Genetics part 2 Flashcards
(45 cards)
Pedigree def
diagram of family tree showing occurrence of heritable characters in parents and offspring over multiple generations
Are human traits studied in same way pea plants are?
No, because they have longer generation time and fewer offspring
What are the goals of a pedigree
Examine inheritance of genetic traits and calculate probability of future children having a particular genotype/phenotype
Look at this image of a pedigree
https://prnt.sc/fsTktcYcrYZv
What do the white circles and white squares indicate in pedigree?
Square is male, female is circle
What do the black circles and black squares indicate in pedigree
Means affected
True or False? Many genetic disorders are inherited as recessive traits, with a large range in severity
True
We know that genes code for proteins, so what do alleles causing genetic disorders code for?
Malfunctioning protein or no protein
Types of recessive disorders
Aa heterozygotes normal in phenotype
aa homozygous recessive inherit one from each parent, heterozygotes can be carrier(Aa)
What are autosomal recessive traits?
traits controlled by gene loci on autosomal chromosomes, must have 2 recessive alleles to have the trait
Carrier def
individual that does not express the recessive trait but has a heterozygous genotype carrying the recessive allele
For autosomal recessive trait pedigrees, why will offspring of 2 affected parents always be affected? why can affected offspring have 2 unaffected parents?
Because parents both have aa, and the unaffected parents have Aa each
- can skip traits because carriers dont show trait
What are autosomal dominant traits?
Traits controlled by gene loci on autosomal chromosomes, where you only need one dominant allele to have the trait
Characteristics of pedigree for autosomal dominant
Affected parents do not always produce affected offspring, affected offspring have at least one affected parent, no generation skip, both genders
Characteristics of sex linked recessive traits
More males affected than females(only one X), male offspring from an affected affected mother always affected, trait is not passed from male to male
Characteristics of pedigree for sex linked dominant traits(which are rare)
More females affected than males, all female offspring of an affected male will be affected
This is how to find pattern pedigree
https://prnt.sc/kju9skOcb8Nz
Reminder: practice problems with genetics
OK
True or False? some alleles more common in certain populations
True, for example sickle cell allele in people of African descent
Wildtype def
most common phenotype in nature(eg. non red hair)
True or False? Alleles occur in different frequencies in population, some recessive alleles more common, meaning just because dominant doesn’t mean frequent
True
What are the characteristics of the recessively inherited disorder cystic fibrosis?
it is a wildtype allele that codes for a membrane protein involved in Cl- transport, homozygous recessive, resulting in thicker mucus coating, building up in pancreas, lungs, digestive tract
Characteristics of sickle cell anemia
Affects 1/400 africans, 1 amino acid substituted in hemoglobin caused by point mutation, heterozygotes may have some symptoms and may persist in population(less malaria risk)
Why are dominantly inherited alleles that are lethal much rarer then recessive?
Causes death before person can reproduce
