Cell Biology: Understanding Cells and Organelles

Cell Theory:
- All living organisms are composed of cells.
- The cell is the basic unit of life.
- All cells arise from pre-existing cells.
Types of Cells:
- Prokaryotic: Simple, no nucleus, e.g., bacteria.
- Eukaryotic: Complex, contains a nucleus, e.g., plants, animals, fungi.
Cell Organelles:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Energy production (ATP).
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum (ER): Protein and lipid synthesis.
  - Rough ER: Studded with ribosomes.
  - Smooth ER: No ribosomes, lipid synthesis.
- Golgi Apparatus: Modifies, sorts, and packages proteins.
- Cell Membrane: Semi-permeable barrier, maintains homeostasis.
Cell Division:
- Mitosis: Somatic cell division for growth and repair.
- Meiosis: Production of gametes (sperm and eggs), involves two rounds of division.

Basic Concepts:
- Gene: A segment of DNA that encodes a protein.
- Allele: Different versions of a gene.
- Genotype: Genetic makeup of an individual.
- Phenotype: Observable characteristics.
Mendelian Genetics:
- Inheritance patterns discovered by Gregor Mendel.
- Dominant and recessive traits.
- Punnett Squares: Used to predict genetic variation.
Molecular Genetics:
- DNA Structure: Double helix, composed of nucleotides (A, T, C, G).
- Replication: Process of copying DNA before cell division.
- Transcription: RNA synthesis from DNA.
- Translation: Protein synthesis from mRNA.
Genetic Variation:
- Mutations: Changes in DNA sequence.
- Recombinant DNA: Combination of DNA from different sources.

Theory of Evolution:
- Proposed by Charles Darwin.
- Natural Selection: Mechanism of evolution where organisms better adapted to their environment tend to survive and reproduce.
Key Concepts:
- Adaptation: Traits that enhance survival and reproduction.
- Speciation: Formation of new and distinct species.
- Common Descent: All species share a common ancestor.
Evidence of Evolution:
- Fossil Records: Show changes in species over time.
- Comparative Anatomy: Homologous structures indicate common ancestry.
- Molecular Biology: DNA comparisons reveal genetic similarities and differences.
Evolutionary Mechanisms:
- Genetic Drift: Random changes in allele frequencies, especially in small populations.
- Gene Flow: Movement of genes between populations.
- Mutation: Source of genetic variation.

Cell Theory: Fundamental principles stating that all living things are made of cells, the cell is the basic unit of life, and all cells arise from existing cells.
Types of Cells:
- Prokaryotic: Simple cellular organization without a nucleus; examples include bacteria.
- Eukaryotic: Complex cells with a defined nucleus; includes plants, animals, and fungi.
Cell Organelles:
- Nucleus: Houses genetic material (DNA) and regulates genes.
- Mitochondria: Powerhouse of the cell, responsible for ATP (energy) production.
- Ribosomes: Sites of protein synthesis, can be free-floating or attached to the rough ER.
- Endoplasmic Reticulum (ER): Synthesizes proteins and lipids; divided into rough ER (has ribosomes) and smooth ER (lacks ribosomes).
- Golgi Apparatus: Processes, sorts, and packages proteins for secretion or use within the cell.
- Cell Membrane: Semi-permeable membrane that controls the movement of substances in and out of the cell, maintaining homeostasis.
Cell Division:
- Mitosis: Type of somatic cell division leading to growth, repair, and replacement of cells.
- Meiosis: Division process that produces gametes (sperm and eggs) involving two rounds of division, leading to genetic diversity.

Basic Concepts:
- Gene: Basic unit of heredity composed of DNA that codes for proteins.
- Allele: Different variants of a gene, contributing to genetic diversity.
- Genotype: The specific genetic constitution of an individual, while phenotype represents observable traits.
Mendelian Genetics:
- Introduced by Gregor Mendel, revealing inheritance patterns through dominant and recessive traits.
- Punnett Squares serve as a tool for predicting potential genetic combinations from parental alleles.
Molecular Genetics:
- DNA Structure: Comprises a double helix formed by nucleotide pairs (Adenine, Thymine, Cytosine, Guanine).
- Replication: DNA duplication process occurring before cellular division.
- Transcription: Synthesis of RNA from the DNA template, leading to mRNA production.
- Translation: Conversion of mRNA sequences into amino acids to build proteins.
Genetic Variation:
- Mutations: Changes or alterations in the DNA sequence that may lead to different traits.
- Recombinant DNA: DNA molecules formed by combining genetic material from different organisms, enabling genetic engineering.

Theory of Evolution: Developed by Charles Darwin, explaining evolution through the natural selection mechanism.
Key Concepts:
- Adaptation: Traits that improve an organism's chances of survival and reproduction in its environment.
- Speciation: The process through which new species arise from existing species.
- Common Descent: The idea that all species share a common ancestor, connecting the tree of life.
Evidence of Evolution:
- Fossil Records: Document historical changes in species and transitions over time.
- Comparative Anatomy: Analysis of homologous structures provides evidence for common ancestry.
- Molecular Biology: Genetic comparisons among species reveal evolutionary relationships and shared traits.
Evolutionary Mechanisms:
- Genetic Drift: Random fluctuations in allele frequencies in small populations, potentially leading to evolutionary changes.
- Gene Flow: The transfer of genetic material between populations, affecting genetic diversity.
- Mutation: Acts as a source of genetic variation, which fuels evolution and adaptation.