DNA and RNA structure, function, and genome organization

What did Mendel introduce in 1866?

The concept of genes (unit factors) as the particles of heredity.

Who discovered DNA in 1869?

Miescher.

What did Flemming discover in 1885?

Chromosomes.

What is the Chromosomal Theory of Inheritance?

Proposed by Sutton and Boveri in 1902, it states that chromosomes are the basis of heredity.

What was Levene's incorrect theory about DNA in 1910?

The Tetranucleotide theory, which stated that DNA consists of equal numbers of each of the four nucleotides.

What did Fredrick Griffith discover in 1927?

The Transforming Principle.

What did Avery, MacLeod, and McCarty identify in 1944?

DNA as the transforming principle.

What significant finding did Hershey and Chase make in 1952?

They showed that DNA is the genetic material in bacteriophages.

What are Chargaff's base pairing rules?

Adenine pairs with Thymine, and Cytosine pairs with Guanine.

What are the two types of nucleic acids?

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

What are nucleotides composed of?

A sugar, a nitrogenous base, and a phosphate group.

What is the structure of DNA?

A double helix formed by two strands of nucleotides.

What type of linkages join nucleotides in nucleic acids?

3'-5' phosphodiester linkages.

According to Chargaff's rules, if DNA contains 20% thymine, what percent of guanine will it contain?

30% guanine.

If a segment of double-stranded DNA is 100 base pairs long and contains 15% cytosine, how many adenine residues does it contain?

35 adenine residues.

Which statement regarding base compositions in DNA is always true?

A + T = C + G.

What does the melting temperature of DNA refer to?

The amount of heat required to separate two strands of DNA.

What is the significance of the DNA double helix structure?

It provides clues into the function of DNA.

What are the components of a deoxyribonucleoside?

A sugar (deoxyribose) and a nitrogenous base.

What are ribonucleosides composed of?

A sugar (ribose) and a nitrogenous base.

What is the role of nucleotides in nucleic acids?

They serve as the building blocks of DNA and RNA.

What did the acceptance of DNA as genetic material lead to?

Increased interest in elucidating its structure.

What is the significance of the year 1953 in DNA research?

Watson and Crick proposed the model for DNA structure.

What is the helical structure of DNA?

DNA has a double helix structure with a constant diameter of 20Å.

What are the two distinct regularities of spacing in DNA?

34Å and 3.4Å.

Who produced the first X-ray diffraction images of DNA?

Rosalind Franklin and Maurice Wilkins.

What model of DNA replication did Watson and Crick propose?

The semi-conservative model.

What holds base pairs together in DNA?

Hydrogen bonds.

What are the key characteristics of genetic material?

Must replicate faithfully, store complex information, be expressible, and capable of variation.

What is the role of messenger RNA (mRNA)?

mRNA serves as a complementary copy of one DNA strand during transcription.

What is the difference between DNA and RNA in terms of structure?

DNA is double-stranded and contains deoxyribose, while RNA is single-stranded and contains ribose.

What nitrogenous base is found in RNA but not in DNA?

Uracil.

What is the direction of synthesis for both DNA and RNA?

5' to 3' direction.

How is the genome of prokaryotes organized?

Prokaryotes typically have a single circular chromosome.

What is the size range of prokaryotic genomes?

1,800,000 to 10,000,000 base pairs.

What is the structure of eukaryotic genomes?

Eukaryotic genomes are divided into multiple linear chromosomes.

What is euchromatin?

Euchromatin is loosely organized and genetically active chromatin.

What is heterochromatin?

Heterochromatin is tightly compacted and genetically inert chromatin.

What is the function of histones in DNA organization?

Histones help package DNA into a compact structure.

What are the components of a nucleosome?

A nucleosome consists of DNA wrapped around histone proteins.

What is the significance of the central dogma of molecular biology?

It describes the flow of genetic information from DNA to RNA to protein.

What is a mutation?

A mutation is a change in the sequence of bases in DNA.

What is the role of transfer RNA (tRNA)?

tRNA transports amino acids to the ribosome during protein synthesis.

What is the role of ribosomal RNA (rRNA)?

rRNA is a component of ribosomes, facilitating protein synthesis.

What is the difference between double-stranded and single-stranded RNA?

Double-stranded RNA has two strands, while single-stranded RNA has one.

What are plasmids?

Plasmids are small, circular DNA molecules found in some prokaryotes.

What is the function of telomeres?

Telomeres protect the ends of chromosomes from deterioration.

What is the significance of the centromere?

The centromere is the region of a chromosome where the two sister chromatids are joined.