Exam 4

Question 1

Remember that in peas, the allele for round seeds (R) is dominant and the allele for wrinkled seeds (r) is recessive. when you cross two plants that each produce round seeds, the resulting seeds are all round. What are the genotype possibilities for the parental plants?

Answer 1

RR and RR,
RR and rr, and
Ra and RR

Question 2

In hedgehogs, the allele for brown fur (B) is dominant and the allele for white fur is recessive. The allele for short quills (S) is dominant and the allele for long quills (s) is recessive. These two genes are not linked. When you cross one parent with the Genotype BsSS with another parent with the genotype BbSs, what will the Brown and short: brown and long: white and short: white and long phenotype ratio be? what do the genotypes of the parents need to be to give the 9:3:3:1 ratio?(you can use a Punnett square if needed.)

Answer 2

3:0:1:0

BbSs and BbSs

Question 3

Two genes determine coat color in mice- the A and B genes. the dominant A allele deposits pigment into the skin and fur, while the recessive a causes the mouse to be albino. the dominant B allele produces a brown pigment which the recessive b allele produces a black pigment. A brown male mouse with the genotype AaBa is mated with a female mouse with the genotype AaBb. A) What are the possible genotypes of the gametes from either the father or the mother? B) What will be the brown:black:albino ratio of the progeny?

Answer 3

A) AB, Ab, aB, and ab

B) 9:3:4

Question 4

One gene (A) is able to modify the effect of the second gene (B). this phenomenon is known as:

Answer 4

Epistasis

Question 5

Flower color in snapdragons id due to a gene with incomplete dominance. RR plants have red flowers, Rr have pink flowers and rr plants have white flowers. which cross is expected to yield progeny with flower colors in a ratio of 1 red: 1 white?

a. Rr x Rr
b. RR x rr
c. RR x Rr
d. Rr x rr
e. none of the above

Answer 5

E. none of the above

No cross will yield that ratio because of the incomplete dominance.

Question 6

Hemophilia is a sex-linked recessive trait in humans. if carrier female had a child with a nonaffected male, what would be the expected outcome(s)?

Answer 6

None of the daughters and half of the sons would have hemophilia.

Question 7

A woman who has blood type A has a daughter who is type O. What is a possible genotype for the father?

Answer 7

Ia Io, Io Io, and Ib Io are all options

Question 8

The AB blood phenotype is an example of:

Answer 8

Codominance

Question 9

Mendelian genetics True or False:

In any population, only two alleles can exist for a given gene.

Answer 9

False

Question 10

The strands that make up DNA are antiparallel. This means that:

Answer 10

While the two strands run next to each other in parallel, the 5’-to-3’ direction of one strand is opposite to the 5’-to-3’ direction of the other strand.

Question 11

A strand of DNA with the sequence 5’- ATTCCG -3’ would have a complementary strand with the sequence:

Answer 11

5’ CGGAAT -3’

Question 12

Semiconservative replication of DNA involves:

Answer 12

Each of the original strands acting as a template for a new strand.

Question 13

True or False:

Primase is needed to initiate DNA replication on both the leading strand and the lagging strand

Answer 13

True

Question 14

The enzyme that restores that phosphodiester linkage between adjacent fragments in the lagging strand during replication is:

Answer 14

DNA ligase

Question 15

The enzyme that unwinds the DNA double strands during DNA replication is:

Answer 15

Helicase

Question 16

The enzyme that adds nucleotides to the growing daughter strand during DNA replication is:

Answer 16

DNA polymerase

Question 17

During DNA replication, the two strands of DNA ______ re-anneal in the wake of the replication fork. During transcription, the two strands of DNA ______ re-anneal in the wake of the transcription bubble. (DO or DO NOT)

Answer 17

DO NOT/ DO

Question 18

You run a PCR reaction for six cycles starting with a single DNA double helix. Theoretically, how many copies of your DNA would you now have?

