3 - Genetics - Genes & Alleles Flashcards
What are Alleles?
Different versions of the same gene
A person may have the same two alleles - homozygous or two different ones - heterozygous
How do Recessive/Dominant Alleles affect inherited characteristics?
Some Alleles are dominant, overruling recessive alleles, meaning if an organism has one dom and one rec allele (Ff) the dominant allele will determine which characteristic is present
For a recessive char to be displayed, both its alleles must be rec (ff)
Explain:
Genotype
Phenotype
Genotype - the combination of alleles you have
Phenotype - the characteristics you have (determined by alleles)
Different Genotypes give rise to different Phenotypes
Explain:
Gamete
Zygote
Gamete - a reproductive cell of an animal of plant
Zygote - a diploid cell resulting from the fusion of two haploid gametes - a fertilized egg
Describe how the sex of offspring is determined at fertilisation
XX = female
XY = male
Dependant on which chromosome the sperm carries at fertilisation
How are sex-linked genetic disordered inherited?
When a sex chromosome passes down a faulty allele
What are most phenotypic features made up of?
Multiple genes rather than single gene inheritance
How does genetic variation influence phenotypes?
Genetic variation is caused by organisms having different alleles - can lead to differences in phenotype
Can also be caused by mutations creating new alleles and sexual reproduction as it combines alleles in different ways
How does environmental variation influence phenotypes?
Most variation is determined by a mix of genetic and environmental factors
Environmental factors (aka acquired characteristics) happen overtime, eg plants growing in sunlight vs no light, human diet influencing growth etc
What were the outcomes of the Human Genome Project?
Identified about 1800 genes related to disease, creating huge potential benefits for medicine
How does the HGP help prediction and prevention of diseases?
Diseases like heart disease and cancer are caused by interactions of genes
If we knew what genes caused these we could get indicidually tailored advice to avoid these problems
Could also let us get checked regularly to spot if any diseases do develop
How can the HGP help testing & treating inherited disorders?
- Able to identify genes & alleles that can cause inherited disorders
- Once identified, people can be tested & easier to create better treatments for disease
How can the HGM help produce new & better medicine
- Able to design specific drugs
- Determine how existing drugs will work on someone
- Help make effective treatment w/ less side effects
What are some drawbacks of the HGP?
Increased Stress
Gene-ism (pressure to not have kids)
Discrimination (life insurance, employers)
Do all mutations affect the phenotype?
most genetic mutations have no effect on the
phenotype, some mutations have a small effect on the
phenotype and, rarely, a single mutation will significantly
affect the phenotype
