5.1.4 AN- Genetics/ Adoption studies Flashcards
What is a gene?
A sequence of DNA that codes certain information.
What is a genome?
All genes in a cell.
How many chromosomes do we have?
23
> 23rd pair= sex cells
What is a dominant gene?
A gene that only needs 1 chromosome for an observable characteristic (phenotype) to show
What is a recessive gene?
A gene that needs 2 of the same chromosome for an observable characteristic (phenotype) to show.
What are the 2 types of twins
Monozygotic
Dyzygotic
What are monozygotic twins and so how much DNA do they share?
Identical-100%
What are dyzygotic twins and so how much DNA do they share?
Non-identical - 50%
Briefly explain what measure determines if a behaviour is genetic in twin studies.
Concordance rates, the higher the rate the more likely the behaviour is to be genetic.
List 3 strengths of twin studies.
1) High reliability
- Uses scientific methods such as DNA sequencing which provides objective quant data
2) High reliability
- The number of multiple births are increasing so can replicate easily
3) High validity
- MZ and DZ twins are naturally occurring variables so low researcher bias
List 3 weaknesses of twin studies.
1) Low generalisability
- MZ twins may not be representative of other twins in a different environment
2) Low reliability
- Environmental differences between MZ and DZ twins may be hard to compare due to differences
3) Low validity
- One twin of an MZ pair may be exposed to different environmental triggers for one gene
Link to AN being a cause of genes imply in regards to twins?
That frequency is higher in MZ than DZ twins
Define ‘heritability estimate’.
The percentage that a characteristic is due to genes.
How is a heritability estimate often calculated?
Looking for similarities between families and twins in relation to that characteristic.
Identify 3 supporting pieces of evidence for anorexia being a cause of genes.
1) Kipman et al (1999)
2) Holland et al (1988)
3) Scott-Van Zealand et al (2013)
