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50 Cards in this Set

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Diploidy
-state where every chromosome has a homologue "2n"
Haploidy
-single chromosomes with no homologues "n"
The function of cell division include:
-growth
-repair
-reproduction
Mitosis
-Produces two genetically identical daughter cells
-Occurs in all somatic cells
-Produces two genetically identical daughter cells
-Occurs in all somatic cells
Meiosis
-Reduction division in two consecutive rounds
-Produces four haploid gametes from one diploid cell
-Reduction division in two consecutive rounds
-Produces four haploid gametes from one diploid cell
Sister Chromatid
Identical halves of a signle chromosome
-become individual chromosomes when split at the centromere
Centromere
Part of chromosome that links sister chromatids
Kinetochore
Associated with the centromeres and interacts with mitotic spindle, moving around the chromosomes
More than 90% of cell life is spent in which phase?
Interphase
What can be seen in a non-dividing cell during interphase?
-decondensed chromatin
-more than one nucleoli
-pair of MTOC's and centrioles
Prophase (prophase II)
-Chromosomes condense
-nucleolus & nuclear membrane slowly disappear
-mitotic spindle forms at the MTOCs which begin to move to opposite poles 
-microtubles start to grow at + ends of MTOC
-star-shaped aster fibers form around centriole
-
-
-Chromosomes condense
-nucleolus & nuclear membrane slowly disappear
-mitotic spindle forms at the MTOCs which begin to move to opposite poles
-microtubles start to grow at + ends of MTOC
-star-shaped aster fibers form around centriole
-
-
Metaphase (Metaphase II)
Early: Nuclear membrane totally disappears
-kinetochores produce movement and start to break the centromeres of the sister chromatids
-chromosomes align on the metaphase plate assisted by kinetochores for maintenance
Anaphase (Anaphase II)
-Microtubules shorten by uncoupling polymers, effectively pulling sister chromatids towards opposite poles
-Each sister chromatid is now called a daughter chromosome
Telophase
-daughter chromosomes position at opposite poles
-kinetochore fibers disappear
-chromosomes decondense
-nucleolus (nucleoli) and nuclear membrane reappear
Cytokinesis
Cleavage furrow that formed by actin and myosin microfilaments and pinches cytoplasm until it ultimately divides. "like a purse bag"
Cytokinesis in Plants
Golgi body vesicles migrate to equator and form a "cell plate" during telophase where they cemented by the middle lamella
Middle Lamella
A pectin layer which cements the cell walls of two adjoining cells together.
What does meiosis I separate?
Pairs of homologous chromosomes
The divisions of meiosis II and mitosis are similar (T/F)
True. Except that the gametes formed in meiosis will contain only 1/2 of the parents genetic information.
Prophase I of meiosis
Begins like prophase of mitosis except:
-synapsis=the pairing of homologues, "tetrads or bivalents"
-chiasmatas=site where genetic info is exchanged between nonsister homologous chromatids called "crossing-over"
-longest phase
Synaptomeal Complex
A protein structure that forms between homologous chromosomes (two pairs of sister chromatids) during meiosis and mediates chromosome pairing, synapsis, and recombination (crossing-over).
*It is now evident that the synaptonemal complex is not required for genetic recombination*
Metaphase I of meiosis
-Homologous pairs of chromosomes are lined up double file along the metaphase plate
-Spindle fibers from the poles attach to the kinetchores via centromeres of each pair of homologues
Anaphase I of meiosis
-Homologous chromosome pairs separate to opposite poles.
-Centromeres DO NOT SPLIT! ---each pole contains one chromosome from each pair of homologues
Telophase I of meiosis
-nuclear envelope reappears
-cytoplasm divides, leaving genetic material from ONLY one pair of homologous chromosomes "n"
Centromeres break after anaphase I (T/F)
False. Centromeres do not split; two chromatids belonging to a single chromosome remain attached
Meiosis II is like mitosis cell division (T/F)
True. Except that one results in 4 haploid gametes and the other produces 2 identical diploid daughter cells
Daughter cells inherit homologues identical of the parent cell in meiosis (T/F)
False.
