DNA and Nucleic acids

Nucleotide

An organic molecule containing a nitrogenous base, a phosphate and a 5-carbon sugar molecule; when repeated in series (as monomers), form polynucleotides, the basic structure of nucleic acids (DNA or RNA). Three main components: - Nitrogenous base - Phosphate - Sugar (deoxyribose)

Radioactive isotope

An unstable isotope of an element.

Deoxyribose

Five-carbon sugar found in DNA nucleotides; differs from ribose in that it lacks a hydroxyl (OH) group at the 2′-carbon.

Ribose

Five-carbon sugar found in RNA nucleotides.

Pyrimidine

Four-carbon ring connected by nitrogen atoms at the one and three positions; one of the two types of nitrogenous bases in nucleotides; includes cytosine, thymine, and uracil.

Ribonucleicacid

Nucleic acid containing ribose as the sugar. Used to transmit genetic information to ribosomes in the cell.

Sugar-phosphate backbone

The backbone of DNA and RNA; composed of alternating molecules of phosphate and ribose or deoxyribose sugar. Sugar connects phosphate backbone with base.

The Griffith Experiment

(~1928) Published the phenomenon of transformation, where eternal DNA is assimilated by a cell.

Gene

A segment of DNA with instructions for protein or RNA synthesis.

Transforming principle

A term used by Frederick Griffith to describe a then-unknown substance that transformed non-virulent R strain bacteria into virulent S strain bacteria; now understood to be DNA.

Chromosome

A tightly compacted structure of DNA and protein found in cells.

Nucleoside

Component of a nucleotide: a five-carbon sugar linked to a nitrogenous base without the phosphate group present.

Phosphodiester bond

Covalent bond in nucleic acids that links nucleotides together; connects the 5′-carbon on one sugar with the 3′-carbon on the next sugar via the phosphate group.

The difference between DNA and RNA

DNA is a double helix made from two strands of deoxyribonucleic acid. In the double helix, A base pairs with T, and G base pairs with C. RNA is typically single-stranded and is made from ribonucleic acids. RNA can fold into hairpins in which A base pairs with U and G base pairs with C. This stem-loop configuration is a common secondary structure of RNA.

Biological genetic information serves two functions:

Direct expression of proteins; and Be passed onto subsequent generations

Complementary base pairs

Erwin Chargaff concluded that in all organisms their DNA is comprised of equal proportions of: A-T and G-C

Phosphate

The phosphate unit links polynucleotides together in the polynucleotide chain.

Conformation

The spatial arrangement or shape of a macromolecule, such as a protein or nucleic acid.

True of false. Many different codons may code for the same amino acid.

True. With four different nucleotides (A,T,C,G), and a codon of three nucleotides, 64 unique codes are possible BUT ooly 21 amino acids are found in humans. So there are more codons to amino acids.

Bioassay

A method used to determine the potency or biological activity of a substance.

How does heredity operate?

A theory in which the genes play a major role. Every single organism that exists on earth has a genetic code. This genetic code is passed on to the offsprings in both bisexual and asexual organisms. The genetic codes that are passed on bring about certain changes in characteristics.

Bacteriophage

A type of virus that infects bacteria.

Phage

A type of virus that infects bacteria; also called a bacteriophage.

Gregor Mendel

(~1865) An experimentalist who examined the scientific basis of inheritance using plant breeding models. He concluded that traits are encoded by 'heritable factors' passed on to the next generation in defined ratios. These heritable factors were later called genes. The ability for factors (genes) to be passed on is called heredity.

Thomas Hunt Morgan

(~1910) Published study on sex-linked inheritance and provided evidence that chromosomes carry Mendel's "heritable factors". Investigated the genetic basis of eye colour using fruit flies (the eye colour is white in mutants, red when normal). Provided evidence that specific genes are located in specific chromosomes.

The Avery Bioassay

(~1944) Oswald Avery's experiment proved the DNA, not RNA or protein, is the "transforming principle".

Erwin Chargaff

(~1950) Erwin Chargaff reports findings that pyrimidines and purines occur in almost the same ratio in the DNA of many species.

Hershey-Chase Experiment

(~1952) Alfred Hershey and Martha Chase publish report that rules out protein as genetic material and demonstrates that DNA is involved in bacteriophage replication.

Watson and Crick

(~1953) James Watson and Francis Crick publish double-helix model for the DNA molecule. Receive Nobel Prize in 1962 for discovery of 3D double-helix structure of the DNA molecule.

Rosalind Franklin

(~1953) publishes X-ray diffraction photograph of DNA showing double-helix structure.

Evolution through natural selection:

- Darwin proposed the process for change which was evolution - Darwin did not explain the physical mechanism - Darwin could not explain mechanism of inheritance

Polynucleotide

They are polymers consisting of multiple nucleotides.

