Gene Expression and Protein Synthesis Quiz

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Questions and Answers

What is the significance of understanding gene expression?

It only relates to protein synthesis.

It only helps in academic research.

It is primarily focused on DNA structure.

It is crucial for determining medical applications. (correct)

What does the term 'degenerate' refer to in the context of the genetic code?

Codons that do not translate into amino acids.

The opposite of functional sequences.

A sequence that has no biological significance.

Multiple codons can code for the same amino acid. (correct)

What is the primary function of a promoter in a eukaryotic gene?

To terminate transcription.

To initiate transcription. (correct)

To protect mRNA from degradation.

To enhance the expression of a gene.

What is the first amino acid coded for by the start codon AUG?

Methionine Signup and view all the answers

Which part of the gene regulates its expression by enhancing or silencing it?

Enhancers and silencers Signup and view all the answers

What hypothesis proposed by Beadle and Tatum states that one gene corresponds to one protein?

One Gene-One Protein Hypothesis Signup and view all the answers

How many total codons exist in the genetic code?

64 Signup and view all the answers

What role does alternative splicing play in gene expression?

It allows for the production of multiple proteins from a single gene. Signup and view all the answers

Which technique allows for the amplification of a specific region of DNA from a single molecule?

Polymerase chain reaction (PCR) Signup and view all the answers

What is the first step involved in the Western blotting process?

Gel electrophoresis Signup and view all the answers

How are DNAs/RNAs separated during gel electrophoresis?

By charge and size Signup and view all the answers

What does quantitative real-time PCR (qPCR) measure?

The number of copies of a gene Signup and view all the answers

Which of the following is NOT a step involved in Western blotting?

DNA amplification Signup and view all the answers

What medical importance does gene expression hold?

It can lead to errors causing diseases Signup and view all the answers

In gel electrophoresis, why do DNA molecules move towards the cathode?

They are negatively charged Signup and view all the answers

What technique can be used to visualize proteins after Western blotting?

Enzyme-linked antibody detection Signup and view all the answers

What is one potential outcome of alternative splicing of the Drosophila Dscam gene?

It can generate 38,016 isoforms. Signup and view all the answers

What type of mutation is introduced when one copy of a gene is not sufficient for normal function?

Haploinsufficiency Signup and view all the answers

Which disorder is specifically associated with a mutation in the DMD gene?

Duchene Muscular Dystrophy Signup and view all the answers

Which mutation is associated with Cystic Fibrosis regarding the SMN1 gene?

The exon 7 is skipped during splicing. Signup and view all the answers

Which transcription factor is commonly over-expressed in various cancers?

MYC Signup and view all the answers

What type of errors can lead to diseases as mentioned in the context provided?

Errors in mRNA processing Signup and view all the answers

What neurodegenerative disease is linked to mutations in the eIF2 gene?

Vanishing White Matter disease Signup and view all the answers

Which mutation leads to a dominant effect over the wild-type protein?

Dominant mutation Signup and view all the answers

Study Notes

Learning Outcomes

Reinforce knowledge from a previous session.
Apply knowledge through exercises.
Understand why studying gene expression is important.
Recognize the medical significance.
Identify techniques used to study DNA, RNA, and proteins.
Explore the possibility of synthesizing DNA, RNA, and proteins in vitro.

The Genetic Code

There are 64 codons that code for 20 amino acids.
Third base in a codon is degenerate meaning multiple codons can code for the same amino acid.
Start codon is AUG, which codes for methionine, the first amino acid in a polypeptide.

One Gene - One Protein Hypothesis

Proposed by Beadle and Tatum in 1941.
Not always true as some genes can make multiple proteins through alternative splicing.

Alternative Splicing

Process where exons are joined together in different combinations to produce various mRNA isoforms.
Example: Drosophila Dscam gene can produce up to 38,016 isoforms through alternative splicing.

Medical Importance of Gene Expression Errors

Errors in gene expression can lead to various disorders, including:
- Duchenne Muscular Dystrophy
- Spinal Muscular Atrophy
- Cystic Fibrosis
- Pulmonary Arterial Hypertension
Can also influence the predisposition to common diseases, such as:
- Breast cancer
- Lung cancer
- Prostate cancer
- Blood cancer

Errors in Genes Causing Diseases

Duchene Muscular Dystrophy: mutation in the DMD gene
Spinal Muscular Atrophy: mutation in the SMN1 gene
Cystic Fibrosis: mutation in the CFTR gene
Pulmonary Arterial Hypertension: mutation in the BMPR2 gene
Breast cancer: mutation in the BRCA1 and BRCA2 genes.

Transcription Errors

Over-expression of the transcription factor (TF) MYC is found in various cancers.
Mutations in one copy of the gene encoding the TF can also lead to diseases:
- Haploinsufficiency: one copy of the gene is not enough (e.g., p53 gene).
- Dominant mutation: change in the gene sequence alters protein function and dominates over the wild-type (e.g., TFCP2L3 gene and genetic deafness).

Splicing Errors

Errors in alternative splicing are common.
In Cystic Fibrosis: mutation in exon 7 of the SMN1 gene leads to its skipping and a non-functional protein.

Translation Errors

Mutations can affect translational efficiency.
Mutations in key translation proteins can lead to disease, including:
- Translation initiation factors (e.g., eIF2 gene - Vanishing White Matter disease).
- Release factors (e.g., eRF3 gene - gastric cancer).
- tRNA transfer proteins or the ribosome itself (rare anemias and several neurodegenerative diseases).

Techniques for Detecting Gene Expression

Gel Electrophoresis of DNA/RNA:
- DNA is negatively charged and moves towards the cathode in an electric field.
- Used to separate DNA or RNA fragments based on size.
Western blotting:
- Used to detect specific proteins.
- Steps:
  - Gel Electrophoresis
  - Blotting
  - Blocking
  - Antibody Probing
  - Detection/Visualisation
PCR: polymerase chain reaction
- Amplifies specific regions of DNA.
- Used for:
  - Gene expression profiling (qPCR)
  - Diagnostics
  - Gene cloning
  - Legal disputes

Making DNA, RNA, and Protein in a Tube

There are protocols available for synthesizing RNA in vitro.
Researchers have successfully created pre-mRNA for splicing in a tube.

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Description

This quiz assesses your understanding of gene expression, its significance in medicine, and the techniques used to study DNA, RNA, and proteins. Additionally, it covers concepts like the genetic code, the one gene-one protein hypothesis, and alternative splicing. Test your knowledge on these critical topics in molecular biology!