Patho ch 2 - Genes & Genetic Diseases

Pathophysiology chapter 2 genes and genetic diseases

a normal individual carries _____ chromosomes, organized into _____ pairs - inside each cell

46, 23

out of the 23 total chromosome pairs, how many are sex chromosomes?

1

which chromosome pair is the sex chromosome?

chromosome 23, XY

out of the 23 total chromosomes, _____ (is/are) non-sex chromosomes.

22

a non-sex chromosome is termed

autosomal

an autosomal chromosome is what type of chromosome?

non-sex

a _____ is the functional unit of heredity. sequence of nucleotides in DNA or RNA

gene

a gene is the functional unit of _____

heredity

nucleosomes are organized into _____ fibers, the repeating building blocks of a chromosome

chromatin

_____ are organized into chromatin fibers, the building blocks of a _____

nucleosomes, chromosome

a _____ is the whole structure that forms the chromosome

chromatin fiber

a chromatin fiber is the whole structure that forms the _____

chromosome

a threadlike structure composed of DNA and proteins, carrying genetic information in the form of genes, essential for cell growth, survival, and reproduction

chromosome

DNA is wrapped around _____ proteins. these structures together create a nucleosome

histone

_____ is wrapped around histone proteins. these structures together create a _____

DNA, nucleosome

the point where two chromatids meet or join

centromere

one of the two identical halves of a chromosome is termed

chromatid

the fixed position of a gene (on a chromosome) is termed the

locus

a variant form of a gene is termed

allele

an individuals genetic makeup is termed

genotype

an individual’s observable characteristics is termed

phenotype

genotype vs phenotype: phenotype is an individuals _____

observable traits

genotype vs phenotype: genotype is an individuals _____

genetic makeup

having two identical alleles for a particular gene are termed

homozygous

having two different alleles for a particular gene is termed

heterozygous

a type of inheritance where both alleles for a trait are fully expressed in a heterozygous individual

codominance

an allele that masks the expression of another allele when both are present is termed

dominant

an allele whose expression is masked by another allele is termed

recessive

an individual who carries one copy of a mutated gene associated with a genetic disorder but does not exhibit the condition themselves is termed

carrier

a gene that is expressed as HH is termed

homozygous dominant

a gene that is expressed as hh is termed

homozygous recessive

A dominant (or single-gene) disorder only requires ____ defective gene(s) in order for the disease to be expressed in an individual

1

a _____ disorder only requires 1 defective gene in order for the disease to be expressed in an individual

dominant (single-gene)

a condition that results from the interaction of multiple genes, rather than a single gene mutation is termed

polygenic

a recessive disorder requires _____ defective gene(s) in order to be expressed in an individual

2

a _____ disorder requires 2 defective genes in order to be expressed in an individual (rr)

recessive

if an individual who has inherited genes for a recessive disorder expresses only 1 defective gene, they are termed

carrier

a change in the structure or number of chromosomes - entire chromosome is defective, termed

chromosomal aberration

a chromosomal aberration is a change in the _____ of a chromosome, causing the entire chromosome to be _____

structure or number, defective

23 pairs for 46 total chromosomes - healthy number, this is termed

euploid

the presence of or the absence of one or more chromosome (missing a copy or having an extra copy) is termed

aneuploidy

the primary cause of aneuploidy is _____

non-disjunction

a failure during cell division where sister chromatids fail to separate properly

non-disjunction

non-disjunction causes _____

aneuploidy

having one copy instead of the usual two of a chromosome is termed

monosomy

monosomy is typically _____, except in the case of _____

lethal, turner syndrome

_____ is typically lethal, except in the case of turner syndrome

having an extra copy (therefor having 3) of a chromosome is termed

trisomy

trisomy is not typically _____

lethal

an example of autosomal aneuploidy is _____, which is an extra copy of chromosome _____

down syndrome, 21

down syndrome is also termed

trisomy 21

an example of sex chromosome aneuploidy is _____, which is an extra copy of chromosome _____ in _____

turner syndrome, 23 (XXX), females

estrogen is a vaso-_____

dilator

the biggest risk factor for a fetus developing down syndrome (trisomy 21) is

maternal age above 35

intellectual disability, low nasal bridge, epicanthal folds, protruding tongue, low-set ears and poor muscle tone are all manifestations of which disorder

down syndrome

1 out of every 800 babies born (or 1:800) are affected by what disorder

down syndrome

a disorder in which a female has only one copy of the X chromosome

turner syndrome

underdeveloped ovaries, short stature, webbed neck, edema, underdeveloped breasts; wide set nipples, and a high number of aborted fetuses are all characteristics of which disorder?

turner syndrome

individuals with down syndrome or turner syndrome are at a higher risk for what conditions?

heart problems, cancer

an autosomal disorder affects which chromosomes?

