Inheritance
Mendel's discoveries
Ever since early times, farmers realised that many characteristics of plant and animal are passed from parent to offspring. They had no idea how these traits were passed and many believed that the offspring was simply a mix of the characteristics of both parents. An Australian monk, Gregor Mendel, in 1865 put this theory to the test. He soon came out with two principles:
1. The various hereditary characteristics were controlled by factors (now known as genes) and that these occur in pairs.
2. During the formation of gametes, the pairs of factors separate. Each gamete only receives one pair of factors or genes and the other going to another gamete. Gametes unite at fertilisation, allowing different combinations of genes to come together.
More information on Mendel's discoveries can be found out here: http://www.biotechlearn.org.nz/themes/mendel_and_inheritance/mendel_s_principles_of_inheritance
Ever since early times, farmers realised that many characteristics of plant and animal are passed from parent to offspring. They had no idea how these traits were passed and many believed that the offspring was simply a mix of the characteristics of both parents. An Australian monk, Gregor Mendel, in 1865 put this theory to the test. He soon came out with two principles:
1. The various hereditary characteristics were controlled by factors (now known as genes) and that these occur in pairs.
2. During the formation of gametes, the pairs of factors separate. Each gamete only receives one pair of factors or genes and the other going to another gamete. Gametes unite at fertilisation, allowing different combinations of genes to come together.
More information on Mendel's discoveries can be found out here: http://www.biotechlearn.org.nz/themes/mendel_and_inheritance/mendel_s_principles_of_inheritance
Dominant and Recessive Traits
The term dominant and recessive refer to the pattern and inheritance of certain traits which are passed from parent to offspring. Every sexually reproducing species including humans contain two copies of each gene which are known as alleles. There is a dominant and a recessive allele. The dominant allele produces a dominant phenotype in the individual, and only needs one copy from one of the parents to have this trait. For a recessive trait to be passed, two copies of the allele must be passed onto the offspring, meaning that the recessive trait must be present in both parents.
For more information: http://learn.genetics.utah.edu/content/inheritance/patterns/
For an interactive quiz: http://anthro.palomar.edu/mendel/quizzes/mendqui2.htm
The term dominant and recessive refer to the pattern and inheritance of certain traits which are passed from parent to offspring. Every sexually reproducing species including humans contain two copies of each gene which are known as alleles. There is a dominant and a recessive allele. The dominant allele produces a dominant phenotype in the individual, and only needs one copy from one of the parents to have this trait. For a recessive trait to be passed, two copies of the allele must be passed onto the offspring, meaning that the recessive trait must be present in both parents.
For more information: http://learn.genetics.utah.edu/content/inheritance/patterns/
For an interactive quiz: http://anthro.palomar.edu/mendel/quizzes/mendqui2.htm
Sex Determination
If you were to examine the birth records for Australia in the past century, you would find the number of girls and boys are basically even. Yet when you would look at a family, almost all of them do not have an even number of girls and boys. This was questioned for many years until scientists began to examine the nuclei of cells and realised that the chromosome sets in the nuclei of males and females are different. The female contains 46 chromosomes in a cells nucleus and 23 matched pairs;, whereas the male contains 46 chromosomes but only 22 matched pairs, the 23rd one being two unmatched chromosomes. The 23rd chromosome determines the sex of the human, an X chromosome for female and Y chromosome for a male. However, in every female egg there is always the X chromosome for the 23rd pair and the male has half with the X chromosome and half with the Y. This ultimately meaning that the males sperm determines the sex of the baby (XX for female, XY for male)
website: http://www.soc.ucsb.edu/sexinfo/article/sex-determination-and-differentiation
video: http://www.youtube.com/watch?v=kMWxuF9YW38
If you were to examine the birth records for Australia in the past century, you would find the number of girls and boys are basically even. Yet when you would look at a family, almost all of them do not have an even number of girls and boys. This was questioned for many years until scientists began to examine the nuclei of cells and realised that the chromosome sets in the nuclei of males and females are different. The female contains 46 chromosomes in a cells nucleus and 23 matched pairs;, whereas the male contains 46 chromosomes but only 22 matched pairs, the 23rd one being two unmatched chromosomes. The 23rd chromosome determines the sex of the human, an X chromosome for female and Y chromosome for a male. However, in every female egg there is always the X chromosome for the 23rd pair and the male has half with the X chromosome and half with the Y. This ultimately meaning that the males sperm determines the sex of the baby (XX for female, XY for male)
website: http://www.soc.ucsb.edu/sexinfo/article/sex-determination-and-differentiation
video: http://www.youtube.com/watch?v=kMWxuF9YW38
Sex-linked Characteristics
When characteristics located on the X-chromosome are studied, it is found that the pattern of inheritance is different in the two sexes. Characteristics that show different patterns in the two sexes are called sex-linked characteristics or X-linked characteristics. Sex linked traits are determined by genes which are located on sex chromosomes.
