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
What are the cells absorbed by the female body during meiosis called?
A polar body
What are some key differences between meiosis and mitosis
Mitosis produces diploid cells, occurs in somatic cells, produces somatic cells and its goal is to induce growth and repair
Meiosis produces haploid cells, occurs in germ cells, produces gonads and its goal is fertilization and reproduction
