Definitions
first round of meiotic cell division; referred to as reduction division because the ploidy level is reduced from diploid to haploid
meiosis 1
What is the main process taking place in meiosis 1?
homologous chromosomes separate
Humans can make 2^23 different combinations of chromosomes in gametes because they have a haploid chromosome number of
23
Mistakes in meiosis are the leading cause of....
miscarriage
in a dihybrid cross, how do we determine what genotypes to place with each square (from the parent's genotypes ie mom is GgBB and Dad is ggBb)
use the foil method
ex: mom- GgBB
f- GB
o- GB
I-gB
L- gB
protein lattice that forms between homologous chromosomes during prophase I, supporting crossover
synaptonemal complex
What is the main process occurring during meiosis 2?
sister chromatids separate
t/f even self-fertilization can lead to genetic variation
true
what is the failure of the chromosomes to separate, which produces daughter cells with abnormal numbers of chromosomes
nondisjunction
we call the crossing of a single trait a
monohybrid cross
the division of nuclear material
karyokinesis
What is a key event of prophase 1?
crossover between non-sister chromatids
The following definition is for what genetic variation-causing factor?
formation of random combinations of chromosomes in meiosis and of genes on different pairs of homologous chromosomes by the passage according to the laws of probability of one of each diploid pair of homologous chromosomes into each gamete independently of each other pair
independent assortment
nondisjunction can occur in what percentage of meiotic divisions?
10%
t/f mendel concluded through his pea plants that it makes a difference whether or not the genetic determinant comes from the male or female gamete
false
formation of a close association between homologous chromosomes during prophase I
synapsis
there are ___ daughter cells.
they are (diploid/haploid)
4, haploid
In what phase of meiosis does crossing over occur?
A person's cells undergo nondisjunction during meiosis 1. Subsequently, they now have 3 of a chromosome rather than two. This condition is called
trisomy
what genotypes must combine in a punnet square to produce a recessive phenotypic trait?
two recessive genotypes (two lowercase)
two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I
tetrad
How many homologs are in each daughter cell?
1
What three things does genetic variation result from?
2. crossing over
3. random combination of egg and sperm
what do we call a zygote with too few or too many chromosomes?
aneuploid
What is the principle of independent assortment?
Alleles of different genes located on different
chromosomes are transmitted independently
of each other