Week 7 - Nucleic Acid

Carbohydrates, Lipids, Proteins, Nucleic Acid

4 Bioorganic Substances

Nucleic Acids

Biopolymers made up of monomeric units of nucleotides; found in the nucleus and are acidic in nature; monomer units are nucleotides

Friedrich Miescher

Swiss physiologist; discovered the nucleic acid

Deoxyribonucleic acid

Found within the cell nucleus; storage and transfer of genetic information; passed from one cell to other during cell division

Ribonucleic acid

Occurs in all part of cell; primary function is to synthesize the proteins

Nucleotides

Building blocks of nucleic acid

Nucleic Acids; Nucleotide

_______ is a polymer in which repeating unit is ________

Pentose sugar, Phosphate group, and heterocyclic base

3 components of nucleotide

Pentose sugar

Ribose is present RNA; 2-deoxyribose in DNA; a-OH is present on Carbon 2' in Ribose while a-H atom in 2-deoxyribose; differ in the identity of the sugar units

Phosphate groups

derived from phosphoric acid; fully dissociated to give a hydrogen phosphate ion

Thymine, Cytosine, and Uracil

Three pyrimidine derivatives

Adenine and Guanine

Two purine derivatives

Uracil

_______ found only in RNA

Thymine

__________found only in DNA

Adenine, Guanine, and Cytosine

found in both RNA and DNA

Nucleotide formation

formation in which sugar, base, and phosphate is present; phosphate attached to C-5' and base is at C-1'

Sugar phosphate group

referred to as nucleic acid backbone - found in all nucleic acids; sugars are different in DNA and RNA

Ribonucleic acid (RNA)

nucleotide polymer in which monomers contains ribose, a phosphate groups, and one of the heterocyclic bases adenine, cytosine, guanine, or uracil

Deoxyribonucleic acid (DNA)

nucleotide polymer in which each of the monomer contains deoxyribose, a phosphate group, and one of the heterocyclic bases adenine, cytosine, guanine, or thymine

Replication

(DNA ---> DNA)

Transcription

(DNA ---> RNA)

Translation

(RNA ---> Protein)

DNA Double Helix

Secondary structure involves two polynucleotide chains coiled around each other in a helical fashion; they run anti-parallel

Base pairing

One small and one large base can fit inside DNA strands; A-T and G-C are complementary bases

Replication

Process in which DNA molecules produce exact duplicate of themselves; has newly synthesized DNA and old DNA strand

5'-to-3'

DNA polymerase enzyme can only function ______ direction

Chromosomes

DNA replication the large DNA molecules interacts with histone proteins to fold long DNA molecules; occur in matched homologous pairs

15%

A chromosome is about _____ by mass DNA

85%

_____ % by mass protein of chromosome

Protein Synthesis

directly under the direction of DNA; responsible for the formation of skin, hair, enzymes, hormones, and so on

Transcription

process by which DNA directs the synthesis of mRNA molecules

Translation

Process in which mRNA is deciphered to synthesize a protein molecule

Heterogenous nuclear RNA (hnRNA)

Formed directly by DNA transcription; post transcription processing converts the hnRNA to mRNA

Messenger RNA

Carries instructions for protein synthesis (genetic information) from DNA; molecular mass of mRNA varies with the length of the protein

small nuclear RNA

facilitates the conversion of hnRNA to mRNA; contains 100-200 nucleotides

Ribosomal RNA (rRNA)

Combines with specific proteins to form ribosomes - the physical site for protein synthesis; molecular masses on the order of 3 million

Transfer RNA (tRNA)

Delivers amino acids to the sites for protein synthesis; smallest nucleotide units of 75-90

Gene

Segment of DNA base sequence responsible for the production of a specific hnRNA/mRNA molecule

Genome

All of the genetic material (the total DNA) contained in the chromosome of an organism

1000-3500 nucleotide units long

Human genes nucleotide count

20,000 - 25,000 genes

Human genome is about ________ genes

Splicing

Excision of introns and joining of exons

Exon

gene segment that codes genetic information

Intron

DNA segment that interrupts a genetic message; splicing process is driven by snRNA

Alternative Splicing

Process by which several different protein variants are produced from a single gene; involves excision of one or more exon

Transcriptome

All of the mRNA molecules that can be generated from the genetic material in a genome; responsible for the biochemical complexity created by splice variants of hnRNA

Genetic Code

base sequence of mRNA determines the amino acid sequence for the protein synthesized

Codon

three-nucleotide sequence in an mRNA molecule that codes for a specific amino acid; there are 64 possible codes

Genetic code

the assignment of the 64 mRNA codons to specific amino acids

Ribosomes

an rRNA - protein complex serves as the site of protein synthesis; contains 4 rRNA molecules and 80 molecules packed; RNA catalyst; mRNA binds to the small subunit

65%

rRNA mass in %

35%

Protein mass in %

Activation of tRNA

Addition of specific amino acids to the 3'-OH group of tRNA

Initiation of protein synthesis

binding of mRNA to small ribosomal subunit such that its first codon occupies a site called the P site

Elongation

Adjacent to the P site in an mRNA - Ribosome complex is A site and the next tRNA with the appropriate anticodon binds to it

Termination

Polypeptide continues to grow via translocation until all necessary amino acids are in place and bonded to each other

Post-translational processing

gives the protein the final form it needs to be functional

Polysome (Polyribosome)

Complex of mRNA and Several ribosomes; can move simultaneously along a single mRNA molecule; reduces the amount of resources and energy that the cell expends to synthesize the needed proteins

Mutation

Error in base sequence reproduced during DNA replication; error in genetic formation passed

Mutagens

Mutations caused; a substance or agent that causes a change in the structure of a gene

Radiation and chemical agents

Two important types of mutagens

Ultraviolet, X-ray, radioactivity, and cosmic radiation

Mutagenic that causes cancer

Repair Enzymes

Under normal condition mutations are repaired by _____________

Viruses

Tiny disease causing agents with outer protein envelope and inner nucleic acid core; cannot reproduce outside their host; invades the cells to reproduce

Vaccines

Inactive virus or bacterial envelope; antibodies produced against inactive viral that will kill the active bacteria or viruses

polymerase chain reaction

method for rapidly producing copies of DNA nucleotide sequence