lec2 - non mendelian laws Flashcards
mendel’s laws are based mostly on definitely dominant or recessive alleles.
define complete dominance.
hybrid resembles one of two parents.
define incomplete dominance.
is there difference between phenotype and genotype ratios?
hybrid resembles neither parent, and phenotype ratios reflect genotype ratios.
define codominance.
is there difference between phenotype and genotype ratios?
hybrid has traits from both parents. phenotype ratios reflect genotype ratios.
what is pleiotropy?
Phenomenon of a single gene determining several distinct and seemingly unrelated characteristics.
what are multifactorial (complex) genetic traits?
Traits involving >1 gene.
a 9:3:3:1 ratio in progeny suggests that there are __(number)__ independently assorting genes for a trait. -> __(number)__ alleles.
this ratio ONLY applies when dominance of alleles at both genes is __(type of dominance)__
2, 4, complete
what would result in a 9:7 ratio in progeny?
complimentary gene function
define complimentary gene function.
functions of both genes work together to produce a final product
what results in complimentary gene function?
epistasis
define epistasis and what it is a common explanation for.
Interactions between genes such that the end phenotype is not a direct sum of traits.
most relevant for the masking of genes: e.g. a genotype aa masks the effects of all B genes.
who transmits y-linked traits and to who?
male to male
what type is
(1) X+ X+
(2) X+ Xm
(3) Xm Xm
(4) X+ Y
(5) Xm Y
(1) Homozygous wild-type female
(2) Heterozygous female carrier
(3) Homozygous mutant female
(4) Hemizygous wild-type male
(5) Hemizygous mutant male
X-linked recessive traits are ____ expressed in __(male or female?)__
always expressed in male
for X-linked recessive trait, which parent of what genotype passes the trait to affected son?
homo- or heterozygous mother
for X-linked recessive trait, what genotype would the parents of an affected female have?
affected father & hetero/homo mother
2 examples of X-linked recessive traits?
red-green colour blindness & haemophilia
what do mitchondrial genes encode for?
proteins that participate in protein synthesis and energy production.
mutations in mtDNA (mitochondrial DNA) is usually associated with which 2 diseases?
- mitochondrial myopathies (weak and flaccid muscles)
- leber optical atrophy (impaired vision)
mtDNA mutate a lot. what is a property of mtDNA that decreases the effects of mutations?
mtDNA has thousands of genes to buffer the mutation.
which parent transmits mitochondrial genes to offspring, and why?
all mit. genes are transmitted from mother to all her offspring, as sperms do not carry any mitochondrial genes.
does mtDNA have crossing over?
No.
mtDNA has (high/low) exposure to ______ free radicals.
high, oxygen.
does mtDNA have histones?
No.
List 7 properties of mtDNA.
- No crossing over
- Fewer types of DNA repair
- Inherited from the mother only
- Many copies per mitochondrion and per cell
- High exposure to oxygen free radicals
- No histones
- Genes not interrupted
