Download Meiosis and Sexual Reproduction: Preserving Variability through Cell Division and more Quizzes Molecular biology in PDF only on Docsity!
How do we preserve information while
keeping it variable at the same time?
Sexual reproduction-for the production of gametes (1n) and thefacilitationof the fusion of gametes to make a zygote (2n) Meiosis-reductional cell division (2n --> n) TERM 2
Very briefly, the fundamental differences
between Meiosis I and Meiosis II
DEFINITION 2 MI-segregation of homologous chromosomes-reductional division MII-segregation of sister chromatid-non-reductional division TERM 3
Meiosis I (1 cell --> 2 cells) (2n --> n)
DEFINITION 3 PI:Same as in mitosis except homologous chromosomes pair up and exchange segments MIHomologous chromosomes line up on metaphase plate; tertrads line up AIHomologous chromo. split into chromatid and moved to opposite poles TISame as mitosis and then cytokinesis into two cells TERM 4
Meiosis II (2 cells --> 4 cells) (n -->
n)
DEFINITION 4 Same as mitosis TERM 5
T/F: Nondisjunction can occur ONLY in Meiosis
II
DEFINITION 5 False - can happen both in meiosis I and II
Application Q: How many alleles can trisomy
21 have?
TERM 7
How does trisomy-21 occur?
DEFINITION 7 Non-disjunction at Meiosis II of chromosome 21. TERM 8
What is the number of possible new
combinations of chromosomes for a species?
DEFINITION 8 2^n where n = haploid chromosome numberex. humans = 2^ TERM 9
During anaphase I is there a separation of
centromeres?
DEFINITION 9 NO! Chromosomes are segregating at this stage. Centromere separation only occurs at anaphase II. TERM 10
What is chiasmata? How do they
form?
DEFINITION 10 A chiasmata is an overlapping region in homologous chromosomes were sectional exchanges occur. They form when homologous chromosomes synapse.
What is asexual reproduction? Where is it
found?
Method of reproduction in which an organism produces an exact copy of itself.-all prokaryotes, some eukaryotes (yeast) TERM 17
Sex Determination - sex can be determined
from two factors. What are they?
DEFINITION 17 Enviroment ex. temperature can influence sexChromosomal ex. XX vs XY in humans
