CH 18 Flashcards
When a cell undergoes mitosis what happens to the genes?
the daughter cells have identical genes, and these genes are identical to those of the ?parent? cells that produced them.
What happens to the organelles when a eukaryotic cell divides?
the daughter cells receive enough of the organelles to start up the new cells and produce additional organelles as needed.
In mitosis, if a ?parent? cell has 16 chromosomes, each daughter cell will have how many chromosomes?
- 16
What is the term describes cells with a double set of genetic information
- diploid.
Give an example of a cell that is NOT a somatic cell)
Sperm, egg
What is the chromosome number in human body cells?
- 46.
Chromatids that are attached at the centromere are called what kind of chromatids?
- sister
DNA replication occurs during what phase(s)?
- S phase
What is the number of chromatids present in a duplicated chromosome?
- 2.
Write out the proper sequence of phases for mitosis.
prophase, metaphase, anaphase, telophase
What is the name of the phase during which the chromosomes are aligned at the spindle equator ?
metaphase.
At the end of which phase is the chromosomes condensed?
prophase.
The spindle apparatus becomes visible during what phase
prophase.
The chromosomes detach from one another and become visibly separated during what phase?
anaphase.
The chromosomes are moving to opposite poles during what phase?
anaphase.
The chromosomes have arrived at opposite poles during during?
telophase.
The nuclear membrane reforms during what phase?
telophase.
Strictly speaking, mitosis and meiosis are divisions of which part(s) of a cell?
nucleus and chromosomes.
In which of the stages below does the chromosome consist of two chromatids?
metaphase and prophase
The distribution of cytoplasm to daughter cells is accomplished during what phase?
cytokinesis (cytoplasmic division).
What does ionizing radiation do to cells?
It breaks apart chromosomes and alters genes.
Why do small doses of ionizing radiation over a long period of time cause less damage than the same amount of radiation in a very short time?
the body has time to repair damaged DNA.
What is the purpose of irradiating foods?
It destroy harmful bacteria, fungi and other microorganisms and limits spoilage.
What kinds of cells go through meiosis?
germ cells
What is the main point of meiosis?
each gamete receives one member of each pair of homologous chromosomes, and gametes are formed that are haploid.
What does gamete formation mean?
the formation of sex cells.
What is gametogenesis?
the formation of sex cells.
Give one advantage of sexual reproduction.
results in new combinations of genetic traits.
What would happen if meiosis did not occur in sexually reproducing organisms?
chromosome number would double in each generation.
If a parent cell has 16 chromosomes and undergoes meiosis, each of the resulting cells will have how many chromosomes?
- 8
Homologous chromosomes may swap segments of genetic information during which phase of meiosis?
prophase I
How many chromatids are in cell in prophase I of spermatogenesis in humans?
- 92
How many cells are produced when one cell goes through meiosis
- 4 haploid cells.
What event begins Anaphase?
Anaphase is initiated when the newly divided centromeres begin to move apart.
Paired homologous chromosomes are found at the spindle equator during what phase?
metaphase I.
What happens to the DNA during meiosis II?
sister chromatids of each chromosome are separated from each other.
Copies of chromosomes linked together at their centromeres at the beginning of meiosis are appropriately called what kind of chromatids?
sister
What is crossing over?
alters the composition of chromosomes and results in new combinations of alleles being channeled into the daughter cells.
Intimate contact between homologous chromosomes and crossing over occur during what phase?
- prophase I.
Why is crossing over important?
It increases variability in gametes.
Pairing of homologues and crossing over occur during what? phase
prophase I.
What are different, or alternative, forms of the same gene called?
- alleles.
During meiosis in what phase are sister chromatids separated from each other?
anaphase II.
Under favorable conditions, during which phase of meiosis will the chromosomes appear as packets of four chromatids?
prophase I
Why is crossing over one of the most important events in meiosis?
it produces new arrays of alleles on chromosomes.
46) During what phase are maternal and paternal chromosomes shuffled most?
- metaphase I.
During anaphase I, each homologue is separated from its partner. What is this process is called?
disjunction.
How is genetic variation associated with meiosis manifested?
There are new combinations of alleles due to crossing over. There is random movement of homologous pairs of chromosomes moving to spindle poles. random chance playing a role when a sperm fertilizes an egg.
In what phase(s) are the events of the cell cycle mainly cytoplasmic, not chromosomal?
- G1 and G2
During which phase of mitosis are the nuclei reformed?
telophase
In which phase of mitosis are the chromosomes lined up on the equator?
metaphase
