MEIOSIS
The stage of meiosis during which homologous chromosomes separate and move toward opposite poles.
What is anaphase I?
These two meiotic processes generate new combinations of alleles in gametes.
What are crossing over and independent assortment?
The probability that a gamete produced by an Aa individual contains the recessive allele.
What is 1/2 or 50%?
This inheritance pattern occurs when the heterozygous phenotype is intermediate between the two homozygous phenotypes.
What is incomplete dominance?
These two factors interact to produce an organism's phenotype.
What are genotype and environment?
This division of meiosis reduces chromosome number from diploid to haploid by separating homologous chromosomes.
What is meiosis I?
The stage of meiosis during which nonsister chromatids of homologous chromosomes exchange corresponding segments of DNA.
What is prophase I?
The probability of the recessive phenotype among offspring from the cross Aa × Aa.
What is 1/4 or 25%?
For an X-linked recessive disorder, this is the probability that a son of a heterozygous carrier mother and an unaffected father will have the disorder.
What is 50%?
Genetically identical hydrangeas produce different flower colours when grown under different soil conditions. This factor explains the phenotypic difference despite identical genotypes.
What is the environment?
In a species with 2n = 12, these are the numbers of chromosomes and chromatids found in one cell at metaphase II.
What are 6 chromosomes and 12 chromatids?
This process results from the random orientation of homologous chromosome pairs at metaphase I.
What is independent assortment?
Assuming independent assortment, this is the probability of producing AAbb from the cross AaBb × AaBb.
What is 1/16?
A recombination frequency of 18% between two genes corresponds approximately to this distance on a chromosome.
What is 18 map units? Or 18 Centimorgans (cM)?
Genetically identical plants grown under different light intensities reach different heights. This observation demonstrates this important relationship.
What is the effect of the environment on phenotype (or genotype-environment interaction)?
Failure of homologous chromosomes to separate during meiosis I produces two gametes with this chromosome number and two gametes with this chromosome number.
What are two n + 1 gametes and two n − 1 gametes?
This exchange between nonsister chromatids creates recombinant chromosomes containing combinations of alleles that were not present on either original chromosome.
What is crossing over?
This cross between an individual showing a dominant phenotype and a homozygous recessive individual can reveal the unknown individual's genotype.
What is a testcross?
This type of inheritance explains why an affected mother can transmit a mitochondrial mutation to both sons and daughters, while an affected father generally does not transmit it to his children.
What is maternal or mitochondrial inheritance?
In Himalayan rabbits, this environmental factor affects the activity of the pigment-producing pathway, causing cooler body regions to develop darker fur.
What is temperature?
Ignoring crossing over, this is the number of genetically different gametes that can be produced through independent assortment by an organism with three homologous chromosome pairs.
What is 8?
(23 = 8)
AaBbCc
2x2x2=8
Ignoring crossing over, these are the respective numbers of possible chromosome combinations in gametes produced by organisms with 3 versus 12 homologous chromosome pairs.
What are 8 and 4,096?
(23=8 ;212 = 4,096)
In the cross AaBb × AaBb, this is the probability that an offspring expresses the dominant phenotype for exactly one of the two traits.
What is 3/8?
A–bb = 3/16 and aaB– = 3/16
3/16 + 3/16 = 6/16 = 3/8
A testcross produces:
AB = 412
ab = 398
Ab = 94
aB = 96
These are the parental phenotypes and the approximate distance between the two genes.
What are AB and ab, and 19 map units?
Recombinants = 94 + 96 = 190
190/1000 × 100 = 19%
Genetically identical plants average 82 cm in high-nutrient soil and 49 cm in low-nutrient soil. Write a testable question for this observation.
What is do environmental conditions influence phenotype?