06. Genetics [DEFINITIONS] Flashcards
Character
A heritable feature that varies among individuals of a population such as hair colour or eye colour is called a character.
Trait
The heritable variants of a character in an organism, such as brown/blond hair or blue/brown/black eye colour in humans are called traits.
Gene
The gene is the basic unit by which genetic information is passed from parent to offspring.
Locus
A locus is a fixed position on a chromosome. A DNA sequence residing usually at a specific locus on a particular chromosome contributes to the development of one or more traits by coding for specific proteins or peptides.
Alleles
Alleles are alternative versions of genes that reside on the same locus of different chromosomes. (they vary in their sequence of nucleotides?)
Homozygous
The condition of having two identical alleles for a given gene is known as homozygous state.
Heterozygous
Having two different alleles for a given gene is referred to as heterozygous state.
Phenotype
A phenotype is brought about by the interaction between genotype of the individual with its environment
Genotype
The genetic make up, or set of alleles of an organism is known as its genotype. (could be either homozygous or heterozygous?)
Dominant Allele
At heterozygous state, the allele which determines the organism’s phenotype by masking the expression of the other is referred to as the dominant allele.
Dominant Trait
The trait produced by the dominant allele is known as the dominant trait
Recessive Allele
The allele which doesn’t exhibit any noticeable effect on the organism’s phenotype at heterozygous state is referred to as the recessive allele.
Recessive Trait
The trait hidden on the recessive allele is the recessive trait. (However, they express their trait when they exist in homozygous state.)
Contrasting Traits
Mendel tracks the characters that only occurred in two distinct, contrasting phenotypic forms (such as tall stem length vs short stem length / purple flower colour vs. white flower colour) Such traits are contrasting traits.
Pure breeding / True breeding
Pure breeding plants are obtained by self-pollinating over many generations, producing only the same variety as the parent plant.
Pure Lines
The uniform lines produced from the self-fertilization of pure breeding varieties over many generations are called pure lines.
Hybridization
The mating or crossing of two pure-breeding varieties with contrasting traits is called hybridization.
P generation (Parental Generation)
The parental generation is referred to as P generation.
F1 Generation (First Filial Generation)
Plant progeny resulted from hybridization events are referred to as the F1 generation
F2 Generation (Second Filial Generation)
The progeny that results from the self or cross pollination between F1 generation plants are known as F2 generation.
Monohybrid
An organism that is heterozygous with respect to a single gene of interest resulting from a cross between parents having homozygous condition for different alleles of specific gene is referred to as a monohybrid.
Monohybrid Cross
A breeding experiment conducted between two organisms with heterozygous condition for a specific character is referred to as a monohybrid cross.
Dihybrid
A heterozygous organism with respect to two genes of interest resulting from a cross between parents having homozygous conditions for different alleles of two specific genes is referred to as a dihybrid.
Dihybrid Cross
The breeding experiment conducted between two organisms with heterozygous conditions for two specific characters is known as a dihybrid cross.
Test Cross
Breeding an organism having an unknown genotype for a specific dominant trait with an organism having homozygous recessive condition for the same specific trait is called a test cross.
Mendel’s Law of Segregation / Mendel’s 1st Law in inheritance
During the formation of gametes, the alleles for a heritable character are separated and get in to each of the gametes formed. This is known as Mendel’s Law of Segregation.
Dependent Assortment
The two characters that could be transmitted from parents to offspring as package is known as dependent assortment of alleles.
Independent Assortment
The two characters (seed colour and seed shape) could be transmitted from parents to offspring independent of each other. This is independent assortment of alleles.
Mendel’s Second Law of Inheritance / The Law of Independent Assortment
This law states that alleles separate and pair up independently during the formation of gametes. As a result, two or more genes assort independently irrespective of the other.
Probability
Probability measures how likely an event is to occur out of the number of possible outcomes.
Multifactorial Cross
When the pattern of inheritance of two or more characters of an organism is being traced during a genetic cross, its called a multifactorial cross.
Monohybrid Test Cross
A test cross performed during the monohybrid cross is called a monohybrid testcross
Dihybrid Test Cross
When an individual with dominant traits for two characters (eg- RrBb) is crossed with a pure recessive for both characters (wwbb) it’s known as a dihybrid testcross.
Non-Mendelian Inheritance
Non-Mendelian inheritance refers to inheritance patterns in which traits do not segregate in accordance with Mendel’s laws of inheritance. Phenotypes that don’t appear in ratios predicted by Mendelian genetics are indicators of Non-Mendelian inheritance.
