Cell Biology and Genetics Overview

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: No nucleus; smaller; bacteria and archaea.
- Eukaryotic: Nucleus present; larger; plants, animals, fungi, and protists.
Cell Structures:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Energy production (ATP) through respiration.
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum (ER): Rough ER (with ribosomes) and Smooth ER (lipid synthesis).
- Golgi Apparatus: Modifies and packages proteins.
- Cell Membrane: Semipermeable barrier regulating movement in and out of the cell.

DNA Structure:
- Double helix formed by nucleotides (A, T, C, G).
- Base pairing rules: A-T, C-G.
Gene:
- Basic unit of heredity; 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 segregate independently.

Natural Selection:
- Mechanism of evolution; organisms with advantageous traits are more likely to survive and reproduce.
Speciation:
- Process by which new species arise; can occur through mechanisms such as geographic isolation and reproductive isolation.

Biomes:
- Large ecosystems defined by climate, vegetation, and wildlife (e.g., tropical rainforest, desert, tundra).
Energy Flow:
- Energy enters ecosystems through sunlight; producers (plants) convert sunlight to chemical energy (photosynthesis).
- Energy transfer occurs through food chains and food webs.
Population Dynamics:
- Factors influencing population size: birth rates, death rates, immigration, emigration.

Organ Systems:
- Circulatory, respiratory, digestive, nervous, and immune systems, each with specialized functions to maintain homeostasis.
Homeostasis:
- Mechanisms that maintain stable internal conditions (e.g., temperature regulation, pH balance).

Bacteria:
- Single-celled prokaryotes; can be beneficial (gut flora) or pathogenic (causing disease).
Viruses:
- Acellular structures that require a host to replicate; can infect all forms of life.

Photosynthesis:
- Process where plants convert light energy into chemical energy (glucose).
- Formula: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.
Plant Structures:
- Roots: Absorb water and nutrients.
- Stems: Support plant; transport nutrients and water.
- Leaves: Site of photosynthesis.

All living organisms are made of cells, which are the fundamental units of life.
Cells arise from pre-existing cells.
Prokaryotic cells lack a nucleus and are generally smaller than eukaryotic cells. They include bacteria and archaea.
Eukaryotic cells have a nucleus and are larger and more complex. Examples include plants, animals, fungi, and protists.
The nucleus contains DNA, the genetic material of the cell.
Mitochondria are responsible for energy production (ATP) through cellular respiration.
Ribosomes are involved in protein synthesis.
The endoplasmic reticulum (ER) is a network of membranes. Rough ER is studded with ribosomes and involved in protein synthesis. Smooth ER lacks ribosomes and is involved in lipid synthesis.
The Golgi apparatus modifies and packages proteins.
The cell membrane is a semipermeable barrier that controls the movement of substances into and out of the cell.

DNA is a double helix composed of nucleotides (adenine, thymine, cytosine, and guanine).
Base pairing rules dictate that adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G).
A gene is a segment of DNA that codes for a specific protein; it is the basic unit of heredity.
The Law of Segregation states that alleles (alternative forms of a gene) separate during gamete formation, meaning each gamete receives only one allele from a pair.
The Law of Independent Assortment states that genes for different traits segregate independently during gamete formation.

Natural selection is the mechanism of evolution where organisms with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring.
Speciation is the process by which new species arise. It can occur through mechanisms like geographic isolation (physical separation of populations) and reproductive isolation (inability of populations to interbreed).

Biomes are large ecosystems characterized by specific climate conditions, vegetation, and wildlife. Examples include tropical rainforests, deserts, and tundras.
Energy flow in ecosystems starts with sunlight, which producers (plants) convert into chemical energy through photosynthesis.
Energy transfer occurs through food chains and food webs, with energy moving from producers to consumers.
Population dynamics involves factors like birth rates, death rates, immigration, and emigration, which influence population size.

The human body is organized into organ systems such as the circulatory, respiratory, digestive, nervous, and immune systems, each with specialized functions.
Homeostasis is the maintenance of a stable internal environment, such as temperature regulation and pH balance, which is crucial for proper body functioning.

Bacteria are single-celled prokaryotes; some are beneficial, such as those found in gut flora, while others are pathogenic and cause diseases.
Viruses are acellular structures that require a host cell to replicate; they can infect all forms of life.

Photosynthesis is the process by which plants convert light energy into chemical energy (glucose). The formula for photosynthesis is 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.
Roots absorb water and nutrients from the soil.
Stems provide support for the plant and are responsible for the transport of water and nutrients.
Leaves are the site of photosynthesis.