chapter 4-sexual cell reproduction Flashcards
daughter cells contain…
half the number of chromosomes from their parent (1N)
the process of creating haploid cells enables species to…
maintain a constant chromosome number from generation to generation.
what happens when haploid cells fuse during fertilization?
diploid cells form containing parental chromosome number (2N)
what is meiosis 1 known as?
reduction division
what happens in meosis 1?
- chromosome number is reduced by one half
- homologous paired chromosomes separate to opposite ends
what is segregation?
when homologous paired chromosomes separate to opposite ends
what happens in crossing over?
genetic material exchanges= greater diversity
what happens in meiosis 2?
- separation of the sister chromatids
- 4daughter cells from original parent cell
what is gametogenesis?
it’s the process in which sex cells are formed
gametogenesis in males:
single cell produces 4 identical sperm cells all capable of fertilazation
gametogenesis in females:
a single cell produces three polar bodies containing 1N chromosomes but very little cytoplasm
=not used in fertilization
4th cell = ootidreceives most of the cytoplasmic material =used for fertilazation.
what is nondisjunction?
the failure of the separation of sister chromatids or homologous chromosomes
when does nondisjunction occur?
when homologous chromosomes move to the same pole during meiosis
result of nondisjunction?
one daughter cell = missing one chromosome, the other carrying an extra
list some disorders
trisomy-3 copies of a chromosome
(Down syndrome=extra chromosome in #21)
monosomy- carries a single chromosome rather than a homologous pair(Turner syndrome=carries only x)
why is cell division important?
growth,repair, reproduction
chromosomes?
long threads of genetic material found in the nucleus of a cell
chromatids?
single stands of a chromosome
centromeres?
structures that hold chromatids together
centrioles?
small protein bodies that are in the cytoplasm of an animal cell
spindle fibers?
protein structures that divide chromosomes during cell division
what happenes in prophase?
spindle fibers act as guide wires for attachment and movement of the chromosomes during division
what happenes in metaphase?
chromosomes composed of sister chromatids move towards the center of the cell
what happenes in anaphase?
centromeres divide and chromatids move to opposite poles
what happenes in telephase?
chromosomes lengthen and intertwine.spindle fibers dissolve. nuclear membrane forms around each mass of chromatin.
what is Interphase?
cell activity between cell divisions.
cells grow, carry out chemical activities that sustain life.
cells produce protein to prep for mitosis
what is cytokinesis?
division of cell cytoplasm
must provide organelles for each of the new cells
what is cloning?
identical offspring are produced from a single cell or tissue.
What is the process of meiosis?
it is the process by which sex cells are formed
