Cell Biology and Genetics

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 cells without a nucleus (e.g., bacteria).
- Eukaryotic: Complex cells with a nucleus (e.g., plant and animal cells).
Cell Organelles:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Powerhouse of the cell (energy production).
- Ribosomes: Site of protein synthesis.
- Endoplasmic Reticulum (ER):
  - Rough ER (with ribosomes): Synthesizes proteins.
  - Smooth ER (without ribosomes): Synthesizes lipids.
- Golgi Apparatus: Modifies and packages proteins for secretion.
- Cell Membrane: Semi-permeable barrier, regulates entry and exit of substances.

DNA Structure: Double helix made of nucleotides (A, T, C, G).
Genes: Segments of DNA that code for proteins.
Chromosomes: DNA packaged with proteins; humans have 46 chromosomes (23 pairs).
Mendelian Genetics:
- Law of Segregation: Alleles segregate during gamete formation.
- Law of Independent Assortment: Genes for different traits assort independently.

Natural Selection: Mechanism by which organisms better adapted to their environment tend to survive and produce more offspring.
Evolutionary Evidence:
- Fossil records.
- Comparative anatomy (homologous and analogous structures).
- Molecular biology (DNA sequencing).

Ecosystems: Communities of living organisms interacting with their environment.
Biomes: Large ecological areas with distinct climates and organisms (e.g., forests, deserts).
Food Chains/Webs: Representation of energy flow through trophic levels (producers, consumers, decomposers).

Organ Systems:
- Circulatory: Transports blood, nutrients, gases, and wastes.
- Respiratory: Facilitates gas exchange (oxygen and carbon dioxide).
- Digestive: Breaks down food for nutrient absorption.
- Nervous: Coordinates body functions through electrical signals.
Homeostasis: The process by which biological systems maintain a stable internal environment despite external changes.

Photosynthesis: Process by which green plants use sunlight to synthesize food from carbon dioxide and water; occurs in chloroplasts.
Plant Structure:
- Roots: Anchor plant and absorb nutrients/water.
- Stems: Support, transport, and sometimes store nutrients.
- Leaves: Main site of photosynthesis.

Microorganisms: Bacteria, viruses, fungi, and protozoa; some are beneficial (e.g., gut flora), others pathogenic (cause disease).
Antibiotics: Medications that inhibit bacterial growth or kill bacteria.

Genetic Engineering: Manipulation of an organism's DNA to achieve desired traits.
CRISPR: A revolutionary gene-editing technology allowing precise modifications of DNA.

Macromolecules:
- Carbohydrates: Main energy source (e.g., glucose, starch).
- Proteins: Made of amino acids; essential for structure and function.
- Lipids: Fats and oils; important for energy storage and cell membranes.
- Nucleic Acids: DNA and RNA; store and transmit genetic information.

Nucleus: Stores DNA, the genetic material.
Mitochondria: Responsible for energy production, often called the "powerhouse of the cell."
Ribosomes: Sites of protein synthesis.
Endoplasmic Reticulum (ER): A network of interconnected membranes.
- Rough ER: Contains ribosomes, synthesizes proteins.
- Smooth ER: Lacks ribosomes, synthesizes lipids.
Golgi Apparatus: Modifies and packages proteins for transport and secretion.
Cell Membrane: A semi-permeable barrier regulating the passage of substances into and out of the cell.

DNA Structure: A double helix composed of nucleotides (adenine, thymine, cytosine, guanine).
Genes: Segments of DNA that encode for specific proteins.
Chromosomes: Structures made of DNA packaged with proteins; humans have 46 chromosomes (23 pairs).

Law of Segregation: Alleles for a trait separate during gamete formation.
Law of Independent Assortment: Genes for different traits assort independently of one another.

Natural Selection: A key mechanism of evolution where organisms best adapted to their environment survive and reproduce more, passing their advantageous traits to offspring.
Evidence of Evolution:
- Fossil Records: Show changes in life forms over time.
- Comparative Anatomy: Comparison of anatomical structures reveals similarities (homologous structures) or differences (analogous structures) based on evolutionary relationships.
- Molecular Biology: DNA sequencing allows scientists to compare genetic relationships between organisms, providing evidence of common ancestry.

Ecosystems: Interacting communities of living organisms and their physical environment.
Biomes: Large-scale ecological areas characterized by distinct climates and organisms (e.g., forests, deserts).
Food Chains/Webs: Visual representations of energy flow through trophic levels (producers, consumers, decomposers).

Organ Systems: Groups of organs working together to perform specific functions.
- Circulatory System: Transports blood, nutrients, gases, and waste throughout the body.
- Respiratory System: Facilitates gas exchange (oxygen in, carbon dioxide out).
- Digestive System: Breaks down food into absorbable nutrients.
- Nervous System: Coordinates body functions through electrical signals.
Homeostasis: The maintenance of a stable internal environment despite external changes.

Photosynthesis: The process by which green plants use sunlight to synthesize food from carbon dioxide and water. Occurs in chloroplasts.
Plant Structure:
- Roots: Anchor the plant and absorb water and nutrients.
- Stems: Provide support, transport nutrients and water, and sometimes store nutrients.
- Leaves: The primary sites of photosynthesis.

Microorganisms: Tiny living organisms including bacteria, viruses, fungi, and protozoa. Some are beneficial (e.g., gut flora), while others are pathogenic (causing disease).
Antibiotics: Drugs that inhibit bacterial growth or kill bacteria.

Genetic Engineering: Manipulation of an organism's DNA to introduce or alter traits.
CRISPR: A revolutionary gene editing technology allowing precise targeted changes in DNA.

Macromolecules: Large complex molecules essential for life:
- Carbohydrates: Provide primary energy source (e.g., glucose, starch).
- Proteins: Built from amino acids, essential for structure and function.
- Lipids: Fats and oils, important for energy storage and cell membranes.
- Nucleic Acids: DNA and RNA, store and transmit genetic information.