Slide 1: Genetic and Evolution - Molecular Basis of Inheritance

• Protein synthesis and its significance
• Introduction to the central dogma of molecular biology
• DNA replication
• Transcription
• Translation

Slide 2: Protein Synthesis

Protein synthesis refers to the process by which cells build proteins. It involves two main steps: transcription and translation.

• Transcription: The process of making an RNA copy of a DNA sequence.
• Translation: The process of using the RNA copy to build a protein.

Slide 3: Central Dogma of Molecular Biology

The central dogma of molecular biology is the principle that genetic information flows from DNA to RNA to protein in living organisms.

• DNA: Carries the instructions for making proteins.
• RNA: Transfers the information encoded in DNA to the protein-building machinery.
• Protein: Performs various functions in the cell.

Slide 4: DNA Replication

DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. It occurs during the S phase of the cell cycle.

• Helicase: Unwinds and separates the DNA strands.
• DNA polymerase: Adds complementary nucleotides to each separated strand, creating two new DNA molecules.
• Replication fork: The Y-shaped structure formed during DNA replication.

Slide 5: Transcription

Transcription is the process through which an RNA molecule is synthesized from a DNA template. It occurs in the nucleus of eukaryotic cells.

• RNA polymerase: Enzyme responsible for synthesizing RNA.
• Promoter: A region of DNA that signals the start of a gene and where RNA polymerase binds.
• Transcription factors: Proteins that regulate the binding of RNA polymerase to the promoter.

Slide 6: Steps of Transcription

Transcription involves the following steps:

1. Initiation: RNA polymerase binds to the promoter, unwinds the DNA, and starts synthesizing RNA.

2. Elongation: RNA polymerase moves along the DNA template, adding complementary nucleotides to the growing RNA strand.

3. Termination: RNA polymerase reaches a termination signal, which causes it to detach from the DNA and release the completed RNA molecule.

Slide 7: Types of RNA

Several types of RNA are involved in protein synthesis:

• Messenger RNA (mRNA): Carries the genetic information from DNA to the ribosomes.
• Transfer RNA (tRNA): Carries amino acids to the ribosomes during translation.
• Ribosomal RNA (rRNA): Part of the ribosomes, where protein synthesis occurs.

Slide 8: Translation

Translation is the process of converting the information encoded in mRNA into a sequence of amino acids, which then form a protein.

• Ribosomes: Complexes made of rRNA and proteins, where translation occurs.
• Codon: A three-nucleotide sequence on mRNA that specifies an amino acid.
• Anticodon: A three-nucleotide sequence on tRNA that is complementary to the mRNA codon.

Slide 9: Steps of Translation

Translation involves the following steps:

1. Initiation: mRNA binds to the ribosome, and the first tRNA carrying the amino acid methionine binds to the start codon.

2. Elongation: tRNAs, with their specific anticodons, bring the corresponding amino acids to the ribosome. Peptide bonds form between the amino acids, forming a polypeptide chain.

3. Termination: When the ribosome reaches a stop codon, the polypeptide chain is released, and the ribosome disassembles.

Slide 10: Examples of Protein Synthesis

Protein synthesis is essential for various biological processes. Some examples include:

• Enzymes: Catalyze biochemical reactions.
• Structural proteins: Form the framework of cells and tissues.
• Hormones: Regulate body functions.
• Antibodies: Defend against foreign substances.
• Transport proteins: Carry molecules across cell membranes.

Slide 11: Structure of Proteins

• Proteins are complex molecules composed of amino acids.
• Amino acids are the building blocks of proteins.
• Proteins have a unique three-dimensional structure.
• The structure of a protein determines its function.
• Examples of protein structures include primary, secondary, tertiary, and quaternary.

Slide 12: Primary Structure of Proteins

• The primary structure of a protein is the sequence of amino acids in the polypeptide chain.
• The sequence is determined by the genetic code.
• Each amino acid is represented by a three-letter or one-letter code.
• The primary structure is crucial for protein folding and function.
• Changes in the primary structure can lead to genetic diseases.

Slide 13: Secondary Structure of Proteins

• Secondary structure refers to the local folding patterns of the polypeptide chain.
• Common secondary structures include alpha helices and beta sheets.
• These structures are stabilized by hydrogen bonding between amino acids.
• Secondary structures play a role in protein stability and function.
• Examples include collagen and keratin.

Slide 14: Tertiary Structure of Proteins

• Tertiary structure refers to the overall three-dimensional shape of a protein.
• It is determined by interactions between amino acid side chains.
• Interactions can include hydrogen bonding, hydrophobic interactions, disulfide bridges, and electrostatic interactions.
• Tertiary structure is critical for protein stability and function.
• Examples include enzymes, antibodies, and hemoglobin.

Slide 15: Quaternary Structure of Proteins

• Quaternary structure refers to the arrangement of multiple polypeptide subunits in a protein complex.
• Multiple subunits can come together to form a functional protein.
• Interactions between subunits can include noncovalent bonding and covalent bonding.
• Quaternary structure is important for protein function and regulation.
• Examples include hemoglobin and DNA polymerase.

Slide 16: Protein Denaturation

• Protein denaturation is the disruption of a protein’s three-dimensional structure.
• Denaturation can be caused by heat, pH extremes, chemicals, or mechanical agitation.
• Denaturation leads to loss of protein function.
• Denatured proteins can sometimes be renatured under the appropriate conditions.
• Examples of denatured proteins include cooked eggs and curdled milk.

