Chapter 10 Flashcards
What is meiosis
cell division by reproductive cells
what are reproductive cells called?
Gametes
Mitosis is performed by what kind of body cells?
normal (somatic cells)
how many rounds are done in mitosis?
one round
what kind of cell division happens in mitosis?
conservative division
how many chromosomes are moved from parent to daughter cells in humans?
46 chromosomes
Meiosis is performed by what kind of cells?
reproductive cells (gametes)
how many rounds of cell division happen in Meiosis?
2 rounds
In miosis, how many chromosomes are transferred from parent to daughter cells?
46 chromosomes to 23 chromosomes.
Why do humans end with 23 chromosomes in meiosis?
Those are the matured egg and sperm cells.
1 haploid egg + 1 haploid sperm = what?
1 diploid zygote
what’s a diploid cell?
cell containing 2 sets of chromosomes
what’s a haploid cell?
cell containing 1 chromosome
independent assortment is what?
gametes carrying random combinations of maternal and parental chromosomes
what is crossing over?
physical exchange of genetic material
what is a tetrad?
4 pairs of chromosomes (bivalent)
in meiosis, prophase 1, what happens in this step?
Tetrads are formed and held together by a synaptonemal complex
what needs to happen before prophase 1 is able to start in meiosis?
DNA is replicated in order to start prophase 1.
crossing over only occurs in what stage of meiosis?
in prophase 1
what happens in metaphase 1 in meiosis?
the tetrads line up along the metaphase plate horizontally.
what happens in anaphase 1 in meiosis?
pairs of sister chromatids move to opposite sides of the cell
what happens in telophase 1 in meiosis?
sister chromatids arrive on opposite sides of the cell, while the sister chromatids are haploid.
how many reductive rounds are formed in telophase 1?
1 round
what is interkinesis?
a resting period between the rounds of cell division.
what happens after interkinesis?
there is 1 conservative round before the next phase.
what happens in prophase 2?
DNA replication does not occur, and chromatids line up in the middle vertically.
what happens in metaphase, anaphase, and telophase 2?
similar to mitosis except 4 haploid daughter cells are formed
spermatogenesis occurs where?
in the male testes
oogenesis happens where?
in the female ovaries
primary oocytes undergo crossing over, when?
before birth then arrests in prophase 1 until ovulation.
what does the zygote inherit from sperm and eggs?
from the sperm it inherits 1 set of chromosomes and a centrosome
from the eggs they inherit all other organelles
what is aneuploid?
having an abnormal amount of chromosomes
what is monosomy?
having one version of a certain chromosome instead of 2.
(a spontaneous miscarriage)
what is trisomy?
having 3 versions of a certain chromosome instead of 2. (spontaneous miscarriage)
nondisjunction
failure of paired chromosomes in cell division
trisomy 21
- aka down syndrome
- 3 copies of chromosome 21
- most common
turner syndrome
- happens in females only
- with only 1 chromosome
Klinefelter’s syndrome
- happens only in males
- has 2 or more chromosomes
