unit 6: genetics (terms)

genetics

the study of heredity and the variation of inherited characteristics

trait

a specific characteristic of an organism, such as eye color or height

gene

a segment of DNA that codes for a specific protein, determining a particular trait

allele

different forms of a gene that can exist at a specific locus

recessive

an allele that is only expressed in the phenotype when two copies are present (homozygous)

dominant

an allele that is expressed in the phenotype even if only one copy is present

heredity

the passing of traits from parents to offspring

purebred

an organism that is homozygous for a particular trait

pure strain

a group of organisms that are genetically uniform for certain traits

P1 generation

the parental generation in a genetic cross

F1 generation

the first filial generation, offspring of the p1 generation

law of segregation

Mendel's principle stating that allele pairs separate during gamete formation and randomly unite at fertilization

law of independent assortment

Mendel's principle stating that genes for different traits assort independently during gamete formation

cross

the breeding of two organisms to study inheritance patterns

phenotype

the observable physical or physiological traits of an organism

genotype

the genetic makeup of an organism, represented by allele combinations

homozygous

having two identical alleles for a particular gene

heterozygous

having two different alleles for a particular gene

genome

the complete set of genes or genetic material in an organism

probability

the likelihood of a specific genetic outcome occurring

monohybrid cross

a genetic cross involving one trait with two alleles

dihybrid cross

a genetic cross involving two traits, each with two alleles

punnett square

a diagram used to predict the genotypic and phenotypic outcomes of a genetic cross

testcross

a cross between an individual of unknown genotype and a homozygous recessive individual to determine the unknown genotype

complete dominance

a pattern of inheritance where the dominant allele completely masks the recessive allele

incomplete dominance

a pattern of inheritance where the heterozygous phenotype is an intermediate blend of the two alleles

codominance

a pattern of inheritance where both alleles are fully expressed in the phenotype

sex chromosomes

chromosomes (X and Y) that determine an individual's biological sex

autosomes

non-sex chromosomes that do not determine sex

sex-linked traits

traits controlled by genes located on sex chromosomes, often the X chromosome

hemophilia

a sex-linked genetic disorder where blood does not clot properly

colorblindness

a sex-linked genetic disorder affecting the ability to distinguish colors

x-inactivation

the process in which one of the two X chromosomes in female mammals is randomly inactivated

barr body

the inactive X chromosome in a female somatic cell

sickle cell anemia

a genetic disorder caused by a mutation in the hemoglobin gene, leading to misshapen red blood cells

hemoglobin

a protein in red blood cells that carries oxygen

huntington's disease

a genetic disorder caused by a dominant allele, leading to progressive brain degeneration

cystic fibrosis

a genetic disorder caused by a recessive allele, leading to thick mucus buildup in the lungs and digestive system

carrier

an individual who has one recessive allele for a genetic disorder but does not express the disorder

polygenetic trait

a trait controlled by multiple genes, such as skin color or height

epistasis

the interaction of genes where one gene affects the expression of another

albinism

a genetic condition caused by a lack of melanin production, resulting in very light skin, hair, and eyes

multiple alleles

the presence of more than two possible alleles for a single gene in a population

abo blood groups

a blood type classification system based on the presence or absence of A and B antigens

Rh factor

a protein found on red blood cells that determines whether blood is Rh-positive or Rh-negative

universal donor

a person with type O-negative blood, which can be donated to individuals of any blood type

universal acceptor

a person with type AB-positive blood, which can receive blood from any donor

karyotype

a visual representation of an organism's chromosomes, used to detect chromosomal abnormalities

monosomy

a genetic condition where a chromosome is missing from a pair (e.g., Turner syndrome)

trisomy

a genetic condition where there is an extra chromosome in a pair (e.g., Down syndrome)

amniocentesis

a prenatal diagnostic test that involves extracting amniotic fluid to detect genetic abnormalities

ultrasound

a medical imaging technique used to visualize a developing fetus

fetoscopy

a medical procedure that involves inserting a small camera into the uterus to examine a fetus

chorion villi sampling

a prenatal test that takes a sample of placental tissue to detect genetic disorders

pedigree

a chart that shows the inheritance patterns of a trait through multiple generations