Slide 1: Biomolecules - Primary structure of nucleic acid

• Nucleic acids are macromolecules composed of nucleotides.
• Nucleotides consist of a sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base.
• The primary structure of nucleic acid refers to the sequence of nucleotides along the DNA or RNA strand.
• DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are the two types of nucleic acids found in living organisms.
• The primary structure of DNA is crucial for genetic information storage and transfer.

Slide 2: Nitrogenous bases in nucleic acids

• Nitrogenous bases are the building blocks of nucleic acids.
• DNA contains four nitrogenous bases: adenine (A), cytosine (C), guanine (G), and thymine (T).
• RNA contains four nitrogenous bases: adenine (A), cytosine (C), guanine (G), and uracil (U).
• Adenine and guanine are purine bases, while cytosine, thymine, and uracil are pyrimidine bases.
• The specific pairing of nitrogenous bases forms the basis of the double helix structure of DNA.

Slide 3: Watson-Crick base-pairing rules

• Watson and Crick proposed the base-pairing rules for DNA in 1953.
• Adenine (A) always pairs with thymine (T) through two hydrogen bonds.
• Cytosine (C) always pairs with guanine (G) through three hydrogen bonds.
• These base-pairing rules determine the complementary nature of DNA strands.
• The base pairing allows for DNA replication and transcription.

Slide 4: Complementary base pairing in RNA

• RNA uses the same base-pairing rules as DNA, except thymine (T) is replaced by uracil (U).
• Adenine (A) always pairs with uracil (U) through two hydrogen bonds.
• Cytosine (C) always pairs with guanine (G) through three hydrogen bonds.
• The complementary base pairing allows mRNA to be transcribed from DNA during protein synthesis.

Slide 5: Primary structure of DNA

• The primary structure of DNA is the sequence of nucleotides that make up the DNA molecule.
• It follows the Watson-Crick base-pairing rules.
• For example, a DNA sequence may be: 5’-ATGCTAGC-3'.
• Each nucleotide in the sequence is connected to the adjacent nucleotide by a phosphodiester bond.
• The primary structure plays a crucial role in determining the genetic information carried by DNA.

Slide 6: Primary structure of RNA

• The primary structure of RNA is similar to that of DNA but can vary in sequence and length.
• RNA can be single-stranded or folded into secondary structures (e.g., hairpins or loops).
• The primary structure of RNA determines its role in various cellular processes, such as transcription and translation.
• For example, an mRNA sequence may be: 5’-AUGCUAGC-3'.
• The nucleotides in the primary structure are connected by phosphodiester bonds.

Slide 7: Role of primary structure in protein synthesis

• The primary structure of nucleic acids is crucial for protein synthesis.
• DNA serves as a template for mRNA synthesis during transcription.
• The mRNA molecule carries the genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm.
• The ribosomes read the mRNA sequence and synthesize proteins based on the codons present.
• The primary structure of mRNA determines the sequence of amino acids in the protein.

Slide 8: Importance of DNA primary structure in genetics

• The primary structure of DNA carries the genetic information encoded in the sequence of nucleotides.
• DNA sequencing techniques allow scientists to determine the exact order of nucleotides in a DNA molecule.
• The primary structure of DNA determines an individual’s unique genetic identity and inheritance of traits.
• Changes or mutations in the DNA sequence can lead to genetic disorders or variations.
• Studying the primary structure of DNA helps in understanding genetic diseases and evolutionary relationships.

Slide 9: Importance of RNA primary structure in gene expression

• The primary structure of RNA plays a crucial role in gene expression.
• Various types of RNA molecules, such as mRNA, tRNA, and rRNA, have distinct primary structures.
• The primary structure of mRNA determines which proteins are synthesized within a cell.
• tRNA molecules bring specific amino acids to the ribosome based on the mRNA sequence.
• rRNA molecules are essential components of ribosomes, where protein synthesis occurs.

Slide 10: Conclusion

• The primary structure of nucleic acids, such as DNA and RNA, refers to the sequence of nucleotides.
• Base-pairing rules determine the complementary nature of DNA and RNA strands.
• The primary structure of DNA carries genetic information, while the primary structure of RNA is involved in gene expression.
• Understanding the primary structure of nucleic acids is essential for studying genetics and molecular biology.

