Slide 1

Biomolecules - Nucleotide Subunits

Nucleotides are the building blocks of nucleic acids: DNA and RNA.
They are composed of three main parts: a nitrogenous base, a sugar, and one or more phosphate groups.
The nitrogenous base can be adenine (A), guanine (G), cytosine (C), thymine (T), or uracil (U) in RNA.
The sugar molecule is either ribose in RNA or deoxyribose in DNA.
The phosphate group(s) are responsible for the acidity of nucleotides.

Slide 2

Structure of Nucleotides

The nitrogenous base is attached to the 1’ carbon of the sugar molecule.
The phosphate group is attached to the 5’ carbon of the sugar molecule.
The sugar molecule is linked to the nitrogenous base and phosphate group through phosphodiester bonds.
The sugar-phosphate backbone is formed by these bonds.

Slide 3

Examples of Nucleotide Structures

Adenosine triphosphate (ATP) is a nucleotide that plays a crucial role in cellular energy transfer.
It consists of the adenine base, ribose sugar, and three phosphate groups.
Guanosine triphosphate (GTP) is another nucleotide involved in energy transfer reactions.
It has the guanine base, ribose sugar, and three phosphate groups.

Slide 4

Nucleotide Function in DNA

In DNA, nucleotides serve as the carriers of genetic information.
Adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C) through complementary base pairing.
The sequence of nucleotides in DNA determines the genetic code.
Variation in the sequence leads to genetic diversity and inheritance traits.

Slide 5

Nucleotide Function in RNA

In RNA, nucleotides are involved in protein synthesis.
Adenine (A) pairs with uracil (U) in RNA, while guanine (G) still pairs with cytosine (C).
Messenger RNA (mRNA) carries genetic information from DNA to the ribosomes where proteins are made.
Transfer RNA (tRNA) brings amino acids to the ribosomes during protein synthesis.

Slide 6

Nucleotide Analogs

Nucleotide analogs are structural mimics of natural nucleotides.
They can be used in research, diagnostics, and medical applications.
Examples of nucleotide analogs include: 5-fluorouracil (5-FU), used as an anticancer drug; AZT (azidothymidine), an antiviral drug; and dideoxyribonucleotides (ddNTPs), used in DNA sequencing.

Slide 7

Nucleotide Polymers - DNA

DNA is composed of two strands of nucleotides arranged in a double helix structure.
The two strands are held together by hydrogen bonds between the complementary bases.
The sugar-phosphate backbones run in opposite directions (antiparallel).
The strands are oriented in a 5’ to 3’ direction, referring to the carbon numbering of the sugar molecule.

Slide 8

Nucleotide Polymers - RNA

RNA is usually single-stranded and can fold into various secondary structures.
It can form base pairs within the same strand, leading to complementary regions.
RNA molecules can have distinct functional roles, such as catalytic activity (ribozymes) or regulatory functions (microRNAs).

Slide 9

Nucleotide Modification

Nucleotides can undergo various modifications after their synthesis.
Modifications such as methylation, acetylation, or phosphorylation can alter their properties or function.
These modifications can affect gene expression, protein synthesis, and other cellular processes.
They contribute to the diversity and complexity of nucleic acid biochemistry.

Slide 10

Summary

Nucleotides are the building blocks of nucleic acids, DNA and RNA.
They consist of a nitrogenous base, a sugar, and one or more phosphate groups.
Nucleotides function in genetic information storage, protein synthesis, and cellular energy transfer.
DNA is a double-stranded helix, while RNA is usually single-stranded.
Nucleotide modifications can have significant impacts on cellular processes.

Slide 11

Nucleotides are the monomers that make up nucleic acids.
They are linked together through phosphodiester bonds.
ATP is a nucleotide that serves as the primary energy currency of cells.
GTP is another nucleotide that plays a role in protein synthesis.
Nucleotides can be synthesized de novo or salvaged from degradation pathways.
Examples of nucleotide degradation products include xanthine and hypoxanthine.

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Slide 12

Nucleotide biosynthesis pathways are highly regulated.
Purine nucleotides are synthesized from simple precursors such as amino acids, ribose-5-phosphate, and carbon dioxide.
Adenine synthesis requires the enzyme adenine phosphoribosyltransferase (APRT).
Guanine synthesis involves the enzymes hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and guanosine monophosphate synthetase (GMPS).

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Slide 13

Pyrimidine nucleotides are synthesized from aspartate and carbamoyl phosphate.
Thymine is synthesized from uracil through the action of the enzyme thymidylate synthase.
The enzyme ribonucleotide reductase converts ribonucleotides into deoxyribonucleotides for DNA synthesis.
Each nucleotide biosynthesis pathway has multiple regulation points to maintain proper cellular balance.

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Slide 14

Examples of Nucleotide Biosynthesis Inhibitors

Methotrexate is a drug that inhibits dihydrofolate reductase, an enzyme critical for purine and pyrimidine synthesis.
5-Fluorouracil (5-FU) is an antimetabolite that inhibits thymidylate synthase, reducing the availability of thymine nucleotides.
Azathioprine is an immunosuppressive drug that interferes with nucleotide biosynthesis, leading to cytotoxic effects on dividing cells.

