ANSC 221 (Exam 4): Pre & HW

What is the correct order of the central dogma, as described by Francis Crick in 1956?

DNA --> RNA --> Protein

Match each triplet codon to its corresponding amino acid or signal: AUG

Met (M) or start

Match each triplet codon to its corresponding amino acid or signal: UAA

Stop

Match each triplet codon to its corresponding amino acid or signal: AGA

Arg (R)

True or false: TATA box is part of the terminator region

False: the TATA box is actually found within the promoter region of genes in eukaryotes and archaea, not the terminator region. 

Which of the following are tRNA binding sites

• Exit site

• peptidyl-tRNA binding site

• aminoacyl-tRNA binding site

True or false: nucleotide base triplets that act as stop codons (UAG, UAA, UGA) also code for amino acids

False because stop codons, also known as nonsense codons (UAA, UAG, and UGA), do not code for any amino acid. Instead, they act as signals for the termination of protein synthesis (translation). When a ribosome reaches a stop codon, a release factor protein binds to the ribosome, causing the newly synthesized polypeptide chain to be released.

Reading symbols in the correct groupings in order to extract the intended message refers to using the correct _____

Reading frame

You are unique, why makes you unique?

Random fertilization

What are some alterations of chromosome structure?

• Duplication

• Deletion

• Inversion

• Translocation

What type of mutation is this?

Missense

What is epigenetics?

Heritable changes in gene expression that do not involve changes to the DNA sequence

What is the function of the transcription initiator complex in eukaryotes?

It assembles at the promoter to help RNA polymerase start transcription

Use this model of a eukaryotic primary transcript to answer the following question. Assuming that: E = exon, I = intron and UTR = untranslated region.

5′- UTR E1 I1 E2 I2 E3 I3 E4 UTR -3′

If the primary transcript is processed and transported to the cytosol, which of the following molecules best represents the mRNA that will be produced?

5′- UTR E1 E2 E3 E4 UTR -3′

Which of the following processes correctly describes alternative RNA splicing?

It can allow the production of proteins of different sizes and functions from a single coding gene.

Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes?

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

Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA?

The primary transcript is larger than the mRNA

Match the question to its answer: Transcription in eukaryotes requires which molecules in addition to RNA polymerase?

Transcription factors

Match the question to its answer: In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?

RNA polymerase II

Match the question to its answer: Which process occurs as part of transcription?

RNA is synthesized

Match the question to its answer: During elongation, nucleotides are added in which direction?

5' to 3' direction

Why is it important to identify the promoter region first before the transcription process can start?

It is where the RNA polymerase binds to so the reading of the bases can start

Which of the following statements about RNA processing is FALSE? 

The spliceosomes remove the exon in pre-mRNA

A particular triplet of bases in the template strand of DNA is 5′-AGT-3′. What would be the corresponding codon for the mRNA that is transcribed?

3′-UCA-5′

Which of the following is most likely to occur if a researcher removes the 5′ cap and poly-A tail of an mRNA and inserts the mRNA molecule into a eukaryotic cell?

The molecule will be degraded by enzymes.

Below is a segment of DNA from within a gene. The beginning of the gene has already been transcribed. Which os the following would be the mRNA sequence transcribed from this DNA segment?

5'-GGCACGCGAAGU-3'

What is the primary function of microRNAs (miRNAs) in eukaryotic cells?

To regulate gene expression by binding to mRNA and blocking translation or promoting degradation

What is an embryonic lethal mutation?

A mutation that prevents an embryo from surviving to birth

Bacteriophage means ___.

"bacteria-eater"

True or false: because bacteria have a nuclear envelope, they can transcribe and translate the same gene simultaneously

False: bacteria do not have nuclear envelopes and so they actually can transcribe and translate a gene simultaneously.

Asexual reproduction by single-celled eukaryotes is called?

Binary fission

A DNA molecule that carriers foreign DNA into a host cell to be replicated is called

Cloning vector

Which of the following are biotechnologies used in the field of genetics?

• DNA sequencing

• DNA cloning

• PCR

• RT-PCR

• In situ hybridization

• RNA seq

• DNA microarray assay

True or false: genomes vary in size, number of genes, and gene density

True: Genomes exhibit significant variation across different organisms in their size, number of genes, and gene density.

