4.1 Flashcards
blending inheritance
hereditary determinants blend in the offspring such that offspring has intermediate traits
the original parental traits were lost or absorbed by the blending in the offspring
particulate inheritance
hereditary determinants are discrete particles and remain intact in the offspring
the original parental traits were not blended in the offspring, rather that they could be passed on
Gregor Mendel’s scientific method
Question: How does the transmission of traits occur?
Hypothesis: Mathematical regularities could be observed in the appearance of a trait.
Experiment: The controlled monohybird cross was designed to test the hypothesis.
Analysis: The data was summarized in a single table to look for math regularities.
Common garden pea
easy to grow
reproductive cycle is short
produces large number of seeds
traits are easily recognizable
easy to control matings
self-pollination
pea reproduction method
pollen encounters ovule within the same plant
female reproductive organ: pistil, creates ovule
male reproductive organ: stamen, creates pollen
cross-pollination
collect pollen from one individual and transfer it to the female organ of an individual whose male organs have been removed
characterisitic
observable physical feature
trait
particular form of a character
monohybrid cross
cross parental varieties with contrasting traits for a single character to produce F1 seeds
F1 plants self-pollinate to produce F2 generation
result of Mendel’s experiment
supported the particulate inheritance hypothesis
trait that was visible in F1 and more abundant in F2: rounded peas
trait that disappeared in F1 and reappeared in F2: wrinkled
monohybrid crosses for several characteristics
F1 progeny only showed the dominant trait
the ratio of F2 individuals with dominant and recessive traits was about 3:1
genes
hereditary determinants occur in pairs and separate from one another during the formation of gametes
2n or n
2n
state of having two copies of each gene
n
having a single copy of each gene
allele
different traits arise from different forms of a gene
homozygous: two identical alleles
heterozygous: two different alleles
phenotype
physical appearance of an organism
genotype
genetic composition of the organism
homologous chromosomes
carry the same genes in the same locations, but each one may contain different alleles
diploid: cells with two homologs of each type of chromosome
somatic cells
diploid
germ-line cells
haploid
sexual reproduction
egg and sperm cells fuse to form a zygote, restoring the chromosome number
animal’s life cycle
gametes are produced from germ cells by meiosis, each parents contributes one gamete to an offspring
two gametes fuse during fertilization to form a zygote
zygote develops through mitosis into an adult of the next generation
