The Brain and Behavior: Chapter 4 Genetics, Evolution, Development and Plasticity

dominant gene

gene that shows a strong effect in either the homozygous or heterozygous condition

recessive gene

gene that shows effects only in the homozygous condition

sex-linked gene

gene on either the X or the Y chromosome

autosomal gene

any gene other those on the X or Y chromosome

sex-limited gene

gene present in both sexes but that exerts its effects primarily in one sex

gene

unit of heredity that maintains its structural identity from one generation to another

chromosome

strand of genes

deoxyribonucleic acid (DNA)

double-stranded molecule that is part of the chromosomes

ribonucleic acid (RNA)

single-strand chemical coded by DNA

homozygous

having two identical genes for a given characteristic

heterozygous

having two unlike genes for a given trait

mutation

heritable change in a DNA molecule

epigenetics

field that deals with changes in gene expression without modification of the DNA sequence

histone

protein that binds DNA into a shape that resembles a string wound around a ball

heritability

estimate of the degree to which variation in a characteristic depends on genetic variations

phenylketonuria (PKU)

genetic inability to metabolize the amino acid phenylalanine

evolution

change over generations in the frequencies of various genes in a population

artificial selection

process of selecting plants/animals for desired traits

Lamarckian evolution

hypothesis that use of some body part will change its size in the next generation

fitness

spreading of genes

altruistic behavior

action that benefits someone other than the actor

proliferation

production of new cells

migrate

movement of brain neurons or glia

myelination

process by which glia produce insulating fatty sheaths that accelerate transmission in many vertebrate axons

neural Darwinism

principle of competition among axons

nerve growth factor (NGF)

protein that promotes the survival of axons in certain axons in the brain

apoptosis

programmed mechanism of cell death

far transfer

improvement of a skill due to practice at a dissimilar skill

stroke

temporary loss of normal blood flow to a brain area

cerebrovascular accident

result of interrupted blood flow to the brain from blood clot or ruptured artery

edema

accumulation of fluid

tissue plasminogen activator (tPA)

drug that breaks up blood clots

diaschisis

decreased activity of surviving brain neurons after damage to other neurons

collateral sprout

newly formed branch of an axon

deafferent

loss of sensory input