Module 25 - Heredity And Hereditary Diseases

Chromosome

Threadlike nuclear structure containing DNA segments called genes

Gene

DNA segment that governs cell function by controlling protein synthesis

Mitosis

Process of somatic cell division resulting in identical chromosome distribution

Gamete

Reproductive cell containing half the standard number of chromosomes

Autosome

Chromosome pair not involved in determining sex totaling twenty-two pairs in humans

Sex Chromosome

Single pair of chromosomes that determines the biological sex of an individual

Allele

Alternative form of a specific gene encoding variants of a trait

Trait

Physical biochemical or physiological characteristic determined by genes

Homozygous

Having two identical alleles for a specific gene

Heterozygous

Having two different alleles for a specific gene

Dominant Allele

Gene version that is always expressed when present regardless of its paired allele

Recessive Allele

Gene version expressed only when paired with an identical recessive allele

Phenotype

Observable physical or physiological traits of an individual

Genotype

Specific genetic makeup or combination of alleles of an organism

Carrier

Heterozygous individual who does not show a recessive trait but can pass the allele to offsprin

Meiosis

Special type of cell division that halves the chromosome number to produce gametes with twenty-three individual chromosomes

Random Assortment

Independent segregation of maternal and paternal chromosomes during meiosis that creates genetic variation in gametes

Gamete

Specialized reproductive cell containing a single set of unpaired chromosomes

Parental Cross

Mating between two individuals that results in the combination of genetic material in offspring

Punnett Square

Grid diagram used by geneticists to predict all possible allele combinations and genotype ratios from a parental cross

Homozygous Dominant

Genotype possessing two identical dominant alleles for a specific gene

Heterozygous

Genotype possessing one dominant and one recessive allele for a specific gene

Homozygous Recessive

Genotype possessing two identical recessive alleles that allows expression of the recessive phenotype

Theoretical Genetic Ratio

Calculated probability of inheriting specific genotypes or phenotypes from a cross which becomes more accurate with larger numbers of offsprin

Sex Chromosomes

Chromosomes that determine an individual biological sex designated as X and Y

X Chromosome

Larger sex chromosome carrying genes for sex determination and numerous non-sex traits

Y Chromosome

Smaller sex chromosome carrying few genes mainly responsible for male sex determination

Sex Determination

Genetic process where an X-bearing sperm produces a female child and a Y-bearing sperm produces a male child

Sex-Linked Trait

Genetic characteristic determined by a gene located on a sex chromosome usually the X chromosome

X-Linked Recessive Trait

Condition caused by a gene on the X chromosome that is expressed in all males with the allele and in females only if homozygous recessive

Sex-Linked Carrier

Heterozygous female who carries one X-linked recessive allele without expressing the trait but can pass it to offsprin

Multifactorial Inheritance

Pattern of inheritance where two or more gene pairs along with environmental factors interact to determine a physical trait or disease susceptibility

Gene Expression

Degree to which a specific gene manifests its influence on an individual observable phenotype

Codominance

Genetic interaction where two different dominant alleles are fully and simultaneously expressed in a heterozygote like type AB blood

Incomplete Dominance

Pattern of inheritance where a heterozygous individual displays an intermediate phenotype between two homozygous conditions

Mutation

Any change or alteration in the DNA sequence or chromosome structure of a cell

Mutagen

Physical or chemical agent that increases the frequency of genetic mutations

Loss of Function Mutation

Recessive genetic mutation that results in a protein that is nonfunctional or absent

Gain of Function Mutation

Dominant genetic mutation that creates a protein with enhanced or abnormal activity

Mitochondrial DNA

Distinct genetic material located inside mitochondria that is inherited exclusively from the maternal ovu

Genetic Disease

Any disorder caused by an abnormality or change in an individual genome or DNA sequence

Congenital Disease

Any condition present at birth regardless of whether it is caused by genetic or environmental factors

Hereditary Disease

Genetically transmitted disorder passed from parents to offspring through reproductive cells

Polydactyly

Congenital and hereditary condition characterized by the presence of extra fingers or toes

Teratogen

Any environmental agent chemical radiation or microorganism that causes congenital malformations during embryonic development

Fetal Alcohol Syndrome or FAS

Group of physical and neurological birth defects caused by maternal alcohol consumption during pregnancy

