Overview of Biology and Cell Structure

Definition: The scientific study of life and living organisms.
Branches:
- Botany: Study of plants.
- Zoology: Study of animals.
- Microbiology: Study of microorganisms.
- Ecology: Study of ecosystems and environmental interactions.
- Genetics: Study of heredity and variation.

Cell Theory:
- All living things are composed of cells.
- Cells are the basic units of life.
- All cells arise from pre-existing cells.
Types of Cells:
- Prokaryotic: Simple, no nucleus (e.g., bacteria).
- Eukaryotic: Complex, with a nucleus (e.g., plant and animal cells).
Cell Organelles:
- Nucleus: Contains genetic material.
- Mitochondria: Powerhouse of the cell; energy production.
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum: Protein and lipid synthesis.
- Golgi Apparatus: Modifies and packages proteins.

DNA Structure: Double helix shape made of nucleotides (A, T, C, G).
Genes: Segments of DNA that code for proteins.
Chromosomes: Thread-like structures carrying genes; humans have 46 chromosomes.
Mendelian Inheritance:
- Dominant and recessive traits.
- Punnett squares used for predicting genotypes.

Theory of Evolution: Proposed by Charles Darwin; natural selection as a mechanism for evolution.
Key Concepts:
- Variation: Differences among individuals.
- Survival of the fittest: Those better adapted survive and reproduce.
- Speciation: Formation of new species due to evolutionary processes.

Ecosystems: Communities of living organisms interacting with their environment.
Biomes: Large ecological areas (e.g., deserts, forests).
Food Chains and Food Webs: Show energy flow in ecosystems.
Biogeochemical Cycles: Movement of elements (e.g., carbon, nitrogen) through living and non-living systems.

Body Systems:
- Circulatory: Transports blood and nutrients.
- Respiratory: Gas exchange.
- Digestive: Breaks down food and absorbs nutrients.
- Nervous: Controls body functions and responds to stimuli.
- Immune: Defends against pathogens.

Photosynthesis: Process by which plants convert sunlight into energy (glucose).
Plant Anatomy:
- Roots: Anchor and absorb water/nutrients.
- Stems: Support and transport.
- Leaves: Main site for photosynthesis.

Animal Behavior: Study of how animals interact with their environment (e.g., mating, foraging).
Physiology: Study of how organ systems function in animals.

Helps understand the complexity of life.
Essential for fields such as medicine, environmental science, and biotechnology.

Biology is the scientific study of life and living organisms.
It encompasses various branches such as botany, zoology, microbiology, ecology, and genetics.

The Cell Theory states that all living things are composed of cells, which are the basic units of life.
All cells originate from pre-existing cells.
Prokaryotic cells are simple and lack a nucleus, while eukaryotic cells are complex and possess a nucleus.
Key cell organelles include the nucleus (containing genetic material), mitochondria (energy production), ribosomes (protein synthesis), endoplasmic reticulum (protein and lipid synthesis), and Golgi apparatus (protein modification and packaging).

DNA, the genetic material, is structured as a double helix composed of nucleotides (adenine [A], thymine [T], cytosine [C], and guanine [G]).
Segments of DNA called genes code for proteins.
Thread-like structures known as chromosomes carry genes; humans have 46 chromosomes.
Mendelian inheritance explains the inheritance of traits through dominant and recessive alleles. Punnett squares are used for predicting offspring genotypes.

Charles Darwin proposed the Theory of Evolution, which explains that natural selection is a driving force in evolution.
Evolution relies on variation among individuals, where individuals with traits better suited for survival and reproduction are more likely to pass on those traits.
New species arise through speciation, driven by evolutionary processes.

Ecosystems are composed of communities of living organisms interacting with their environment.
Biomes are large ecological areas with distinct characteristics (e.g., deserts, forests).
Food chains and food webs demonstrate energy flow through ecosystems.
Biogeochemical cycles illustrate the movement of elements (e.g., carbon, nitrogen) through living and non-living systems.

Through photosynthesis, plants convert sunlight into energy (glucose).
Plant anatomy includes roots (anchoring and nutrient absorption), stems (support and transport), and leaves (primary site for photosynthesis).

Animal behavior involves studying how animals interact with their environment (e.g., mating, foraging).
Animal physiology examines how organ systems function in animals.