Mitosis and Meiosis Flashcards
Gene
genomic sequence corresponding to a unit of inheritance
Locus
location of a gene on the physical map
Cytology
chromosomes are stained for identification using special stains; result is G banding pattern characteristic to each chromosome
What is the life cycle of a diploid, multicellular organism?
Meiosis and Gametogenesis -> Fertilization -> Mitosis and Differentiation -> Sexual Maturity -> Meiosis and Gametogenesis
What is the cell cycle?
Interphase (G1, S, and G2 phases), Mitosis
G1 phase
cells prepare for replication
S phase
DNA replicates and new chromosomes are formed
G2 phase
cells prepare for mitosis or division
Mitosis
asexual cell division for growth and development; steps: Prophase, Metaphase, Anaphase, Telophase and Cytokinesis
Prophase (Mitosis)
chromosomes condensed and replicated chromosomes become visible and attach to spindle via kinetochore; nucleolus and nuclear membrane start to disappear
Metaphase (Mitosis)
chromosomes align @ the equatorial plate (middle line)
Anaphase
sister chromatids separate & migrate to opposite poles
Telophase
cell division starts and reformation of nucleus and nucleolus
What is the result of mitosis?
An identical daughter cell w/ no change in genetic material or chromosome #.
Meiosis
sexual cell division used to make gametes and occurs in germ cells; steps: Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, Prophase 2, Metaphase 2, Anaphase 2, Telophase 2, and Cytokinesis
What are the products of spermatogenesis and oogenesis (meiosis in male and female)?
Males: 4 sperms
Females: 1 egg and 3 degenernate polar bodies
Prophase 1
chromosomes condense and replicated chromosomes become visible; homologous chromosomes pair (form tetrad) or synapse and exchange information; nucleolus and nuclear membrane start to disappear; spindles start to form
Metaphase 1
homologous chromosomes pair at midplane; nucleolus and nuclear membrane disappear and spindles form
Anaphase 1
homologous chromosomes separate
Telophase 1
cell division into two cells; nuclear membrane may appear
Prophase 2
not much change; nuclear membrane breakdowns, spindle fibers begin to form and centrioles begin to move to poles
Metaphase 2
Spindle forms, chromosomes align at midplane, and no pairing of chromosomes
Anaphase 2
centromeres divide and sister chromatids are separated
Telophase 2
nuclear envelope forms and cells start to divide into 4 haploid cells
What is the difference between Anaphase 1 and Anaphase 2?
In Anaphase 1, homologous chromosomes separate. In Anaphase 2, sister chromatids separate.
What is the result of meiosis?
4 genetically different haploid cells
Independent assortment
Alleles of a locus assort independently during meiosis
What occurs when there are two different types of alleles on a chromosome?
Ex: Gene A alleles assort independently of gene B alleles on different chromosome
What is used to study cell division?
Neurospora crassa-haploid organism
