DNA Structure and Genetic Material Quiz

DNA Structure and Properties

• The distance between two base pairs in a DNA helix is approximately 3.4 angstroms.
• The pitch of the DNA helix is 34 angstroms, meaning one complete turn of the helix covers this distance.
• Each turn of the DNA helix contains 10 base pairs.
• The base stacking interactions between adjacent base pairs contribute to the stability of the DNA double helix.
• The two strands of the DNA helix coil in a right-handed direction.

Reverse Transcription and the Central Dogma

• Reverse transcription is the process where genetic information flows from RNA to DNA, observed in some viruses.
• The Central Dogma of Molecular Biology states that genetic information flows unidirectionally from DNA to RNA to protein.

DNA Structure and Composition

• Base pairing between adenine and thymine (A-T) and guanine and cytosine (G-C) contributes to the uniform distance between the two polynucleotide chains in DNA.
• The backbone of a polynucleotide chain is composed of alternating sugar (deoxyribose) and phosphate groups.
• Uracil is the nitrogenous base found in RNA instead of thymine.

Key Discoveries and Concepts

• Friedrich Miescher first identified DNA and named it 'Nuclein'.
• The complementary nature of DNA strands is due to specific base pairing interactions, A-T and G-C.
• The anti-parallel polarity of the DNA strands, where one strand runs 5' to 3' and the other 3' to 5', is essential for DNA replication and transcription.

DNA Structure and Function

• Adenine and thymine form two hydrogen bonds.
• Guanine and cytosine form three hydrogen bonds, contributing to stronger bonding.
• X-ray diffraction patterns of DNA obtained by Rosalind Franklin allowed Watson and Crick to propose the Double Helix model.
• The sequence of chromosome 1 was completed in 2006.

Human Genome and Genetics

• The average size of a human gene is around 30,000 base pairs.
• 99.9% of nucleotide bases are identical in all humans.
• The estimated total number of genes in the human genome is 20,000 to 25,000.
• Chromosome 1 contains the most genes among all human chromosomes.
• Less than 2% of the human genome codes for proteins.

DNA Polymorphisms and Genetics

• SNPs (Single Nucleotide Polymorphisms) are variations in a single nucleotide that occur at a frequency of more than 1% in a population.
• Repetitive DNA sequences likely function in chromosome structure and regulation.
• The primary function of DNA in most organisms is to store and transmit genetic information.

RNA and Cellular Processes

• RNA primarily acts as a messenger in cellular processes, carrying genetic information from DNA to ribosomes for protein synthesis.
• Transcription is the process of synthesizing RNA from a DNA template.
• The genetic code determines the sequence of amino acids in a protein.

RNA Function and Nucleic Acid Structure

• One role of RNA beyond acting as a messenger is its involvement in ribosome structure and function.
• The relationship between nucleotides and nucleic acids is that nucleotides are the building blocks of nucleic acids.

Genomics and DNA Replication

• A major advancement in genomics over the last decade is the development of next-generation sequencing, which allows for high-throughput DNA sequencing.
• DNA replication is responsible for copying DNA for cell division.

DNA Polymorphism Applications and Significance

• The primary significance of DNA polymorphism in forensic applications is individual identification.
• DNA polymorphism is defined in terms of genetic variation frequency as more than 1% in a population.
• Mutations are the primary source of DNA polymorphisms.
• Polymorphisms play a role in evolution and speciation by providing genetic variation upon which natural selection can act.
• Mutations related to polymorphisms are typically inherited in a Mendelian fashion.
• Mutations in non-coding DNA are more likely to result in observed polymorphisms.

DNA Fingerprinting and Mutagenic Effects

• Alec Jeffreys developed the technique of DNA fingerprinting.
• If a germ cell mutation does not impair reproductive capability, it may be passed on to offspring.//