Meiosis Flashcards
(40 cards)
How many chromosomes are there in humans?
23
Each pair lines up and separates independently during meiosis I.
What is a gene?
An inherited factor (region of DNA) that helps determine a characteristic.
What is an allele?
One of two or more alternative forms of a gene.
What is a locus?
A specific place on a chromosome occupied by an allele.
What is a genotype?
A set of alleles possessed by an individual organism.
What is a heterozygote?
An individual organism possessing two different alleles at alocus.
What is a homozygote?
An individual organism possessing two of the same alleles at a locus.
What is a phenotype?
The appearance or manifestation of a characteristic.
What is a characteristic?
An attribute or feature possesed by an organism.
What occurs during interphase?
DNA synthesis and chromosome replication.
In meiosis I, homologous chromosomes separate. How is the chromosome number affected?
It is reduced by half.
What separates in meiosis II?
Sister chromatids.
This is known as equatorial division.
True or false: homologous chromosomes are similar, but no identical.
True.
Each homolog carries the asme genes in the same order, but the allelets for each trait may not be the same.
What is the term for the point on a chromsome by which it is attached to a spindle fiber during cell division?
Centromere
What is a chromatid?
Two daughter strands of a duplicated chromosome that are joined by a single centeromere and separate during cell divisio to become individual chromosomes.
In prophase I, synapsis of homologous chromosomes occurs. What is synapsis?
Close pairing of homologous chromosomes.
What is a tetrad?
Closely associated four-sister chromatids of two homologous chromosomes.
What is the first mechanism of generating genetic variation in newly formed gametes?
Crossing over.
What is the second mechanism of generating genetic variation in the newly formed gametes?
Anaphase I.
The homologous chromosomes are randomly distributed into two newly divided cells.
When does crossing over take place?
Late prophase I
What is a disadvantage of corssing over?
It can result in unequal exchange of genetic material producing chromosomes with deleted or duplilcaed regions.
Crossing over is essential for meiosis. Why is so essential?
Crossing over is essential for the normal segregation of chromosomes during meiosis.
It also adds additional genetic variation.
Crossover is ___ across the centromere.
Independent
Crossing over is proportional to ____.
distance
