Lecture 2 Flashcards
What is a dominant trait?
-the trait of a dichotomous pair that is expressed in the phenotypes of heterozygotes
-the trait that Mendel observed in all the first-gen offspring when he cross bred true-breeding brown seed pea plants with true-breeding white-seed pea plants
lol say that 10 times fast
What is a recessive trait?
-the trait of a dichotomous pair that is NOT expresses in the phenotypes of heterozygous individuals
-the trait Mendel observed in about one quarter of the second gen offspring from cross breeding true breeding brown seed pea plants with true breeding white seed pea plants
What is a phenotype?
An organisms observable traits
What is a genotype?
Traits that an organism can pass on to its offspring through its genetic material
What is a Gene?
-an inherited factor
-situated in the same location on each of the chromosomes in a particular pair and that controls a specific trait
-humans have about 20,000
-has protein-encoding (i.e., structural) versions, which constitute only about 2% of human DNA
-in Mendels experiments, the inherited seed colour would be an example of this
What is an allele?
-one of the two genes that control different versions of the same trait
-for each dichotomous trait, is what each organism randomly inherits one from two of its fathers genes and one from two of its mothers genes
What is a chromosome?
-a threadlike structure in the cell nucleus that contains genes
-humans have 23 pairs of this in almost all of their body cells
-composed of tow complementary strands of DNA
What is a Zygote?
-a fertilized egg cell
-the immediate result of a sperm cell and an egg cell combining during fertilization
What is a codon?
-a group of three consecutive nucleotide bases on a DNA or messenger RNA strand
-specifies the particular amino acid that is to be added to an amino acid chain during protein synthesis
What is “epigenetic”?
-type of mechanism that can influence the expression of genes without changing the genes themselves
-type of mechanisms that are assumed to be the means by which a small number of genes are able to orchestrate the development of humans in all their complexity
-the study of these mechanisms has recently shown rapid growth as a result of the discovery that genes compose only 2% of human DNA
What is a monozygotic twin?
-also known as an identical twin
-type of twin that develops from the same zygote as its twin sibling
-genetically identical to its twin sibling
What is a dizygotic twin?
-also known as a fraternal twin
-type that develops from a different zygote than its twin sibling
-no more genetically similar to its twin than it would be to a non-twin sibling
What is a heritability estimate?
-a numerical estimate of the proportion of variability that occurs in a particular trait in a particular study as a result of the genetic variation in that study
-tells us about the contribution of genetic differences to phenotypic differences among the subjects in a study
-depends on the amount of genetic and environmental variation from which it was calculated
What was found to be low for IQ from twins whose families were very poor but high for IQ from twins whose families were rich? Who found this?
Heritability estimate
Turkheimer et al.
