Lecture 2 Genetics Flashcards
DNA
Deoxyribonucleic acid
Double helix composed of nucleotides and nitrogen bases
Gene
Blueprint for producing protein
Chromosome
46 in total (23 pairs)
Large unit of heredity composed of thousands of base pairs
Autosomal
Chromosome that isn’t a sex chromosome (chromosome 1-22)
Locus
Location of a gene in a chromosome
Alleles
Matching pairs of genes the same trait in the same location in a pair of chromosomes
Homozygote
A pair of alleles is identical
Heterozygote
A pair of alleles is different
Genotype
genetic pattern (Bb)
Phenotype
Expression if gene (physical feature)
Dominant
Will be seen if one copy is present
Recessive
Manifiest if identical pair is present
Carrier
Person with one recessive gene and trait isn’t expressed
Genomics
Study of multiple genes and their interactions
Pharmacogenomics
Study of how genes influence an individuals response to medications
Penetrance
Ration of how many person with phenotype have genotype
Expressivity
Disorder can be expressed more or less severely in different individuals
Polygenic/ multi factorial disorders
Multiple imperfect genes stimulated by environmental factors expressing an undesirable treat
Epigenetics
Study of heritable changes in gene expression that don’t involve DNA alterations
Chromosome disorders
Changes in # or structure of chromosome
Gene expression
Whether gene will be active or not
Translocation
When one part of chromosome breaks off and connects to another chromosome
Repression
Gene expression is decreased
Mutations
Accidental errors in duplication or destruction of parts of genetic code
Somatic mutations
Alterations in genetic code of body’s somatic cells
Mosaic
Cells with different #s of chromosomes within the same individual
Autosomal dominant inheritance
Single gene disorder when defective allele is dominant and overrides normal allele
Signs and symptoms occur later on
50% chance of inheriting
Ex: Huntington, neurofibromatosis, Marfan syndrome, familial hypercholesterolemia
Huntington’s Disease
Defect on chromosome 4 causing CAG to repeat causing overproduction of “Huntington” chemical causing progressive brain damage
Huntington disease side effects
Chorea (movement) Parkinsonism features Ridged Severe depression/sucidal thoughts common Meds used but no cure
Neurofubromatosis (NF)
Autosomal dominant
Rumors grow on nerves and decrease prod. of proteins
“Elephant man syndrome”
Marfan syndrome
Autosomal dom. Disorder
Connective tissue disorder w/abnormalities in skeletal and cardiovascular systems
Common in males
Scoliosis, kyphosis, long arms, visual probs, pingeon chest, etc
Familial hypercholesterolemia
Autosomal dom. Disorder
Absent or dysfunctional LDL receptors by mutation of 19p gene locus
Unable to remove LDL
Autosomal recessive inheritance
Must have 2 copies of allele to be seen Children who have become carriers More prominent in children 25% chance of inheritance Ex: Phenylketonuria (PKU), Sickle cell, tay-Sachs, cystic fibrosis, thalassemia
Phenylketonuria (PKU)
Autosomal recessive disorder
Metabolic disorder-by elevated levels of phenylalanine (toxic to brain)
Seizures, hyperactivity, dec. pigmentation, mental retardation in untreated infants
Sickle cell disease
Autosomal recessive disorder
Abnormal sickle cell shape in hemoglobin
Ridgid
Can cause blockage
Tay-Sachs disease
Lysosomal enzyme, mutation on chromosome 15
Destroys nerve cells in brain+spinal cord
Ganglioside accumulates
Red spot on retina, weakened muscles, seizures, vision and head lung loss
Fatal by age 5
Cystic fibrosis
Autosomal recessive disorder
Defects in CFTR gene
Thick mucous secretion
No cure and expected to learn 30-40
Thalassemia
Genes good for Hogan formation are missing
S&S: anemia, fatigue, weakness, SOB,
No cure but symptomatic treatment is
X-linked disorders
Defect on X chromosome
Males can’t be carriers but will be expressed since they only have one X and 50% chance of prod. Affected male
Females have 2 X chromosome but recessive traits are inhibited and 50% chance prod, female carrier
X- disorders examples
Fragile x- syndrome
Hemophilia A
Dúchenme dystrophy
Glucose - 6- phosphate dehydrogenase deficiency (G6PD)
Fragile X Syndrome
Don’t make FMR1 gene (needed for normal brain development)
Autistic behavior, developmental delays makes have long face and large mandible
Hemophilia
Deficiencies of clotting factors cause failure in prod. clots
Duchenne Muscular Dystrophy (DMD)
Generic disorder characterized by progressive muscle degeneration and ness from mutation in dystrophin gene
G6PD deficiency
X linked disorder that’s the Most common enzyme disorder that primary affects men. Causes hemolysis (break apart RBC)
Disjunction
Separation of homologous chromosomes to prod. 2 daughter cells with 23 chromosomes
Nondisjunction
Pair of chromosomes fails to separate resulting in abnormal distribution of chromosomes in daughter cells
Down Syndrome
Trisomy 21 (extra chromosome) Flattened facial profile, small hand and feet, protruding tongue
Nondisjunction of sex chromosomes
Can cause individuals to be born female with one X (Turner syndrome) or extra C (Klinefelter syndrome)
Turner Syndrome
Female with one X
Extra fold of skin on neck, short stature, heart defects, low hairline, early loss of Carina function
Klinefelter syndrome
Males have extra X chromosome
Lack testes development; skeletal/cardiovascular abnormalities, feminine distribution, tall and lanky
Multi factorial/ polygenic disorders
Two or more genes or gene loci influence the expression of gene trait
Environmental triggers are thought to be necessary for the trait to be expressed
Ex: cleft lip and palate, TEV,
Cleft lip and palate
Incomplete closure of the maxillary facial bones
Cleft palate occurs when the tissue that makes up the roof of the mouth is not joined together
Congenital talipes equivocaría (TEV)
Club foot
Foot deformity that causes the bones and tendons of the IV to turn in word
Teratogen
Substance that produces abnormalities during embryonic or fetal development
Fetal Alcohol Syndrome (FAS)
Exposure to excess maternal alcohol consumption while in utero throughout the entire pregnancy
Born with restarted physical growth, intellectual disability, cardiac defects, and musculoskeletal abnormalities
Mental retardation
Thalidamide
A teratogenic drug given to pregnant women for morning sickness relief
Babies born with deformed missing limbs (phocomelia)