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Slide 15

Nucleotide metabolism also involves nucleotide salvage pathways.
Salvage pathways recycle nucleotides from degradation products.
Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) salvages purine bases.
Xanthine oxidase converts hypoxanthine to xanthine and then to uric acid, which is excreted in urine.

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Slide 16

Nucleotide excision repair is a DNA repair mechanism that removes bulky DNA lesions caused by chemical or physical agents.
Base excision repair corrects DNA damage caused by oxidation, deamination, or hydrolysis.
Mismatch repair fixes errors during DNA replication that occur due to misincorporation or slippage of nucleotides.

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Slide 17

Nucleotide analogs can be used as antimetabolites in cancer therapy.
For example, 6-mercaptopurine (6-MP) is a purine analog that inhibits nucleotide biosynthesis in cancer cells.
Cytarabine is a pyrimidine analog used to treat leukemia.
These analogs interfere with DNA or RNA synthesis, inhibiting cell division and growth.

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Slide 18

Nucleotide analogs can also be used as tools in molecular biology and research.
2’,3’-dideoxyribonucleotides are used in DNA sequencing by chain termination.
Adenosine triphosphate (ATP) analogs labeled with fluorescent dyes are used in ATP detection assays.
Nucleotide analogs can be modified to incorporate fluorescent or radioactive labels for visualization or tracking purposes.

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Slide 19

The polymerase chain reaction (PCR) relies on the use of nucleotides.
PCR is a technique used to amplify DNA segments.
It requires DNA polymerase, primers, and nucleotides for DNA synthesis.
Nucleotides labeled with fluorescent dyes or radioisotopes can be used to label the newly synthesized DNA fragments.

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Slide 20

In conclusion, nucleotides are essential building blocks of nucleic acids with diverse functions.
They are involved in genetic information storage, cellular energy transfer, and protein synthesis.
Nucleotide biosynthesis is a highly regulated process, and its disruption can have detrimental effects on cell function.
Nucleotide analogs have applications in medicine, research, and diagnostics, significantly impacting various fields of study.

Slide 21

Carbohydrates

Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen atoms.
They are the primary source of energy in living organisms.
Monosaccharides are the simplest form of carbohydrates, such as glucose, fructose, and galactose.
Disaccharides are formed when two monosaccharides are joined together through a glycosidic bond.

Slide 22

Structure and Function of Carbohydrates

Carbohydrates can exist as linear chains or form ring structures.
They have various functions in living organisms, including energy storage, structural support, and cell recognition.
Polysaccharides like starch, glycogen, and cellulose are important energy storage and structural components.

Slide 23

Lipids

Lipids are a diverse group of compounds that are insoluble in water but soluble in organic solvents.
They serve as energy storage molecules, insulation, and structural components of cell membranes.
Triglycerides, phospholipids, and steroids are common types of lipids.

Slide 24

Structure and Function of Lipids

Triglycerides are composed of three fatty acid chains attached to a glycerol molecule.
Phospholipids have a hydrophilic head and hydrophobic tails, making them important components of cell membranes.
Steroids have a characteristic four-ring structure and are involved in numerous physiological functions.

Slide 25

Proteins

Proteins are macromolecules composed of amino acid subunits.
They play essential roles in cell structure, signaling, enzymes, and defense.
Amino acids are linked together through peptide bonds to form polypeptide chains.
The primary structure of a protein is the specific sequence of amino acids.

Slide 26

Protein Structure and Function

Proteins fold into specific three-dimensional structures: secondary, tertiary, and quaternary structures.
Secondary structures include alpha helix and beta sheets.
Tertiary structure involves the overall folding of the protein.
Quaternary structure refers to the arrangement of multiple protein subunits.

Slide 27

Nucleic Acids

Nucleic acids, including DNA and RNA, play a central role in storing and transmitting genetic information.
DNA contains the genetic instructions for the development, functioning, and reproduction of all living organisms.
RNA functions in protein synthesis and gene regulation.
Nucleic acids are composed of nucleotide subunits.

Slide 28

Structure of DNA

DNA is a double-stranded molecule made up of two complementary strands.
It forms a double helix structure, with the base pairs held together by hydrogen bonds.
Adenine (A) pairs with thymine (T), while guanine (G) pairs with cytosine (C).
The DNA helix has a sugar-phosphate backbone.

Slide 29

Structure of RNA

RNA is usually single-stranded, but it can fold into complex secondary structures.
It has ribose sugar instead of deoxyribose and uracil (U) instead of thymine (T).
mRNA carries genetic information from DNA to the ribosomes.
tRNA brings specific amino acids to the ribosomes during protein synthesis.

Slide 30

Summary

Biomolecules, including nucleotides, carbohydrates, lipids, proteins, and nucleic acids, are vital for the structure and function of living organisms.
Nucleotides are the building blocks of nucleic acids, DNA, and RNA.
Carbohydrates serve as a source of energy and provide structural support.
Lipids have various functions, including energy storage and serving as structural components of cell membranes.
Proteins are involved in a wide range of cellular functions.
Nucleic acids store and transmit genetic information.