Chapter 4 Review Flashcards
What are the 2 strands of a double-stranded chromosome called?
sister chromatids
Describe what happens during Anaphase I of meiosis.
spindle fibres contract, separating homologous pairs of chromosomes
Describe what happens during Metaphase of mitosis.
spindle fibres pull chromosomes into a single line along the equatorial plate
Is Metaphase of mitosis more similar to Metaphase 1 or Metaphase 2 of meiosis? Explain.
Metaphase of mitosis is more similar to Metaphase 2 of meiosis. In both, chromosomes line up in a single line along the equatorial plate.
What are 2 purposes for cells in an organism to undergo mitosis?
- growth
- repair (replacement of damaged or dead cells)
Define and contrast diploid and haploid.
- diploid describes a cell with 2 sets (or the full set) of chromosomes
- haploid describes a cell with 1 set (or half of the full set) of chromosomes
What is the only type of cell that could not be used for cloning an individual organism?
a gamete because it doesn’t contain the full set of an organism’s chromosomes
Name the only type of cell that undergoes meiosis in a human male.
spermatocytes (in the testes of the human male)
What is synapsis and when does it occur during meiosis?
Synapsis is the pairing of homologous chromosomes. It occurs during Prophase 1 of meiosis.
What is crossing over and when does it occur during meiosis?
Crossing over is the exchange of genetic material between 2 homologous chromosomes. It occurs during Prophase 1 of meiosis (and possibly during early Metaphase 1).
If an oocyte undergoes meiosis, what does it produce? (Be specific about the number and type of cells it produces)
Meiosis of an oocyte will produce 3 nuclei (polar bodies) and 1 immature egg cell (ootid)
A cat has 38 chromosomes in its muscle cells. How many chromosomes does it have in its heart cells?
38 (muscle cells and heart cells are both diploid)
What do ‘2n’ and ‘n’ refer to?
- ‘2n’ refers to the diploid number
- ‘n’ refers to the haploid number
What is a karyotype?
A karyotype is a picture of a cell’s chromosomes.
How many autosomes are there in a normal human sperm cell?
There are 22 autosomes (and 1 sex chromosome) in a normal human sperm or egg cell.
What is nondisjunction?
Nondisjunction is when homologous pairs do not split during Anaphase 1 of meiosis.
Name a nondisjunction disorder, and describe its karyotype.
- Down syndrome (trisomy 21)
- Klinefelter’s syndrome (trisomy 23, XXY)
- Turner syndrome (monosomy 23, XO)
- Trisomy 13 (trisomy 13)
Explain how a trisomic female (XXX) would be produced.
Nondisjunction would have caused the egg cell to have 2 X chromosomes. When it was fertilized by a normal sperm cell, there would be 3 X chromosomes in the zygote.
What are 2 events that occur during interphase?
cell growth, repair, normal cell functions, DNA replication
What is amniocentesis and what is it used for?
Amniocentesis is the extraction of a sample of the amniotic fluid of an unborn fetus. It can be used to screen for genetic disorders such as Down Syndrome in a fetus.
