Unit 7 Flashcards
What are the two forms of reproduction?
Sexual and asexual
What is asexual reproduction
Binary fission
What cells are asexual
Prokaryotic cells
Describe binary fission
Parent cell divides into 2 genetically identical daught cells
What are the steps of binary fission
1-chromosome attaches to plasma membrane
2-chromosome is replicated at the ori
3-cell elongates, pushing chromosomes towards opposite ends
4-parent cell is divided into two
What is the benefit of sexual reproduction
Genetic density=better chance at survival
What is meiosis
Diploid germ cell divides into four haploid gametes
What are the characteristics of meiosis
-reductive division
-cells can undergo it once
-introduces genetic variation
-happens only in gonads
What are the traits of prophase I
-microtubules attracts tetrads from opposite sides
-chromosomes coil tighter and nuclear enveloppe dissolves
-homologues form a tetrad during synapsis
-Crossing over between non-sister chromatids
Characteristics of metaphase I
-tetrads align at the metaphase plate
-independant assortment, random orientation of homologue pair
Characteristics of Anaphase I
-homologues are suspended, sister chromatid remain attached
Characteristics of telophase I
-nuclear enveloppe forms around each set, the nucleus is now a haploid and no longer identical
What is interkenesis
The phase between meiosis I and meiosis II
Not the same as interphase: the chromosomes dont get duplicated
What are the main characteristics of meiosis II
-chromosome seperates, forming two haploid cells that are genetically different
-at the end, 4 new cells are formed
What is the difference between female and male meiosis
Female only forms one ovule while male forms 4 sperms
Constant meiosis in males but 1 meiosis per cycle for females
