begins
- Less/highly condensed regions form
- Each chromosome contains 2 strands of DNA connected by centromere
- Centromeres divides and migrate to opposite poles of the cell
3 important steps in prometaphase
- Disruption of nuclear envelope into membrane vestibles
- Spindle mictotubules enter nuclear region
- Kinetochore mature and attach to the kinetochore microtubules
4 important steps of metaphase
- Nuclear membrane disappears
- Chromosomes become maximally condensed
- Kinetochore microtubules align chromosomes at equitorial plate midway between the poles of the cell
- Polar microtubules begin to associate in preparation for anaphase
4 important steps of anaphase
- Centromeres abruptly separate
- Each sister chromatid is pulled to opposite pole by shortening of kinetochore microtubules
- Polar microtubules elongate, pushing the spindle apparatus further to cell pole
- The arrival of the chromosomes at the spindle pole marks the end of anaphase
4 important steps in telophase
- Spindle apparatus begins to decondense
- Polar microtubules elongate, further separating the two poles
- Nuclear envelop begins to form around aggregated chromosomes at each pole of the cell
- Chromosomes decondense and nucleoli reappear
List of metacentric chromosomes
1 2 3 19 20
List of submetacentric chromosomes
4 5 6 7 8 9 10 11 12 16 17 18 X
List of acrocentric chromosomes
13 14 15 21 22 Y
Uniparental disomy
Both chromosomes are inherited from one parent