biology ch 23 genetic diseases

pedigree

chart of family history w/ regards to a particular genetic trait

in a pedigree, female is ____ and male is ____

circle, square

individuals affected by genetic trait in pedigree are

shaded

autosomal dominant

means a single copy of a mutated gene from 1 parent is enough to cause a disorder, meaning it has 50% chance to be passed on to each child

autosomal recessive

requires 2 copies of the mutated (one from each parent) for the disorder to manifest

autosomal means it is..

one of the 22 non-sex chromosomes

in a pedigree, you can see that it is recessive if

it skips generations, parents aren’t affected but child is (if parents are heterozygous)

parents are considered carriers if

they are unaffected but can have children who are capable of being affected

tay-sachs disease

autosomal recessive

occurs because a lysosomal enzyme is missing that breaks down fat, meaning without fat buildup in lysosome

lysosome storage is mainly in neurons which is they psychomotor skills are affected

seen in infants, not at first, but 4-8 months in development

tay Sachs disease symptoms

gradual blindness, develops uncontrollable seizures, eventually becomes paralyzed

no cure

cystic fibrosis

autosomal recessive

chloride ions fail to pass through channel protein on plasma membrane

ordinarily when chloride ions pass sodium and water follow

lack of water accumulates abnormally thick mucus in bronchial tubes and pancreatic ducts

CF symptoms

difficulty breathing, frequent lung infections, digestive issues

no cure

phenylketonuria PKU

autosomal recessive, affected individuals lack the enzyme needed for normal metabolism of the amino acid phenylaline

meaning they cannot eat certain proteins, if they do severe intellectual disabilities will follow

no cure but can be treated with a strict low phenylaline diet

sickle cell disease

autosomal recessive

caused by one amino acid diff that causes hemoglobin to stack into insoluble rods

red blood cells are irregular and sickle-shaped

because sickle cells can’t pass along narrow capillary passageways as normal ones can, they clog the vessels and break them down

sickle cell symptoms

clogging of blood vessels, breakdown of red blood cells, poor circulation, anemia, low infection resistance, internal hemorrhaging

can be cured through genotherapy or stem cell (bone marrow) transplant

sickle cell disease provides protection against..

malaria

autosomal dominant pedigrees are

affecting every generation

can tell if both parents are affected but kids aren’t (possible if parents are heterozygotes)

both male and female affected at same rates

marfan syndrome

autosomal dominant, mutation is protein fibrillin, an elastic connective tissue protein

present in eye lens, bones of limbs, fingers and aorta

symptoms of marfans syndrome

dislocated lens, long limbs and fingers, caved in chest because aorta wall is weak, causing a risk for an aneurysm

no cure

Huntington’s disease

neurological disorder that leads to progressive degeneration of brain cells

caused by a mutated copy of the gene for a protein called Huntington

most patients are middle aged and already have children

huntgintons disease symptoms

motor, cognitive, and psychiatric skills are all affected

no effective treatment/cure, but they can test for the presence of the gene

osteogenesis imperfecta

autosomal dominant

results in weakened brittle bones

leads to a defective collagen 1, one of the most abundant proteins in the human body

approximately 1 in 5,000 live births are affected

symptoms of OI

blue tint in sclera (white portion of eye), reduced skin elasticity, weakened teeth, brittle bones, occasional heart valve abnormalities

treatable with drugs that increase bone mass

incomplete dominance

when a dominant and recessive are blended