L25 ,26 , 27 ;) Flashcards
what is the seven trait of garden pea?
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who is mandle ?
father of genetics/ his law are applicable in predicting inheritance of monogenic humsn disorder/ use garden pea
why mandle select pea plant ?
grow faster/large number
a bigamous plantتقدر تلقح نفسها
easy cross pollnation التلقيح الخلطي سهل
what is true or pure breed plant ?
a plant that retained the same phenotype[سمات] on growin generation after gneration [homozygous]
what is monohybrid cross?
a cross between 2 plant carrying pure[homozygous] contrasting phenotype of a single trait and the product of this cross is monohybrid
what is the law of dominite ?
what is the law of segraction ?
1- In the hybrid, only the dominant factor expressed and the recessive was suppressed
TT or Tt dominite is appeared
2- Dwarf (recessive) phenotype reappeared in the ratio of
3:1 / During gamete formation, factors segregate so that each haploid gamete receives one or the other factor with equal
likelihood
when recessive factor expresses ?
in pure condition tt &tt
or homozygous [hybrid condition] tt
IMP note Tt is g
heterozygous condition
Tt & Tt will give us ?
1 [pure tall] ; 2 [hybrid tall] ; 1 [dwarf pure small]
TT Tt tt
when we use punnet sequare or hardy-weinberg equation ?
to calculate disease freq of an individual = pinnet square
to calculate disease/ carrier freq in population =hardy weinberg equation
a phenotype is determined by ..?
a pair of factor
however, mamdel nation was [one gene one phenotype]
tt [white flower] & X [violet flower] give us
299 violet and 310 white
what is X ?
X= Tt
understand
what are unit factors?
where are they located ?
unite factors are genes or alleles and located in chr /in human we have
22 pair [autosomes]
1 pair [sex chr] we have only one pair so there is less diseases associated with it
what is gene ?
what is genome?
1- a gene if the functional part of thr chr or DNA that encode RNA / protain or that produce a phenotype
2- The genome is the entire set of genetic instructions found in a cell. In humans, the genome consists of 23 pairs of chromosomes
in the genome 2% genes [Euchromatin] [functoinal part] and 98% nonfunctional part [heterchromatin]
what is locus ?
it is the location of a gene on the chr [plural=loci] it is fixed [ثابت]
but some gene change / move [mobile gene / transposons]
transposition is rerest [rare] phenomenon and it’s causes abrupt changes in the phenotype يعني تغير لي من صفات الجين
what is allale ?
an allele is a variant / alternative form or an additional copy of a gene
2.Both copies of a gene at
a locus calle Allele pair
what is homozygous / heterozygous/ hemizygous?
what is phenylketonuria?
Phenylketonuria, a monogenic autosomal recessive disease is caused by a gene (P) present on the chromosome 1
what is dihybrid cross?
a cross between 2 plant with 2 pure trait contrasting [وحده متنحبه ووحدهه سائده]
same as hybrid cross but here we have 2 trait
what is law of independent ?
it’s factors controlling different trait are independent of each other / and they assort randomly without inflencing each other
law of independent pased in what ?
passed in dihybrid cross
what is the medical relevance in genetic disease?
1- predict disease inheritance
2-genetic counseling
3-preventive measure
[you can’t cure genetic disease yhe only treatment is preventation]
how recessive disease happen ?
in homozygous condition [pure]
don’t happen in heterozygous condotoion شي طبيعي لانه بهذي الحاله [called carriers]الصفه السائده هي اللي تظهر وبيكون هو مجرد حامل للمرض carriers [spread the disease]
what are the types of human disease?
/
what is the variance effect of mendel law?
شنو القوانين اللي كانت ما تتبع قوانين مندل؟
incomplete dominance
espistasis
pleiotropic
what is the difference between alleles in population and allele in individual ?
in a population an allele has more than two forms of allele [Multiple alleles]
But an individual plant inherits only a pair of alleles
In human we have ——–blood group genotypes
and ————blood group phenotypes
9 genotypes
4 phenotypes
AB blood group does not follow the law of dominance
why?
it is co-dominance bcz both alleles A and B are dominant
ex] if I have BO it is follow the low of dominant
لانه هنيه فصيلة الدمB لانه ال B اهو السائد
what are the plant that follow incomplete dominance effect?
4 oclock plant
snapdragon plant
andalusian fowl
thay don’t follow the law of dominance
what is the explanation for the pink phenotype?
it follow incomplete domininace ……mixing of individual phenotypes [allales DO NOT mix] and produce incomplete pr partial phenotype [pink]
in this case both allleles are dominant
what are the difference betweeen incomplete dominance and Codominance ?
in hybrid condition يعني بس ندرس صفه وحده
in codominance there are no mixing of indiviual phenotype
what is Epistasis ?
is defined as the inhibition of a dominant gene by a recessive gene present at a different locus
mandel said -genes are independent not-linked
but now we know – Genes do not function in isolation. A gene can induce or suppress other gene(s)
F1 ratio in epistasis is similar to the mendel dihybrid cross but the ratio of the F2 offspring
is different. Why?
the ratio in F2 is 9;3;4
bcz there is a genetic interaction in epostasis so the recessive allele inhibits a dominant gene
what is the relationship between epistasis and human blood group phenotypes?
H gene -> present in chr19 and called bombay antigen gene
1- HH or Hh expression [give us] A and B alleles
2-hh [recessive][bombay phenotype] inhibits both A and B and give us O blood group so here we use epistasis
what is pleiotropy ?
it mean one gene give us many phenotype
عكس كلام مندل لما قال الجين يطلع لي صفه وحده بس
what is polygenic inheritance ?
many gene give us one phenotype and it follows incomplete dominance
ex] three dominant gene give us human skin color [one phenotype]
what is the differnce between pleiotropy and polygenic inheritance ?
one gene one phenotype —mendelian
one gene many phenoypes—-pleiotropy
many gene one phenotype——polygenic inheritance
what is the carrier freq?
2Cc
phenotype in polygenic inheritsnce depend on what ?
the phenotype depend on the quantity of the dominant alleles [quantitave inheritance]
ex] if the number of dominant alleles decrease the skin color become lighter
اخذي نفس عميق واستوعبي القوانين اللي بهذي السلايده
how can we know the number of phenotype ?
there is a diffirenet between genotype and phenotype
phenotype = 2 n +1
n= gene
does the the environnment effect the expression of gene and phenotype ?
yes environment effect gene expression or phenotype