What constitutes the phosphodiester bonds in DNA? Please choose from one of the following options. a. Covalently linked nucleotides b. Hydrogen bonds between complementary strands c. Covalently linked amino acids d. Hydrogen bonds between nucleosides

a. Covalently linked nucleotides

What is the functional relationship between codons and amino acids? a. Many different codons may code for the same amino acid b. Codons and amino acids randomly associate around a particular tRNA c. A given amino acid is only coded for by a single codon d. A single codon may code for many different amino acids

a. Many different codons may code for the same amino acid. With four different nucleotides (A,T,C,G), and a codon of three nucleotides, 64 unique codes are possible ​​Only 21 amino acids are found in humans. The codon system is characterized by 'redundancy' in the code, which protects against single nucleotide mutations/mistakes.

Which of the following is NOT a function of the 5' terminus of mRNA? a. Promotes ribosomal binding for translation b. Promotes polyadenylation of the 3' terminus c. Protects the mRNA from degradation d. Regulates nuclear export of mRNA

b. Promotes polyadenylation of the 3' terminus (DOES NOT HAPPEN) The 5' terminus does, in fact, protect mRNA from degradation. The 5' terminus is required for ribosomal binding, and regulates nuclear export of mRNA. However, the 5' terminus has no role in polyadenylation of the 3' terminus.

RNA - key differences to DNA

bonds between nucleotides = phosphodiester sugar in nucleotides = ribose nucleobases = adenine, uracil, guanine, cytosine

DNA - key differences to RNA

bonds between nucleotides =phosphodiester sugar in nucleotides = deoxyribose nucleobases adenine, thymine, guanine, cytosine primary function = information storage

Base pairing

Hydrogen bonding between nitrogenous bases within polynucleotides; specifically hydrogen bonding between guanine and cytosine and between adenine and thymine in DNA; in RNA the base pairs are guanine and cytosine, and adenine and uracil.

Hairpin

Important secondary structure formation in RNA.

Chargaffs rule

In a given sample of double-stranded DNA, the amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of cytosine (founded by Erwin Chargaff)

Proteins

Mediate the structure and function of cells

Nucleic acids

Include both DNA and RNA. They are one of four classes of large biological molecules essential to cellular structure and function (the others being carbohydrates, lipids and proteins).

Guanine

One of the purine nitrogenous bases; complement to cytosine.

Adenine

One of the purine nitrogenous bases; complement to thymine.

Thymine

One of the pyrimidine bases; complement to adenine.

Cytosine

One of the pyrimidine nitrogenous bases; complement to guanine.

Nitrogenous base

One of the three components of a nucleotide that makes each unique: adenine, guanine, cytosine, thymine and uracil; grouped into two families: pyrimidines and purines. Key element of complementary base-pairing of nucleic acids.

Purine

Pyrimidine ring connected to an imidazole ring, forming a double ring structure; one of the two types of nitrogenous bases in nucleotides; includes adenine and guanine.

Transformation

The alteration of a bacterial cell's genetic composition caused by the introduction of exogenous DNA (DNA originating outside an organism that has been introduced into the organism).

Deoxyribonucleic acid (DNA)

The primary molecule of inheritance in nearly all organisms; a double-stranded polymer of nucleotides that contain the sugar deoxyribose.

Double helix

Two antiparallel strands of DNA held together by hydrogen bonds coiled into a helical shape. Sometimes also referred to as a "twisted ladder."

Antiparallel

Two complementary strands running in opposite directions.

Structural characteristic of DNA

Two polynucleotide strands with sugar-phosphate backbones linked by purine-pyrimidine pairs. Each strand has directionality (5' to 3' direction of one strand is opposite to the complementary strand, oriented in a 3' to 5' direction).

The lagging strand of a DNA molecule undergoing replication reads 3'-CGCATGTAGCGA-5'. What is the code of the DNA that is the template for the complementary leading strand of this segment? Please choose from one of the following options. a. '-GCGTACATCGCT-3' b. 5'-CGCATGTAGCGA-3' c. 3'-CGCATGTAGCGA-5' d. 3'-GCGTACATCGCT-5'

c. 3'-CGCATGTAGCGA-5' The leading strand is complementary to the lagging strand, i.e. 5'-GCGTACATCGCT-3'. The newly synthesized strands of DNA (the leading and lagging strands) are complementary to their template strands. The template strand for the leading strand is complementary to the leading strand. The newly synthesized leading strand is also complementary to the lagging strand. As the template leading strand and the newly synthesized lagging strand are both complementary to the newly synthesized leading strand, the template leading strand and the newly synthesized lagging strand will have the same sequence. As the newly synthesized lagging strand's sequence was given as 3'-CGCATGTAGCGA-5', this is the sequence of the template leading strand, a