Biology Chapter 17: From Gene to Protein

Questions and Answers

What is gene expression?

The process of DNA replication

The process of cell division

The process of protein degradation

The process by which DNA directs the synthesis of proteins (correct)

In eukaryotic cells, transcription can begin without transcription factors binding to the promoter.

False

What is the anticodon of a particular tRNA molecule complementary to?

mRNA codon

Identify a 5′ → 3′ sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys: 5′-_____-3′.

CTTCGGGAA Signup and view all the answers

Which of these is a tRNA?

B Signup and view all the answers

What enzyme catalyzes the attachment of an amino acid to tRNA?

aminoacyl-tRNA synthetase Signup and view all the answers

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.

CUG Signup and view all the answers

The initiator tRNA attaches at the ribosome's _____ site.

P Signup and view all the answers

Who formulated the one gene-one enzyme hypothesis?

Beadle and Tatum Signup and view all the answers

In what form is genetic information of eukaryotic cells transferred from the nucleus to the cytoplasm?

RNA Signup and view all the answers

What is a 5' cap?

A modified form of guanine nucleotide added onto the 5' end of pre-mRNA. Signup and view all the answers

Who was the first to suggest that genes dictate phenotypes through enzymes?

Archibald Garrod Signup and view all the answers

What are 'inborn errors of metabolism'?

Inherited diseases reflecting a person's inability to make a particular enzyme. Signup and view all the answers

Who were Tatum and Beadle?

American geneticists that coined the 'one gene-one enzyme' hypothesis. Signup and view all the answers

What does the one gene-one enzyme hypothesis state?

The function of a gene is to dictate the production of a specific enzyme. Signup and view all the answers

The 'one gene-one polypeptide' concept is completely accurate.

False Signup and view all the answers

What are the differences between RNA and DNA?

<ol> <li>Ribose instead of deoxyribose as a sugar, 2) Uracil not thymine, 3) Usually single stranded.</li> </ol> Signup and view all the answers

What is transcription?

The synthesis of RNA using DNA as a template. Signup and view all the answers

What does messenger RNA (mRNA) do?

Carries information from DNA to the cell's protein-synthesizing machinery. Signup and view all the answers

What is translation?

The synthesis of a polypeptide under the directions of mRNA. Signup and view all the answers

Where does translation occur?

At the ribosomes. Signup and view all the answers

What is the difference in genetic information flow between bacteria and eukaryotes?

DNA is not segregated from ribosomes in bacteria. Signup and view all the answers

What results from the lack of segregation of DNA in bacteria?

Simultaneous translation and transcription. Signup and view all the answers

What is a primary transcript?

An initial RNA molecule synthesized from a DNA template. Signup and view all the answers

What is the central dogma of Francis Crick?

The flow of genetic information from DNA to RNA to protein. Signup and view all the answers

What is the process of bacterial transcription/translation?

In a bacterial cell, mRNA produced by transcription is immediately translated. Signup and view all the answers

How does eukaryotic translation and transcription differ from bacteria?

Eukaryotic cells have a nucleus that separates transcription and translation. Signup and view all the answers

What is the triplet code?

A set of three-nucleotide-long words that specify the amino acids for polypeptide chains. Signup and view all the answers

What is the template strand?

The DNA strand that provides the pattern for ordering the sequence of nucleotides in RNA. Signup and view all the answers

Study Notes

Gene Expression

Gene expression involves the synthesis of proteins or RNAs directed by DNA.
In eukaryotic cells, transcription requires the binding of several transcription factors to the promoter.

tRNA and Codons

The anticodon of tRNA is complementary to the mRNA codon, crucial for accurate protein synthesis.
Example: tRNA anticodon GAC pairs with mRNA codon CUG.
tRNA molecules exist; identification typically involves structures resembling the described tRNA.

Initiation of Translation

The initiator tRNA binds to the P site of the ribosome, marking the start of translation.

Genetic Relationships and Hypotheses

Beadle and Tatum proposed the one gene-one enzyme hypothesis, linking specific genes to enzyme production.
Archibald Garrod introduced the term "inborn errors of metabolism," referring to diseases caused by enzyme deficiencies.
The one gene-one enzyme hypothesis evolved to the one gene-one polypeptide concept, recognizing that some genes produce multiple related polypeptides via alternative splicing.

RNA Characteristics

RNA differs from DNA: it contains ribose sugar and uracil instead of thymine.
mRNA serves as the carrier for genetic information from DNA to ribosomes for protein synthesis.

Transcription and Translation Processes

Transcription is the process of synthesizing RNA from a DNA template.
Translation synthesizes polypeptides under mRNA direction at ribosomes.
Ribosomes are the site of polypeptide synthesis.

Genetic Information Flow

Bacterial DNA is not segregated by a nucleus, allowing simultaneous transcription and translation.
Eukaryotes have transcription occurring in the nucleus, where pre-mRNA undergoes processing to form mature mRNA before leaving the nucleus for translation.

Additional Concepts

The primary transcript undergoes modifications before it becomes mature mRNA.
The central dogma, described by Francis Crick, outlines the flow of genetic information: DNA → RNA → Protein.
The triplet code in mRNA consists of three-nucleotide sequences (codons) that specify amino acids for polypeptide chains.
The template strand of DNA directs the sequence of nucleotides in RNA during transcription, with uracil replacing thymine.

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Description

Dive into the intricate process of gene expression and its critical role in synthesizing proteins in eukaryotic cells. This quiz covers key concepts such as transcription factors, tRNA, and the relationship between mRNA and anticodons. Test your understanding of molecular biology and the flow of genetic information.