single gene inheritance Flashcards
what are the characteristics of single-gene diseases
can infer that a person inherited a single gee disease by considering how he or she is related
tests can predict the risk of developing symptoms
how can the single gene diseases be “fixable” (example)
by replacing what is missing in the body
(providing a missing enzyme or clotting factor or even by adding a working copy of the gene to affected cells)
how does the mode of inheritance of single-gene diseases affect familied in patterns
the disease is ez to trace how disease moves through a fam tree
families in pattern = as it shows up in recognizable patterns bcs they are caused by changes in just ne gene
autosomal dominant vs autosomal recessive (examples)
autosomal dominant (Huntington Disease)
- need just one affected gene from either parents to show up for the disease to appear
- 50% chance the child will inherit
autosomal recessive (Cystic Fibrosis)
- requires 2 affected gene, 1 frm each parent
- if inherits one only, they wont have disease but may be a carrier
it reveal which single-gene health conditions we have, carry or may develop
exome and genome sequencing
he derives the 2 laws of inheritance that determine how these traits are transmitted from one generation to the next
Gregor Mendel
briefly explain Mendel’s experiment
dominant is more likely to show up if at least one parent passes them
while
recessive only appears if both parents passed on the recessive version of the gene
it always produce the same phenotype
“true-breeding” - pure breeding line
monohybrid cross -
self crossed -
monohybrid cross - follows one trait
self crossed - plants are hybrids
hybrids are their offspring and may show inheritance pattern
it explains the actions of chromosomes and the genes that they carry during meiosis
law of segregation
homozygous vs heterozygous
homozygous:
an indiv with 2 identical alleles for a gene
-homozygous dominant:
2 dominant alleles, TT
-homozygous recessive:
2 recessive allele, tt
heterozygous:
“non-true breeding” or “hybrid”
an indiv with 2 diff alleles
-heterozygous: 1 dominant, 1 recessive, Ttt
-compound heterozygous: indiv with 2 diff recessive alleles for the same gene
[capital letter is dominant while small letters are recessive]
true or false:
an organism’s appearance reveals its allele
false - does not always
it is the most common expression of a particular allele combination in a population
wild type phenotype
may be recessive or dominant
it is a variant of a gene’s expression that arises when the gene undergoes a change or mutation
mutant phenotype
briefly explain the Mendel’s law of Segregation
index card
it represents how genes in gametes join if they are on different chromosomes
punnett square
*crossing the patterns produced offspring numbers that are close to these ratios
crossing an individual of unknown genotype with a homozygous recessive individual
test cross
single gene on chromosome 15
it demo how 1 gene affects a specific traits
main difference between punnett squares and test cross
punnett squares:
predict offspring traits
test cross:
reveal unknown genotypes
briefly explain the similarities and difference between autosomal dominant and autosomal recessive
similarities :
males and females affected w equal frequency
differences:
D has successive generations affected until no one inherits the mutation while R can skip generations
a person has inherit 2 copies of the mutated gene. 1 gene from each parent
homozygous recessive genotype
it is the wild type allele masks expression of the mutant allele
heterozygotes (carriers)
- ppl with 1 normal gene and 1 mutated gene = cant show traits but can pass mutated genes to their children
this is introduced between relatives, which means “shared blood” - a figurative description, because genes are not passed in blood
consanguinity
this is when alleles inherited from shared ancestors
“identical by descent”
- relative inherit genes from common ancestors
what is the second’s law of Mendel
Law of Independent assortment
it arises from the genotype and reflect the characteristics or abundance of a protein
dominance and recessiveness
'’loss-of-function” -
“gain-of-function” -
'’loss-of-function” - dominant because they result from the action of an abnormal
“gain-of-function” - recessive as it prevents the production of normal protein
which of the 2 (dominant and recessive) is more severe in terms of disease
recessive genetic disease often independent cause more severe symptoms and appear earlier in life compared to dominant disease
if dominant mutation causes serious health issue early on, individuals with that mutation may not survive long enough to pass it on
these can be used to trace a conditional probability
pedigrees
punnett squares
it is used to display family relationships and depicts which relatives have specific phenotypes and sometimes genotypes
pedigree analysis
vertical lines:
horizontal lines that connect 2 shapes at their centers:
shapes connected by vertical lines that are joined horizontally:
squares:
circles:
diamonds:
roman numbers:
arabic numerals:
dotted lines:
vertical lines: generations
horizontal lines that connect 2 shapes at their centers: partners
shapes connected by vertical lines that are joined horizontally: siblings
squares: male
circles: female
diamonds: individuals of unspecified sex
roman numbers: generations
arabic numerals: individuals in a generation
dotted lines: adopted
*more on ppt
it states that the the chance that 2 independents events will both occur equals the product of the chances that either event will occur alone
probability theory: product rule
it states that 2 genes on different chromosomes, the inheritance of one gene does not influence the chance of inheriting the other gene
law of independent assortment
*bcs they r packed aged into gametes at random chromosomes
