Introduction to Molecular Biology (2)

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Questions and Answers

What is the primary function of messenger RNA (mRNA)?

To transport amino acids during protein synthesis

To regulate gene expression through RNA interference

To serve as a structural component of ribosomes

To carry information from DNA to ribosomes for protein synthesis (correct)

Which type of RNA makes up the largest portion of total RNA in a cell?

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA (rRNA) (correct)

Non-coding RNA (ncRNA)

What characterizes transfer RNA (tRNA) among the different types of RNA?

It has the longest nucleotide sequence.

It is primarily involved in the transcription process.

It is essential for linking amino acids during protein synthesis. (correct)

It constitutes the majority of RNA in the cell.

How do ribosomal RNA (rRNA) molecules function within ribosomes?

They form structural elements and catalyze peptide bond formation. Signup and view all the answers

Which statement about non-coding RNAs (ncRNA) is true?

They can have various roles including gene regulation and RNA processing. Signup and view all the answers

What is a major structural difference between RNA and DNA?

RNA is single-stranded while DNA is typically double-stranded. Signup and view all the answers

Which of the following best describes a function of non-coding RNAs?

They are involved in regulating gene expression. Signup and view all the answers

What type of chromatin is primarily associated with gene silencing?

Heterochromatin Signup and view all the answers

How are nucleosomes organized within chromatin?

DNA wraps around histone proteins to form nucleosomes. Signup and view all the answers

Which statement accurately reflects gene expression regulation?

Environmental factors can influence gene expression. Signup and view all the answers

What is the estimated percentage of the human genome that consists of coding DNA?

2% Signup and view all the answers

What defines genetic polymorphism in the context of DNA?

The occurrence of two or more variant forms of a specific DNA sequence. Signup and view all the answers

What role do centromeres play in cellular division?

They direct the assembly of microtubules for chromosome segregation. Signup and view all the answers

What is the primary function of the linker histone H1 in relation to nucleosomes?

It stabilizes the 30-nm fiber and higher-order chromatin structures. Signup and view all the answers

Which characteristic distinguishes euchromatin from heterochromatin?

Euchromatin is enriched in genes and often active in transcription. Signup and view all the answers

What can be concluded about the role of different H1 histone subtypes in gene expression?

Some H1 subtypes can attenuate or accentuate position effects in gene expression. Signup and view all the answers

Which statement accurately describes the composition of heterochromatin?

It denotes regions that are more compact and darkly stained. Signup and view all the answers

What is the role of the arrangement of linker histones on chromatin fiber?

It influences higher-order chromatin structure and gene expression levels. Signup and view all the answers

Which of the following describes a significant feature of chromosomes?

They represent the highest level of DNA organization and are formed from condensed chromatin fibers. Signup and view all the answers

Which of the following statements reflects a similarity between euchromatin and heterochromatin?

Both consist of polynucleotide chains of DNA. Signup and view all the answers

In the context of gene regulation, what is the importance of histone H1 subtypes?

They play differential roles in the regulation of gene expression. Signup and view all the answers

Study Notes

Introduction to Molecular Biology (2)

Course module: Cell biology and molecular biology
Academic year: 2022-2023
Instructor: Pr. Raouf Alami
Course material covers: RNA and DNA, eukaryotic chromosomes organization, human genome, genetic polymorphisms, and relevant methods/tests

Course Contents

Ribonucleic acid (RNA):
- RNA and DNA structure comparison
- RNA size variation
- RNA backbone components (phosphate and ribose)
- RNA structures (primary, secondary, and tertiary)
- RNA functions (coding, decoding, regulating, expressing genes, carrying out biochemical reactions, and serving as enzymes)
- RNA integrity assessment methods (denaturing agarose gel with ethidium bromide)
- Types of RNA (mRNA, rRNA, tRNA, non-coding RNAs, microRNA and ncRNA)
- Relative abundance of each RNA type in a human cell (rRNA ~ 80%, tRNA~15%, mRNA ~ 5%)
Organization of eukaryotic chromosomes:
- Chromatin structure (nucleosome, 30nm chromatin fiber, and higher-level structures)
- Nucleosome makeup (histone octamer and DNA wrapping)
- Telomeres (repeated DNA sequences at chromosome ends)
- Telomere sequence (TTAGGG)
- Telomere function (protecting chromosome ends)
- Eukaryotic nucleus size ranges from 5-10 µm
- Euchromatin vs heterochromatin (structural and functional differences)
- Euchromatin (less compact, rich in genes, actively transcribed)
- Heterochromatin (more compact, less active transcription)
Human Genome:
- Genome definition (complete set of nucleic acid sequences)
- Chromosome number (23 pairs in humans)
- DNA molecule regions (coding and non-coding)
- Human Genome Project (HGP) overview (goal was to determine the sequence of 3 billion base pairs, including identifying genes)
- Estimated gene number (20,000 – 25,000)
- Gene redundancy (two copies of each gene, one from each parent)
- Non-coding DNA function (genetic regulation and other roles)
Genetic Polymorphism:
- Definition (variation in DNA sequences among individuals/populations)
- Types (single nucleotide polymorphisms (SNPs), short tandem repeats (STRs))
- Application in forensic investigations (comparing DNA profiles to identify suspects)
- Paternity testing approach (comparing DNA profiles for biological father determination)
Quiz Questions:
- Number of chromatins per chromosome (1)
- Number of DNA molecules per chromosome (1)
- Three major differences between RNA and DNA
- RNA backbone components (phosphate and ribose)
- Method for assessing RNA integrity (run an aliquot of RNA on a denaturing agarose gel)
- mRNA first description (1961 by Jacob and Monod)
- tRNA function (essential component of translation)
- Non-coding RNA examples (tRNA, rRNA, hammerhead ribozyme)
- Chromatin first description (1880 by Fleming)
- Base pairs per nucleosome (~ 147)
- Proteins per nucleosome (8)
- DNA compaction ratio for a chromosome (10,000-20,000 fold)
- H1 histone function (linker histones for DNA entry/exit and stabilize the 30nm chromatin fiber)
- Similarities between euchromatin and heterochromatin (both made up of nucleotides, visible more distinctly in interphase & interact with histones)
- Differences between euchromatin and heterochromatin
- Heterochromatin presence in prokaryotes (yes)
- Role of chromosomes (protecting DNA from tangling & damage)
- Definition of karyotype (lab produced image of chromosomes)
- Human telomere sequence (TTAGGG)
- Telomere repeated times (~ 3,000 to 15,000)
- Role of centromeres (linking pair of sister chromatids during cell division)
Number of DNA molecules in a human cell. (46)
Definition of "junk DNA" (regions of DNA that don't code for proteins in genetics)
Date of the human genome gold standard release (2003)
SNP meaning (single nucleotide polymorphism)
Tandem repeat application (genetic markers and DNA fingerprinting)

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Description

This quiz covers key concepts in molecular biology, focusing on RNA structures, functions, and the organization of eukaryotic chromosomes. Students will explore genetic elements, including human genome aspects and genetic polymorphisms. Assess your understanding of molecular biology fundamentals with this quiz.