Behavioral Genetics - exam 1

Question 1

what is behavioral genetics

Answer 1

studies the role of genetics in behavior, plus the role of the environemnt and the interaction between the two - in causing a particular trait characteristic or disorder

Question 2

what is a gene

Answer 2

• segment of DNA that codes for the synthesis of a protein.
• found in chromosomes
• proteins are the bricks and tools of the body

Question 3

what is DNA

Answer 3

• double stranded polynucleotide chain

Question 4

what is a chromosome

Answer 4

• threadlike structure made up of tightly wound DNA molecules

Question 5

what is a genotype

Answer 5

• genes that someone has inherited

Question 6

what is a phenotype

Answer 6

how genes are expressed (what they look like)
genotype + environment = phenotype

Question 7

what is a dominant gene and what disorder did we study that is dominant

Answer 7

a dominant gene only needs one copy to be expressed. Hutingtons is autosomal dominant

Question 8

what is a recessive gene

Answer 8

a recessive gene needs both copies present to be expressed

Question 9

what is an allele

Answer 9

an allele is a place where a specific gene is found on a chromosome

Question 10

what is polygenetic/complex inheritance

Answer 10

polymorphisms are differences in the DNA sequence of a particular gene

Question 11

what chromosomal disorder is a common cause of intellectual disability

Answer 11

Trisomy 21- down syndrome. Non disjunction in chromosome 21 resulting in 47 chromosomes rather than 46

Question 12

what are SNPs and CNVs

Answer 12

• SNP: single nucleotide polymorphisms. Differences in a single nucleotide pair
• CNV: copy number variation: extra sections (or deleted sections) within the gene

Question 13

what disorder is an example of CNV

Answer 13

Huntingtons disease:
- CAG repeates on chromosome 4. Greater number of repeats = more severe disease

Question 14

what is epigenetics

Answer 14

study of how environmental influences alter the expression of genes

Question 15

what affects whether or not a gene is read

Answer 15

methylation and acetylation
acetylation enhances transcription: gene on
deacetylation repress transcription: gene off
DNA methylation usually represses transcription: gene off

Question 16

mechanisms of methylation and histone acetylation/ deacetylation

Answer 16

acetylation: acetyl groups attached to histone proteins can affect the accessibility of the DNA
methylation: addition of a methyl group to the DNA’s cytosine base

Question 17

what is monozygotic

Answer 17

identical twins resulting from a single fertilized egg
have identical genetics

Question 18

what is dizygotic

Answer 18

non-identical twins resulting from fertilization of 2 seperate eggs.
same genetic similarity as regular siblings

Question 19

what is proband

Answer 19

study of genetic relatedness through the family method
proband is the starting member of the family for a genetic study

Question 20

what is the family method/ linkage method

Answer 20

• discovers chromosomal location of a specific gene
• DNA sequences that are close together on a chromosome tend to be inherited together
• locate a disease causing gene by indentifying genetic markers of known chromosomal location that are coinherited with the trait of interest
• follow family trees

Question 21

what is the genetic relatedness of an individual to their:
parents
grandparents
siblings
monozygotic twin
dizygotic twin

Answer 21

parents: 50%
grandparents: 25%
siblings: 50%
monozygotic twin: 100%
dizygotic twin: 50%

Question 22

what was the method used to discover the gene that cause huntingtons disease

Question 23

what was the person responsible for doing the research to find the gene related to huntingtons that took almost 20 years