11. DNA Replication

• DNA replication is the process of copying the entire DNA sequence.
• It occurs during the S phase of the cell cycle.
• The replication process is semi-conservative, meaning that each new DNA molecule consists of one original strand and one newly synthesized strand.
• Enzymes involved in DNA replication include DNA helicase, DNA polymerase, and DNA ligase.
• The replication fork is the point where the DNA strands separate and replication occurs.

12. Steps of DNA Replication

• Initiation: DNA helicase unwinds the double helix, creating a replication fork.
• Elongation: DNA polymerase adds complementary nucleotides to each separated strand, synthesizing new DNA strands.
• Leading strand: Synthesized continuously.
• Lagging strand: Synthesized in small fragments called Okazaki fragments.
• Okazaki fragments are later joined by DNA ligase.
• Termination: The replication process ends when the entire DNA sequence has been replicated.

13. Transcription

• Transcription is the process of synthesizing an RNA molecule from a DNA template.
• It occurs in the nucleus of eukaryotic cells.
• RNA polymerase is the enzyme responsible for RNA synthesis.
• The DNA sequence is transcribed into mRNA, which carries the genetic information to the ribosomes for protein synthesis.
• Transcription involves three steps: initiation, elongation, and termination.

14. Steps of Transcription

• Initiation: RNA polymerase binds to the promoter region of the DNA strand, signaling the start of transcription.
• Elongation: RNA polymerase adds complementary nucleotides (A, U, G, C) to the growing mRNA strand, following the base pairing rules.
• Termination: RNA polymerase reaches the termination sequence, causing the mRNA strand and RNA polymerase to detach from the DNA template.

15. Translation

• Translation is the process of protein synthesis, where the mRNA sequence is converted into a sequence of amino acids.
• It occurs in the cytoplasm, at the ribosomes.
• Transfer RNA (tRNA) molecules carry specific amino acids to the ribosome based on the codons present on the mRNA.
• There are 20 different types of amino acids, each specified by a unique codon or combination of codons.

16. Steps of Translation

• Initiation: The small ribosomal subunit binds to the mRNA molecule, and the start codon (AUG) signals the start of translation.
• Elongation: The ribosome moves along the mRNA, reading the codons and facilitating the formation of peptide bonds between amino acids, creating a polypeptide chain.
• Termination: A stop codon (UAA, UAG, or UGA) signals the end of translation, and the polypeptide chain is released.

17. Codons and Anticodons

• Codons are three-nucleotide sequences on the mRNA that specify a particular amino acid.
• Anticodons are the complementary three-nucleotide sequences on tRNA molecules.
• The anticodon of each tRNA matches with the codon on the mRNA during translation, ensuring the correct amino acid is added to the growing polypeptide chain.

18. Genetic Code

• The genetic code is the set of rules that determine the translation of mRNA into amino acids.
• Each codon specifies a specific amino acid, except for the start (AUG) and stop codons (UAA, UAG, UGA).
• The genetic code is universal, meaning it is nearly identical in all living organisms.
• Example: The codon UUU codes for the amino acid phenylalanine.

19. Gene Expression Regulation

• Gene expression can be regulated at various levels, such as transcription, translation, and post-translational modifications.
• Regulatory proteins, enhancers, promoters, and repressors control gene expression.
• Gene expression regulation plays a crucial role in cell differentiation, development, and response to environmental stimuli.
• Mutations or dysregulation in gene expression can lead to diseases, including cancer.

20. Conclusion

• Understanding the primary structure of nucleic acids and the processes involved in DNA replication, transcription, and translation is essential for studying genetics and molecular biology.
• These processes ensure the transfer of genetic information and the synthesis of proteins.
• The genetic code and regulatory mechanisms control gene expression, leading to the diversification and specialization of cells in multicellular organisms.
• By studying these topics, we can gain insights into the molecular basis of life and the inheritance of traits.

