Cell Biology and Genetics Overview

Cell Biology

Basic Unit of Life: The cell is the fundamental building block of all living organisms.
Types of Cells:
- Prokaryotic: No nucleus, smaller (e.g., bacteria).
- Eukaryotic: Contains a nucleus and organelles (e.g., animal and plant cells).
Cell Organelles:
- Nucleus: Controls cell activities, contains DNA.
- Mitochondria: Powerhouse, produces energy (ATP).
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum: Protein and lipid synthesis (Rough ER has ribosomes; Smooth ER does not).
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
- Lysosomes: Digestive enzymes for waste processing.

Genetics

DNA Structure: Double helix made of nucleotides (adenine, thymine, cytosine, guanine).
Gene: A segment of DNA that codes for a specific protein.
Alleles: Different versions of a gene (dominant vs. recessive).
Mendelian Genetics:
- Law of Segregation: Alleles separate during gamete formation.
- Law of Independent Assortment: Genes for different traits segregate independently.
Genetic Disorders: Caused by mutations in genes (e.g., cystic fibrosis, sickle cell anemia).

Evolution

Theory of Evolution: Explains the diversity of life through natural selection, as proposed by Charles Darwin.
Natural Selection: Individuals with favorable traits are more likely to survive and reproduce.
Speciation: The process by which new species arise.
Evidence for Evolution:
- Fossil records.
- Comparative anatomy (homologous and analogous structures).
- Molecular biology (DNA similarities).

Ecology

Ecosystem Components:
- Biotic factors: Living organisms (plants, animals).
- Abiotic factors: Non-living components (water, soil, climate).
Trophic Levels:
- Producers: Organisms that make their own food (e.g., plants).
- Consumers: Organisms that eat other organisms (herbivores, carnivores, omnivores).
- Decomposers: Break down dead organic matter (e.g., fungi, bacteria).
Biomes: Large ecological areas with distinct climates and organisms (e.g., desert, rainforest).

Physiology

Homeostasis: The process of maintaining a stable internal environment despite external changes.
Human Body Systems:
- Circulatory: Transports blood and nutrients.
- Respiratory: Facilitates gas exchange (oxygen and carbon dioxide).
- Digestive: Breaks down food for nutrient absorption.
- Nervous: Processes information and coordinates responses.
- Endocrine: Regulates body functions via hormones.

Microbiology

Microorganisms: Include bacteria, viruses, fungi, and protozoa.
Bacteria: Prokaryotic, can be beneficial (gut flora) or pathogenic (cause disease).
Viruses: Non-cellular, require a host to replicate; can cause various diseases.
Fungi: Eukaryotic, play key roles in decomposition and nutrient cycling.

Biotechnology

Genetic Engineering: Manipulation of an organism's DNA (e.g., CRISPR technology).
Cloning: Producing genetically identical individuals.
Biopharmaceuticals: Drugs produced using biological sources (e.g., insulin).

Plant Biology

Photosynthesis: Process by which plants convert sunlight into energy (glucose).
Plant Structure:
- Roots: Anchor plants and absorb water/nutrients.
- Stems: Support and transport substances.
- Leaves: Main site of photosynthesis.
Reproduction: Can be sexual (flowers, seeds) or asexual (cuttings, runners).

Animal Biology

Animal Classification: Divided into invertebrates (no backbone) and vertebrates (backbone).
Reproductive Strategies:
- Sexual reproduction: Involves gametes (sperm and egg).
- Asexual reproduction: Offspring arise from a single organism (budding, fission).
Behavioral Ecology: Study of animal behavior in natural environments, including mating, foraging, and social structures.

Cell Biology

The cell is recognized as the basic unit of life in all organisms.
Cells are categorized into prokaryotic (no nucleus, smaller, e.g., bacteria) and eukaryotic (with a nucleus and organelles, e.g., animal and plant cells).
Key organelles include:
- Nucleus: Holds DNA; regulates cell functions.
- Mitochondria: Generates ATP, the energy currency of the cell.
- Ribosomes: Sites for protein synthesis.
- Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; Smooth ER synthesizes lipids.
- Golgi Apparatus: Processes and ships proteins and lipids.
- Lysosomes: Contain digestive enzymes for breaking down waste.

Genetics

DNA has a double helix structure, composed of four nucleotides: adenine, thymine, cytosine, and guanine.
A gene is a DNA segment that encodes for a specific protein, while alleles are variations of a gene, categorized as dominant or recessive.
Mendelian genetics includes:
- Law of Segregation: Alleles split during the formation of gametes.
- Law of Independent Assortment: Genes for different traits segregate independently.
Genetic disorders, like cystic fibrosis and sickle cell anemia, result from gene mutations.

Evolution

The theory of evolution, proposed by Charles Darwin, explains biological diversity through natural selection.
Natural selection favors individuals with advantageous traits, increasing their survival and reproductive success.
Speciation is the process of forming new species over time.
Evidence supporting evolution comes from:
- Fossil records showing transitional forms.
- Comparative anatomy highlighting homologous and analogous structures.
- Molecular biology, specifically DNA sequence comparisons.

Ecology

Ecosystems consist of biotic (living organisms) and abiotic (non-living elements, such as water and climate) factors.
Trophic levels describe the feeding hierarchy:
- Producers: Autotrophs like plants that create their own food.
- Consumers: Heterotrophs that consume other organisms (herbivores, carnivores, omnivores).
- Decomposers: Organisms like fungi and bacteria that recycle nutrients by breaking down dead matter.
Biomes are large ecological regions characterized by distinct climate and organisms (e.g., deserts, rainforests).

Physiology

Homeostasis refers to maintaining a stable internal environment regardless of external changes.
Key human body systems include:
- Circulatory: Distributes blood and nutrients throughout the body.
- Respiratory: Enables gas exchange, primarily oxygen and carbon dioxide.
- Digestive: Breaks down food for nutrient absorption.
- Nervous: Processes sensory information and coordinates bodily responses.
- Endocrine: Controls bodily functions through hormone regulation.

Microbiology

Microorganisms encompass bacteria, viruses, fungi, and protozoa.
Bacteria, as prokaryotes, can be beneficial (e.g., gut flora) or pathogenic (cause diseases).
Viruses are non-cellular entities that require a host for replication, often leading to illness.
Fungi, as eukaryotes, are vital for decomposition and nutrient cycling.

Biotechnology

Genetic engineering involves altering an organism's DNA, with CRISPR technology being a notable method.
Cloning refers to creating genetically identical organisms.
Biopharmaceuticals are drugs derived from biological sources, such as insulin produced by rDNA technology.

Plant Biology

Photosynthesis is the process where plants convert sunlight into glucose for energy.
Plant structures play distinct roles:
- Roots: Anchor the plant and absorb nutrients and water.
- Stems: Provide structural support and transport substances.
- Leaves: The primary site for photosynthesis.
Reproductive methods include sexual (involving flowers and seeds) and asexual (e.g., cuttings, runners).

Animal Biology

Animals are classified into two broad groups: invertebrates (no backbone) and vertebrates (with a backbone).
Reproductive strategies include:
- Sexual reproduction: Involves the combination of gametes (sperm and egg).
- Asexual reproduction: Offspring develop from a single parent (e.g., budding, fission).
Behavioral ecology examines how animal behavior adapts to natural environments, affecting mating, foraging, and social interactions.