the picture below shows the sex linked trait causing haemophilia
Notice how the females are only carriers of the trait and not affected. Sex-linked traits only affect males whether it be a dominant or recessive trait. The mother's X1 chromosome is the cause of the trait from passing to offspring. There is a 50% chance that a male offspring will posses haemophilia and a 50% chance for a female carrier.
follow the link to find out more information: http://www.youtube.com/watch?v=-ROhfKyxgCo
follow the link to find out more information: http://www.youtube.com/watch?v=-ROhfKyxgCo
Codominance
Codominance is where an offspring shows characteristics from both parents. This happens in many situations in genetics where the alleles of a particular gene are neither dominant nor recessive. For example a four o-clock flower was bred, one being a homozygous red and the other a homozygous white. what they found was that this created a pink coloured flower offspring. the blend of the two is known as Codominance. This can also be shown in humans too. For M and N antigens in the blood. As neither are dominant to the other, it can create either M blood, N blood or MN blood.
video: http://www.youtube.com/watch?v=DxCIrv2q_Cc
Codominance is where an offspring shows characteristics from both parents. This happens in many situations in genetics where the alleles of a particular gene are neither dominant nor recessive. For example a four o-clock flower was bred, one being a homozygous red and the other a homozygous white. what they found was that this created a pink coloured flower offspring. the blend of the two is known as Codominance. This can also be shown in humans too. For M and N antigens in the blood. As neither are dominant to the other, it can create either M blood, N blood or MN blood.
video: http://www.youtube.com/watch?v=DxCIrv2q_Cc
Multiple alleles
Sometimes there are more than two alleles for a particular characteristic, these are known as multiple alleles. A big case of this is the ABO blood group system. Blood groups inherited and the ABO blood grouping system is based on the fact that a person can belong to the blood groups A, B, AB or O.
This website contains more information: http://www.hobart.k12.in.us/jkousen/Biology/multalle.htm
Sometimes there are more than two alleles for a particular characteristic, these are known as multiple alleles. A big case of this is the ABO blood group system. Blood groups inherited and the ABO blood grouping system is based on the fact that a person can belong to the blood groups A, B, AB or O.
This website contains more information: http://www.hobart.k12.in.us/jkousen/Biology/multalle.htm
Genetic diseases within population
A genetic disorder is caused by an altered gene or set of genes.The four main ways of inheriting an altered gene are autosomal dominant, autosomal recessive, X-linked dominant and X-linked recessive. The four broad groups of genetic disorders are single gene disorders, chromosome abnormalities, mitochondrial disorders and multifactorial disorders.
This website shows more on the specific types of genetics disorders: http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Genetic_disorders
A genetic disorder is caused by an altered gene or set of genes.The four main ways of inheriting an altered gene are autosomal dominant, autosomal recessive, X-linked dominant and X-linked recessive. The four broad groups of genetic disorders are single gene disorders, chromosome abnormalities, mitochondrial disorders and multifactorial disorders.