Slide 17: Protein Folding and Chaperones

• Protein folding is the process by which a protein acquires its functional three-dimensional structure.
• Proteins often fold spontaneously, guided by their primary structure.
• Chaperones are proteins that assist in the folding process.
• Chaperones help prevent misfolding and aggregate formation.
• Examples of chaperones include heat shock proteins (HSPs).

Slide 18: Importance of Protein Synthesis

• Protein synthesis is essential for various biological processes.
• Proteins perform diverse functions in cells and organisms.
• Proteins are involved in enzyme reactions, cell signaling, transport, and structural support.
• Genetic diseases can arise from mutations in proteins or protein synthesis pathways.
• Understanding protein synthesis helps us understand diseases and develop therapeutics.

Slide 19: Regulation of Protein Synthesis

• Protein synthesis is regulated at various levels.
• Transcriptional regulation controls the production of mRNA.
• Post-transcriptional regulation controls mRNA processing and stability.
• Translation can be regulated by factors that affect ribosome binding and elongation.
• Protein degradation also plays a role in regulating protein levels.
• Examples of regulatory mechanisms include transcription factors and microRNAs.

Slide 20: Protein Synthesis and Evolution

• Protein synthesis plays a central role in evolution.
• Changes in protein structure and function contribute to the diversity of life.
• Mutations in genes can lead to variations in protein sequences.
• Natural selection acts on these variations, promoting beneficial traits.
• Evolutionary studies help us understand the origin and relatedness of organisms.

Slide 21: What is Protein Synthesis?

• Protein synthesis is the process by which cells build proteins.
• It involves translating the genetic information encoded in DNA into functional proteins.
• Proteins are made up of amino acids, which are linked together in a specific sequence.
• The sequence of amino acids determines the structure and function of the protein.
• Protein synthesis is a highly regulated and complex process.

Slide 22: Importance of Protein Synthesis

• Proteins are essential for various biological processes in living organisms.
• They perform structural, enzymatic, regulatory, and signaling functions.
• Proteins are involved in cell growth, development, metabolism, and immune response.
• Without protein synthesis, cells would not be able to perform their necessary functions.
• Understanding protein synthesis helps in the study of genetic diseases and the development of therapeutics.

Slide 23: Transcription and Translation

• Protein synthesis involves two main steps: transcription and translation.
• Transcription occurs in the nucleus and involves the synthesis of mRNA from DNA.
• Transcription factors and RNA polymerase are involved in this process.
• Translation occurs in the cytoplasm and involves the synthesis of proteins from mRNA.
• Ribosomes and tRNA play crucial roles in translation.

1. Initiation: RNA polymerase binds to the promoter region of a gene.

2. Elongation: RNA polymerase synthesizes the mRNA molecule by adding complementary nucleotides to the template DNA strand.

3. Termination: RNA polymerase reaches a termination sequence in the DNA, and the mRNA molecule is released.

1. Initiation: The small ribosomal subunit binds to mRNA, and the start codon is recognized.

2. Elongation: tRNA molecules bring amino acids to the ribosome according to the mRNA codon sequence.

3. Peptide bonds form between the amino acids, resulting in the formation of a polypeptide chain.

4. Termination: The ribosome reaches a stop codon, and the polypeptide chain is released.

Slide 26: Genetic Code and Codons

• The genetic code is the set of rules by which information is encoded in DNA and mRNA.
• It specifies the correspondence between nucleotide sequences and amino acids.
• Codons are three-letter sequences on mRNA that code for specific amino acids.
• There are 64 possible codons, including start and stop codons.
• Some amino acids are coded by multiple codons.

Slide 27: Examples of Protein Synthesis

• Hemoglobin: A protein responsible for carrying oxygen in red blood cells.
• Insulin: A hormone involved in regulating blood sugar levels.
• Collagen: A protein that provides structure to connective tissues.
• Actin and myosin: Proteins involved in muscle contraction.
• Antibodies: Proteins that help the immune system recognize and fight off pathogens.

Slide 28: Regulation of Protein Synthesis

• Protein synthesis is highly regulated to ensure proper cellular function.
• Gene expression can be controlled at the transcriptional and translational levels.
• Transcription factors, regulatory proteins, and signaling molecules play important roles in regulating gene expression.
• Environmental factors and cellular signals can influence protein synthesis.
• Dysregulation of protein synthesis can lead to various diseases.

Slide 29: Protein Synthesis and Genetic Disorders

• Genetic disorders can occur due to mutations in genes involved in protein synthesis.
• Mutations can alter the structure or function of a protein, leading to abnormal phenotypes.
• Examples of genetic disorders caused by protein synthesis defects include cystic fibrosis, phenylketonuria (PKU), and muscular dystrophy.
• Understanding the molecular basis of protein synthesis can help in developing treatments or interventions for these disorders.

Slide 30: Summary

• Protein synthesis is the process by which cells build proteins using the genetic information encoded in DNA.
• Transcription converts DNA into mRNA, while translation converts mRNA into proteins.
• Protein synthesis is essential for various biological functions.
• Regulation of protein synthesis ensures proper cellular function.
• Mutations in genes involved in protein synthesis can lead to genetic disorders.