Meiosis quiz 1 Flashcards
Somatic cells
normal body cells
Gamete cells
sex cells (sperm and eggs)
What does it mean when homologous chromosomes are homozygus?
They have two of the same alleles
What does it mean when homologous chromosomes are heterozygus?
They have two different alleles
Define homologous chromosomes
chromosomes that have the same genes at the same loci, but don’t necessarily have the same alleles
Allele
version of a gene
e.g. the eye gene could have the brown allele or blue allele, etc
When are sister chromatids not identical?
after crossing over
what is the final autosome?
number 23 is the pair of sex chromosomes (usually XX or XY)
Fertilization and it’s product
it is the union of sperm and egg, and the product is a zygote (fertilized egg)
Crossing over (or synapsis) and when it occurs
when two non sister chromatids in a tetrad overlap at chiasmata and exchange DNA
occurs in prophase I
What is the point of overlap in crossing over called?
A chiasma, or many chiasmata
Tetrad
A pair of homologous chromosomes that are attached (synapsis)
What is the difference between metaphase I and metaphase II?
in metaphase I, homologous chromosomes line up together, making it a double file line of chromosomes at the metaphase plate
in metaphase II, they line up single file, just like mitosis
What does it mean that chromosomes line up during metaphase I independent of each other?
the chromosomes can arrange (orient) in any way at the metaphase plate, independently from other chromosomes
How many possible gametes are there in humans?
2 to the 23rd power
