Meiosis
Explain what crossing over is and why it is necessary
Paired homologous chromosomes exchange segments of DNA, this contributes to genetic variation
When does spermatogenesis begin?
Puberty
Explain the difference between a dominant and a recessive allele
A dominant allele will mask the expression of a recessive allele when both are present
What is the phenotypic ratio when a heterozygous man with brown eyes has children with a heterozygous woman with brown eyes?
3 brown : 1 blue
Blood types, flower color (red + white = red and white), etc
Explain what independent assortment is and why it is important
Homologous chromosomes line up randomly during metaphase I, this contributes to genetic variation
When does oogenesis begin?
In the fetus
What is a genotype?
An individuals genetic makeup (alleles that are responsible for a given trait)
What is the genotypic ratio when a heterozygous man with brown eyes (Bb) has children with a heterozygous woman with brown eyes (Bb)?
1 BB : 2 Bb : 1 bb
Give an example of incomplete dominance
Hypercholesterolemia, hair type, flower color (red + white = pink)
What is synapsis?
Pairing of homologous chromosomes (one maternal and one paternal) during prophase I
What is produced in meiosis I of oogenesis?
one secondary oocyte and one polar body
What is a phenotype?
An individual's actual appearance/characteristics
Describe a situation where a child does not have the same phenotype as either of his parents
Possible answer: both parents are heterozygous and the child receives both recessive alleles
What is polygenic inheritance?
A trait is controlled by two or more genes (ex: skin color, height)
List all the phases of meiosis in order
Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II
When does meiosis II occur during oogenesis?
When the secondary oocyte is fertilized
What is the difference between homozygous and heterozygous
Homozygous is when the two alleles for a trait are the same and heterozygous is when they are different
A man (type A) and a woman (type B) have a child with type A blood. How is this possible?
The woman has the genotype IBi and passed on the i allele, while the man passed on the IA allele
Neither allele is completely dominant
What is a tetrad?
A pair of homologous chromosomes with 4 chromatids
How many gametes are produced in spermatogenesis and oogenesis?
4 sperm from spermatogenesis, 1 functional egg cell from oogenesis
Explain the law of segregation
Alleles segregate (separate) during gamete formation in meiosis
A man (AB) and a woman (B) have kids. What blood type is impossible for their kids to have?
Type O
What is codominance?
Both alleles are equally dominant