1. Genetic variation and inheritance is determined by genes found on chromosomes in the cell nucleus that are passed from parents to offspring.
2. Sexual reproduction involves the fusion of male and female gametes (sperm and egg) from two parents, leading to genetic variation in offspring. Asexual reproduction involves only one parent and no fusion of gametes, resulting in clones with no genetic variation.
3. Variation between individuals can be due to genetic factors like sexual reproduction and inheritance of different genes, or environmental factors like nutrition, temperature, and physical forces during development.
Examples of Codominance. The best example, in this case, is the codominance blood type. ABO group is considered to be a codominant blood group where both father’s and mother’s blood group is expressed. It means that the properties of the blood groups exist in the ABO type.
Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked.
Examples of Codominance. The best example, in this case, is the codominance blood type. ABO group is considered to be a codominant blood group where both father’s and mother’s blood group is expressed. It means that the properties of the blood groups exist in the ABO type.
Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked.
It is a powerpoint presentation that discusses about the lesson or topic: Non-Mendelian Inheritance. It also talks about the definition, history and the laws included in the Non-Mendelian Inheritance or Non-Mendelian Genetics.
It is a powerpoint presentation that discusses about the lesson or topic: Non-Mendelian Inheritance. It also talks about the definition, history and the laws included in the Non-Mendelian Inheritance or Non-Mendelian Genetics.
Genetics is the scientific study of genes and heredity of how certain qualities or traits are passed from parents to offspring (National Institute of General Medical Sciences, 2022)
Molecular basis of inheritance, Patterns of genetic transmission, Gene mutation, structure of chromosome, chromosomes in Man, Genetic disorders, Numerical disorders, structural disorder, Genetics in an orthodontic perspective, Butler's field theory, methods of studying role of genes.
B4FA 2012 Nigeria: Principles of Genetics - Charles Amadib4fa
Presentation by Dr Charles Amadi, National Root Crops Research Centre, Umudike, Nigeria
Delivered at the B4FA Media Dialogue Workshop, Ibadan, Nigeria - September 2012
www.b4fa.org
2. Genetic variation and inheritance
Key words
Cell
Chromosone
Nucleus
Gene
Sexual reproduction
Asexual reproduction
Gamete
Zygote
Clone
Propogation
Binary fusion
Genetic factors
Environmental factors
3. Genetic material
•A cell is the basic unit of life; all organisms
are made up of cells.
•The nucleus is a large organelle found in
all cells, that contains the genetic
information.
•Chromosomes are thread-like structures
made of DNA found in the nucleus.
•Genes are small sections of a
chromosome that control the
characteristics of an organism.
• These are passed on from parent to
offspring, resulting in offspring of plants
and animals having similar characteristics
to their parents. Eg hair colour and petal
colour
• Different genes control the development
of different characteristics of an organism.
5. Sexual reproduction
•Involves two parents.
•They produce male and female sex cells (gametes).
•In humans these are sperm and eggs.
•In plants these are pollen and ovules
•Fertilisation occurs - the joining (fusion) of male and female gametes.
•The mixture of the genetic information from two parents leads to variation
in the offspring.
•Genes are passed on in the gametes, from which the offspring develop.
6. Asexual reproduction
•Involves only one individual as a
parent.
•There is no fusion of gametes.
•There is no mixing of genetic
information and so no variation in the
offspring.
•These genetically identical individuals
are known as clones.
Examples:
•Bacteria or yeast cells use
binary fission
•Plants can use runners, bulbs or
vegetative propagation.
•Some invertebrate animals like
starfish and hydra can produce
asexual offspring.
7. The causes of variation
Differences in the characteristics of different individuals of the same
kind may be due to differences in:
• the genes they have inherited (genetic causes)
• the conditions in which they have developed (environmental causes)
• or a combination of both.
Genetic factors
Sexual reproduction - leads to genetic variety
in the offspring.
All offspring (except for identical twins)
inherit different characteristics.
Asexual reproduction – no genetic variation in
the offspring (unless mutations occur)
Environmental factors
•Nutrition
•Temperature
•Light
•Physical forces