Complete Dominance
The phenomenon of dominant allele completely masking the recessive phenotype, resulting similar phenotypes for both the homozygous dominant zygote as well as the heterozygous zygote is called complete dominance
Incomplete Dominance
The phenomenon of expressing blend phenotypes from both alleles at the heterozygous state is known as incomplete dominance.
Co-dominance
In certain traits, at heterozygote state, expression of both alleles contributes equally to the phenotype. Such phenomenon is called co-dominance.
Polyallelism (Multiple Alleles)
Polyallelism refers to the presence of multiple alleles for a single genetic locus, a phenomenon where certain traits are determined by the combination of more than two types of alleles.
Epistatis
Epistasis is the phenomenon resulting from interactions between genes of different loci. Here, the alteration in the phenotypic expression of a gene at one locus is due to the interference of another gene at a different locus.
Dominant Epistasis
Dominant epistasis is when a dominant allele at a specific locus alters the expression of a separate gene at a different locus.
Recessive Epistasis
Recessive epistasis is when a homozygous recessive genotype of a particular chromosomal locus alters/masks the expression of a separate gene at a different locus.
Polygenetic Inheritance
Inheritance of a phenotype such as quantitative characters (height, skin colour, intelligence, quotient, etc.) which results from a cumulative expression of two or more genes is called polygenic inheritance.
Normal Distribution Curve
Data for a polygenic character representing a population results in a normal distribution curve. The majority of offspring would be expected to have intermediate phenotypes (skin colour in the middle range)
Genetic Linkage
Pleiotropy
The phenomenon where the expression of a single gene affects the expression of multiple traits which are not related to each other is called pleiotropy.
Epigenetics
The study of the occurrence of certain phenotypes of certain characters controlled by factors other than their DNA sequence or genetic code is called epigenetics.
Hardy-Weinberg Equilibrium
The Hardy-Weinberg Equilibrium is used to assess whether a population is evolving with respect to a particular characteristic/genetic locus.
Artificial Selection
Artificial selection is a process of selective breeding where plants or animals with specific traits were selected to breed so that their desired traits could be passed to the next generations to produce a high performing new variety.
Inbreeding
Inbreeding is the breeding among genetically similar individuals.
Inbreeding Depression
The phenomenon of having a reduced genetic fitness in a given population as a result of inbreeding is called inbreeding depression.
Outbreeding / Cross Breeding
When plants or animals of different breeds (races) are mated with each other, it’s known as outbreeding or cross breeding.
Hybrid Breeding / Outcrossing
Hybridization or outcrossing is when genetically unrelated pure-bred plants or animals in the same species are mated with each other.
Out cross
The offspring of hybridization/outcrossing which possess stable characteristics and hybrid vigor is known as the out cross
Hybrid Vigor / Heterosis
Hybrid Vigor is the increase in such characteristics as size, growth rate, fertility, and yield in the hybrid organism over those of its parents.
Interspecific Breeding / Interspecific Hybridization
In this approach, male and female organisms of two different species are mated
Polyploidy
Polyploidy is the presence of more than two complete sets of homologous chromosomes per cell nucleus.
Mutation Breeding
Genetic Modification / Genetic Engineering
Genetic modification is the direct manipulation of an organism’s genes to change the genetic makeup of cells.
Widow’s peak
The pointed contour of the hairline on the forebrain is widow’s peak.
Dimples on cheek
When a person smiles, the shorter muscle on the face pulls up the facial skin in turn creating a slight depression in the skin which is called a dimple :)akkiboo
Rolling of Tongue
The ability to roll the lateral edges of the tongue upwards into a tube is thus
Bent Thumb / Hitchhiker’s thumb
Hitchhiker’s thumb is a condition where the thumb bends backwards while stretching due to hyper extensibility of interphalangeal joints
Methylation
methylation is where methyl groups are added to wild type DNA sequence .
Methylation
Methylation is where methyl groups are added to a wild type DNA sequence
Demethylation
Demethylation is where methyl groups are removed from a methylated DNA sequence (wild type DNA sequence)
Epigenetic Inheritance
Inheriting epigenetic traits from parents to the children’s generation is called epigenetic inheritance.
Hardy-Weinberg Equilibrium principle
According to mathematician G.H Hardy and german physician Weinberg, in a population that is not evolving, allele and genotype frequencies will remain constant from generation to generation.
