Genetics Test 2

Front 1

The phenomenon in which a gene’s expression is determined by its parental origin is called _______.
A. maternal effect
B. sex-limited
C. genomic imprinting

Back 1

1. C genomic imprinting

Front 2

In order to determine if mutations from different organisms that exhibit the same phenotype are allelic, which test should be performed?
A. test cross
B. epistasis test
C. complementation test

Back 2

2. C complementation test

Front 3

In humans, blood types A and B are codominant to each other and each is dominant to type O. What possible blood types will result in the offspring from a cross between a parent that is IAIB and IAIA?
A. A and AB
B. A, AB, and O
C. A, B, and AB

Back 3

3. A A and AB

Front 4

Which organelle in an animal cell, in addition to the nucleus, contains genes?
A. lysosome
B. mitochondria
C. ribosome

Back 4

4. B mitochondria

Front 5

Eggplant color demonstrates incomplete dominance where PP=purple, pp=white, Pp=violet. What will the phenotype of the offspring resulting from a cross between Pp (violet) and pp(white)?
A. ¾ purple, ¼ white
B. ½ violet, ½ white
C. ¾ violet, ½ white

Back 5

5. B ½ violet, ½ white

Front 6

In ________, the presence of two recessive alleles (homozygous genotype) inhibits the expression of an allele at a different locus.
A. recessive epistasis
B. dominant epistasis
C. maternal genetic effect

Back 6

6. A recessive epistasis

Front 7

Coat color in Labrador retrievers exhibits recessive epistasis where one allele encodes black (BB, Bb) or brown (bb) and a second allele, E (EE or Ee) allows deposition of the color in the hair shaft and (ee) prevents deposition. The following phenotypes result:
B_E_ Black
bbE_ Brown
B_ee yellow
Bbee yellow
If you cross two Black dogs (BbEe), what will be the phenotypes of the offspring?
A. 1/16 black, 3/16, brown, 9/16 yellow
B. ½ black, ¼ brown, 3/16 yellow
C. 9/16 black, 3/16 brown, 4/16 yellow

Back 7

7. C 9/16 black, 3/16 brown, 4/16 yellow

Front 8

The bicoid mutation (bcd-) in fruit flies is inherited as a genetic maternal effect recessive allele. What is the expected ratio of phenotypes in the offspring of a cross between bcd+/bcd- female and a bcd+/bcd- male
A. ¾ normal, ¼ mutant
B. all normal
C. all mutant

Back 8

8. B all normal

Front 9

What is the possible inheritance pattern of the following pedigree 1?
A. Autosomal recessive
B. Autosomal dominant
C. X-linked dominant

Back 9

9. A Autosomal recessive

Front 10

What is the possible inheritance pattern of pedigree 2
A. X-linked dominant
B. X-linked recessive
C. Either A or B are possible

Back 10

10. C Either A or B are possible

Front 11

Male-limited precocious puberty is a genetic disorder resulting from an autosomal dominant allele that is expressed only in males, it has zero penetrance in females. This is an example of a
A. Recessive epistasis
B. Sex-influenced characteristic
C. Sex-limited characteristic

Back 11

11. C Sex-limited characteristic

Front 12

In epistasis, the gene that is masked is the _______gene.
A. epistatic
B. hypostatic
C. neither

Back 12

12. B hypostatic

Front 13

The person from whom a pedigree is initiated is called the _________.
A. proband
B. concordant
C. discordant

Back 13

13. A proband

Front 14

_______twins are genetically identical.
A. monozygotic
B. dizygotic

Back 14

14. A monozygotic

Front 15

. _________ involves taking some of the cells from the outer layer of the placenta for genetic testing.
A. Amniocentesis
B. Chorionic villus sampling
C. PKU testing

Back 15

15. B Chorionic villus sampling

Front 16

The genetic test for PKU, a autosomal recessive genetic disease in which the metabolism of phenylalanine impaired is an example of
A. maternal blood testing
B. preimplantation diagnosis
C. newborn screening

Back 16

16. C newborn screening

Front 17

Which of the following is not a characteristic of A-form DNA compared to B-or Z-form DNA

A. has right-handed helices
B. exists when less water is present
C. is long and narrow

Back 17

1. C is long and narrow

Front 18

Which of these sequences could form a hairpin?

A. 5-GGGGTTTTCCCC-3
B. 5-AAAAAAAAAAAA-3
C. 5-TTTTTTTCCCCCCC-3

Back 18

2. A 5-GGGGTTTTCCCC-3

Front 19

If a DNA molecule is 30% cytosine (C), what is the percentage of guanine (G)?

A. 30%
B. 15%
C. 60%

Back 19

3. A 30%

Front 20

If the DNA sequence of one strand is 5-GCTAGCGTCG-3, what is the sequence of the complementary strand?

