Genetics (Techniques)

Question 1

Gene

Answer 1

A segment of DNA that carries instructions for making a protein or functional RNA, determining traits and functions in an organism

Question 2

Chromosome

Answer 2

A threadlike structure of nucleic acids and proteins found in the nucleus of living cells, carrying genetic information in the form of genes

Question 3

DNA (Deoxyribonucleic Acid)

Answer 3

The molecule that carries genetic information for the development and function of an organism

Question 4

Genotype

Answer 4

Are combinations of alleles that contribute to the phenotype

Question 5

Allele

Answer 5

Different form of the same gene

Question 6

Phenotype

Answer 6

The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment

Question 7

Homozygous

Answer 7

When there is two identical copies of alleles in the DNA gene sequence that encode for a particular trait

Question 8

Heterozygous

Answer 8

Having two different alleles of a particular gene or genes

Question 9

Dominant Allele

Answer 9

Always expressed, even if one copy is present

Question 10

Recessive Allele

Answer 10

Does not produce a trait at all when only one copy is present

Question 11

Mutation

Answer 11

A change in the DNA sequence of an organism
* mutations can result from errors in the DNA replication during cell division etc.

Question 12

Heritability

Answer 12

A measure of how well differences in people’s genes account for differences in their traits

Question 13

Epigenetics

Answer 13

A recent field which investigates how the environment can affect the way genes work

Question 14

Genetic Predisposition

Answer 14

A tendency for a certain trait to be inherited (physical, mental, diseases) based on genetic makeup

Question 15

Natural Selection

Answer 15

It is the process by which organisms with traits that are better suited to their environment tend to survive and reproduce more successfully than those with less advantageous traits

Question 16

Genome

Answer 16

A complete set of genetic material (DNA/RNA) present in an organism

Question 17

Genetic Expression

Answer 17

The process by which the information encoded in a gene is turned into a function

Question 18

Evolutionary psychology

Answer 18

Explores how evolutionary principles influence human thoughts, emotions & behaviors

Question 18

Polymorphism

Answer 18

The presence of two or more variant forms of a specific DNA sequence that can occur among different individuals or populations

Question 19

Behavioural genetics

Answer 19

The study of genetic and environmental influences on behaviours

Question 20

Molecular genetics

Answer 20

The study of the molecular structure of DNA, its cellular activities (including its replication), and its influence in determining the overall makeup of an organism

Question 21

What type of method is mostly used in genetics?

Answer 21

Correlational studies
* researcher establishes relationship between variables but does not manipulate IV
* no cause and effect can be determined

Question 22

Prospective studies

Answer 22

When it is suspected that a behaviour might be genetic, the genetically vulnerable individual is followed to see if it actually develops
* logitudinal study used to see through if the observed ever develops condition

Question 23

Issues with prospective studies (2)

Answer 23

• may cause undue stress and lead to actual effects on those labeled as vulnerable
• self-fulfilling prophecy: (also known as Pygmalion effect) your belief about what will happen drives the actions that make that outcome utlimately come to pass

Question 24

Family studies (3)

Answer 24

* twin studies * kinship studies * adoption studies

Question 25

Twin studies

Answer 25

Studies based on principle of genetic relatadness looking at differences in concordance rates between MZ and DZ twins

Question 26

Analysis of MZ and DZ comparison

Answer 26

* MZ twins share 100% of genetic makeup (one split fertilised egg), DZ twins share 50% of genetic makeup (two fertilised eggs) * if MZ concordance rates of a psychological disorder are higher than DZ ones, it suggests the disorder is genetically inherited * if a given characteristic was entirely environmentally caused the concordance rate for MZ and DZ should be the same as both kinds of twins have similar environments

Question 27

Concordance rate

Answer 27

A statistical measure that describes the proportion of pairs of individuals that share an attribute, given that one already possesses this characteristic * high concordance means casual connection (likely to have same characteristics)

Question 28

Limitations of twin studies (name 3)

Answer 28

* environmental factors can't be eliminated (twins often share same experiences) * concordance rates are rarely 100% for behavioural traits * they are still an indirect measure of genetic inheritance * DZ twins can still have common DNA

Question 29

Strengths of twin studies (name 3)

Answer 29

* genetic similarity: allow researchers to isolate the influence of genetics from environmental factors * control of genetic influence * study of nature vs nurture: extent to which difference in behaviours is due to genetic or environmental factors * longitudinal studies: provide insight into how behaviour or traits develop over time * high reliability * useful in studying mental health disorders

Question 30

Kinship studies

Answer 30

Based on principle of genetic relatedness looking at broader scale and across generations and genetic relatedness spreads * shared diagnoses between relatives * sibling similarity greater than cousins etc.

