Week 10 - Gene and Inheritance Flashcards
What are the mendel laws (4)
- “Alternative versions of genes account for variations in inherited characteristics”
- “For each characteristic , an organism inherits 2 copies of a gene, one from each parent”
- “If the two alleles at a locus differ, then the dominant allele, determines the organisms appearance”
- “two alleles for a heritable character segregate during gamete formation and end up in different gametes” - law of segregation
No really a mendel law
“Each pair of alleles segregates independently of each other pair of alleles”
law of independent assortment
What are the 2 inheritance hypothesis
- Blending hypothesis
- The particulate hypothesis
Explain the law that Alternative versions of genes account for variations in inherited characteristics
This law describes the concept of alleles and their role in generating variations in inherited traits among individuals.
What is allele
Different versions of a gene which can result in variations in a particular trait.
E.g. the gene for flower colour in pea plants has 2 alleles: 1 for purple flowers and another for white flowers (P or p)
What are phenotypes
refers to the observable characteristics of an organism which results from the interaction between its genotype and environmental factors
e.g. eye colour, hair colour, height
What is a genotype
refers to its genetic makeup, or the combination of alleles it carries for a particular trait. e.g. Pp, PP, pp
Explain the law that “For each characteristic , an organism inherits 2 copies of a gene, one from each parent”
Most organisms including humans have 2 sets of chromosomes in each set, one set form each parent. Therefore, diploid organisms inherent 2 copies of each gene, one from each parent.
What is homozygotic
If the alleles from each parent are the exact same (bb)
What is heterozygotic
If the alleles from each parent are different (Bb)
Explain the law that “If the two alleles at a locus differ, then the dominant allele, determines the organisms appearance”
In many cases, one allele may be dominant over another allele, meaning that it will be expressed in the phenotype (observable characteristics) of the organism even if the individual carries both alleles (heterozygous).
What is a dominant gene
The allele which is expressed in the phenotype of an organism regardless of whether the organism is homozygous (two identical alleles) or heterozygous (two different alleles) for that allele.
What is a recessive gene
A recessive allele is one that is only expressed in the phenotype of an organism when it is present in the homozygous state
What is a locus
Specific physical location or position on a chromosome where a gene is located. Each gene occupies a distinct locus on a chromosome.
Explain the law of segregation
During gamete formation through the process of meiosis, the alleles segregate from each other so that each gamete receives only one allele for each gene.
Explain the law of independent assortment
It states that the inheritance of one trait is not dependent on the inheritance of another trait, E.g. Just because you have brown hair does not mean that you will have brown eyes
What does degrees of dominance inheritance
extent to which one allele (the dominant allele) masks the expression of another allele (the recessive allele) in the phenotype (observable characteristics) of an organism.
Degrees of dominance can vary depending on the specific alleles involved and the traits they control.
E.g. its where the red and white alleles are both being expressed
What is pleiotropy
Is where a single gene influences multiple phenotypic traits. In other words a single gene can result in several phenotype outcomes.
E.g. In sickle cell anemia
What is co-dominance
where both alleles of a gene are expressed equally in the phenotype of heterozygous individuals. Neither allele is dominant or recessive to the other, and both alleles contribute to the observable characteristics of the organism.
E.g. Blood types
What is epitasis
The expression of one gene masks or modifies the expression of another gene at a different locus.
Example
Black coat colour (B) is dominant to brown (b).
A second gene (E) determines whether or not pigment will be deposited in the hair
If ee then no colour is deposited no matter if BB, Bb or bb.
What is polygenic inheritance
The converse of pleiotropy
Polygenic inheritance is a pattern of inheritance where a trait is controlled by multiple genes, often located on different chromosomes.
What are the 2 different types of traits/characteristics
monogenic and polygenic
What are polygenic characteristics
traits that are controlled by multiple genes
What are examples of polygenic characteristics
height, skin colour, eye colour, intelligence, weight
What are monogenic characteristics
traits which are determined by a single gene - controlled by alleles at a single gene locus.
What are examples of monogenic characteristics
Mendelian traits, blood type