A. 3- GCTAGCGTCG-5
B. 5-CGATCGCAGC-3
C. 3- CGATCGCAGC-5

Back 20

4. C 3- CGATCGCAGC-5

Front 21

The Holliday model describes which process?

A. semiconservative replication
B. homologous recombination
C. end replication

Back 21

5. B homologous recombination

Front 22

Which activity is not associated with DNA polymerases?

A. Ability to attach a DNA nucleotide to the 3 end of previously incorporated DNA nucleotide
B. Ability to read a template strand 3 to 5 and synthesize a complementary strand
C. Ability to synthesize a DNA strand from scratch without a primer

Back 22

6. C Ability to synthesize a DNA strand from scratch without a primer

Front 23

. __________replication is unidirectional, requires a break to be introduced in the DNA molecule, and occurs primarily in viruses and bacteriophages.

A. Theta
B. Rolling circle
C. Linear chromosome

Back 23

7. B Rolling circle

Front 24

. __________is required to replicate the ends of chromosomes.
A. Primase
B. Gyrase
C. Telomerase

Back 24

8. C Telomerase

Front 25

. _________catalyzes phosphodiester bonds at DNA nicks.
A. DNA ligase
B. DNA gyrase
C. DNA primase

Back 25

9. A DNA ligase

Front 26

In the diagram below, which letter indicates the 5 end of the leading strand?
A. A
B. B
C. C
D. D

Back 26

10. C C

Front 27

Three Models of DNA Replication

Back 27

Fully conserved replication-entire double-stranded DNA molecule serves as a template for a whole new DNA molecule
Dispersive replication-nucleotide strands break down into fragments and serve as templates for new fragments, reassemble
Semiconservative replication-each DNA strand serves a template for a new molecule

Front 28

Hershey -Chase experiment

Back 28

demonstrated that DNA is hereditary material and is passed on to progeny (protein is not)
Transforming principle/transforming substance identified as DNA

Front 29

Different Secondary Structures

Back 29

3-D structure can change in different conditions, predominant structure in cells
B-DNA structure exists in water, no unusual base seqence, right-handed, clockwise
Spiraling creates major and minor grooves, binding sites for proteins

Front 30

A-DNA Structure

Back 30

Exists if less water is present
Alpha (right-handed) helix
Shorter and wider than B-DNA
Not common, little evidence that A-DNA exists in physiological conditions

Front 31

Z-DNA

Back 31

Left-handed helix
Molecule contains long stretches of alternating C and G nucleotides
Regions linked to those that are actively transcribed
Role in gene expression

Front 32

Stages of DNA Replication

Back 32

Initiation
Unwinding
Elongation
Termination

Front 33

Enzymes that function in DNA replication

Back 33

Primase
Gyrase/topoisomerase
Helicase
Polymerases
Ligase
telomerase

Front 34

Bacterial versus Eukaryotic DNA replication

Back 34

Initiator proteins-DnaA/Origin recognition complex
Origins-oriC, autonomously replicating sequences
Topoisomerases/helicases-unwinding process is similar
Elongation-different DNA polymerases
Termination-similar, E. coli has Tus protein

Front 35

Special Structures Can Form in DNA and RNA

Back 35

Sequences within a single strand of nucleotides may be complementary and form hydrogen bonds
Hairpin-sequences of nucleotides on the same strand are inverted complements
Region of paired bases (stem) and intervening unpaired bases (loop)

Front 36

Twin Studies/Pre-natal testing

Back 36

Genetic traits demonstrate a high concordance in twins, traits influenced by other factors are discordant
Examples of pre-natal tests

Front 37

Epistasis/Dominance/Co-dominance

Back 37

Epistasis-one gene masks the effect of another gene at a different locus
Similar to dominance, however, dominance refers to alleles at the same locus

Front 38

Sex-influenced characteristics

Back 38

Determined by autosomal genes that expressed differently in males and females
Presence of a beard in goats is determined by an autosomal gene that is dominant in males and recessive in females

Front 39

Sex-Limited Characteristic

Back 39

Encoded by autosomal genes that are expressed only in one sex
The trait has zero penetrance in the other
Male-limited precocious puberty
Autosomal dominant allele expressed only in males
Females with the gene have a normal phenotype
Males undergo puberty before age 4

Front 40

Genetic Maternal Effect

Back 40

Phenotype of offspring determined by genotype of the mother
Substances present in the cytoplasm of an egg (encoded by maternal genes) are important for development
Shell coiling in snails
Dextral-(s+s+) shell coils to right, dominant
Sinistral (ss)-coils to left, rare

Front 41

Recombination

Back 41

Occurs during crossing-over
Holliday model(single-strand breaks)
Double strand breaks