Slide 1 - Genetics and Evolution: Molecular Basis of Inheritance - Bacterial Ribosome

Introduction to the molecular basis of inheritance in bacteria.
Bacterial ribosome as the site of protein synthesis.
Importance of bacterial ribosome in genetic processes.
Structure of the bacterial ribosome.
Function and components of the bacterial ribosome.

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Slide 2 - Importance of Bacterial Ribosome

Bacterial ribosome plays a crucial role in protein synthesis.
It is responsible for translating genetic information from mRNA to synthesize proteins.
Essential for cell growth, development, and survival.
Antibiotics specifically target bacterial ribosomes to inhibit protein synthesis.
Understanding the structure and function of the bacterial ribosome is essential in studying genetic processes.

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Slide 3 - Structure of Bacterial Ribosome

Bacterial ribosomes are composed of two subunits, the large subunit, and the small subunit.
Large subunit (50S) contains three RNA molecules and proteins.
Small subunit (30S) contains a single RNA molecule and proteins.
The combination of the large and small subunits forms the functional ribosome (70S).

Example: The combination of 16S rRNA and various proteins forms the small subunit of the bacterial ribosome.

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Slide 4 - Function of Bacterial Ribosome

Bacterial ribosome is responsible for protein synthesis.
It binds to the mRNA molecule and reads the information encoded in the nucleotide sequence.
The ribosome then assembles amino acids in the correct order to form a polypeptide chain.
This process is called translation and occurs in ribosomes present in the cytoplasm of bacterial cells.

Example: The bacterial ribosome translates the mRNA sequence AUG (start codon) into the amino acid methionine, initiating protein synthesis.

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Slide 5 - Components of Bacterial Ribosome

Bacterial ribosomes are composed of ribosomal RNA (rRNA) and proteins.
Ribosomal RNA forms the structural backbone of the ribosome.
Proteins associated with rRNA stabilize the structure and aid in ribosome function.
Over 50 different proteins are found in bacterial ribosomes, each playing a specific role.

Example: S7 protein in bacterial ribosomes has been implicated in the initiation of protein synthesis and translation accuracy.

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Slide 6 - Molecular Basis of Inheritance in Bacteria

Bacterial ribosomes are essential for the transmission of genetic information from one generation to another.
They play a key role in mediating the expression of genetic traits.
The sequence of nucleotides in mRNA determines the amino acid sequence in a protein.
Mutations in the nucleotide sequence can alter the protein structure and function, leading to phenotypic changes.

Example: The presence of a mutation in the bacterial ribosome gene can confer resistance to certain antibiotics.

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Slide 7 - Antibiotics and Bacterial Ribosomes

Antibiotics target bacterial ribosomes to inhibit protein synthesis.
Different antibiotics bind to specific regions of the ribosome, causing disruption in its function.
By targeting bacterial ribosomes, antibiotics selectively kill or inhibit the growth of bacteria, without affecting human cells.
Bacterial resistance to antibiotics can arise due to mutations in ribosomal genes, preventing antibiotic binding.

Example: Erythromycin, a commonly used antibiotic, binds to the bacterial ribosome and inhibits protein synthesis.

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Slide 8 - Summary

Bacterial ribosome is an essential structure involved in the molecular basis of inheritance.
It plays a crucial role in protein synthesis and genetic processes.
Understanding the structure and function of the bacterial ribosome helps in studying the transmission of genetic traits and the development of antibiotic resistance.
The ribosome serves as a target for antibiotics, enabling selective inhibition of bacterial growth.

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Slide 9 - Quiz

What is the function of bacterial ribosomes?
What are the two subunits of the bacterial ribosome?
How does the ribosome translate mRNA into proteins?
Name one example of an antibiotic that targets bacterial ribosomes.
How can mutations in ribosomal genes lead to antibiotic resistance?

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Slide 10 - References

Insert references and sources used for this lecture.

Slide 11 - The Central Dogma of Molecular Biology

The central dogma of molecular biology explains how genetic information flows from DNA to RNA to proteins.
DNA (deoxyribonucleic acid) is the genetic material that carries the instructions for building and maintaining an organism.
Transcription is the process by which DNA is copied into RNA (ribonucleic acid) by an enzyme called RNA polymerase.
RNA serves as an intermediary between DNA and proteins.
Translation is the process by which RNA is converted into proteins by the ribosomes.

