Genetics Exam 1

Question 0

Mendel’s first law/Law of segregation

Answer 0

Identifies segregation of alleles during gamete formation and proposes the random union of gametes to produce progeny in predictable proportions determined by chance. 2 alleles for each trait will separate.

Question 1

Mendel’s second law/ Law of Independent Assortment

Answer 1

During gamete formation, the segregation of alleles at one locus is independent of segregation of alleles at another locus

Question 2

Chromosome theory of heredity

Answer 2

Chromosomes are the cell structures that carry genes

Question 3

Reciprocal cross

Answer 3

Where same genotypes are crossed but sexes of donating parents are switched

Question 4

Test cross

Answer 4

Cross between F1 heterozygous and a pure breeding recessive phenotype

Question 5

Haplosufficient

Answer 5

One copy is sufficient to produce wild type phenotype

Question 6

Haploinsufficient

Answer 6

A single copy is not sufficient to produce wild type phenotype

Question 7

Loss of function mutation

Answer 7

Results in a significant decrease or complete loss of functional activity of a gene product

Question 8

Gain of function mutation

Answer 8

Identify alleles that have acquired a new function or express substantially more activity than the wild type allele

• almost always dominant
• some are lethal in a homozygous state

Question 9

Incomplete dominance

Answer 9

Dominance of one allele over another is not complete. Phenotype of heterozygous is distinctive and is typically more similar to one homozygous phenotype than the other.

Question 11

Codominance

Answer 11

Leads to a heterozygous phenotype different from the phenotype of either homozygous parent. Is characterized by the detectable expression of both alleles in heterozygotes.

Question 12

sex-influenced traits

Answer 12

the phenotype corresponding to a particular genotype differs depending on sex of organism

Question 13

nonpenetrant

Answer 13

when a particular genotype fails to produce corresponding phenotype

Question 14

incomplete penetrance

Answer 14

when traits for which nonpenetrant individuals occasionally/routinely occur

Question 15

variable expressivity

Answer 15

the same genotype produces phenotypes that vary in the degree/magnitude of expression of allele

Question 16

pleiotropy

Answer 16

the alteration of multiple, distinct traits of an organism by a mutation in a single gene

Question 17

epistasis

Answer 17

• causes altered ratios of wild type and mutant phenotypes
• minimum of 2 genes required
• results from mutation in pathways that require a specific activity from every gene in the pathway for wild type phenotype to be produced

Question 18

duplicative recessive epistasis/9:7

Answer 18

results from complementary gene interaction that requires genes to work in tandem to produce a single product

Question 19

genetic complementation

Answer 19

ability of 2 mutants with same mutant phenotype to produce progeny with wild type phenotype
-shows more than 1 gene is involved in determining the phenotype

Question 20

duplicate dominant epistasis/15:1

Answer 20

a redudant genetic system in which any genotype possessing at least one copy of a dominant allele at either locus will produce dominant phenotype

Question 21

dominant gene interaction/9:6:1

Answer 21

recessive at either gene causes same phenotype but recessive for both gene causes 1/16 different phenotype

Question 22

recessive epistasis/9:3:4

Answer 22

homozygosity for a recessive allele at one locus can mask the phenotypic expression of a 2nd gene

Question 23

dominant epistasis/12:3:1

Answer 23

a dominant allele at 1 locus masks the expression of alleles at a 2nd locus

Question 24

non genetic complementation

Answer 24

offspring of a cross between 2 mutants will have a mutant phenotype and mutations are on the SAME gene

Question 25

gene

Answer 25

fundamental unit of heredity
- controls some aspect of an organism’s form,
function, or behavior (phenotype)
- a segment of DNA that contains the genetic
information to express a (usually) protein

Question 26

central dogma

Answer 26

DNA -> RNA -> Protein

Question 27

Mitosis

Answer 27

ensures that all somatic cells of the body have the same set of chromosomes and 2 copies of each

Question 28

Sister chromatids are the same, True or False?

Answer 28

True

Question 29

Homologous chromosomes are the same, True or False?

Answer 29

False

Question 30

Meiosis

Answer 30

specialized cell division that produces haploid gametes

Question 31

5 important things about Mendel’s methods

Answer 31

1. only used discontinuous traits
2. counted everything and used real numbers
3. did reciprocal crosses
4. studied only monogenic traits
5. studied traits without genetic linkage in crosses

Question 32

When does crossing over occur?

Answer 32

Meiosis I during late prophase I

Question 33

G1 phase

Answer 33

active gene expression and cell activity: preparation for DNA synthesis

Question 34

S phase

Answer 34

DNA replication and chromosome duplication

Question 35

G2 phase

Answer 35

preparation for cell division

Question 36

M phase

Answer 36

Mitosis for somatic cells and Meiosis for germ-line cells

Question 37

Interphase

Answer 37

Chromosomes are not visible but are duplicated

Question 38

Prophase

Answer 38

Chromosomes condense and become visible as a pair of sister chromatids joined at centromere

Question 39

Telomere

Answer 39

Stable ends of chromosome

Question 40

Centromere

Answer 40

a constricted region of the chromosome where the kinetechores form and spindle microtubules attach

Question 41

Chromosome

Answer 41

2 sister chromatids attached at centromere

Question 42

Prometaphase

Answer 42

-nuclear envelope breaks down and
mitotic spindleforms
-microtubules connect to sister chromatids at
centromere

Question 43

Metaphase

Answer 43

chromosome pairs line up along metaphase plate

Question 44

Anaphase

Answer 44

Centromeres divide and the sister chromatids move to opposite poles of the cell

Question 45

Telophase

Answer 45

• nuclear envelope forms around chromosomes
• cell divides into two -cytokinesis
• chromosomes return to interphase state