1-22

a genetic disorder that affects the sex chromosomes is termed

sex-linked or x-linked

a diagram that shows the occurrence of certain traits through different generations of a family is termed

pedigree

the probability that an individual will develop and manifest a genetic disease

recurrence risk

when one parent is affected by an autosomal dominant disease and the other is normal, the recurrence risk for each child is _____

50%

the probability of a gene or trait being expressed; genotype

penetrance

when an individual who has a gene or trait for a disease but does not express the disease

incomplete penetrance

_____ describes whether a specific genotype leads to the expression of the associated phenotype, while _____ describes the degree to which that phenotype is expressed

penetrance, expressivity

autosomal dominant disorders dont _____

skip generations

what type of genetic disorders do not skip generations

autosomal dominant

autosomal dominant genetic disorders often present when

later in life

von willebrand’s disease, marfan syndrome, huntington’s disease, and neurofibromatosis (von recklinhausen disease) are all examples of which type of genetic disease

autosomal dominant

_____ disorders have no carriers. the individual is either affected or unaffected

autosomal dominant

autosomal dominant disorders have no _____. the individual is either _____ or _____

carrier, affected or unaffected

_____ parent(s) need(s) to carry the defective gene in order for it to express in their offspring for autosomal dominant disorders

1

autosomal dominant disorders are also termed

delayed lethal genotype

a rare, inherited disorder that causes nerve cells in the brain to break down, leading to uncontrolled movements, cognitive decline, and behavioral changes

huntington’s disease

huntington’s disease affects which chromosome

4

neurofibromatosis type 1 (NF1), a genetic disorder characterized by tumors growing on nerves and skin

von recklinghausen disease

von recklinghausen disease is also termed

neurofibromatosis

neurofibromatosis (von recklinghausen disease) affects which chromosome

17

an inherited disorder that affects connective tissue, affects the heart, eyes, blood vessels and bones. present tall and thin with long arms, legs, fingers and toes

marfan syndrome

marfan syndrome affects which chromosome

15

autosomal recessive disorders need _____ defective gene(s) to be expressed

2 (hh)

which type of disorder needs 2 defective genes in order to be expressed?

autosomal recessive

autosomal recessive disorders requires both parents to be _____

carriers

recurrence risk for offspring to express an autosomal recessive disorder is _____

25%

recurrence risk for offspring to express a(n) _______ disorder is 25%

autosomal recessive

cystic fibrosis, sickle cell anemia, phenylketonuria (PKU), tay-sachs disease are examples of what type of genetic disorder

autosomal recessive

female x-linked inheritance: XXʰ = the defective gene is _____, the female is a _____

recessive, carrier

male x-linked inheritance: XʰY = the defective gene is _____, the male is _____

dominant, affected

X-linked disorders: males are _____ and females are _____

affected, carriers

males affected with x-linked disorders cannot transmit the genes to _____, but they can transmit them to all _____

sons, daughters

males affected with _____ disorders cannot transmit the genes to sons, but they can transmit them to all daughters

x-linked recessive

sons of females who carry defective x-linked genetics have a _____ risk of being affected

50%

most x-linked disorders are _____

recessive

hemophilia A, B & C, muscular dystrophy (both duchenne and becker), red-green color blindness, and alport syndrome are all examples of what kind of genetic disorder

x-linked

genetic influences combined with environmental factors is termed

multifactorial

cleft palate, congenital hip dislocation, congenital heart disease, type 2 diabetes mellitus are examples of what kind of genetic disorder

multifactorial

alpha-fetoprotein and amniocentesis testing are used to detect which disorders

down syndrome and neural tube defect

a visual representation of a person's chromosomes arranged in numerical order - an individual's complete set of chromosomes

karyotype