-Receives 2 copies of only one member of the each homologous pair
Fundamental differences between mitosis and meiosis.
-Mitosis: 2 daughter cells with 1 copy of all chromosomes
-Meiosis: 4 haploid gametes with 1 copy of 1 member of each homologous pair
*All begins with tetrad formation during prophase I*
What type of cell division is asexual reproduction?
Mitosis
3 types of genetic variation
1) Independent assortment
2) Crossing over
3) Random fertilization
Independent assortment
Separation of homologous chromosomes depending on the random way in which they line up on the metaphase plate during metaphase I.
Ex: 2 possible orientations so 50% chance.
Combo of maternal and paternal chromosomes in each gamete is 2^23=~8 million
Two functional limitations for cell size limit growth or influence the start of a new cell division:
1) Surface-to-volume ratio (S/V)
-V ↑ by radius cubed, SA ↑ by radius squared
-large S/V ratio is need for cell to effectively exchange nutrients and waste with environment

2) Genome-to-volume ratio (G/V)
-Large G/V ratio needed for nucleus to provide enough substances (enyzmes, biosynthetic) for growing cell
*reason why some large cells (muscle) are multi-nucleated*
Cell-specific factors that influence the onset of cell division (5)
1) Checkpoints
2) Cyclin-dependent kinases (Cdk's)
3) Growth Factors
4) Density-dependent inhibition
5) Anchorage dependence
Checkpoints
Specific stop-points during cell cycle that evaluates internal/external condition to determine whether cell or not to continue through cell cycle
G1 checkpoint
-Occurs near end of G1 phase
-If conditions are unfavorable or cell is genetically programmed not to divide: G0 state
G2 checkpoint
-Occurs at the end of G2 phase
-Evaluates accuracy of DNA replication and signals whether or not to begin mitosis
M checkpoint
-Occurring during metaphase
-Ensures that microtubles (spindle) are properly attached to all kinetochroes at the metaphase plate before division continues with anaphase
Cyclin-dependent kinases Cdk's
-Phosphorylate proteins that regulate cell cycle
Cyclin----> Cdk's----> cell cycle reg. proteins
*presence of cyclin varies during the different phases
Growth factors
Naturally occurring substances capable of stimulating cellular growth, proliferation and cellular differentiation
I.e. cytokines, TGF-B, hormones (erythropoietin)
Density-dependent inhibition
(contact inhibition)
When cells stop dividing because surrounding cell density reaches a certain maximum "overcrowding"
Anchorage dependence
Most cells (animal) divide when anchored to an external surface such as: petri dish (in vitro), membrane (in vivo)
Cancer
Uncontrolled cell growth and division. Proliferate without regard to cell cycle regulation and factors.
"Disease of the Cell Cycle"
Spermatogonia (-ium)
Undifferentiated diploid cells
What do spermatogonia become after multiplying, enlarging, and undergoing genomic replication?
Primary Spermatocytes (diploid)
Spermatids
-Immature sperm cells that differentiate in mature spermatazoon with: head (acrosome from golgi), midpiece, and tail.
-Released from sertoli cells and travel to epididymis to gain motility
Pathway of sperm cells during ejaculation from testes
seminiferous tubules--> epididymis ---> vas or ductus diferens ---> ejaculatory duct ----> urethra
Difference between the products of the 1st and 2nd meiotic divisions in males and females?
Unequal division of cytoplasm between progeny producing polar bodies in females
(1st= 1 polar body, 2nd= 2 polar bodies)
What forms the outer and inner layer of an ovum after released from follicle?
Outer- corona radiata
Inner- zona pellucida in mammals aka vitelline membrane
When is fertilization complete?
When sperm and ovum nuclei fuse to form a zygote
Placenta
-complex mix of embryonic/maternal tissue develops @ site of implantation
-transfers nutrients, waste, gas (O2, CO2) between fetus and mother