Biology Chapter on Cell Structure and Genetics

Cell Structure and Function

• Basic unit of life: All living organisms consist of cells.
• Prokaryotic cells: Lack a nucleus, smaller, simpler (e.g., bacteria).
• Eukaryotic cells: Have a nucleus, larger, more complex (e.g., plants, animals).
• Cell organelles:
  • Nucleus: Contains genetic material (DNA).
  • Mitochondria: Powerhouse, energy production (ATP).
  • Ribosomes: Protein synthesis.
  • Endoplasmic reticulum: Protein (rough ER) and lipid (smooth ER) synthesis.
  • Golgi apparatus: Modifies and packages proteins.
  • Lysosomes: Digestive enzymes for waste processing.

Genetics

• DNA structure: Double helix, composed of nucleotides (A, T, C, G).
• Gene expression:
  • Transcription: DNA → RNA in the nucleus.
  • Translation: RNA → protein at ribosomes.
• Mendelian genetics:
  • Dominant and recessive alleles: Traits determined by alleles.
  • Punnett squares: Used to predict offspring genotypes/phenotypes.

Evolution

• Natural selection: Process where organisms better adapted to their environment tend to survive and reproduce.
• Species adaptation: Changes in physical or behavioral characteristics over generations.
• Common descent: All species share a common ancestor.

Ecology

• Ecosystems: Composed of living (biotic) and non-living (abiotic) components.
• Food chains/webs: Represents the flow of energy through trophic levels (producers, consumers, decomposers).
• Biomes: Major ecological communities (e.g., forests, deserts, tundras) characterized by climate and vegetation.

Physiology

• Homeostasis: Process of maintaining stable internal conditions (e.g., temperature, pH).
• Organ systems:
  • Circulatory: Transports nutrients and oxygen.
  • Respiratory: Gas exchange (oxygen in, carbon dioxide out).
  • Digestive: Breaks down food into nutrients.
  • Nervous: Control and communication through signals.

Plant Biology

• Photosynthesis: Process by which plants convert sunlight into energy (glucose); takes place in chloroplasts.
• Plant structure:
  • Roots: Anchor and absorb water/nutrients.
  • Stems: Support and transport materials.
  • Leaves: Primary site of photosynthesis.

Animal Behavior

• Innate behavior: Instinctive, not learned (e.g., reflexes).
• Learned behavior: Acquired through experience (e.g., conditioning).
• Social behavior: Interactions among individuals within species (e.g., cooperation, competition).

Human Biology

• Cell types: Somatic (body) cells and gametes (sex cells).
• DNA: Carries genetic instructions for development and function.
• Immune system: Protects against pathogens; includes innate and adaptive immunity.

Microbiology

• Bacteria: Single-celled prokaryotes; vital for ecosystems and human health.
• Viruses: Infectious agents that require a host to replicate; not classified as living organisms.
• Fungi: Eukaryotic organisms that decompose organic material; can be multicellular or unicellular (e.g., yeasts).

Cell Biology

• The fundamental unit of life is the cell.
• Two main types of cells exist: prokaryotic and eukaryotic.
• Prokaryotic cells lack a nucleus and are simpler and smaller, examples include bacteria.
• Eukaryotic cells contain a nucleus and are larger and more complex, examples include plant and animal cells.
• Cell organelles are specialized structures within cells that perform specific functions.
• The nucleus houses the genetic material (DNA).
• Mitochondria are responsible for energy production (ATP) and are often referred to as the "powerhouse" of the cell.
• Ribosomes are the sites of protein synthesis.
• The endoplasmic reticulum (ER) comes in two forms: rough ER (involved in protein synthesis) and smooth ER (involved in lipid synthesis).
• The Golgi apparatus modifies and packages proteins.
• Lysosomes contain digestive enzymes that break down waste materials.

Genetics

• DNA has a double-helix structure consisting of nucleotides, each with a specific base: adenine (A), thymine (T), cytosine (C), and guanine (G).
• Gene expression involves two main steps: transcription and translation.
• Transcription is the process of converting DNA into RNA in the nucleus.
• Translation is the process of converting RNA into protein at ribosomes.
• Mendelian genetics describes how traits are inherited based on alleles.
• Alleles are alternative forms of a gene, some are dominant and some are recessive.
• Punnett squares are diagrams used to predict the genotypes and phenotypes of offspring.

Evolution

• Natural selection drives the process of evolution.
• Organisms that are better adapted to their environment are more likely to survive and reproduce.
• Species adaptation refers to the gradual changes in physical or behavioral characteristics over generations that improve survival and reproduction.
• Common descent is the idea that all species share a common ancestor.

Ecology

• Ecosystems are composed of both living (biotic) and non-living (abiotic) components.
• Food chains/webs illustrate the flow of energy through different trophic levels: producers (autotrophs), consumers (heterotrophs), and decomposers.
• Biomes are large-scale ecological communities characterized by distinct combinations of climate and vegetation.

Physiology

• Homeostasis is the maintenance of a stable internal environment in living organisms.
• This includes regulating factors such as temperature, pH, and blood sugar levels.
• Organ systems work together to maintain homeostasis in the body.
• The circulatory system transports nutrients and oxygen throughout the body.
• The respiratory system facilitates gas exchange (oxygen in, carbon dioxide out).
• The digestive system breaks down food into nutrients.
• The nervous system controls and coordinates bodily functions through signals.

Plant Biology

• Photosynthesis is the process by which plants convert light energy into chemical energy (glucose).
• This process occurs in chloroplasts.
• Plant structure supports key functions:
  • Roots anchor the plant and absorb water and nutrients.
  • Stems provide support and transport materials between roots and leaves.
  • Leaves are the primary site of photosynthesis.

Animal Behavior

• Innate behaviors are instinctive and not learned.
• Examples include reflexes, such as withdrawing a hand from a hot surface.
• Learned behaviors are acquired through experience.
• Examples include conditioning, where associations are formed between stimuli and responses.
• Social behavior describes interactions among individuals within a species.
• This can include cooperation, competition, and communication.

Human Biology

• Human cells are classified as somatic (body) cells and gametes (sex cells).
• DNA contains the genetic instructions for development and function.
• The immune system protects the body from pathogens.
• This system includes both innate and adaptive immunity.

Microbiology

• Bacteria are single-celled prokaryotes found in various environments.
• They play crucial roles in ecosystems and human health.
• Viruses are infectious agents that require a host to replicate.
• They are not considered living organisms.
• Fungi are eukaryotic organisms that decompose organic matter.
• They can be multicellular (e.g., mushrooms) or unicellular (e.g., yeasts).

Explore the fundamental concepts of cell structure and function in this biology quiz. Learn about prokaryotic and eukaryotic cells, cell organelles, and the principles of genetics including DNA structure and gene expression. Test your knowledge on key biological processes essential for life.