Chapter 9 - Patterns of Inheritance Flashcards
Character
A heritable feature that varies among individuals
Ex. flower colour
Trait
A variant of a character,
Ex. purple or white flowers
Carpel
The female part of the plants that contains the stigma style and ovary. (The stigma is the sticky part on top of the carpet that traps the pollen.)
Stamen
The pollen producing male part of the flower that consists of a filament (stalk) and an anther (top where the pollen is)
Note: pollen contains the sperm of the plant
Self fertilization
When the pollen of the plant fertilizes the egg of the same plant. Makes for true breeding meaning that the new plant is identical to the parent plant
Cross fertilization
Fertilization of one plant with the pollen of another plant.
Hybrid
The offspring of two different varieties
Genetic cross / hybridization
The crossing of two different varieties
P generation
True breeding parental plants
F1 generation
The first filial generation
These are the hybrid offspring from crossing two different, true breeding varieties.
F2 generation
The second filial generation.
The result of crossing two F1 hybrids together.
Allele
An alternate version of a gene that resides at the same locus on homologous chromosomes
Monohybrid cross
Crossing 2 true-bred plants that differ in only one character (WW)
Ex. White flower and purple flower
Mendels 4 hypotheses
- There are alternate versions of genes.
- For each character, an organism inherits 2 alleles that could either be homo/heterozygous.
- If the 2 alleles differ, one will be dominant and one recessive.
- A sperm or egg carries only 1 allele (law of segregation)
Dihybrid cross
Crossing two true-breeding plants that differ in two characters (RRYy)
Genotype
An organisms genetic makeup
Expressed as (for example) BB, Bb, or bb
Phenotype
An organisms physical traits that you can actually see being expressed. (Dependant on the genotype)
Epistasis
An interaction between the products of two genes, in which one of these genes modifies the phenotypic expression produced by the other.
Incomplete dominance
Where a trait of the F1 offspring appears as a blending of the parents traits.
Ex. One red flower and one white flower producing a pink flower
Pleiotropy
When a single gene affects many phenotypic characters
Ex. Melanin pigment gene, sickle cell disease
Polygenic inheritance
When two or more genes affect a single phenotypic character.
Ex. Skin colour which is controlled by 3 genes
Epigenetics
Heritable changes, and gene expression that are not attributable to alterations in the genetic code of DNA.
i.e. your environment can cause changes that affect the way your genes work. Certain things you do will turn certain genes on or off and these on/off genes can be passed down to offspring.
The chromosome theory of inheritance
States that genes occupy specific loci (locus) on chromosomes, and it is the chromosomes that undergo segregation and independent assortment during meiosis.
The law of segregation
Allele pairs separate from eachother during the production of gametes. They split during anaphase I of meiosis
Linked genes
Genes located close together on the chromosome (tend to be inherited together)
Sex-linked gene
A gene on a sex chromosome that codes for something other than determination of sex.
True breeding
A kind of breeding in which the parents would produce offspring that carry the same phenotypes as the parent.
Means the parent generation but be homozygous for each trait.
The law of independent assortment
The separation of the alleles into gametes is random and independent.
This works if the alleles are on different chromosomes and are not linked.
The rule of addition
The probability for all possible outcomes of an event to occur, must always add up to 1
Questions using this rule use OR
Ex. Change of guessing a number between 1-10 is 1/10, chance of not guessing it right is 9/10 = 10/10 (1)
The rule of multiplication
The outcomes of each event are independent of each other.
Question using this rule use AND
Ex. Probably of coin 1 landing on heads (= 0.5), and the second coin landing on heads (= 0.5)
0.5 x 0.5 = 0.25 or 25%
