-duplicated chromosomes condense -spindle attaches to chromosomes -nuclear envelope begins to break
-condensed chromosomes align -the 2 sister chromatids have a "tug of war" with the spindles
the "tug of war" ends when the chromosomes separate
-begins when chromosomes reach opposite ends -nuclear envelope forms -cell divides
Nucleoli are present during which phase?
Cytokinesis often, but not always, accompanies what phase?
Chromosomes become visible during what phase?
Centromeres divide and sister chromatids become full-fledged chromosomes during what phase?
Spindle fibers attach to kinetochores during what phase?
During prophase a homologous pair of chromosomes consists of what?
two chromosomes and four chromatids
Meiosis I produces _____ cells, each of which is _____.
two ... haploid
Meiosis II typically produces _____ cells, each of which is _____.
four ... haploid
During _____ sister chromatids separate.
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
Synapsis occurs during _____.
Homologous chromosomes migrate to opposite poles during _____.
During _____ chromosomes align single file along the equator of a haploid cell.
At the end of _____ and cytokinesis there are four haploid cells.
During _____ a spindle forms in a haploid cell.
growth phase of a cell
-G1: growth phase of a cell -S Phase: DNA duplicates -G2 Phase: Organelles duplicate -M phase: Mitosis (nuclear division) -C phase: Cytokinesis
In a gamete cell, the cell will contain _____________ chromosome (s) from each homologous pair
which of these is not a function of mitosis in humans?
a.) repair of wounds b.) growth c.) production of gametes from diploid cells d.) replacement of lost or damaged cells
c.) production of gametes from diploid cells
in what sense are the 2 daughter cells produced by mitosis identical ?
when there are identical genes
Why is it difficult to observe individual chromosomes?
Chromosomes are extremely thin and compact
A biochemist measures the amount of DNA in cells growing in the laboratory. The quantity of DNA in a cell would be found to double a.) between prophase and anaphase of mitosis b.) between the G1 and G2 phases of the cell cycle c.) during the M phase of the cell cycle d.) between prophase I and prophase II of meiosis
b.) Between the G1 and G2 phases of the cell cycle
which 2 phases of mitosis are essentially opposites in terms of changes in the nucleus?
prophase and telophase
if an intestinal cell in a dog contains 78 chromosomes, a dog sperm would contain _________ chromosomes
A picture of a dividing cell from a mouse shows 19 chromosomes, each consisting of 2 sister chromatids. During which stage of meiosis could this picture have been taken?
prophase II or metaphase II; it cannot be meiosis I because you would see an even number of chromosomes; it cannot be a later stage of meiosis because you would see the sister chromosomes separated
A diploid body (somatic cell) from a fruit fly contains 8 chromosomes. This means that ____________ different combinations of chromosomes are possible in its gametes.
16 (2n=8, so n=4)
it does not involve the fertilization of egg and sperm
requires fertilization of egg and sperm
fibers with DNA and protein
protein molecule around which DNA is tightly coiled in chromatin
repeating subunit of chromatin fibers, consisting of DNA coiled around histones
2 identical chromosomes fused together
What does cancer have to do with cell division?
when a cell has a malfunction while dividing
What is the connection between the process of crossing over and evolving?
Crossing over introduces genetic variation into gametes. Genetically variable gametes will allow genetically variable offspring to be produced. As a result, a population of organisms become genetically variable overtime .
through meiosis, gamete cells turn into ________ cells
Cytokinesis in plant cells vs. animal cells
Plant cells are still fused together in a way
how many homologous pairs are there in a human somatic cell?