Lecture 2: Neurogenetics

Question 1

Mendelian Genetics

Answer 1

dominant vs recessive genes; genotype vs phenotype; homozygous (same 2) vs heterozygous (1 of each)

Question 2

Autosomal/Sex chromosome

Answer 2

sex-linked traits (eg. colour blindness); recessive on X (more common in males)

Question 3

Genetic coding process

Answer 3

DNA —(transcription)–> MRNA — (translation)–> protein

Question 4

Transcription

Answer 4

messenger DNA (mRNA) synthesized from DNA; mRNA leaves nucleus and attaches to ribosome in cell cytoplasm

Question 5

Translation

Answer 5

ribosome synthesizes protein according to 3 base sequences (codons) of mRNA

Question 6

Modern genetics

Answer 6

20k genes (1% of DNA), only small amount have protein coding genes; RNA role beyond translation: microRNA: translational regulation role

Question 7

Gene Enhancers

Answer 7

stretches of DNA that determine whether particular structural genes initiate synthesis of proteins, and at what rate

Question 8

Transcription factors

Answer 8

proteins bind to DNA and influence the extent that they are expressed; histone acetylation enhances transcription

Question 9

DNA methylation

Answer 9

plays an important role in cell differentiation

Question 10

Neurogenetics

Answer 10

studies the role of genetics in the development and function of the NS; neural characteristics are phenotypes; the influence of genetic alterations on neurology and behavior

Question 11

Drosophila advantages

Answer 11

it has a well known genetic model, simple, practical and cheap; it also has a relatively rich behavioral repertoire (both species specific and adaptive behavior)

Question 12

Forward genetics approach to Drosophila

Answer 12

Identify genes responsible for phenotypes

1) Mutagenesis
2) Breed mutants
3) Check for abnormalities
4) Map affected gene
5) Clone gene

Question 13

Learning mutant (strict)

Answer 13

single gene mutation that affects some aspect of learning and memory but does not affect other processes that may account for a behavior change

Question 14

Learning mutant (relaxed)

Answer 14

single gene mutation that affects learning or memory and whose effects on these processes can be reasonably dissociated from the effects on other functions of the organism

Question 15

How could genetic aberrations affect learning? (3)

Answer 15

1) Activity of gene product directly relevant for cellular processes of learning
2) Activity of gene product directly relevant for cellular processes of learning
3) Altered NS development: missing cells contribute to learning deficits
Circumvented through reverse genetics

Question 16

Reverse genetics

Answer 16

analyze phenotype after disruption of a known gene

Question 17

Chemical Mutagenesis in Drosophila (5)

Answer 17

1) Dunce (dnc)
2) Amnesiac (amn)
3) Rutabaga (rut)
4) Turnip (tur)
5) Dopa decarboxylase (Ddc)

Question 18

The learning deficits in mutant Drosophila

Answer 18

early memory phase primarily affected; dunce did the most damage

Question 19

Gene knockout (deletion) techniques

Answer 19

get rid of a particular protein product by deleting gene; measure behavioral and psychological abnormalities

Question 20

Gene knockout problem

Answer 20

behaviors are polymorphic, eliminating 1 gene alters the experience of another, gene expression is dependent on experience which may be altered by absence of missing gene

Question 21

Gene knock-in (replacement) techniques

Answer 21

replace one gene with another; implications for genetically related diseases

Question 22

Transgenic animals

Answer 22

genetic info from different species implanted; can turn on or off genes