Chapter 10 and 11 (Meiosis and Mitosis) Flashcards
The reproduction of bacteria is _____
clonal
_______ is a simple form of cell division
binary fission
What is binary fission?
asexual reproduction by division of one cell or boy into two equal or early equal parts
What are SMC?
structural maintance proteins
What are two SMC proteins?
cohesion and condesion
____ numbers vary among species
chromsomes
When defining the number of different chromosomes in a species, geneticists count ____ number of chromosomes
haploid
What has two sets of chromsomes?
diploid
What refers to a pair of the same kind of chromosome in a diploid cell?
homologous
What refers to one pair of chromosomes of the same kind located in diploid cells?
homologue
What is the particular array of chromosomes an individual organism possesses?
Karyotype
How is DNA compartmentalized?
Territories—> compartments–> TADS—> nucleosomes—> Histones
What are TADs?
topologically associated domains
What is the cell cycle?
repeating sequence of growth and division through which cells pass each generation
What phases are in interphase?
G1, S, G2
What phases are in the M phase?
Mitosis and Cytokinesis
What is G0?
the stage of the cell cycle occupied by cells that are not actively dividing
What happens in G1?
the cell undergoes major growth
What happens in S phase?
each chromosome replicates to produce?
What happens in G2?
the chromsomes begin to condense. and cohesions are replaced by condensins
How are the sister chromatids held together?
cohesion proteins
When does prophase occur?
Occurs when condensed chromsomes first become visible, and ends when the nuclear envelope breaks down
What is the spindle apparatus?
carries out separation in cell division and forms during prophase
What is the aster?
radial array of microtubules extending from the centrioles toward plasma membrane
What breaks down during prophase and is absorbed by the ER?
the nuclear envelope
When does prometaphase occur?
occurs when the nuclear envelope dissembles, and the spindles attach to the kinetochores of sister chromatids
In prometaphase, what do the sister chromatids connect to?
to opposite poles of the spindles
What are the potential forces that move the chromosomes in the prometaphase?
- assembly and disassembly of microtubules
- motor proteins located at the kinetochore and plates pull
What occurs in metaphase?
microtubules become organized into a spindle, and the chromosomes come to lie in the spindle’s equatorial plate
What is the metaphase plate?
the imaginary perpendicular axis
What happens in anaphase?
it occurs by the separation of sister chromatids, daughter chromosomes move to opposite poles of the cell, and it removes the cohesin proteins concentrated at centromeres
What happens in Anaphase A?
Kinetochores are pulled towards the poles, they shorten
What happens in Anaphase B?
poles move away
What happens in telophase?
The spindle breaks down, the nuclear envelope of each daughter cell forms,
What is cytokinesis?
division of the cytoplasm of a cell after nuclear division
How does cytokinesis occur in animals or eukaryotes without cell walls?
cleavage furrow
In plants with cell walls how does cytokinesis occur?
The cell plate grows outward–> two new cells–> cellulose creates 2 new cell walls, and then they are impregnated with proteins called ( middle lamelda)
In fungi and protists, what does not dissolve but just splits in cytokinesis?
the nuclear envelope
What is the essence of sexual reproduction?
it is the genetic contribution of two cells
What does meiosis reduce?
the number of chromosomes
Who discovered chromosomes in 1879?
Edourd van Benedan
What are gametes?
haploid reproductive cells
What are somatic cells?
nonreproductive cells (diploids)
What are zygotes?
the diploid cell resulting from the fusion of male and female
What is fertilization?
the fusion of two haploid gamete nuclei to form a diploid zygote nucleus
What happens in meiosis I?
homologous chromosomes separate, and the daughter cells only have the haploid number of chromsomes
What is sexual reproduction?
the process of producing offspring through an alternation of fertilization and meiotic reduction in chromosome bumber
What are germ-line cells?
cells that will be gametes are set aside early in development
How are germ-line cells held together?
- cohesion proteins
What is synapsis?
ends of chromosomes seem to be attached to the nuclear envelope at specific ends
What occurs in prophase I?
crossing over and synapsis
What are bivalents?
homologous pairs locked together
What does it mean if sister chromatids have monopolar attachment?
sister chromatids act as a unit to capture polar microtubules
What happens in anaphase I?
Microtubules begin to shorten, the connections between homologous at chiasmata are broken, allowing homologs to be pulled to opposite ends
What is independent assortment?
results from the random orientation of different homologous pairs during metaphase I of meiosis
What happens in telophase I?
chromsomes have segrated into two clusters, one at each pole, nuclear envelope begin to reform
What is achiasmate segregation?
the accurate segregation of homologous during meiosis I without the formation of chiasmata between homologues
What does Meiosis II result in?
four haploid cells
What is an error that can occur in meiosis?
nondisjunction: there can be failure to move chromsomes to polarize
What is aneuploid?
an organism where cells have lost or gained a chromosome
What are four traits of meiosis?
- Homologous pairing and crossing over joins maternal and paternal homologous
- sister chromatids remain connected at the centromere and segregate together during Anaphase 1
- Kinoetochores of sister chromatids at same pole in meiosis 1
- DNA replication is supressed
