Mendelian, Quantitative, and Evolutionary Genetics

particulate inheritance

The observation that genes from two parents do not blend together to form a new physical entity in offspring, but instead remain separate or particle-like.

true-breeding

another way to say that organisms are homozygous for a trait

gene

a heritable unit that affects a phenotype

Allele

a version of a gene

Homozygote

organism that inherits two alleles of the same type for a given gene

Heterozygote

organism that inherits two different alleles for a given gene

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits.

Law of Segregation

first law of heredity stating that pairs of alleles for a trait separate randomly when gametes are formed

independent assortment

the alleles of two (or more) different genes get sorted into gametes independently of one another

Product Rule

the probability that two independent events will both occur at the same time

sum rule

the probability that one or the other of two mutually exclusive events will occur is the sum of their individual probabilities

Chi-square test

A statistical method of testing for an association between two categorical variables. Specifically, it tests for the equality of two frequencies or proportions.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

Mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes

spindle fibers

Protein structures which move the chromosomes during cell division.

Kinetichore

complex of DNA/proteins to which spindle fibers attach and shorten

Microtubules

Spiral strands of protein molecules that form a tubelike structure

cohesion proteins

proteins on the centrosome region of a chromosome which help two sister chromatids or 2 homologs stick together

Centrosome

A structure in animal cells containing 2 centrioles from which the spindle fibers develop.

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

prophase I

The chromosomes condense, and the nuclear envelope breaks down. crossing-over occurs.

metaphase I

Pairs of homologous chromosomes move to the equator of the cell.

anaphase I

Homologous chromosomes move to the opposite poles of the cell.

telophase I

A nuclear membrane forms around each cluster of chromosomes. Two daughter cells formed

Cytokinesis

Division of the cytoplasm during cell division

Meiosis II

the second phase of meiosis consisting of sister chromatids separating, along with the two diploid cells splitting in two

Diploid

containing two complete sets of chromosomes, one from each parent.

Haploid

having a single set of unpaired chromosomes

X-linked recessive

carried by females and affects males more is what is usually the case

X-linked dominant

a mode of genetic inheritance by which a dominant gene is carried on the X chromosome. an affected father affects all his daughters

autosomal recessive

two copies of an abnormal gene must be present in order for the disease or trait to develop. usually doesn't have much a difference in who is affected between sexes

autosomal dominant

Name the pattern of genetic transmission characterized thus: both M and F are affected; M may transmit to M; each generation has at least one affected parent; and one mutant allele may produce the disease.

checkpoints in cell cycle

G1, S, G2, M

Nondisjunction

Error in meiosis I in which homologous chromosomes fail to separate. Or sister chromatids in meiosis II

Y-linked traits

only affect males, and affect all sons of an affected male.

Mitochondrial inheritance

Disease occurs in both males and females, inherited through females only

heterogametic sex

The sex (male or female) that produces two types of gametes with respect to sex chromosomes. For example, in the XX-XY sex-determining system, the male produces both X-bearing and Y-bearing gametes.

homogametic sex

The sex (male or female) that produces gametes that are all alike with regard to sex chromosomes. For example, in the XX-XY sex-determining system, the female produces only X-bearing gametes.

environmental sex determination

a process in which sex is determined largely by the environment, such as by temperatures

temperature-dependent transcription factors

what causes some fish or reptiles to develop into a male or female during egg incubation

dosage compensation

Mechanism in which X chromosome inactivation equalizes gene expression between males and females. Different organisms have different mechanisms for this

X chromosome inactivation

in female mammals, the inactivation of one X chromosome in each somatic cell. Barr bodies make them inaccessible for transcription

dihybrid cross

Cross or mating between organisms involving two pairs of contrasting traits

partial dominance (incomplete dominance)

the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties

Codominance

A condition in which neither of two alleles of a gene is dominant or recessive. The phenotype is those traits coexisting rather than an intermediate of them

multiple alleles

three or more forms of a gene that code for a single trait

epistatis

when the expression of multiple genes are influenced by each other. they all affect a single phenotype

Pleiotropy

one gene affects multiple traits

linked genes

Genes located on the same chromosome that tend to be inherited together in genetic crosses.

