Chapter 2 - Evolution, Genetics and Experience Flashcards
Dichotmous traits
traits that occur in one form or the other, never in Combination
true-breeding lines
breeding lines in which interbred members always produce offspring with the same trait, eg brown seeds, generation after generation
dominant trait
the trait of a dichotomous pair that is expressed in the phenotypes of heterozygous individuals
recessive traits
the trait of a dichotomous pair that is not expressed in the phenotype of heterozygous individuals
phenotype
an organisms observable traits
genotype
that trait that it can pass on to offspring through genetic material
alleles
two genes that control the same trait
homozygous
organisms that possess two identical genes for a trait are said to be homozygous
heterozygous
organisms that possess two different genes for a trait are said to be heterozygous
chromosomes
threadlike structures in the cell nucleus that contain the genes, each chromosome is a DNA molecule
- they occur in matched pairs, and each species has a characteristic number of pairs in each of its body cells (23 pairs)
gametes
egg cells and sperm cells
meiosis
in meiosis, the chromosomes divide and one chromosome of each pair goes to each of the two gametes that results from cell division
> as a result, each gamete only has half the usual number of chromosomes
zygote
a fertilized egg cell, it is produced in meiosis, when a sperm and egg cell combine during fertilization with the full complement of chromosomes
genetic recombination
the meiotic process by which pairs of chromosomes cross over one another at random points, break apart and exchange genes
mitosis
the process of cell division that produces cells with the same number of chromosomes as the parent cell
DNA - deoxyribonucleic acid
the double-stranded, coiled molecule of genetic material,
each strand is a sequence of nucleotide bases attached to a chain of phosphate and deoxyribose
four nucleotide bases: adenine & thymine, guanine & cytosine
DNA - replication
critical process by which the DNA molecule duplicates itself
mutations
errors in duplication take the form of mutations—accidental alterations in individual genes.
autosomal chromosomes
chromosomes that come in matched pairs
sex-chromosomes
one exception to the autosomal chromosomes, pair of chromosomes that determines the individual’s sex
sex-linked traits
traits that influenced by genes on the sex chromosomes
Proteins
long chains of amino acids, they control the physiological activity of cells and are important components of cellular structure
Enhancers
stretches of DNA whose function is to determine whether particular structural genes initiate the synthesis of proteins and at what rate
> they are found in the stretches of DNA that lack structural genes
gene expression
the production of the protein specified by particular genes
transcription factors
Proteins that bind to DNA and influence the extent to which genes are expressed
> many of the description factors that control enhancers are influenced by signals received by the cell from the envrionment
RNA (ribonucleic acid)
a molecule that is similar to DNA except that has the nucleotide base uracil and a phosphate and ribose backbone
mRNA (messenger RNA)
a strand of RNA that is transcribed from DNA and then moves out of the cell nucleus where it is translated into a protein
ribosomes
a structure in the cell’s cytoplasm that translates strands of messenger RNA into proteins
codon
each group of three consecutive nucleotide bases along the mRNA strand
> instructs the ribosome add 1 of the 20 different kinds of amino acids
transfer RNA
molecules of RNA that carry amino acids to ribosomes during protein synthesis; each kind of amino acid is carried b a different kind of transfer RNA molecule
Human Genome Project
the international research effort to construct a detailed map of human chromosomes
Epigenetics
the study of the all mechanisms of inheritance other than the genetic code and its expression
DNA methylation
reaction that occurs when a methyl group attached to a DNA molecule; usually at cytosine
> can either increase or decrease expression
Histone remodeling
reaction that occurs when histones (proteins around which DNA is coiled) change their shape and therefore influence the adjacent DNA
> can either increase or decrease expression
RNA editing
some epigenetic effects regulate gene expression by acting on mRNA rather than genes
transgenerational epigenetics
epigenetic mechanisms passed on to future generations
> examines the transmission of experiences via epigenetic mechanisms across generations
phenylperuvic acids
a substance that is found in abnormally high concentrations in the urine of those suffering from phenylketonuria
Phenylketonuria (PKU)
a neurological disorder whose symptoms are vomiting, seizures, hyperactivity, hyper irritability, intellectual disability, brain damage and high levels of phenylpyruvic acid
sensitive period
period early in life, during which a particular experience must occur to have a major effect on the development of a trait
sensory phase
the first of the two phases of birdsong development, during which young birds do not sing but form memories of the adult songs they hear
sensorimotor phase
the second of the two phases of birdsong development, during which juvenile birds progress from sub songs to adult songs
monozygotic twins
develop from the same zygote and thus are genetically similar
dizygotic twins
developed from two zygotes and thus are no more similar than any pair of siblings
heritability estimate
a numerical estimate of the proportion of variability that occurred in a particular trait in a particular study and that resulted from genetic variation among the subjects in that study
> tells us about the contribution of genetic differences to phenotypic differences among the participants in a study; they have nothing to say about the relative contributions pf genes and experiences to the development of individuals
