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., plant and animal cells).
Cell Organelles:
- Nucleus: Contains DNA, controls cell activities.
- Mitochondria: Powerhouse of the cell, energy production (ATP).
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum (ER): Rough ER (with ribosomes, protein synthesis) and Smooth ER (lipid synthesis).
- Golgi Apparatus: Modifies, sorts, and packages proteins.

DNA Structure: Double helix, composed of nucleotides (adenine, thymine, cytosine, guanine).
Gene: Segment of DNA that codes for a protein.
Chromosomes: Structures containing DNA; humans have 46 chromosomes (23 pairs).
Mendelian Genetics:
- Dominant vs. recessive traits.
- Punnett squares: Predict genetic variation.
Mutations: Changes in DNA sequence; can be beneficial, neutral, or harmful.

Theory of Natural Selection: Organisms better adapted to their environment tend to survive and reproduce.
Speciation: Process by which new species arise; can occur through allopatric (geographic separation) or sympatric (same area) mechanisms.
Fossil Record: Provides evidence of the history of life and evolutionary changes.

Ecosystem: Community of living organisms interacting with their environment.
Biomes: Large ecological areas with distinct climates, flora, and fauna (e.g., desert, rainforest).
Food Chains/Webs: Energy transfer from producers to consumers and decomposers.
Biodiversity: Variety of life in an area; crucial for ecosystem health.

Homeostasis: Maintenance of stable internal conditions (temperature, pH, etc.).
Organ Systems:
- Circulatory: Transports nutrients, gases, hormones.
- Respiratory: Gas exchange (oxygen intake, carbon dioxide removal).
- Digestive: Breakdown and absorption of food.
- Nervous: Control and communication through electrical signals.
- Endocrine: Hormonal regulation of bodily functions.

Photosynthesis: Process by which plants convert sunlight into chemical energy (glucose).
Plant Structures:
- Roots: Absorb water and nutrients, anchor the plant.
- Stems: Support and transport; contain vascular tissue (xylem and phloem).
- Leaves: Main site for photosynthesis.

Body Systems: Interconnected systems functioning for homeostasis and response (e.g., immune, circulatory, nervous).
Genetic Disorders: Result from mutations or abnormalities in DNA; examples include cystic fibrosis, Down syndrome.

Macromolecules:
- Carbohydrates: Energy source (sugars, starches).
- Proteins: Made of amino acids; crucial for structure and function.
- Lipids: Fats and oils, energy storage, cell membranes.
- Nucleic Acids: DNA and RNA, involved in genetic information storage and transfer.

Prokaryotic cells lack a nucleus and are characterized by their smaller size and simpler structure. Examples include bacteria.
Eukaryotic cells possess a nucleus and are generally larger and more complex than prokaryotic cells. Examples include plant and animal cells.

The nucleus contains the cell's DNA and controls cellular activities.
Mitochondria are often referred to as the "powerhouses of the cell" because they are responsible for producing energy (ATP).
Ribosomes are responsible for protein synthesis.
The endoplasmic reticulum (ER) is divided into two categories:
- Rough ER contains ribosomes and is involved in protein synthesis.
- Smooth ER lacks ribosomes and is responsible for lipid synthesis.
The Golgi apparatus modifies, sorts, and packages proteins.

DNA has a double helix structure and is composed of nucleotides (adenine, thymine, cytosine, and guanine).
A gene is a segment of DNA that carries the code for a protein.
Chromosomes are structures that contain DNA. Humans have 46 chromosomes organized into 23 pairs.

Dominant traits are expressed when present, while recessive traits are only expressed when two copies of the recessive allele are present.
Punnett squares are a tool used to predict the genetic variation in offspring based on the genotypes of the parents.
Mutations are changes in DNA sequence that can have beneficial, neutral, or harmful effects.

The Theory of Natural Selection states that organisms best suited to their environment are more likely to survive and reproduce.
Speciation is the process by which new species arise. It can occur through two main mechanisms:
- Allopatric speciation involves geographic separation of populations, leading to the evolution of distinct species.
- Sympatric speciation occurs when new species evolve within the same geographic area due to factors such as reproductive isolation.
The fossil record provides evidence of the history of life and evolutionary changes over time.

An ecosystem is a community of living organisms interacting with their environment.
Biomes are large ecological areas defined by distinct climates, flora, and fauna. Examples include deserts and rainforests.
Food chains and food webs illustrate the transfer of energy from producers to consumers and decomposers.
Biodiversity refers to the variety of life in a particular area. It plays a crucial role in maintaining healthy ecosystems.

Homeostasis is the maintenance of stable internal conditions, such as temperature and pH.
Organ systems are groups of organs that work together to perform specific functions. Examples include:
- Circulatory system: Transports nutrients, gases, and hormones.
- Respiratory system: Responsible for gas exchange (oxygen intake and carbon dioxide removal).
- Digestive system: Breaks down food and absorbs nutrients.
- Nervous system: Controls and coordinates bodily functions through electrical signals.
- Endocrine system: Regulates bodily functions through the production and release of hormones.

Photosynthesis is the process used by plants to convert sunlight into chemical energy (glucose).
Essential plant structures include:
- Roots: Anchor the plant and absorb water and nutrients.
- Stems: Provide support and a pathway for the transportation of substances; they contain vascular tissue (xylem and phloem).
- Leaves: The primary site of photosynthesis.

Bacteria are single-celled organisms that can be beneficial or pathogenic.
Viruses are non-cellular infectious agents that require a host to reproduce.
Fungi are decomposers that may be unicellular (e.g., yeast) or multicellular (e.g., molds).

Body systems are interconnected and function together to maintain homeostasis and respond to stimuli. Examples include the immune, circulatory, and nervous systems.
Genetic disorders result from mutations or abnormalities in DNA. Examples include cystic fibrosis and Down syndrome.

Macromolecules are large molecules essential for life. These include:
- Carbohydrates: Provide energy and include sugars and starches.
- Proteins: Made up of amino acids and play crucial roles in structure and function.
- Lipids: Include fats and oils, serve as energy storage, and form cell membranes.
- Nucleic acids: DNA and RNA, involved in storing and transferring genetic information.