Cell Biology Overview

Cell Biology

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: Lack a nucleus, smaller in size (e.g., bacteria).
- Eukaryotic: Have a nucleus and organelles, larger (e.g., plant and animal cells).
Cell Organelles
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Powerhouse of the cell, site of ATP production.
- Ribosomes: Sites of protein synthesis.
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; involved in protein synthesis.
  - Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
- Lysosomes: Contain enzymes for digestion.
- Cell Membrane: Semi-permeable barrier that regulates entry and exit of substances.
Cell Division
- Mitosis: Process of cell division for growth and repair, resulting in two identical daughter cells.
- Meiosis: Specialized form of cell division that leads to the production of gametes (sperm and egg); involves two rounds of division.
Cell Communication
- Signaling pathways: Cells communicate via chemical signals (hormones, neurotransmitters).
- Receptors: Proteins on cell surfaces that bind to signaling molecules.

Genetics

DNA Structure
- Composed of nucleotides (adenine, thymine, cytosine, guanine).
- Double helix structure, held together by base pairing (A-T, C-G).
Genes and Chromosomes
- Genes: Segments of DNA that code for proteins.
- Chromosomes: Structures that organize DNA; humans have 46 chromosomes (23 pairs).
Mendelian Genetics
- Principles of inheritance discovered by Gregor Mendel:
  - Law of Segregation: Alleles segregate during gamete formation.
  - Law of Independent Assortment: Genes for different traits are inherited independently.
Genetic Variation
- Sources of variation include mutations, sexual reproduction, and genetic recombination.
Biotechnology in Genetics
- DNA Cloning: Creating copies of DNA segments.
- CRISPR: A gene-editing technology that allows for precise modifications of the genome.
- Genetic Testing: Identifies mutations associated with genetic disorders.
Population Genetics
- Study of genetic variations within populations and how they change over time.
- Key concepts: Allele frequency, Hardy-Weinberg equilibrium, genetic drift, and natural selection.

Cell Biology

Cell Theory posits that all living organisms consist of cells, with the cell serving as the fundamental unit of life, and that all cells originate from pre-existing cells.
Types of Cells
- Prokaryotic cells are smaller, lack a nucleus, and include organisms such as bacteria.
- Eukaryotic cells are larger, contain a nucleus and organelles, and can be found in plants and animals.
Cell Organelles
- Nucleus: Stores genetic material (DNA).
- Mitochondria: Often referred to as the powerhouse of the cell, responsible for ATP production.
- Ribosomes: Sites where protein synthesis occurs.
- Endoplasmic Reticulum (ER):
  - Rough ER is covered with ribosomes and plays a crucial role in protein synthesis.
  - Smooth ER is ribosome-free and focuses on lipid synthesis and detoxification processes.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport.
- Lysosomes: Organelles that contain digestive enzymes to break down waste materials.
- Cell Membrane: A semi-permeable barrier that regulates the entry and exit of substances, maintaining homeostasis.
Cell Division
- Mitosis: A process that enables growth and repair, producing two identical daughter cells.
- Meiosis: A specialized division that creates gametes (sperm and egg), involving two successive division rounds.
Cell Communication
- Cells utilize signaling pathways to communicate through chemical signals like hormones and neurotransmitters.
- Receptors are proteins on cell surfaces that interact with these signaling molecules.

Genetics

DNA Structure
- DNA is made up of nucleotides, specifically adenine (A), thymine (T), cytosine (C), and guanine (G), and forms a double helix held together by base pairing (A with T, C with G).
Genes and Chromosomes
- Genes are segments of DNA coding for proteins, while chromosomes organize DNA; humans have 46 chromosomes, arranged in 23 pairs.
Mendelian Genetics
- Gregor Mendel established key inheritance principles:
  - Law of Segregation: Alleles separate during the formation of gametes.
  - Law of Independent Assortment: Genes for different traits are inherited independently of one another.
Genetic Variation
- Variation arises from mutations, sexual reproduction, and genetic recombination.
Biotechnology in Genetics
- DNA Cloning: Involves creating replicas of DNA segments.
- CRISPR: A frontier editing technology that allows for targeted changes to the genome.
- Genetic Testing: Techniques used to identify mutations linked to genetic disorders.
Population Genetics
- This field studies genetic variations within populations, focusing on changes over time, including concepts like allele frequency, Hardy-Weinberg equilibrium, genetic drift, and natural selection.