Haplotype

A group of alleles of different genes on a single chromosome that are closely enough linked to be inherited usually as a unit

Parental haplotype

pair of alleles for two different genes exactly like an F1 parent

Recombinant haplotype

pair of alleles for two different genes not present in the F1 parent

genetic distance

a measure of how far apart genes are from each other

complex traits

traits controlled by multiple genes, the interaction of genes with each other, and with environmental factors where the contributions of genes and environment are undefined. Human height is a classic example. They are quantitative as well

Quantitative Trait Locis

the genomic regions that contribute to a quantitative trait

Variance

(n.) - a squared difference between what is expected and what actually occurs. take the square root for the standard deviation

common garden experiment

individuals are all in a common environment so variation among them must be genetically based

Heritability

The proportion of variation among individuals that we can attribute to genes

Broad sense heritability (H^2)

the proportion of the total phenotypic variance of a trait that is attributable to genetic variance, where genetic variance is represented in its entirety as a single value

concordance

the probability that a pair of individuals will both have a certain characteristic, given that one of the pair has the characteristic

normal distribution

a bell-shaped curve, describing the spread of a characteristic throughout a population (around 95% of values fall within 2 standard deviations of the mean)

genetic mapping

The process of determining the location and chemical sequence of specific genes on specific chromosomes.

markers

any DNA sequence that varies in your genetic mapping population. Most markers are SNPs

linkage mapping

the mapping of genes or other genetic sequences along a chromosome by analyzing the outcome of crosses

association mapping

look for linkage disequilibrium between polymorphisms and phenotype. only gives correlations and doesn't determine causation. is often a more practical alternative to linkage mapping

population genetics

Study of allele frequency distribution and change under the influence of evolutionary processes.

Hardy-Weinberg equilibrium

The condition describing a non-evolving population (one that is in genetic equilibrium).

non-random mating

occurs when the probability that two individuals in a population will mate is not the same for all possible pairs of individuals

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection. Is more impactful in smaller populations

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits due to environmental factors doing the selecting

Migration

when organisms move from the place of one population to another. provided they're the same species, they can mate with members of the population they've migrated to. More isolated populations are more likely to undergo speciation over time

Mutation

change in a DNA sequence that affects genetic information. a way to introduce new alleles into the population

allele frequency

Number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene

genotype frequency

proportion of each genotype among individuals in the population

positive assortative mating

Mate with individuals LIKE yourself. Decreases heterozygotes, increases homozygotes

negative assortative mating

Mate with individuals UNLIKE yourself. Increases heterozygotes, decreases homozygotes

Inbreeding

breed from closely related people or animals, especially over many generations.

Homogenization

Making populations more genetically similar to each other. This is often done through individuals migrating between populations

founder effect

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.

bottleneck effect

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

directional selection

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.

e.g. peppered moths before and after the industrial revolution

purifying selection

Typically stabilizes at population at a particular mean phenotype, which reduces phenotypic variability.

e.g. birth weight in humans

balancing selection

occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population.

e.g. sickle-cell anemia in humans

multiregional model

Model that postulates H. sapiens populations in different regions evolved from H. erectus and Neanderthals in those regions. It says those populations interbred to form the current homo sapiens species.

Out of Africa Model

model (hypothesis) proposing a common ancestor of all modern humans evolved in Africa and then migrated out to the whole Earth eventually

Race and Genetics

Race is not a concept that emerged from within modern genetics.

It was imposed by colonial history!

It's meaning is inseparable from cultural origin

"The Concept of Race is the Stone Age Genetics!"

We are a Huge "Extended Family!"

Alleles between races often overlap, but having certain alleles can allow geneticists guess where you may be from

Eugenics

study of factors that influence the hereditary qualities of the human race and ways to improve those qualities. justified for racist, classist, ableist, etc. reasons

scientific inquiry

what is (in the physical)

bioethical inquiry

what should be

stakeholders

physical, emotional, economic, environmental, etc.

bioethical principles

respect for persons, less harm and more benefit, and fairness