Spina Bifida

Congenital neural tube defect involving incomplete closure of the vertebral column and spinal cor

Down Syndrome or Trisomy 21

Nonhereditary genetic disorder caused by an extra copy of chromosome 21 resulting in distinctive facial features decreased muscle tone and intellectual disability

Klinefelter Syndrome

Sex chromosome disorder in males characterized by an extra X chromosome resulting in XXY genotype

Turner Syndrome

Sex chromosome disorder in females characterized by a missing X chromosome resulting in XO genotype

Marfan Syndrome

Autosomal dominant genetic disorder affecting connective tissue causing long limbs hyperextensible joints and cardiovascular defects

Huntington Disease

Progressive neurodegenerative autosomal dominant disorder caused by genetic repeat expansion that usually manifests in midlife

Phenylketonuria or PKU

Autosomal recessive metabolic disorder where the body cannot properly break down the amino acid phenylalanine leading to intellectual disability if untreated

Sickle Cell Anemia

Autosomal recessive blood disease characterized by abnormal hemoglobin causing crescent-shaped red blood cells and tissue ischemia

Cystic Fibrosis

Autosomal recessive disease causing abnormally thick mucus secretions in the respiratory tract digestive system and pancreas

Tay-Sachs Disease

Autosomal recessive lysosomal storage disorder leading to lipid accumulation in brain neurons and rapid neurological decline

Floppy Baby Syndrome or Progressive Muscular Atrophy

Genetic condition causing severe infantile muscle weakness wasting and respiratory failure

Albinism

Autosomal recessive disorder affecting melanocytes causing a complete lack of melanin pigment in the skin hair and eyes

Fragile X Syndrome

X-linked recessive genetic condition associated with a fragile site on the X chromosome and the leading inherited cause of intellectual disability

Osteogenesis Imperfecta

Genetic disorder of connective tissue commonly known as brittle bone disease causing frequent bone fractures

Neurofibromatosis

Genetic disorder characterized by the development of multiple nerve sheath tumors along nerves throughout the bod

Genetic Counseling

Specialized medical field providing risk assessment education and support for individuals at risk of passing on genetic disorders

Pedigree Chart

Graphic diagram or family tree tracking traits and disease inheritance across multiple generations

Filial Generation or F Generation

Sequence of offspring generations derived from specific parents designated as F1 or F2

Nuchal Translucency Test or NT Test

First-trimester ultrasound screening measuring fluid accumulation at the back of the fetal neck to assess chromosomal risk

Pregnancy-Associated Plasma Protein A or PAPP-A

Placental protein measured in maternal blood during early pregnancy to screen for chromosomal abnormalities

Human Chorionic Gonadotropin or hCG

Placental hormone measured in maternal blood to assess fetal risk for chromosomal disorders like Down syndrome

Alpha-Fetoprotein or AFP

Protein synthesized by the fetus and measured in maternal blood to screen for neural tube defects and chromosomal anomalies

Amniocentesis

Prenatal diagnostic procedure involving the aspiration of amniotic fluid and cells around fourteen to sixteen weeks of pregnancy

Chorionic Villus Sampling or CVS

Early prenatal diagnostic procedure sampling placenta tissue between eight to ten weeks to analyze fetal chromosomes

Karyotype

Systematic visual arrangement of an individual chromosomes mapped and ordered by size and morpholog

Maple Syrup Urine Disease

Genetic metabolic disorder treated with high thiamin doses and restricted amino acid intake to prevent severe damage

Wilson Disease

Genetic disorder characterized by abnormal copper accumulation in tissues causing neurological symptoms and liver damage

Phenylketonuria Screening

Routine blood test done after birth and protein intake to detect PKU and prevent severe intellectual disability

Genetic Engineering

Future therapeutic approach aimed at introducing altered cells or replacing faulty genes to treat genetic disease

Auto Root

Meaning self

Chromo Root

Meaning color

Hetero Prefix

Meaning other or different

Homo Prefix

Meaning same

Pheno Root

Meaning to show or manifest

Multi Prefix

Meaning many

Cele Suffix

Meaning swelling or protrusion

Con Prefix

Meaning with or together

Dactylo Root

Meaning digit finger or toe

Terato Root

Meaning malformed fetus or monster

Centesis Suffix

Meaning surgical puncture or tapping

Karyo Root

Meaning nucleu