Exam 1

Question 1

Model Organism: yeast S. cerevisiae

Answer 1

Cell division mechanisms
Chromosome nondisjunction
Spindle formation

Question 2

Model Organism: flies D. melanogaster

Answer 2

Body patterning
Behavior
Neuro-development

Question 3

Model Organism: worms C. elegans

Answer 3

Embryogenesis
Cell Fate
Cell Death/Apoptosis

Question 4

Model Organism: fish D. rerio

Answer 4

Embryogenesis
Neuro-development
Organ development

Question 5

Model Organism: mice M. musculs

Answer 5

Neurodegenerative diseases
Immunology
Cancer

Question 6

Model Organism: E. coli

Answer 6

DNA replication mechanism
Gene regulation
Protein synthesis

Question 7

Desirable characteristics of model organisms

Answer 7

short life cycle
large number of offspring
easily and inexpensively grown in small space
features that correspond to a variety of organisms
genomic DNA that can be sequenced

Question 8

Advantages/Disadvantages of Model Organisms

Answer 8

controlled environment
learn about common genes
different species may have same diseases that can be studied

not all species are identical, so results can be invalid or unusable

Question 9

Advantage of variation

Answer 9

natural selection/evolution. Allows species to become better adapted if their genotypes vary over time.

Question 10

Independent Assortment

Answer 10

Traits controlled by different genes that are found on different chromosomes segregate independently during meiosis

Question 11

Types of mutations

Answer 11

nullomorph- mutation that leads to a gene not being transcribed into a protein
neomorph- dominant gain of a gene function different from normal gene function
hypomorph- partial loss of a gene function
hypermorph- partial increase of a gene function

Question 12

Law of Segregation

Answer 12

Each parent contributes half of genetic material to offspring

Question 13

Law of Dominance

Answer 13

Some alleles are dominant over others, and heterozygotes express dominant phenotype

Question 14

Sum rule

Answer 14

add fractions/probabilities of phenotype occurring (probability of this OR that)

Question 15

Product rule

Answer 15

multiply fractions/probabilities of phenotype occurring (probability of this AND that)

Question 16

Chi square test

Answer 16

x^2=sum of (observed-expected)^2/expected

Question 17

Variable Penetrance

Answer 17

having a specific genotype may increase the risk of having a disease/phenotype, but does not guarantee it

Question 18

Variable Expressivity

Answer 18

Range of phenotypic expression that can occur from same allele

Question 19

Autosomal Inheritance

Answer 19

Passed down through first 22 chromosomes

Question 20

Sex-Linked Inheritance

Answer 20

Passed to offspring on sex chromosomes

Question 21

Mitochondrial Inheritance

Answer 21

DNA found in mitochondria is passed to offspring (only comes from the mother)

Question 22

SRY gene

Answer 22

Sex determining Region of Y chromosome
leads to production of testosterone and MIF (Mullerian Inhibiting Factor: shuts down Mullerian system, creating female body)

Question 23

XY system

Answer 23

XX-female (default gender)
XY-male
most mammals

Question 24

ZW system

Answer 24

ZZ-male (default gender)
ZW-female
fish and birds

Question 25

X0/XX system

Answer 25

only one sex chromosome X0-male (1n) XX-hermaphrodite (2n) nematodes

Question 26

Hermaphrodites

Answer 26

In X0/XX system, can self-fertilize or be fertilized by males and make up 95% of population

Question 27

Haplodiploid system

Answer 27

unfertilized egg results in haploid male (example of parthenogenesis) fertilized egg results in diploid female bees

Question 28

Parthenogenesis

Answer 28

ability of an unfertilized egg to reproduce a mature organism; virgin birth

Question 29

Monoecious vs diecious

Answer 29

monoecious: both male and female parts on one organism (often times plants) diecious: only male or female on one organism

Question 30

Protogyny

Answer 30

conversion from female to male

Question 31

Protandry

Answer 31

conversion from male to female

Question 32

Sex-limited traits

Answer 32

Both genders have same gene but is only phenotypically present in one gender. 100% penetrance in one gender, 0% in the other NOT ON SEX CHROMOSOME

Question 33

Sex Influenced traits

Answer 33

One gender's version of the allele is recessive while the other is dominant. NOT ON SEX CHROMOSOME

Question 34

Environmental determination

Answer 34

Incubation temperature of eggs can determine gender | Protogyny and protandry (change sex while organism is already mature)

Question 35

Dosage compensation mechanisms

Answer 35

a mechanism by which species with sex chromosomes ensure the homogametic sex does not have too much of the sex gene nor does the heterogametic sex have too little

Question 36

Examples of dosage compensation mechanisms

Answer 36

Mammals: males keep X; females drop one X C. elegans (nematodes): males are X0; females are XX. Both female X's are reduced to half size Drosophilia: males X; females XX Males' X doubles

Question 37

Additive effect

Answer 37

If certain genes are found together (A and B) and there is a mutation in A or B, the unmutated gene will make up for the other being mutated

Question 38

Duplicate Gene action

Answer 38

Two genes have same function. Only presence of one of the genes is necessary for it to function; a mutation in gene A will not cause phenotypic disturbance if gene B is still functional

Question 39

Recessive lethal alleles

Answer 39

Cause organism to die if this specific recessive allele is produced

Question 40

Epistasis

Answer 40

When the expression from the genotype from one gene depends on another gene

Question 41

Pleiotropy

Answer 41

When a mutation in one gene affects several different phenotypes

Question 42

Dominant lethal alleles

Answer 42

Cause organism to die if allele is present. Only affect organisms later in life or else would have been disposed of through natural selection

Question 43

Complementation

Answer 43

production of the wild-type phenotype when two different mutations contributed by parents are combined in the offspring (mutant x mutant results in wild type: aB x Ab results in AB)