Slide 21: Types of Biomolecules

• Biomolecules are organic compounds essential for the structure and function of living organisms.
• There are four main types of biomolecules: proteins, carbohydrates, lipids, and nucleic acids.
• Each biomolecule has a unique structure and plays a specific role in cellular processes.
• Proteins are involved in enzymatic reactions, cell signaling, and structural support.
• Carbohydrates are a source of energy and serve as structural components.
• Lipids are important for energy storage and as components of cell membranes.
• Nucleic acids store and transfer genetic information.

Slide 22: Proteins

• Proteins are polymers made up of amino acids linked by peptide bonds.
• There are 20 different amino acids that can be combined in various sequences to form proteins.
• The primary structure of a protein is the sequence of amino acids.
• The secondary structure refers to the folding of the protein chain into alpha helix or beta sheet.
• The tertiary structure indicates the overall 3D shape of the protein.
• The quaternary structure is the arrangement of multiple protein subunits.

Slide 23: Carbohydrates

• Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen.
• Monosaccharides are the simplest form of carbohydrates (e.g., glucose, fructose).
• Disaccharides consist of two monosaccharides joined by a glycosidic bond (e.g., sucrose, lactose).
• Polysaccharides are long chains of monosaccharides and serve as energy storage or structural molecules (e.g., starch, cellulose).

Slide 24: Lipids

• Lipids are hydrophobic molecules and include fats, oils, and phospholipids.
• Triglycerides are the most common form of dietary fats and serve as a source of energy.
• Phospholipids are essential components of cell membranes, consisting of a hydrophilic head and hydrophobic tail.
• Steroids, such as cholesterol, are important for the structure and function of cell membranes and hormone synthesis.

Slide 25: Nucleic Acids

• Nucleic acids, including DNA and RNA, are responsible for storing and transferring genetic information.
• DNA (deoxyribonucleic acid) is found in the nucleus and forms a double helix structure.
• RNA (ribonucleic acid) is involved in protein synthesis and can be single-stranded or form secondary structures.
• The primary structure of nucleic acids is the sequence of nucleotides.
• Nucleotides consist of a sugar, phosphate group, and nitrogenous base.

Slide 26: Importance of Nucleic Acids

• Nucleic acids are essential for genetic information storage and transfer.
• DNA contains the instructions for the synthesis of proteins and determines an organism’s traits.
• RNA helps in decoding DNA and carries the genetic information to the ribosomes for protein synthesis.
• Understanding the primary structure of nucleic acids is crucial for studying genetics and molecular biology.

Slide 27: Examples of Proteins

• Hemoglobin is a protein found in red blood cells that transports oxygen throughout the body.
• Enzymes, such as amylase and lactase, are proteins that catalyze biochemical reactions.
• Collagen is a structural protein that provides strength and support to connective tissues.
• Antibodies are proteins produced by the immune system to recognize and neutralize foreign substances.
• Actin and myosin are proteins responsible for muscle contraction.

Slide 28: Examples of Carbohydrates

• Glucose is a monosaccharide and the primary source of energy for cellular processes.
• Starch is a polysaccharide found in plants and serves as a storage form of glucose.
• Cellulose is a polysaccharide that provides structural support to plant cell walls.
• Glycogen is a highly branched polysaccharide that serves as a storage form of glucose in animals.
• Lactose is a disaccharide found in milk, consisting of glucose and galactose.

Slide 29: Examples of Lipids

• Triglycerides, such as vegetable oils and fats, are a major source of energy in the diet.
• Phospholipids are important components of cell membranes, maintaining their integrity and fluidity.
• Cholesterol is a lipid involved in hormone synthesis and is found in cell membranes.
• Steroids, such as estrogen and testosterone, are lipid-based hormones involved in various physiological processes.
• Waxes are lipids that provide waterproofing and protection to plants and animals.

Slide 30: Summary

• Biomolecules are organic compounds essential for living organisms.
• Proteins are polymers of amino acids, with primary, secondary, tertiary, and quaternary structures.
• Carbohydrates are composed of monosaccharides, disaccharides, and polysaccharides, serving as energy sources and structural molecules.
• Lipids include triglycerides, phospholipids, cholesterol, and steroids, playing roles in energy storage and membrane structure.
• Nucleic acids, including DNA and RNA, store and transfer genetic information.
• Understanding the primary structure of biomolecules is crucial for studying their functions and their importance in biological processes.