Anorexia: Biological Explanation - Genetics Flashcards

1
Q

What is a gene?

A

A sequence of DNA that codes certain information.

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2
Q

What is a genome?

A

All genes in a cell.

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3
Q

How many pairs of chromosomes do we have?

A

23

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4
Q

What is a dominant gene?

A

A gene that only needs 1 chromosome for an observable characteristic (phenotype) to show.

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5
Q

What is a recessive gene?

A

A gene that needs 2 of the same chromosome for an observable characteristic (phenotype) to show.

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6
Q

How are genetics studied in psychology?

A

Twin/adoption studies.

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7
Q

What are the two types of twins?

A
  • Monozygotic

- Dyzygotic

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8
Q

What are monozygotic twins and so how much DNA do they share?

A

Identical - 100%

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9
Q

What are dyzygotic twins and so how much DNA do they share?

A

Non-identical - 50%

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10
Q

Briefly explain what measure determines if a behaviour is genetic in twin studies.

A

Concordance rates, the higher the rate the more likely the behaviour is to be genetic.

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11
Q

List 3 strengths of twin studies.

A

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

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12
Q

List 3 weaknesses of twin studies.

A

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

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13
Q

What would anorexia being a cause of genes imply in regards to twins?

A

That frequency is higher in MZ than DZ twins.

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14
Q

Define ‘heritability estimate’.

A

The percentage that a characteristic is due to genes.

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15
Q

How is a heritability estimate often calculated?

A

Looking for similarities between families and twins in relation to that characteristic.

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16
Q

Identify 3 supporting pieces of evidence for anorexia being a cause of genes.

A

1) Kipman et al (1999)
2) Holland et al (1988)
3) Scott-Van Zealand et al (2013)

17
Q

What did Kipman et al (1999) find in regards to the cause for anorexia.

A

P - Kipman et al (1999) supports the genetic cause of anorexia
E - He gave the concordance rate for MZ twins as 44% and 12% for DZ twins
E - This therefore demonstrates that anorexia has genetic components

18
Q

What did Holland et al (1988) find in regards to the cause for anorexia.

A

P - Holland et al (1988) supports the genetic cause of anorexia
E - He looked at 25 MZ and 20 DZ twins who were all female and found a 56% concordance rate in MZs compared to 5% in DZ
E - This therefore demonstrates that anorexia has genetic components

19
Q

What did Scott-Van Zealand et al (2013) find in regards to the cause for anorexia.

A

P - Scott-Van Zealand et al (2013) supports the genetic cause of anorexia
E - He took a DNA sample from 261 anorexics and 500 healthy controls to research 152 potential genes and found that EPHX2 genes (associated with cholesterol and depression) linked with AN
E - This therefore demonstrates that anorexia has genetic components

20
Q

Identify 2 rejecting pieces of evidence for anorexia being a cause of genes.

A

1) Garner and Fairburn (1988)

2) Wade et al (2007)

21
Q

What did Garner and Fairburn (1988) find in regards to the cause for anorexia.

A

P - Garner and Fairburn (1988) rejects the genetic cause of anorexia
E - They argued that the increase in eating disorders of 15 in 1979 to over 140 in 1986 cannot be genetic due to no major genetic changes in the past 3 decades
E - Therefore there must be other factors involved such as the environment that is experienced

22
Q

What did Wade et al (2007) find in regards to the cause for anorexia.

A

P - Wade et al (2007) rejects the genetic cause of anorexia
E - Researched Australian female twins showed that families of anorexics made frequent comments about weight during childhood
E - This therefore shows the role of nurture influencing development of anorexia and so it is not just due to genetics

23
Q

Using the acronym ‘GRV’, evaluate a low ‘generalisability’ point for research into anorexia being genetic.

A

P - Low generalisability
E - Sample sizes are often small and unrepresentative as twins only make up 1.5% of the population
E - This therefore cannot be generalised to people who don’t have a twin

24
Q

Using the acronym ‘GRV’, evaluate a high ‘reliability’ point for research into anorexia being genetic.

A

P - High reliability
E - Concordance rates for AN being genetic are consistent in supporting the biological basis of this disorder
E - Therefore shows the consistency of findings and how studies can be compared and replicated easily

25
Q

Using the acronym ‘GRV’, evaluate 2 low ‘validity’ points for research into anorexia being genetic.

A

P - Low validity
E - There is never a 100% concordance rate for anorexia being genetic in twins
E - Therefore there must be other factors such as the environment affecting whether or not someone develops anorexia with different interactions stimulating different genes
P - Low validity
E - If the first twin is diagnosed with anorexia then the diagnosis of the second twin may be biased as a result
E - This is open to researcher bias and so reduces credibility of results

26
Q

Suggest an alternative explanation for the development of anorexia.

A

P - Social Learning Theory
E - Someone may idolise a role model who they pay attention to being praised for being skinny by the media and so they may reproduce this behaviour by starving themselves to be as skinny as them, receiving motivation through external reinforcement of praise for weight loss from friends
E - Therefore demonstrating that anorexia may instead be a disorder caused by the environment

27
Q

Describe a conclusion to the argument of anorexia being biological.

A

Anorexia may not be completely genetic. The interactionist theory of diathesis-stress model states that someone may be predisposed to developing anorexia but environmental stressors trigger the disorder instead of the genes themselves.