Biology CH 8 part 2
in meiosis
haploid gametes are produces in diploid organisms - 4 gametes are produces interphase is followed by two consecutive divisions, meiosis I and meiosis II
fertilization, zygote
haploid sperm fused with a haploid egg during ______ to form a diploid ______
trisomy
having 3 of a chromosome instead of 2
meiosis I
homologous chromosomes separate
haploid
human gametes are _____ having only one set of chromosomes -- only have 1/2 (23) becyase they have to meet with other 23
diploid
humans are ____ organisms; their somatic cells contain two sets of chromosomes --2 complete sets of chromosomes from mom/dad
2
humans have ___ sex chromosomes which determine your gender
mitotic spindle
in nondisjuction, the ____ ____ grabs the wrong number of chromosomes
down syndrome
is a well known example of nondisjuction also called trisomy 21 individual has extra chromosome 21
karyotype
is an imagine that reveals an orderly arrangement of chromosomes
random fertilization
is another way we get genetic variation but doesnt occur during meiosis
4
meiosis starts with one cell, and ends with ___ celss
70 trillion
more than_____ different possible chromosome combination
variable
offspring produces from sexual reproduction are genetically identical or variable
anti codons
on top
genetic variation
produces offspring that contain a unique combination of genes from the parents
human somatic cell
regular cell in your body skin, kidney, liver, heart has 46 chromosomes (2 sets of 23)
meiosis
1/2 the # of chromosomes 1/2 from mom/dad -uses this to make sperm and egg(sex cells)
asexual reproduction
___ ____ conveys an evolutionary advantage when plants are sparsley distributed or superbly suited to a stable enviroment
sexual reproduction
___ ____ may convey an evolutionary advatage by speeding adaption to a changing enviroment or allowing a population to more easily rid itself of harmful genes
mitosis, diploid
_____ uses one division and produces two ____ cells
meiosis, haploid
______ uses two divisions and produces four _____ cells
prophase I
crossing over occurs during _____. homologoys chromosomes exhancge genetic info results in 4 gametes that are all genetically different
alleles
different versions of the same genes
gametes
genetic variation is produced in the ____. Includes independent assortment and crossing over
meiosis II
sister chromatids separate
Nondisjuction
something goes wrong, disorder, syndromes members of a chromosome pair fail to separate during anaphase producing gametes with an incorrect number of chromosomes
codons
the bottoms,in threes
what happens when errors occur in meiosis
the gametes get the wrong number of chromosomes
what are gametes
they are sex cells (sperm and egg, egg and pollen) in humans 23 chromosomes, in meiosis half # of parent chromosomes
Sexual reproduction
uses meiosis and fertilization
autosomes
what all of our other chromoses that arent sex chromosomes are called --- all regular chromosomes except ones that deal with gender
crossing over, independent assortment
what are the two main processes responsible for producing genetic variation that occur during meiosis?
somatic cell
what do we call a regular body cell
Metaphase I
which stage of meiosis has the side by side orientation of each homologous pair of chromosomes is a matter of chance
haploid, diploid
your gametes are ____ meaning they have only one set of DNA, whereas all your body cells are ___ meaning they have two sets of DNA