Cell Biology and Genetics Overview

Cell Theory:
- All living organisms are composed of cells.
- Cells are the basic unit of life.
- All cells arise from pre-existing cells.
Types of Cells:
- Prokaryotic: No nucleus, smaller, simpler (e.g., bacteria).
- Eukaryotic: Nucleus present, larger, complex (e.g., plants, animals).
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.
- Golgi Apparatus: Modifies, sorts, and packages proteins.
- Lysosomes: Digestive organelles, break down waste.

DNA Structure:
- Double helix made of nucleotides (adenine, thymine, cytosine, guanine).
Gene: A segment of DNA that codes for a protein.
Mendelian Genetics:
- Law of Segregation: Alleles separate during gamete formation.
- Law of Independent Assortment: Genes for different traits can segregate independently.
Genetic Variation:
- Caused by mutations, recombination, and independent assortment.

Natural Selection:
- Mechanism of evolution; individuals with advantageous traits survive and reproduce.
Evolutionary Evidence:
- Fossil records, comparative anatomy, molecular biology, biogeography.
Speciation:
- Formation of new species through processes like allopatric and sympatric speciation.

Ecosystem: A community of living organisms and their physical environment.
Biomes: Large ecological areas with distinct climates and types of organisms (e.g., tundra, rainforest).
Food Chains and Webs:
- Producers (plants) -> Primary consumers (herbivores) -> Secondary consumers (carnivores).
Population Dynamics:
- Factors affecting populations: birth rates, death rates, immigration, emigration.

Homeostasis: Maintaining stable internal conditions (e.g., temperature, pH).
Organ Systems:
- Circulatory, respiratory, digestive, nervous, muscular, immune, endocrine, and reproductive systems.
Plant Physiology:
- Photosynthesis: Conversion of light energy into chemical energy (glucose).
- Transpiration: Water movement from roots to leaves.

Bacteria:
- Prokaryotic organisms; can be beneficial (e.g., gut microbiota) or harmful (pathogens).
Viruses:
- Non-cellular entities that require a host to replicate.
Fungi:
- Eukaryotic organisms; decomposers; can be unicellular (yeast) or multicellular (mushrooms).

Macromolecules:
- Carbohydrates: Energy sources and structural components.
- Proteins: Made of amino acids; perform various functions.
- Lipids: Fats and oils; store energy and form cell membranes.
- Nucleic Acids: DNA and RNA; store and transfer genetic information.

Cell Theory: All living organisms consist of cells, which are the fundamental units of life that arise from existing cells.
Types of Cells:
- Prokaryotic cells lack a nucleus, are smaller, and simpler (e.g., bacteria).
- Eukaryotic cells possess a nucleus, are larger, and more complex (e.g., plants and animals).
Cell Organelles:
- The nucleus houses genetic material (DNA) essential for heredity.
- Mitochondria serve as the powerhouse, primarily producing ATP through cellular respiration.
- Ribosomes, found in the cytoplasm or on the rough ER, are crucial for protein synthesis.
- Rough Endoplasmic Reticulum (ER) has ribosomes for protein production, while Smooth ER is involved in lipid synthesis.
- The Golgi Apparatus modifies, sorts, and packages proteins for transport.
- Lysosomes act as digestive organelles, breaking down waste materials.

DNA Structure: DNA is structured as a double helix formed from nucleotides; key bases include adenine (A), thymine (T), cytosine (C), and guanine (G).
Gene: A gene is a DNA segment encoding functional proteins.
Mendelian Genetics:
- The Law of Segregation states that allele pairs separate during the formation of gametes.
- The Law of Independent Assortment indicates that genes for different traits segregate independently.
Genetic Variation: Variations arise from mutations, genetic recombination, and the independent assortment of chromosomes.

Natural Selection: Natural selection is a process where individuals with advantageous traits are more likely to survive and reproduce.
Evolutionary Evidence: Evidence includes fossil records, comparative anatomy across species, molecular biology studies, and biogeographical distribution.
Speciation: New species arise through allopatric speciation (geographic separation) and sympatric speciation (occurring within the same area).

Ecosystem: Comprised of interacting communities of organisms and their physical surroundings.
Biomes: Large ecological areas defined by distinct climates and characteristic organisms (e.g., tundra, rainforest).
Food Chains and Webs: Energy flows from producers (plants) to primary consumers (herbivores) and secondary consumers (carnivores).
Population Dynamics: Birth rates, death rates, immigration, and emigration significantly influence population sizes.

Homeostasis: The process of maintaining stable internal conditions like temperature and pH balance.
Organ Systems: Includes circulatory, respiratory, digestive, nervous, muscular, immune, endocrine, and reproductive systems, each with specialized functions.
Plant Physiology:
- Photosynthesis converts light energy into chemical energy (glucose).
- Transpiration refers to the movement of water from roots to leaves, essential for nutrient transport.

Bacteria: Prokaryotic organisms that can be beneficial, such as gut microbiota, or pathogenic, causing disease.
Viruses: Non-cellular entities that need a host to replicate and cause infections.
Fungi: Eukaryotic decomposers that can be unicellular (like yeast) or multicellular (like mushrooms).

Macromolecules:
- Carbohydrates serve as energy sources and structural components.
- Proteins, composed of amino acids, execute diverse functions including signaling and catalysis.
- Lipids, which include fats and oils, are essential for energy storage and forming cell membranes.
- Nucleic Acids (DNA and RNA) are responsible for storing and transferring genetic information.