Answer 18

128 copies

Question 19

The parasite Plasmodium falciparum is the most serious form of the tropical disease: malaria. on a molar basis, the genome of P. falciparum contains only 10% cytosine. what is the % of adenosine in the DNA of P. falciparum?

a. 40%
b. 10%
c. 60%
d. 20%
e. It is not possible to calculate from this number based on this information.

Answer 19

a. 40%

Question 20

The point at which the DNA strands begin to be separated to initiate DNA synthesis is called the:

Answer 20

Origin of replication

Question 21

True or false:
The lagging strand is synthesized in short 5’ - 3’ fragments, while the leading is synthesized in one long continuous strand 5’ - 3’ strand.

Answer 21

True

Question 22

Cells lacking telomerase do not survive for the entire lifetime of an organism because:

Answer 22

The removal of the RNA primer following DNA replication leads to a shortening of the telomeric DNA on the lagging strand, which eventually causes loss of DNA and triggers cell death

Question 23

Which of the following mutations would probably shorten a protein and definitely cause it to have a new sequence at its C-terminus?

a. A silent mutation
b. A nonsense mutation
c. A frameshift mutation
d. A mutation that prevents removal of an intron during splicing
e. Both C and D

Answer 23

e. both a frameshift and a mutation that prevents removal of an intron during spicing

Question 24

Chromosomal mutations…

Answer 24

Can result in deletions, duplication, or even inversion of large parts of chromosomes

Question 25

True or False:

Primase is needed to initiate transcription

Answer 25

False

Question 26

DNA polymerase synthesizes a new strand of DNA in the ______ direction and travels along the template strand in the ______ direction.

Answer 26

5’ -> 3’ / 3’ ->5’

Question 27

RNA polymerase synthesizes a new strand of RNA in the ____ direction and travels along the template DNA in the ______ direction. finally, proteins are synthesized when the ribosome travels along the mRNA molecule in the ____ direction while synthesizing a protein _____

Answer 27

5’ -> 3’/ 3’-> 5’/ 5’ -> 3’/ N-terminus -> C-terminus

Question 28

True or False:

DNA encodes information that is transcribed into RNA, and RNS encodes information that is translated into proteins

Answer 28

True

Question 29

The point at which RNA polymerase binds and separates DNA strands to initiate RNA synthesis is called the:

Answer 29

Promoter

Question 30

Transcription continues until:

Answer 30

A terminator sequence is encoded

Question 31

pre-mRNA splicing: True or False:

It removes exons.

Answer 31

False

Question 32

Which enzyme catalyzes the attachment of an amino acid to tRNA before translation can proceed?

Answer 32

aminoacyl-tRMA synthetase

Question 33

Each tRNA has two critical sites that are important for its function in decoding mRNA. these are the:

Answer 33

Amino acid attachment site in the 3’ end of the tRNA and the anticodon loop

Question 34

What is the fourth step when going from initiation to elongation of translation?

Answer 34

Anticodon of charged tRNA base pairs with its codon on mRNA.

Question 35

During translation, the amino acid (or peptide) attached to the tRNA at the _____ is added to the N-terminus of the amino acid attached to the tRNA at the ____. this is catalyzed by the_____.

Answer 35

P site/ A site/ large ribosomal subunit

Question 36

The genetic code is “redundant” or “degenerate”, meaning that more than one ____ often codes for a given _____.

Answer 36

Codon/Amino acid

Question 37

Translation continues until:

Answer 37

A stop codon is encountered and enters the A site of the ribosome.

Question 38

What occurs in the E site of the ribosome during translation/

Answer 38

An uncharged tRNA is ejected from this site as the ribosome slides to the next codon.

Question 39

What anticondon in tRNAhis would pair with the codon 5’ - CAU - 3’ in mRNA

Answer 39

5’-AUG-3’

Question 40

The PCR reaction mixture does not include:

Answer 40

Helicase