Meiosis Flashcards
What are somatic cells also known as
Body cells
How many cells does Meiosis produce?
4
How many chromosomes does each gamete have?
23 chromosomes
What is Meiosis?
Sexual reproduction
Prophase l
Longest and most complex stage of PMAT. Synapsis occurs
What is Synapsis?
When homologous chromosomes come together to form a tetrad.
What is a Tetrad composed of?
Two chromosomes or four chromatids.
Metaphase l
Shortest Phase. Tetrads align on the equator.
When does “crossing over” happen?
Prophase l
What does “crossing over” cause?
Genetic Variation
Anaphase l
The homologous chromosomes separate and move towards the poles. The sister chromatids remain attached at their centromeres
Telophase l
Each pole now has a diploid set of chromosomes. Cytokinesis occurs and two diploid daughter cells are produced
What does Haploid mean?
The presence of a single set of chromosomes in a organism’s cells
What does Diploid mean?
A full set of chromosomes (2 homologous chromosomes)
What is similar to Meiosis ll
Mitosis
Explain Prophase ll
Same as Prophase in Mitosis
Metaphase ll
Same as Metaphase in Mitosis
Anaphase ll
Same as Anaphase in Mitosis
Telophase ll
Same as Telophase in Mitosis
What are the three sources of genetic variation?
-“Crossing over”
-Independent assortment
-Random Fertilization
A cell containing 40 chromatids at the beginning of meiosis (after DNA replication) would, at its completion, produce cells containing how many chromosomes?
10 chromosomes
What is a alternate name for down-syndrome?
Trisomy 21
What causes genetic variation?
Crossing Over, Random Fertilization, & independent assortment
What are the cells produced in meiosis called?
Gametes/Sex Cells
What is it called when a sperm and egg meet?
Fertilization
What are alleles?
Two forms of single genes
What is the genetic disorder caused when a child is born with three copies of chromosome 21?
Down Syndrome
Each half of a duplicated chromosome is a?
sister chromatid
What is it called when chromosomes fail to separate resulting in abnormal numbers of chromosomes?
Nondisjunction
When does independent assortment occur?
Metaphase l &/or ll
What is independent assortment?
Chromosomes will be lined up in random orders in metaphase l & ll
When are homologous chromosomes separated?
Metaphase l
When are sister chromatids separated?
Anaphase ll
What is another name for Edwards Syndrome?
Trisomy 18
What chromosome pair tells you the sex of the organism?
The 23rd chromosome pair
What is another form of XY to tell an individual’s sex on a karyotype chart?
Xx
What is the equation for fertilization?
n + n = 2n
What is a zygote?
The product of a sperm and a egg cell
What is the next stage after a zygote?
Embryo
What stage does an embryo grow in?
Mitosis
Chromosomes that contain the same genes. You get one from each parent
Homologous Chromosomes
Which phase/s can nondisjunction occur?
Anaphase l & ll