Question 31

Limitations of kinship studies (name 3)

Answer 31

* Members sharing the same environment can make it difficult to rule out factors * an indirect measure of genetic inheritance (there is no actual identification of specific genes) * data is often anecdotal (ex. what you remember from your grandmother). * waiting several generations to determine if a behaviour is genetic is inefficient strategy in human research (Works better in animal research) * modern understandings of epigenetics show that this strategy is not as clear cut as it may seem

Question 32

Strengths of kinship studies

Answer 32

* wide range of Genetic Relatedness: allow researchers to examine different degrees of genetic relatedness * cross-generational study * useful for inheritance of disorders * control for environmental similarity * naturalistic setting * non-invasive and ethical

Question 33

Adoption studies (2 connection to genetics)

Answer 33

* If an adopted child demonstrates traits that closely resemble those of the adoptive family, the influence of genetics is refuted * If an adopted child reflects traits of the biological parents, it supports the role of genetics

Question 34

Limitations of adoption studies (name 3)

Answer 34

* selective placement: babies tend to be placed with families in backgrounds similar to birth mother * adopted children are not representative of all children * living in adoptive family and knowing you are adopted may have effect on your behaviour * ethical considerations: privacy, undue stress etc.

Question 35

Strengths of adoption studies (name 3)

Answer 35

* separation of genetic and environmental factors: comparison between biological and adoptive families * study of nurture * ethical alternative study: efefcts of different environments whilst not directly manipulating child's upbringing * insight into development disorders * control of genetic bias:

Question 36

Human genome project

Answer 36

Worldwide research initiative started in 1990 * goal: to map and sequence human genome * found out: there are approx. 22,300 genes that make up human genome * led to direct approach of linkage studies

Question 37

Linkage analysis / genetic mapping

Answer 37

Indicated which chromosome contains the gene related to a certain behaviour * collected blood samples from members of families in which behaviour is common (e.g. schizophrenia) examine DNA for presence of genetic variations * look for genetic markers

Question 38

Advantage of linkage analysis

Answer 38

* more direct approach to studying genetic influence (biological advantage) * technique identifies specific genes and allows for testing in other samples

Question 39

Limitations of linkage analysis (3)

Answer 39

* results are correlational, causation cannot easily be established * research is usually carried out within families, EF and lifestyle habits (diet, family strategies for coping with stress) may play role in gene expression * small sample sizes: lack of reliability

Question 40

Genetic-wide association studies (GWAS)

Answer 40

Used when a gene is supected of having a role in behaviour * compares DNA of experimental and control grou * if a genetic marker is more frequent in experimental, it is said to be associated with behaviour * large amounts of data are mapped in a Manhattan plot

Question 41

Advantages of GWAS (2)

Answer 41

* very large samples (often tens of thousands of samples): eliminates influence of outliers * have already been used for a wide variety of behaviours (scizophrenia, anorexia, Alzheimer's disease)

Question 42

Limitations of GWAS

Answer 42

* difficult to manage due to size * correlational nature of all techniques used * false positives: good GWAS have multiple tests in order to identify polymorphism to control for this * may be too reductionist of an approach to explain complex behaviours

Question 43

Limitations of genetic studies (3)

Answer 43

* reductionist: reducing complex conditions to the supposed activity of small number of genes (too simplistic) * deterministic: no hope of controlling conditions as genes can't be controlled consciously * bidirectional ambiguity: sometimes hard to tell what causes what in psychological illness (impossible to establish cause and effect - coincidentality is likely and possible)