Cell Biology Overview

Cell Biology

Definition: Study of cell structure, function, and processes.
Types of Cells:
- Prokaryotic: No nucleus, smaller, e.g., bacteria.
- Eukaryotic: Nucleus present, larger, e.g., plant and animal cells.
Cell Structure:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Powerhouse; site of ATP production.
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; synthesizes proteins.
  - Smooth ER: Lipid synthesis and detoxification.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
- Cell Membrane: Selectively permeable barrier; composed of phospholipids and proteins.
Cell Division:
- Mitosis: Process of cell division resulting in two identical daughter cells.
- Meiosis: Division that produces gametes with half the genetic material for sexual reproduction.
Cell Communication:
- Signaling molecules (hormones, neurotransmitters) interact with receptors on target cells.
- Types of signaling: Autocrine, paracrine, endocrine, and juxtacrine.

Ecology

Definition: Study of interactions between organisms and their environment.
Levels of Organization:
- Individual: Single organism.
- Population: Group of individuals of the same species.
- Community: Interacting populations in a specific area.
- Ecosystem: Community plus abiotic factors (e.g., soil, water).
- Biosphere: Global ecological system encompassing all living beings.
Ecosystem Components:
- Biotic Factors: Living components (plants, animals, microorganisms).
- Abiotic Factors: Non-living components (temperature, water, nutrients).
Energy Flow:
- Producers (Autotrophs): Convert sunlight into energy (photosynthesis).
- Consumers (Heterotrophs): Obtain energy by consuming other organisms.
  - Primary consumers: Herbivores.
  - Secondary consumers: Carnivores.
  - Tertiary consumers: Apex predators.
Nutrient Cycling:
- Carbon Cycle: Movement of carbon among atmosphere, oceans, soil, and living organisms.
- Nitrogen Cycle: Conversion of nitrogen from the atmosphere into a usable form for organisms and back.
Ecological Succession:
- Primary Succession: Occurs on previously uninhabited land (e.g., after volcanic eruptions).
- Secondary Succession: Follows disturbances that destroy a community without destroying the soil (e.g., after a forest fire).
Biodiversity:
- Importance: Enhances ecosystem productivity and resilience.
- Threats: Habitat loss, pollution, climate change, invasive species.

Cell Biology

Cell Biology: Focuses on the structure, function, and processes of cells, fundamental units of life.
Types of Cells:
- Prokaryotic Cells: Lacks a nucleus, generally smaller; examples include bacteria.
- Eukaryotic Cells: Contains a nucleus; larger and includes plant and animal cells.
Key Cell Structures:
- Nucleus: Houses genetic material (DNA).
- Mitochondria: Functions as the powerhouse of the cell, responsible for ATP production.
- Ribosomes: Sites for protein synthesis, can be free-floating or attached to the endoplasmic reticulum.
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; synthesizes proteins.
  - Smooth ER: Involved in lipid synthesis and detoxification processes.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.
- Cell Membrane: Selectively permeable barrier made of phospholipids and proteins, regulating what enters and exits the cell.
Cell Division:
- Mitosis: Process resulting in two identical daughter cells, ensuring genetic consistency.
- Meiosis: Specialized division producing gametes with half the genetic material for sexual reproduction.
Cell Communication:
- Involves signaling molecules like hormones and neurotransmitters that bind to specific receptors on target cells.
- Types of signaling:
  - Autocrine: Targets the same cell that releases the signal.
  - Paracrine: Targets nearby cells.
  - Endocrine: Involves hormones transported through the bloodstream to distant cells.
  - Juxtacrine: Requires direct contact between signaling and target cells.

Ecology

Ecology: The study of interactions between organisms and their environment, encompassing relationships and ecosystem dynamics.
Levels of Organization:
- Individual: A single organism.
- Population: A group of individuals of the same species in a specific area.
- Community: Interacting populations of different species in a defined area.
- Ecosystem: Comprises the living community plus abiotic factors like soil and water.
- Biosphere: The global ecological system, integrating all living beings and their interactions.
Ecosystem Components:
- Biotic Factors: Living components such as plants, animals, and microorganisms.
- Abiotic Factors: Non-living components including temperature, water, and nutrient availability.
Energy Flow:
- Producers (Autotrophs): Organisms that convert solar energy into chemical energy via photosynthesis.
- Consumers (Heterotrophs): Obtain energy by consuming other organisms, categorized into:
  - Primary Consumers: Herbivores that eat plants.
  - Secondary Consumers: Carnivores that feed on herbivores.
  - Tertiary Consumers: Apex predators at the top of the food chain.
Nutrient Cycling:
- Carbon Cycle: Carbon movement among the atmosphere, oceans, soil, and organisms, crucial for life.
- Nitrogen Cycle: Transformation of nitrogen between the atmosphere and usable forms for organisms.
Ecological Succession:
- Primary Succession: Occurs on barren, previously uninhabited land (e.g., after volcanic eruptions).
- Secondary Succession: Follows disturbances (e.g., forest fires) affecting communities but not destroying the soil.
Biodiversity:
- Importance: Enhances ecosystem productivity and resilience, contributing to ecological stability.
- Threats: Includes habitat loss, pollution, climate change, and the introduction of invasive species, all endangering biodiversity.