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Slide 12 - Transcription

Transcription is the process in which a segment of DNA is copied into RNA by RNA polymerase.
It occurs in the nucleus of eukaryotic cells and the cytoplasm of prokaryotic cells.
Three main steps in transcription: initiation, elongation, and termination.
RNA polymerase recognizes a specific region on DNA called the promoter to start transcription.
The resulting RNA molecule is known as the primary transcript or mRNA (messenger RNA).

Example: In bacteria, the lac operon is transcribed when lactose is present, leading to the production of the enzyme lactase.

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Slide 13 - RNA Modification

Primary transcripts undergo various modifications before becoming functional RNA molecules.
Addition of a 5’ cap and a poly-A tail to protect the RNA molecule from degradation.
Removal of non-coding regions called introns through a process called splicing.
These modifications are essential for the stability, transport, and translation of the RNA molecule.

Example: Alternative splicing in eukaryotes allows a single gene to code for multiple proteins, increasing genetic diversity.

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Slide 14 - Translation

Translation is the process by which the genetic code carried by mRNA is converted into proteins by ribosomes.
It occurs in the cytoplasm of both prokaryotic and eukaryotic cells.
Three main steps in translation: initiation, elongation, and termination.
Initiation involves the binding of the ribosome to the mRNA and the assembly of the first amino acid.
Elongation involves the addition of amino acids to the growing polypeptide chain.
Termination occurs when the ribosome reaches a stop codon on the mRNA, and the protein synthesis is complete.

Example: The genetic code is universal, meaning that the codons in mRNA specify the same amino acids in all living organisms.

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Slide 15 - Genetic Code

The genetic code is a set of rules that defines how the sequence of nucleotides in mRNA is translated into a sequence of amino acids in a protein.
Each three-nucleotide sequence on the mRNA is called a codon and codes for a specific amino acid or a stop signal.
There are 64 possible codons, including 61 codons that specify amino acids and three stop codons.
The start codon AUG codes for the amino acid methionine and also initiates the process of translation.

Example: UUU codes for the amino acid phenylalanine, while UGA is a stop codon.

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Slide 16 - Genetic Mutations

Genetic mutations are changes in the DNA sequence that can alter the structure or function of proteins.
Mutations can occur during DNA replication, transcription, or translation.
Types of mutations include substitutions, insertions, deletions, and frameshift mutations.
Mutations can have various effects on an organism, from no noticeable change to severe consequences.
Mutations can be harmful, beneficial, or neutral depending on their impact on protein structure and function.

Example: Sickle cell anemia is caused by a single-point mutation in the hemoglobin gene, resulting in a change in the protein structure.

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Slide 17 - Regulation of Gene Expression

Gene expression refers to the process by which information from a gene is used to synthesize a functional gene product, usually a protein.
Cells have mechanisms to control when and how often each gene is expressed.
Gene regulation is essential for proper development, differentiation, and response to environmental changes.
Transcription factors and regulatory proteins bind to specific DNA sequences to activate or repress gene expression.
Gene expression can be regulated at various levels, including transcription, RNA processing, and translation.

Example: The lac operon in bacteria is under both positive and negative regulation, allowing the efficient use of lactose as an energy source.

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Slide 18 - Epigenetics

Epigenetics refers to changes in gene expression or cellular phenotype that do not involve alterations in the DNA sequence.
Epigenetic modifications can be heritable and reversible.
DNA methylation and histone modifications are two key epigenetic mechanisms.
Epigenetic changes play a crucial role in development, aging, and the susceptibility to diseases.
Environmental factors can influence epigenetic modifications, providing a link between genetics and the environment.

Example: X-chromosome inactivation in female mammals is an epigenetic process that ensures equal dosage of X-linked genes.

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Slide 19 - Applications of Molecular Biology

Molecular biology has numerous applications in various fields of science and medicine.
Genetic engineering allows the manipulation of DNA to create genetically modified organisms (GMOs) with desired traits.
PCR (polymerase chain reaction) enables amplification of specific DNA sequences for analysis.
DNA sequencing techniques have revolutionized genome research and personalized medicine.
Disease diagnosis, forensic analysis, and paternity testing rely on molecular biology techniques.
Biotechnology and pharmacology heavily rely on molecular biology for drug development and genetic therapies.

Example: The development of insulin through recombinant DNA technology has revolutionized diabetes treatment.

