Topic 3 (Genetics And Inheritance) Flashcards
Define phenotype and genotype
Phenotype is the characteristics you have and genotype is the combination of alleles you have.
Explain gregor Mendel experiment (pea plant)
He crossed two pea plants of different heights a tall pea plant and a dwarf pea plant the offspring’s produced were all tall pea plants.
He then bread two of these tall offspring together, he found that when the offspring from the first cross were crossed with each other, 3 tall offsprings were produced for everyone dwarf offspring overall.
3:1 ratio tall: dwarf pea plant
The conclusions Mendel made after his experiment
Characteristics in plants are determined by hereditary units which are passed onto offspring unchanged from both parents one unit from each parent. Hereditary units can be dominant or obsessive. If an individual has both the dominant and the recessive unit the dominant characteristic will be expressed. For the recessive unit to be expressed there needs to be two recessive units.
Hereditary units are genes.
What are the female characteristics and the male characteristics?
Female is XX and male is XY
What is monohybrid inheritance?
It is the inheritance of one single characteristic
How does sex linked to genetic disorders occur
By the faulty alleles located on the sex chromosomes
What are the full potential blood types?
O, A, B and AB
I^A and I^B are codominant which means the individual will have both the alleles.
I^O is recessive so you need two to have blood type O
Explain how marble with blood group A and a father with blood group B can have a child with blood group O
The mother must have the genotype I^A I^O and the father must have the genotype I^B I^O to produce a child with the genotype I^O I^O and blood to group O
What is genetic variation?
It is within a species caused by organisms having different alleles which can lead to different phenotypes. Can be caused by new alleles arising through mutations. Sexual reproduction has genetic variation because of the different ways that the alleles are combined.
What does environmental variation?
Plants growing on a sunny windowsill could grow luscious and green. The same plant of grown in darkness would grow tall and spindly and its leaves will turn yellow.
Genetic mutations
Mutations are changes in the base sequence of DNA which results in an allele or a different version of the gene.
They don’t always have a big effect on the phenotype of an organisms. In fact most mutations don’t have any effect but are neutral. what mutations do you have small effect on the phenotype such as a mutation for long hair or short hair.
Very rarely single mutation will have a big effect - production of different proteins such as cystic fibrosis could happen.
The human genome project
Many common diseases like cancer and heart disease are caused by the interaction of different genes and lifestyle factors. If doctors knew what genes predisposed people to what diseases, individual tailored advice can be given on the diet and lifestyle to avoid likely problems. Doctors could also regularly check patients to ensure early treatment if we do develop the diseases we are susceptible to
The human genome project
Inherited disorders caused by the presence of one or more faulty all yours in a persons genome. We are now able to identify the genes and alleles that are susceptible of causing inherited disorder than in the past. once identified people can get tested and it may be possible to develop better treatments or even a cure for the disease
The human genome project
Has highlighted, some common variation, some variations affect how individual bodies react to certain diseases and possible treatments. Knowledge can be used to design new drugs which are specifically tailored to people with particular genetic variation and can determine how well an existing drug will work. by knowing how a disease affects us on a molecular level, it makes it possible to design more effective treatments with fewer side-effects
What are the drawbacks of the human genome project?
Increase stressed if someone knew from an early age that there susceptible to a disease.
Gene-ism people with genetic problems could come under pressure not to have children.
Discrimination by employees and insurers -Life insurance could become impossible to get.
