Division and Chromosomal Heredity Flashcards
(47 cards)
what are the different morphological types of chromosomes
metacentric-equal length arms
submetacentric-p arm shorter
acrocentric-no p arm
differences between homologous chromosomes and sister chromatids
Homologous-similar NOT IDENTICAL. carry different versions of the same gene
Sister-genetically identical
how many pairs of chromosomes are found in a typical human somatic cell
23 pairs(46 chromosomes)
prime difference between mitosis and meiosis
mitosis produces diploid cells 2 genetically identical (diploid) daughter cells
meiosis produces 4 genetically different haploid cells for sexual reproduction
T/F between interphase and mitosis cells can enter G0 stage in which they are quiescent
True
T/F DNA synthesis occurs during S phase of interphase stage
TRUE. DNA is replicated
T/F the interphase is characterized by absence of visible chromosomes
TRUE
T/F transitions from one interphase stage to the other are controlled by cell cycle checkpoints
TRUE
what is the role of chromosomes in cell division
allow DNA to be replicated accurately
what is a karyotype? when is the best time to obtain one during mitosis?
image of a complete set of chromosomes in an organism taken during metaphase
stages of mitosis and brief description
Prophase-nuclear membrane breakdown
Prometaphase- chromosomes begin to condense, formation of spindles
Metaphase-full chromosome condensation, spindles attach
Anaphase-separation of sister Chromatids
Telophase-formation of 2 new nuclear membranes
if 2n=6 how many DNA molecules and chromosomes are there for each cell in:
G1
G2
mitotic metaphase
mitotic anaphase
G1: 6 chromosomes, 6 DNA molecules
G2: 6 chromosomes, 12 DNA molecules
mitotic metaphase: 6 chromosomes, 12 DNA molecules
mitotic anaphase: 12 chromosomes, 12 DNA molecules
what is the effect of colchicine on the cell cycle
causes damage to the spindle and arrests mitosis(at metaphase)
T/F at completion of metaphase, the chromosomes align in metaphase plate with spindles attached to TELOMERES
FALSE. They attach at the kinetochore
what is karyokinesis? what phase does it occur
formation of 2 new nuclear membranes. occurs during telophase
what is cytokinesis? what phase does it occur
formation of 2 new cell membranes, occurs during telophase
stages of meiotic division and brief description
prophase I(5 stages)
metaphase I-tetrads orient on metaphase plate
Anaphase I-disjunction (separation of homologs)
Telophase I-much shorter than mitotic phase
Prophase II-telophase II-similar to mitosis
explain monad, dyad, and tetrad, and how many DNA molecules and strands in each
Monad-1 molecule, 2 strands
Dyad-2 molecules, 4 strands
tetrad-4 molecules, 8 strands
what are chiasmata and when do they occur?
site of recombination, occurs in prophase I (pachynema)
what is crossing over? what is its biological importance?
homologs exchange genetic material
leads to genetic variation
T/F in spermatogenesis, spermatogonia undergo first meiotic division to produce primary spermatocytes
TRUE
what are recombination hotspots? what is an example?
they are short regions all over genome for recombination
-major histocompatibility complex
-pseudoautosomal region in males
what are recombination coldspots? what are examples?
on centromeres
T/F secondary spermatocytes undergo meiosis II to produce haploid spermatids
TRUE, however sperm cells become haploid after meiosis I