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Slide 20 - Summary

The central dogma of molecular biology describes the flow of genetic information from DNA to RNA to proteins.
Transcription and translation are the processes involved in gene expression.
The genetic code and genetic mutations play a crucial role in protein synthesis and genetic diversity.
Regulation of gene expression and epigenetics control the timing and amount of gene expression.
Molecular biology has numerous applications in various fields, from genetic engineering to personalized medicine.

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Slide 21 - DNA Replication

DNA replication is the process by which a DNA molecule is copied to produce two identical copies.
It occurs during the S phase of the cell cycle.
The enzyme DNA polymerase is responsible for synthesizing the new DNA strands.
The replication process is semi-conservative, meaning each new DNA molecule consists of one original strand and one newly synthesized strand.
Many proteins and enzymes are involved in the replication process, including helicase, DNA primase, and DNA ligase.

Slide 22 - Steps of DNA Replication

Initiation: Replication begins at specific sites called origins of replication.
Unwinding: Helicase enzyme separates the two DNA strands by breaking hydrogen bonds.
Primer Synthesis: RNA primers are synthesized by DNA primase to initiate replication.
Elongation: DNA polymerase adds complementary nucleotides to the growing DNA strand.
Termination: Replication is completed when DNA polymerase reaches the end of the DNA molecule.
Proofreading: DNA polymerase checks for errors and corrects them during replication.

Slide 23 - DNA Replication - Examples

DNA replication is essential for cell division and growth.
In humans, DNA replication occurs during the formation of gametes (sperm and egg).
Errors in DNA replication can lead to mutations and genetic disorders such as cancer.
DNA replication also plays a role in DNA repair mechanisms.

Slide 24 - Gene Expression Regulation

Gene expression regulation refers to the control of the transcription and translation processes.
DNA sequences called promoters and enhancers control the initiation of transcription.
Transcription factors bind to these sequences to activate or repress gene expression.
Epigenetic modifications like DNA methylation and histone modification can also regulate gene expression.
Post-transcriptional modifications and regulatory RNA molecules further regulate gene expression at the translation level.

Slide 25 - Examples of Gene Expression Regulation

Developmental processes: Specific genes are expressed at different stages of development to control growth and differentiation.
Environmental response: Genes involved in stress response are upregulated in response to environmental conditions.
Different cell types: Different cells in the body express different sets of genes to carry out their specialized functions.
Disease development: Abnormal regulation of gene expression can lead to diseases like cancer and genetic disorders.
Hormonal regulation: Hormones can activate or repress gene expression in specific tissues.

Slide 26 - Point Mutations

Point mutations are changes in a single nucleotide in the DNA sequence.
Types of point mutations include substitutions, insertions, and deletions.
A substitution mutation replaces one nucleotide with another, potentially changing the amino acid sequence of the protein.
Insertion and deletion mutations can shift the reading frame, leading to a frameshift mutation that alters all subsequent codons.

Slide 27 - Genetic Diseases and Point Mutations

Many genetic diseases are caused by point mutations in specific genes.
Sickle cell anemia is caused by a single nucleotide substitution in the beta-globin gene, resulting in abnormal hemoglobin.
Cystic fibrosis is caused by a deletion mutation in the CFTR gene, affecting the transport of ions across cell membranes.
Huntington’s disease is caused by a duplication of a specific DNA sequence in the huntingtin gene, leading to neurodegeneration.

Slide 28 - Non-Mendelian Inheritance

Non-Mendelian inheritance refers to inheritance patterns that do not follow the classic Mendelian principles.
Examples of non-Mendelian inheritance include incomplete dominance, codominance, multiple alleles, polygenic inheritance, and epistasis.
In incomplete dominance, the heterozygous phenotype is a blend of the two homozygous phenotypes.
In codominance, both alleles are expressed in the heterozygous genotype, without blending.

Slide 29 - Examples of Non-Mendelian Inheritance

Inheritance of blood types in humans is an example of codominance.
ABO blood types are determined by the presence of different alleles (A, B, O) of the same gene.
Rh factor inheritance is an example of an interaction between two genes, which exhibit epistasis.
Skin color in humans is an example of polygenic inheritance, where multiple genes contribute to the trait.

Slide 30 - Summary

DNA replication is essential for cell growth and reproduction, occurring in multiple steps.
Gene expression regulation controls when and how genes are expressed, crucial for cell development and response to the environment.
Point mutations can lead to genetic diseases by altering protein structure and function.
Non-Mendelian inheritance patterns deviate from Mendelian genetics and involve factors like incomplete dominance, codominance, multiple alleles, polygenic inheritance, and epistasis.