VCAA Biology What is the role of nucleic acids and proteins in maintaining life?

Carbohydrates, such as glucose, are the substrates being broken down during metabolism, not the catalysts driving the reactions.

Nucleotides are the building blocks of DNA and RNA or act as energy carriers like ATP, rather than functioning as metabolic enzymes.

Lipids are primarily used for long-term energy storage and forming cell membranes, not for catalyzing biochemical reactions.

Incorrect. Measuring gene expression involves analyzing RNA levels using techniques like RT-qPCR or RNA sequencing, whereas DNA profiling looks at the DNA sequence itself.

Incorrect. While genetic markers can be used in population genetics, DNA profiling specifically focuses on identifying unique genetic patterns of individuals rather than tracking the movement of alleles between populations.

Incorrect. Creating transgenic organisms requires recombinant DNA technology and genetic engineering to insert foreign genes, which is entirely different from analyzing existing DNA profiles.

Incorrect. Regulating gene expression is primarily the role of regulatory proteins, such as transcription factors, rather than structural proteins.

Incorrect. Transmitting information between cells is the function of signaling proteins, such as hormones, and receptor proteins.

Incorrect. Catalyzing metabolic reactions is the specific function of enzymes, which are catalytic proteins rather than structural ones.

This is incorrect because the sequence clearly contains nucleotides, meaning it must contain codons.

This is incorrect. Three is the number of nucleotides that make up a single codon, not the total number of codons in the given sequence.

This is incorrect. Twelve is the total number of individual nucleotides in the sequence, not the number of three-nucleotide codons.

Cutting DNA at specific sites is the function of restriction enzymes (endonucleases), not PCR.

Determining the specific order of nucleotides is the goal of DNA sequencing, whereas PCR is used only for amplification.

Separating DNA fragments based on size is achieved through gel electrophoresis, not PCR.

Uracil is found in RNA, where it pairs with adenine. In DNA, thymine replaces uracil.

Guanine pairs with cytosine via three hydrogen bonds, not with adenine.

Cytosine pairs with guanine via three hydrogen bonds, not with adenine.

Ribosomes are the cellular structures responsible for synthesizing proteins, not for transporting them to the plasma membrane.

While the Golgi apparatus modifies and packages proteins, it relies on vesicles budding from its membrane to actually transport these proteins to the plasma membrane.

The endoplasmic reticulum is involved in the synthesis and folding of proteins, which are then sent to the Golgi apparatus rather than directly to the plasma membrane.

While scientists use recombinant plasmids in biotechnology to produce human insulin, this is an artificial application. The natural function of CRISPR-Cas9 is immune defense, not acting as a plasmid.

A promoter is a DNA sequence where RNA polymerase binds to initiate transcription. CRISPR-Cas9 is an RNA-guided endonuclease complex that cuts DNA, not a transcriptional promoter.

Antibiotic resistance is typically conferred by specific genes that degrade or efflux antibiotics. CRISPR-Cas9 defends against foreign genetic material like viruses, not chemical antibiotics.

An insertion would add a base to the sequence. The comparison shows that a nucleotide has been removed (deleted) rather than added, as the sequence has shifted to the left.

A substitution replaces one nucleotide with another without changing the length of the sequence. The observed change is a frameshift mutation caused by a deletion, which alters the reading frame of all subsequent codons.

This describes a substitution mutation. However, the sequences show that a base was removed entirely, causing the downstream sequence to shift, which characterizes a deletion mutation rather than a substitution.

Incorrect. DNA repair involves identifying and fixing damaged DNA strands, whereas PCR is designed to synthesize new copies of a DNA template rather than fix errors.

Incorrect. Transcription is the cellular process of synthesizing RNA from a DNA template, while PCR synthesizes new DNA strands.

Incorrect. Translation is the process of building proteins from an mRNA template at the ribosome, which is entirely different from the DNA amplification performed in PCR.

Non-disjunction involves the failure of chromosomes to separate during meiosis, leading to an abnormal number of chromosomes (aneuploidy) rather than a mutation within the DNA sequence.

Base pair substitution involves replacing one nucleotide with another (point mutation), which affects a single codon but does not shift the reading frame of the entire gene.

Heat damage typically causes chemical changes like deamination or depurination, which usually result in base substitutions (point mutations) rather than the insertions or deletions required for a frameshift.

This describes the function of DNA helicase, which unwinds the double helix by breaking hydrogen bonds between base pairs.

This describes the function of DNA ligase, which joins DNA fragments (such as Okazaki fragments) together to form a continuous strand.

RNA primers are synthesized by the enzyme primase, not DNA polymerase, to initiate DNA synthesis.

Nitrite ($NO_2^-$) is an intermediate formed during the reduction of nitrate; it is generally toxic to plants in high concentrations and is not the primary source absorbed for protein synthesis.

While nitrogen is incorporated into organic molecules as ammonium ($NH_4^+$), free ammonia ($NH_3$) is toxic to plant cells, and nitrate is the predominant form of nitrogen available in and absorbed from the soil.

Plants cannot directly utilize atmospheric nitrogen ($N_2$) because they lack the enzyme nitrogenase required to break the strong triple bond between nitrogen atoms; they rely on nitrogen-fixing bacteria or soil nutrients.