Genetics Flashcards
(22 cards)
What are the four blood types in humans?
A, B, AB, O
What is blood type controlled by?
Alleles (A, B,O)
Which blood type is recessive and which are co-dominant?
Recessive = O Co-dominant = A and B
What does inheritance of quantitative traits and polygenic inheritance refer to and give an example?
The inheritance of a phenotype characteristic which vary in degree. E.g. human skin colour
Polygenic traits can be attributed to the interactions between how many genes and what?
2 or more genes
Environment
The expression of polygenic characteristics in the phenotype follow a what distribution in the population?
Normal
What is epistatis and when does it occur?
The interaction between genes and occurs when the action of one gene is modified by one or several other genes
What is the difference between epistatic and hypostatic?
Epistatic = the gene whose phenotype is expressed Hypostatic = the phenotype is altered
What is a lethal gene?
A gene that causes the organism to die at any stage in their life
Are the majority of lethal genes recessive or dominant?
Recessive
What happens if you have a dominant lethal allele?
A copy of the allele results in death e.g. Huntingtons disease
Does letheality occur before or after birth?
Both
What is an example of a lethal gene in aniamls?
Creeper in chickens.
Causes legs to be short and stunted.
Dominant gene, hetrozygous chickens display the creeper phenotype. If 2 creeper chickens are crossed, 1 would be expected to have 3/4 of the offspring creeper and 1/4 normal. Instead it is 2/3 creeper and 1/3 normal - because homozygous chickens die.
What is epigenesis/perfomanisation?
The idea that “each embryo or organism is gradually produced from an undifferentiated mass by a series of steps and stages” (Magner, 2002).
e.g. baby growing in womb
What are nucleotide substitutions?
Mutations resulting in the substitution of the nucleotide pair in a duplex with a different nucleotide pair,
Transitions = pyrimidine replaced by other pyrimidine
= purine replaced by other purine
Transversions = purine replaced by pyrimidine or vice versa
What is the equation for chi2?
x2 = (O - E) 2/ E
When do you accept the null hypthoesis in chi 2?
When the x2 value is greater than or 0..05
What do Mendels laws suggest about breeding experiments?
The outcomes are predictable and quantifiable
Mendelian genetics predicts the offspring from monohybrid and dihybrid crosses will fall into distinctive ratios of what?
3:1 (9:3:3:1)
Mendels first law was the law of segregation. What were the four parts of this law?
1) Alternative versions of genes (alleles) accounted for variations in inherited characteristics
2) For each characteristic an organism inherits 2 alleles from each parent
3) If the alleles differ, then the allele with the dominant trait will be fully expressed in the organisms appearance. While the recessive trait has no noticeable effect of organisms appearance.
4) The 2 alleles for each characteristic segregate durig the gamete production. I.e. the gamete can only carry one pair of alleles for a particular characteristic
/What was mendels second law
The law of independent assortment.
The inheritance pattern of the trait will not affect the inheritance pattern of another trait. i.e. the two traits will not assort independently
What were Mendels main contributions to our understanding of genetics?
1)
2) Both sexes contribute equally to the next generation (through the particles in the gametes)
3) Predictions about the ratios of the offspring ca be made (quantifiable approach)
