genes and transcription

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Questions and Answers

What is the initial process of gene expression that occurs in the nucleus?

Transcription (correct)

Translocation

Replication

Translation

Which part of RNA's structure allows it to have multiple distinct shapes?

Nucleotide subunits

Phosphodiester bonds

Flexible backbone (correct)

Double-stranded nature

What is one of the primary functions of messenger RNA (mRNA)?

Participates in RNA splicing

Forms the structural framework of ribosomes

Transports amino acids to ribosomes

Carries genetic information from DNA to ribosomes (correct)

Which of the following statements about RNA is NOT true?

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

How do cells utilize the fixed set of DNA they possess?

Different cells can transcribe different parts of the DNA Signup and view all the answers

What is the primary function of DNA in living organisms?

Storage of genetic information Signup and view all the answers

What is the central dogma of molecular biology?

DNA to RNA to proteins Signup and view all the answers

Which of the following correctly describes the structure of DNA?

Double-stranded forming a helix Signup and view all the answers

What are the basic subunits that make up DNA?

Nucleotides Signup and view all the answers

In the context of genetic inheritance, which statement is true?

Both genes and environmental factors contribute to traits Signup and view all the answers

Which process follows DNA transcription in the expression of genes?

Translation Signup and view all the answers

What role do nucleotides play in the structure of DNA?

They serve as building blocks of DNA Signup and view all the answers

Why is DNA considered a universal medium for storing genetic information?

All living beings on Earth utilize DNA for genetic storage Signup and view all the answers

What characterizes a charged tRNA?

It has an amino acid attached. Signup and view all the answers

Which structure of proteins involves the sequence of amino acids?

Primary structure Signup and view all the answers

What happens during the formation of a peptide bond in protein synthesis?

Two amino acids are linked together. Signup and view all the answers

Which factor is responsible for moving the tRNA during elongation in protein synthesis?

Elongation factor G Signup and view all the answers

Which of the following is NOT a type of post-translational modification (PTM)?

Translation Signup and view all the answers

What is the role of hydroxylation in post-translational modifications?

It alters protein stability. Signup and view all the answers

In which protein structural level do alpha helices and beta-sheets appear?

Secondary structure Signup and view all the answers

Which of the following statements about eukaryotic ribosomal units is correct?

The large subunit is 60S. Signup and view all the answers

What components make up each nucleotide?

A sugar molecule, a phosphate molecule, and a nitrogen-containing base Signup and view all the answers

Which base is found in DNA but replaced by another in RNA?

Thymine Signup and view all the answers

Which of the following bases are classified as purines?

Adenine and Guanine Signup and view all the answers

What term describes a nucleotide that lacks a phosphate group?

Nucleoside Signup and view all the answers

What is the significance of the sugar-phosphate linkages in DNA strands?

They join nucleotides together and provide polarity Signup and view all the answers

What is the primary reason for Thymine's presence in DNA as opposed to RNA?

It is less prone to mutation Signup and view all the answers

What functional groups make up the backbone of a DNA strand?

Sugar and phosphate groups Signup and view all the answers

What distinguishes the structure of purines from pyrimidines?

Purines have a double-ring structure while pyrimidines have a single ring Signup and view all the answers

What does the directionality of DNA chains indicate?

It guides how DNA is interpreted and copied. Signup and view all the answers

Which base pairs correctly according to DNA pairing rules?

Adenine pairs with Thymine. Signup and view all the answers

What type of bond holds nucleotides within an individual strand of DNA?

Covalent bonds. Signup and view all the answers

What characterizes the structure of DNA as a double helix?

The strands are anti-parallel. Signup and view all the answers

What is the approximate length of DNA from chromosome 22 if laid out as a continuous double helix?

1.5 cm. Signup and view all the answers

How is human DNA organized within the nucleus?

In highly condensed form in chromosomes. Signup and view all the answers

What type of bond connects individual nucleotides across different DNA strands?

Hydrogen bonds. Signup and view all the answers

What is a misconception about the condensation of DNA into chromosomes?

It compromises the stability of genetic information. Signup and view all the answers

Study Notes

DNA structure

DNA stands for deoxyribonucleic acid and is made up of nucleotides.
Each nucleotide has a sugar molecule (deoxyribose), a phosphate molecule and a nitrogen-containing side-group, or base.
The four bases are Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
Thymine is replaced by Uracil (U) in RNA.
Adenine and Guanine are derivatives of purine, whilst Cytosine and Uracil/Thymine are derivatives of pyrimidine.
A single strand of DNA consists of nucleotides joined together by sugar-phosphate linkages.
The backbone of the strand is asymmetric, which gives the strand polarity (directionality).
Guanine pairs with cytosine.
Adenine pairs with thymine.
Nucleotides within an individual strand are bonded by strong covalent bonds (phosphodiester bonds).
Nucleotides between individual strands are held together more weakly by hydrogen bonds.
The two strands together produce the ‘double helix’.
DNA is called antiparallel because the strands run in opposite directions.

DNA Location and Structure

DNA is stored in chromosomes.
Each chromosome contains long lists of genes.
The DNA is highly condensed, even though a single chromosome’s DNA is 1.5cm long, the nucleus which holds it is only 6 μm in diameter.

RNA Structure and Function

RNA is typically single-stranded.
RNA has nucleotide subunits linked together by phosphodiester bonds.
The flexibility and self-bonding of RNA can lead to multiple distinct shapes.
RNA folding is an extensive field of study, with misfolding leading to disease.
The three most abundant classes of RNA are rRNA, mRNA, and tRNA.

The Central Dogma

The flow of genetic information is from DNA to RNA to proteins.

Protein synthesis

The cycle begins with peptidyl-tRNA in the P site.
An aminoacyl-tRNA binds in the A site.
A new peptide bond forms.
The tRNAs and the mRNA are translocated through the action of elongation factor G, which moves the deacylated tRNA to the E site.
Once there, the tRNA is free to dissociate to complete the cycle.
The process continues until a stop codon is reached.

Protein Structure

Proteins are macromolecules made up of one or more polypeptides and additional small molecules (cofactors).
The four levels of protein structure are primary, secondary, tertiary, and quaternary.

Post-translational Modifications (PTMs)

PTMs can have significant impact on function e.g. the glucocorticoid receptor (GR, NR3C1) can be phosphorylated at S211 and S226, which has opposing effects on its activity levels.
Eukaryotic proteins are also subject to a variety of post-translational modification (PTM), such as:
- Phosphorylation
- Methylation
- Acetylation
- Ubiquitination
- Hydroxylation
- Glycosylation.

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Description

Test your knowledge on the structure of DNA, including the components that make up nucleotides and the rules for base pairing. This quiz will cover essential concepts such as the double helix formation and the significance of covalent and hydrogen bonds in DNA structure.