exam 4 study set

What is the function of DNA polymerase III in E. coli?

To add nucleotides to the 3' end of a growing DNA strand.

What explains why Mendel's pea plant traits obeyed the principle of independent assortment?

All of the genes controlling the traits behaved as if they were on different chromosomes.

How did Mendel account for traits disappearing in the F1 generation and reappearing in F2?

Traits can be dominant or recessive, and the recessive traits were 'hidden' by the dominant ones in the F1.

How does the primary transcript in a eukaryotic cell nucleus compare to functional mRNA?

The primary transcript is larger than the mRNA.

Which statement is correct about independent assortment or segregation?

The law of independent assortment describes the behavior of two or more genes relative to one another.

What accurately describes the structure of a eukaryotic chromosome?

It is a single linear molecule of double-stranded DNA plus proteins.

What dipeptide will form from the mRNA sequence 5'-CCG-ACG-3'?

proline-threonine

If a family exhibits a dominant trait W, what is the possible genotype of individual II-5?

ww

Which structure, if missing, would usually prevent translation from starting?

AUG codon

What is the first event in translation in eukaryotes?

The small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA.

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?

HT

What is meant by 'antiparallel' regarding DNA double helix strands?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

What was Mendel's most significant conclusion from experiments with pea plants?

Traits are inherited in discrete units and are not the result of 'blending.'

A child is the first in her family to be diagnosed with neurofibromatosis, a dominant gene condition. What is the best explanation?

One of the parents has a mild expression of the gene.

Gray seed color is dominant to white, and a cross produces 302 gray and 98 white offspring. What is the most probable genotype of each parent?

Gg × Gg

What characteristic of DNA allows it to carry a vast amount of hereditary information?

sequence of bases

If a heterozygous pea plant is crossed with a homozygous tall pea plant, what is the probability that the offspring will be dwarf?

0

Accuracy in mRNA translation depends on specificity in what process?

binding of the anticodon to the codon and the attachment of amino acids to tRNAs

Boxes 1-4 in the Punnett square represents a cross between dark-leaved plant and a light-leaved one. Which of the boxes marked 1-4 correspond to plants with a heterozygous genotype?

2 and 3

Mendel's observation of allele segregation is based on which phase of cell division?

anaphase I of meiosis

How might a single base substitution in a gene's sequence affect the encoded protein's amino acid sequence?

Only a single amino acid could change, because the reading frame would be unaffected.

A DNA coding sequence contains the base triplet AAA. What is the anticodon on the tRNA that binds the mRNA codon?

UUU

What effect would a nonsense mutation have on a gene?

It introduces a premature stop codon into the mRNA.

Why did all F1 offspring in Mendel's pea crosses resemble one of the parental varieties?

One allele was dominant.

If a DNA template is 3' CCTAGGCTGCAATCC5', and an RNA primer forms starting at the underlined T, what is the primer sequence?

5' ACGUUAGG3'

Which phenotype exemplifies polygenic inheritance?

Skin pigmentation in humans

High heterozygosity for the sickle-cell anemia allele in Africa, reducing malaria frequency, relates to what?

Darwin's explanation of natural selection

What process occurs during transcription?

RNA is synthesized

Which investigator(s) discovered that in DNA from any species, the amount of adenine equals thymine, and guanine equals cytosine?

Erwin Chargaff

A template strand of DNA has the bases 5'-AGT-3'. What is the corresponding mRNA codon?

3'-UCA-5'

What does the chromosome theory of inheritance state?

Mendelian genes are at specific loci on chromosomes and segregate during meiosis.

In semiconservative replication, what serves as the template?

One strand of the DNA molecule

According to Beadle and Tatum's hypothesis, how many genes are necessary for a simple metabolic pathway with two enzymatic steps?

2

Which components of a eukaryotic transcript (5'-UTR E1 I1 E2 I2 E3 I3 E4 UTR-3') will be found in mRNA in the cytosol?

5'-UTR E1 E2 E3 E4 UTR-3'

Which individuals will inherit an X-linked allele from a man who carries it?

All of his daughters

What would happen if the dnaB gene, which codes for helicase, is mutated in E. coli?

No replication fork will be formed.

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5'→ 3' direction?

DNA polymerase III

Which molecules help hold DNA strands apart during replication?

Single-strand DNA binding proteins

Which molecules are required for translation?

mRNA, tRNA, and rRNA

What is the function of topoisomerase in DNA replication?

Relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix

What inheritance pattern is demonstrated when a red-flowered plant and a white-flowered plant yield all-purple offspring?

Incomplete dominance

What correctly describes the difference between the leading and lagging DNA strands?

The leading strand is synthesized in the same direction as the replication fork, and the lagging strand is synthesized in the opposite direction.

How many unique gametes can be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

8

What is a possible anticodon for a tRNA that transports proline to a ribosome?

3'-GGC-5'

What does it mean when we say the genetic code is redundant?

More than one codon can specify the addition of the same amino acid.

What bases will be added to the primer as DNA replication proceeds?

3' T, C, T, G, C, T, G 5'

Which process occurs in prokaryotes, but not eukaryotes?

Transcription and translation occur simultaneously

What is the addition rule of probability?

The probability that either one of two independent events will occur

Which molecular structures contain codons?

mRNA

Why were all the white-eyed flies in Thomas Hunt Morgan's experiment male?

The gene involved is located on the X chromosome.

During elongation, which ribosomal site is where a codon is being read?

A site

Cytosine is 42% of nucleotides in a DNA sample. What percent will be thymine?

8%

Rank these mutations from most to least likely to affect polypeptide structure: 1. intron insertion, 2. exon 3rd position substitution, 3. exon 2nd position substitution, 4. exon deletion

4, 3, 2, 1

What explains why hydrangea plants of the same genotype produce blue and pink flowers?

Environmental factors such as soil pH affect the phenotype

Which boxes in the Punnett square correspond to plants with dark leaves?

1, 2, and 3

What can one logically assume given that the genetic code is essentially the same for all organisms?

A gene from an organism can theoretically be expressed by any other organism.

What best describes the significance of the TATA box in eukaryotic promoters?

It is the recognition site for the binding of a specific transcription factor.

What accurately describes the differences between prokaryotic and eukaryotic DNA replication?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

How likely are women to have Duchenne muscular dystrophy?

One-half of the daughters of an affected father and a carrier mother could have this condition.

How do eukaryotic codons and prokaryotic codons compare?

Codons are a nearly universal language among all organisms.

A man and woman both show normal pigmentation, but both have one parent who has albinism (without melanin pigmentation). What is the probability that their first child will have albinism?

1/4

What is the probability that individual III-1 is Ww?

1

Which of the following DNA mutations is most likely to damage the protein it specifies?

a base-pair deletion

Which of the following processes occurs when termination of translation takes place?

A stop codon is reached.

Which of the following statements supports the one gene-one enzyme hypothesis?

A mutation in a single gene can result in a defective protein.