DNA Structure and Function Quiz

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Questions and Answers

What best describes the structure of DNA?

A single strand consisting of ribose sugars and uracil bases.

A linear chain of amino acids connected by peptide bonds.

A double helix consisting of two strands with adenine, thymine, cytosine, and guanine. (correct)

A circular molecule made entirely of nucleotides.

Which of the following accurately describes the roles of RNA in protein formation?

RNA is solely responsible for the synthesis of ribosomal components.

RNA carries genetic information exclusively between cells.

RNA transcribes information from DNA and translates it into proteins. (correct)

RNA aids in DNA replication within the nucleus.

In what way do prokaryotic cells differ from eukaryotic cells?

Prokaryotic cells do not contain organelles. (correct)

Eukaryotic cells are typically smaller than prokaryotic cells.

Eukaryotic cells lack a cell membrane.

Prokaryotic cells have multiple nuclei.

What initiates the production of tryptophan in E. coli when tryptophan is removed?

The trp operon genes are transcribed resulting in amino acid production. Signup and view all the answers

Which statement accurately differentiates between transcription and translation?

Transcription converts DNA into RNA; translation converts RNA into proteins. Signup and view all the answers

What experimental evidence did Watson and Crick rely on to propose the structure of DNA?

X-ray diffraction images from Rosalind Franklin. Signup and view all the answers

What is a significant difference between DNA and RNA in terms of structure?

DNA has deoxyribose sugar while RNA has ribose sugar. Signup and view all the answers

What occurs during the translation phase of protein synthesis?

tRNA molecules bring amino acids to the ribosome based on mRNA codons. Signup and view all the answers

What occurs when tryptophan is added to E. coli?

The repressor protein binds to the operator and blocks transcription. Signup and view all the answers

Which characteristic is unique to eukaryotic cells compared to prokaryotic cells?

Containment of genetic material within a nucleus. Signup and view all the answers

How does RNA differ from DNA in terms of nucleotide composition?

RNA contains uracil, DNA contains thymine. Signup and view all the answers

During which phase of protein synthesis does the mRNA serve as a template to create proteins?

Translation. Signup and view all the answers

What is the function of RNA polymerase during transcription?

It creates a complementary RNA strand from DNA. Signup and view all the answers

What is the relationship between codons and tRNA during translation?

Each codon matches with a specific tRNA carrying an amino acid. Signup and view all the answers

How did Watson and Crick conclude the double helix structure of DNA?

By interpreting X-ray diffraction images. Signup and view all the answers

What is a primary feature of protein formation in cells?

It requires both transcription and translation processes. Signup and view all the answers

Study Notes

DNA Structure

DNA is a double helix with two strands.
Each strand is composed of sugar, phosphate, and four bases (A, T, C, G).
A pairs with T, and C pairs with G.

DNA Discovery

Watson and Crick determined DNA's double helix structure in 1953.
Their work relied on X-ray diffraction data from Rosalind Franklin.

DNA vs. RNA

Similarities: Both contain nucleotides with sugar, phosphate, and bases; both carry genetic information.
Differences: DNA has thymine (T), RNA has uracil (U). DNA is double-stranded, RNA is single-stranded.

Eukaryotic vs. Prokaryotic Cells

Eukaryotic: Contains a nucleus and organelles (like plant and animal cells).
Prokaryotic: Lacks a nucleus and is smaller (e.g., bacteria).

Transcription vs. Translation

Transcription: DNA creates RNA in the nucleus.
Translation: RNA creates proteins in the ribosome.

Protein Synthesis Process

Transcription:
- Occurs in the nucleus.
- DNA serves as a template to generate messenger RNA (mRNA).
- RNA polymerase builds a complementary mRNA strand using DNA's instructions (e.g., DNA's A pairs with RNA's U).
Translation:
- Occurs in the ribosome (cytoplasm).
- mRNA is read in three-base codons.
- Each codon corresponds to a specific transfer RNA (tRNA) carrying a particular amino acid.
- tRNA delivers the correct amino acids to the ribosome, forming a protein chain.
- The chain continues until a stop codon is encountered.
- The final protein folds into its functional shape.

Tryptophan Regulation in E. coli

Tryptophan Addition: Tryptophan binds to a repressor protein, activating it.
- The activated repressor blocks RNA polymerase from transcribing genes for tryptophan production, conserving energy.
Tryptophan Removal: Without tryptophan, the repressor becomes inactive, allowing RNA polymerase to transcribe genes to synthesize tryptophan.
This process demonstrates how E. coli regulates tryptophan biosynthesis based on environmental levels.

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Description

Test your knowledge on DNA structure, its discovery, and the comparison between DNA and RNA. This quiz also covers the differences between eukaryotic and prokaryotic cells, as well as the processes of transcription and translation in protein synthesis.