This website shows more on the specific types of genetics disorders: http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Genetic_disorders
Better Health Channel. (n.d.). Genetic Disorders. Retrieved October 6, 2014, from Better Health Channel: http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Genetic_disorders
Dragonfly TV. (n.d.). Games. Retrieved october 6, 2014, from Dragonfly TV: http://pbskids.org/dragonflytv/games/game_dogbreeding.html
Genetic Science Learning Center. (n.d.). What are Dominant and Recessive? Retrieved October 6, 2014, from Learn.Genetics: http://learn.genetics.utah.edu/content/inheritance/patterns/
Biology, H. (n.d.). Codominance Punnett Square . Retrieved October 9, 2014, from YouTube: http://www.youtube.com/watch?v=DxCIrv2q_Cc
IncOMpleTe & COdominANce. (n.d.). Retrieved october 6, 2014, from http://www.hobart.k12.in.us/jkousen/Biology/inccodom.htm
Miko, I. (n.d.). Gregor Mendel and the Principles of Inheritance. Retrieved October 6, 2014, from Scitable : http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593
O'Neil, D. (n.d.). Practice Quiz for probability of Inheritance. Retrieved October 6, 2014, from http://anthro.palomar.edu/mendel/quizzes/mendqui2.htm
O'Neil, D. (n.d.). Probability of Inheritance. Retrieved october 9, 2014, from http://anthro.palomar.edu/mendel/mendel_2.htm
schmoop. (n.d.). The Theme of Sex Determination and the Inheritance of Sex Linked Traits in Genetics. Retrieved October 6, 2014, from schmoop: http://www.shmoop.com/genetics/sex-determination-linked-traits.html
Reedy, A. (n.d.). Sex determination: More complicated than you thought. Retrieved October 9, 2014, from YouTube: http://www.youtube.com/watch?v=kMWxuF9YW38
about.com. (n.d.). Sex-Linked Traits. Retrieved October 6, 2014, from about Education: http://biology.about.com/od/genetics/ss/sex-linked-traits.htm
Human Sex Determination. (n.d.). Retrieved October 9, 2014, from SexInfo: http://www.soc.ucsb.edu/sexinfo/article/sex-determination-and-differentiation
Dragonfly TV. (n.d.). Games. Retrieved october 6, 2014, from Dragonfly TV: http://pbskids.org/dragonflytv/games/game_dogbreeding.html
Genetic Science Learning Center. (n.d.). What are Dominant and Recessive? Retrieved October 6, 2014, from Learn.Genetics: http://learn.genetics.utah.edu/content/inheritance/patterns/
Biology, H. (n.d.). Codominance Punnett Square . Retrieved October 9, 2014, from YouTube: http://www.youtube.com/watch?v=DxCIrv2q_Cc
IncOMpleTe & COdominANce. (n.d.). Retrieved october 6, 2014, from http://www.hobart.k12.in.us/jkousen/Biology/inccodom.htm
Miko, I. (n.d.). Gregor Mendel and the Principles of Inheritance. Retrieved October 6, 2014, from Scitable : http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593
O'Neil, D. (n.d.). Practice Quiz for probability of Inheritance. Retrieved October 6, 2014, from http://anthro.palomar.edu/mendel/quizzes/mendqui2.htm
O'Neil, D. (n.d.). Probability of Inheritance. Retrieved october 9, 2014, from http://anthro.palomar.edu/mendel/mendel_2.htm
schmoop. (n.d.). The Theme of Sex Determination and the Inheritance of Sex Linked Traits in Genetics. Retrieved October 6, 2014, from schmoop: http://www.shmoop.com/genetics/sex-determination-linked-traits.html
Reedy, A. (n.d.). Sex determination: More complicated than you thought. Retrieved October 9, 2014, from YouTube: http://www.youtube.com/watch?v=kMWxuF9YW38
about.com. (n.d.). Sex-Linked Traits. Retrieved October 6, 2014, from about Education: http://biology.about.com/od/genetics/ss/sex-linked-traits.htm
Human Sex Determination. (n.d.). Retrieved October 9, 2014, from SexInfo: http://www.soc.ucsb.edu/sexinfo/article/sex-determination-and-differentiation