Inheritance Flashcards
(17 cards)
What is a phenotype?
The outward, physical manifestation of an organisms genetic code.
What is a character?
A heritable feature, e.g. flower colour
What is a trait?
A variant of a character, e.g. purple or white flower colour
What is a genotype?
The coded, inheritable information in an organisms DNA.
What is an allele?
One specific form of a gene that differs from other alleles by one or a few bases and occupies the same locus as other alleles of the gene.
What is Mendel’s law of dominance?
Some alleles are dominant, which means they will determine the external phenotype over any recessive allele.
What is Mendel’s law of segregation?
The two alleles at any one locus in a diploid individual separate (segregate) during gamete formation. Each one is equally likely to be included in the resulting gametes.
What is Mendel’s law of independent assortment?
Each pair of alleles segregates independently of other pairs of alleles.
What is Neo-Darwinism.
Mendelian genetics + Darwin’s ‘origin’
Also called The Modern Synthesis.
Describe co-dominance?
Both the alleles are dominant and are equally expressed. For example if red and white are equally dominant then the flower will be pink. e.g. RR = red RW = red and white WW = white
Describe incomplete dominance.
When both the alleles need to be dominant in order to show the dominant trait. e.g. RR = red Rr = pink rr = white
What is a lethal gene?
A gene that leads to the death of an individual; these can be either dominant or recessive in nature. Can be completely unrelated to health usually. e.g. YY = yellow and dead Yy = yellow yy = grey
What is a sex linked gene?
Genes that are located on the sex chromosome.
e.g. the gene for being seeing colour is on the X chromosome
What is a polygenetic trait?
Individual heritable characters are often controlled by groups of several genes. Each allele intensifies or diminishes the phenotype.
Variation is continuous or quantitative (‘adding up’) - also called quantitative inheritance.
What is genetic linkage?
When alleles at separate loci are inherited together
and thus do not obey Mendel’s law of independent assortment
What is cytoplasmic inheritance?
Some traits are inherited by orangellar DNA.
What is meiotic drive?
Any process which causes some alleles to be over-represented in the gametes which are formed during meiosis. e.g. in mice TT = normal long tails Tt = short tails tt = sterile