True or false: retrotransposons move by means of a DNA intermediate

False: Retrotransposons move by means of an RNA intermediate, not a DNA intermediate. They use the enzyme reverse transcriptase to convert their RNA transcript back into DNA before inserting it into a new location in the genome. 

True or false: sometimes recombination occurs between misaligned nonsister chromatids, which leaves one chromatid with 2 copies of a gene, and the other with 0 copies

True: This phenomenon, known as unequal crossing over, occurs during meiosis when homologous chromosomes misalign due to repetitive DNA sequences. The result is that one resultant chromatid receives a duplication of a gene segment (two copies), while the other receives a deletion (zero copies). 

Which of the following processes is the best way to determine whether alternative splicing of a given gene occurs?

Isolate mRNA from the given gene and compare the sequences.

A cell is considered to be differentiated if it has which of the following characteristics?

The cell produces proteins specific to a particular cell type.

A researcher introduced many copies of a RNA into a culture of mammalian cells and used a fluorescent probe to follow it. She found that the introduced strands separated; double-stranded RNA degraded and the single-stranded RNA remained. She hypothesizes that the remaining strand is acting as a miRNA. The remaining strand is able to do which process?

Bind to complementary regions of target mRNAs

A researcher introduced many copies of a RNA into a culture of mammalian cells and used a fluorescent probe to follow it. She found that the introduced strands separated; double-stranded RNA degraded and the single-stranded RNA remained. She hypothesizes that the remaining strand is acting as a miRNA. Which piece of evidence would support her claim?

The rate of accumulation of the polypeptide encoded by the target mRNA is reduced

Which of the following is NOT included in the regulations of the eukaryotic post-transcriptional process of gene expression?

Automatic removal of RNA polymerase when a specific number of nucleotides is reached

Cell differentiation always involves ______?

the production of tissue-specific proteins

Which of the following processes destroys RNA molecules if they have a sequence complementary to an introduced double-stranded RNA?

RNA interference

Cytoplasmic determinants are best described as having which of the following characteristics?

They are maternal substances in the egg that influence the course of early development.

Within a cell, the amount of protein made using a given mRNA molecule in that cell depends partly on:

the rate at which the mRNA is degraded

Which of the following is an example of post-transcriptional control of gene expression?

The removal of introns and alternative splicing of exons

Which of the following statements about the DNA in one of your brain cells is true?

It is the same as the DNA in one of your liver cells.

All copies of every type of allele at every locus in all members of a population is called ______?

Gene pool

Which of the following can alter allele frequencies in a population

• Natural selection

• Genetic drift

• Gene flow

True or false: the bottleneck effect is when a few individuals isolate from their population, and that small groups new population has a different gene pool than the source population

False: The scenario describes founder effect: A few individuals become isolated and start a new population with a different gene pool. VS. Bottleneck effect: A population is drastically reduced in size due to a disaster, leaving behind a small, unrepresentative gene pool.

Radioactive thymine is added to media containing one actively dividing E. coli bacterium. Which of the following outcomes would be seen after a single cell division?

DNA in both daughter cells would be radioactive.

DNA is isolated from bacteria undergoing DNA replication. After heat treatment to disrupt H-bonds the DNA is centrifuged and it separates into two classes. One class of DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). Which types of DNA do the two classes most likely represent?

leading strands and Okazaki fragments

Which of the following processes occurs in prokaryotes but not in eukaryotes?

Simultaneous transcription and translation of the same mRNA

If a bacteria contained a mutant aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNAs with the anticodon AAA which of the following would occur?

Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

If a mutation deactivated a regulatory gene of a repressible operon in an E. coli cell which of the following describes the most likely outcome?

Continuous transcription of the structural gene controlled by that regulator

Prokaryote's ability to regulate patterns of gene expression most likely promotes the organism's survival by:

Allowing an organism to adjust to changes in environmental conditions

If a researcher moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following results would be most likely?

Beta galactosidase will not be produced

If a researcher moves the operator to the far end of the operon, which of the following processes would likely occur when the cell is exposed to lactose?

The genes of the lac operon will be transcribed continuously

A rise in extracellular glucose results in which of the following changes at the lac operon?

cAMP receptor protein (CRP) detaches from the lac promoter

Under what conditions does the trp repressor block transcription of the trp operon?

When the repressor binds to tryptophan

Quantitative genetics are controlled by polygenic genes and influenced by environmental factors, what does this mean?

There is a large range of phenotypes

What is an example of a polygenic trait?

Height