Top2-Ch3-P43-48 Flashcards
What are the two types of melanin (causes darker hair) responsible for hair colour?
Eumelanin (brown/black) and pheomelanin (red/yellow)
What does melanin do?
protects from sun
The cause of red hair was discovered when, what is it called and what chromosome is it on?
- Discovered in 1993
- melanocortin-1 receptor
- on Chromosome 16
Most redheads have _____ mutated _____ copies, which means a ______ inheritance pattern.
But about ______ people have only one.
two, MCR1, recessive, 10-20%
Who discovered the basic principles of heredity?
Gregor Mendel
What plant did Mendel use for his experiments and why was it a good choice?
the pea plant (pisum sativum)
Advantages: easy to cultivate, grew quickly for a plant and had a large number of varieties.
What were the seven characteristics that Mendel chose to study?
- Seed (endosperm) color - yellow or green
- Seed shape - round or wrinkled
- Seed coat colour - gray or white
- Pod colour - yellow or green
- Pod shape - inflated or constricted
- Flower position - axial (along stem) or terminal (at tip of stem)
- Stem length - short or tall
When did Mendel publish his findings?
1866
Gene is?
a genetic factor (region of DNA) that helps determine a characteristic.
Allele?
One of two or more alternative forms of a gene.
Locus?
Specific place on a chromosome occupied by an allele. Plural is loci.
Genotype?
Set of alleles possessed by an individual organism.
Heterozygote?
An individual organism possessing two different alleles at a locus.
Wikipedia: Diploid organisms have the same genes on each of their two sets of homologous chromosomes, except that the sequences of these genes may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous for the trait. If they are different, the organism is heterozygous for that trait.
Homozygote
An individual organism possessing two of the same alleles at a locus.
Wikipedia: Diploid organisms have the same genes on each of their two sets of homologous chromosomes, except that the sequences of these genes may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous for the trait. If they are different, the organism is heterozygous for that trait.
A phenotype or trait is?
wikipedia: the composite of an organism’s observable characteristics or traits, such as its morphology, development, biochemical or physiological properties, phenology, behavior, and products of behavior (such as a bird’s nest). Phenotypes result from the expression of an organism’s genes as well as the influence of environmental factors and the interactions between the two.
book: appearance or manifestation of a character
How did Mendel stop the peas from self-fertilising?
He opened the buds before the anthers (male sex organs) were fully developed, removing the anthers and then dusting the stigma (female sex organs) with pollen from a different plant’s anthers.
