Nucleic Acids Overview

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Questions and Answers

What are the basic components of nucleotides?

A nitrogenous base, a five-carbon sugar, and a phosphate functional group.

Which of the following nitrogenous bases are found in DNA?

Uracil (U)

Cytosine (C) (correct)

Adenine (A) (correct)

Thymine (T) (correct)

What sugars are present in nucleotides?

Ribose and deoxyribose.

What is the difference between a nucleotide and a nucleoside?

A nucleotide contains a nitrogenous base, a sugar, and a phosphate, while a nucleoside contains only the sugar and nitrogenous base. Signup and view all the answers

Nucleic acids are formed by nucleotides linked through phosphodiester bonds.

True Signup and view all the answers

What is the structural description of DNA?

Double helix Signup and view all the answers

What are complementary base pairs in DNA?

Adenine pairs with Thymine, and Guanine pairs with Cytosine. Signup and view all the answers

DNA is separated into 46 pieces called chromosomes.

True Signup and view all the answers

What is the role of messenger RNA (mRNA)?

To serve as a template for protein synthesis. Signup and view all the answers

What facilitates the translation process in protein synthesis?

Transfer RNA (tRNA). Signup and view all the answers

What occurs during transcription?

DNA unwinds and a complementary copy of RNA is created. Signup and view all the answers

What is a mutation?

Any change in a DNA nucleotide sequence. Signup and view all the answers

What are common sources of mutations?

All of the above Signup and view all the answers

What is a virus?

A small particle containing genes that can infect cells. Signup and view all the answers

What is HIV?

A retrovirus responsible for AIDS. Signup and view all the answers

What is recombinant DNA technology?

A method of altering the genome of one organism by splicing in DNA from another. Signup and view all the answers

What is cloning?

Creating an exact genetic copy of an organism. Signup and view all the answers

Study Notes

Components of Nucleic Acids

Nucleic acids are composed of nucleotides, each containing a nitrogenous base, a five-carbon sugar, and a phosphate group.
Nucleic acids form from sequences of four types of nucleotides.

Nitrogen Bases

Four nitrogenous bases are involved: adenine (A), guanine (G), thymine (T), and cytosine (C) in DNA; uracil (U) replaces thymine in RNA.
Bases fall into two categories: purines (A and G) and pyrimidines (T, C, and U).

Ribose and Deoxyribose

Nucleotides include ribose in RNA and deoxyribose in DNA, distinguished by a prime symbol to indicate nucleotide carbon positions.

Naming Nucleotides

Nucleotides are named by combining the nucleoside name (sugar + nitrogenous base) with the number of phosphate groups.
Abbreviations indicate the sugar type (d for deoxyribose) and the base.

Nucleic Acid Formation

Nucleic acids are formed by linking nucleotides via phosphodiester bonds between the 3′ and 5′ carbons of adjacent sugars.

DNA Structure

DNA sequences encode cellular proteins; Chargaff's rules establish base pairing (A = T and G = C).
DNA's double helix structure was modeled by Watson and Crick in 1953, with antiparallel strands and complementary base pairing (A-T, G-C).

Chromosomes

DNA compacts into 46 chromosomes through supercoiling around histone proteins, with human DNA stretching about 6 feet when fully extended.

Messenger RNA and Transcription

Transcription creates mRNA from a DNA template; RNA polymerase synthesizes mRNA that is complementary to the DNA strand.

Ribosomal RNA and the Ribosome

Ribosomes consist of rRNA and proteins, decoding mRNA to produce proteins; mRNA aligns with ribosome subunits during translation.

Transfer RNA and Translation

tRNA transports specific amino acids to ribosomes, featuring a three-base anticodon that pairs with mRNA codons, ensuring accurate protein synthesis.

Protein Synthesis Steps

Transcription: DNA unwinds, and mRNA forms before traveling to the ribosome.
Translation: mRNA directs tRNA to assemble amino acids into proteins, starting with the start codon AUG.

Termination of Protein Synthesis

Protein synthesis concludes when a stop codon is reached; the polypeptide chain is released and may require folding for functionality.

Genetic Mutations

Mutations involve changes in DNA sequences, affecting protein sequences and functions; most DNA does not encode proteins, limiting impact.

Sources of Mutations

Errors during DNA replication can lead to spontaneous mutations; environmental mutagens like sodium nitrate can induce changes.
Germ cell mutations can pass to offspring, potentially causing genetic diseases.

Viruses

Viruses, containing nucleic acid and a protective capsid, need host cells to replicate; they commandeer cellular machinery to produce more viral particles.

HIV-1 and AIDS

HIV is a retrovirus attacking T4 lymphocytes, weakening the immune response; therapies aim to disrupt the viral life cycle.

Recombinant DNA Technology

Involves splicing genes from different organisms to produce desired proteins; uses plasmids as vectors for gene incorporation and expression.

Nuclear Transplantation - Cloning

Cloning creates genetically identical organisms by inserting somatic cell nuclei into enucleated egg cells; Dolly the sheep was the first cloned mammal, born in 1996.

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Description

This quiz covers the fundamental components of nucleic acids, including the structure of nucleotides, the types of nitrogenous bases, and the differences between DNA and RNA. Test your knowledge on nucleotide naming conventions and the formation of nucleic acids through phosphodiester bonds.