Cell Biology & Genetics

Posted on Nov 13, 2024 in Geology

Eukaryotic Cells and Organelles

Eukaryotic cells, the most complex animal cell type, contain various organelles with specific functions:

  • Ribosomes: Synthesize proteins.
  • Endoplasmic Reticulum: Provides materials to the cell and destroys waste.
  • Mitochondria: Carry out cellular respiration.
  • Golgi Apparatus: Processes and packages proteins.
  • Lysosomes: Perform digestion.
  • Vacuole: Stores nutrients.
  • Cytoskeleton: Provides cell shape and support (microtubules and microfilaments).
  • Chloroplast (in plants): Contains chlorophyll for photosynthesis.
  • Centrioles: Involved in cell reproduction.

Nucleus and Organelle Functions

The nucleus, the most important part of the cell, houses DNA and controls cell activities.

  • Nuclear Envelope: Surrounds the nucleus.
  • Nucleoplasm: The nuclear liquid.
  • Nucleolus: Produces ribosome components.
  • Chromatin: Composed of DNA and proteins.

Cell Movements

  • Amoeboid: Movement using pseudopods (extensions).
  • Ciliary/Flagellar: Movement using vibrating cilia or flagella.
  • Contractile: Shortening or lengthening using contractile filaments.

Passage of Substances Through the Membrane

  • Diffusion: For small substances.
  • Protein Channels/Pumps: For larger or charged molecules.
  • Vesicles: For very large substances (membrane engulfs the particle).

Cell Reproduction

  • Bipartition: Cell divides into two equal daughter cells.
  • Budding: A small bud emerges, forming a daughter cell.
  • Sporulation: Nucleus and cytoplasm divide into many spores.

Nucleic Acids

Nucleic acids (DNA and RNA) are composed of C, H, O, N, and phosphorus. They are formed by nucleotides, which consist of:

  • Nitrogenous Base: Adenine, cytosine, guanine, thymine (DNA), and uracil (RNA).
  • 5-Carbon Sugar: Deoxyribose (DNA) or ribose (RNA).
  • Phosphate Group:

DNA is found in the nucleus (chromatin), while RNA is found in both the cytoplasm and nucleus.

Mitosis

  • Prophase: Chromatin condenses into chromosomes, centrioles duplicate, nuclear membrane breaks down.
  • Metaphase: Chromosomes align in the center, spindle fibers attach.
  • Anaphase: Chromatids separate and move to opposite poles.
  • Telophase: Chromatids reach poles, nuclear membrane reforms, chromosomes decondense.

Meiosis

  • Prophase I: Homologous chromosomes pair up, genetic recombination occurs.
  • Metaphase I: Chromosome pairs align in the center.
  • Anaphase I: Chromosomes separate and move to opposite poles.
  • Telophase I: Chromosomes decondense, nuclear membrane reforms, interkinesis occurs.
  • Prophase II: Chromosomes condense.
  • Metaphase II: Chromosomes align in the center.
  • Anaphase II: Sister chromatids separate.
  • Telophase II: Chromatids reach poles, nuclear membrane reforms, chromosomes decondense.

Cell Division in Eukaryotes

  • Interphase: Cell growth and DNA replication.
  • Division: Mitosis and cytokinesis.

Mendel’s Laws

  1. Law of Uniformity: Homozygous crosses produce identical offspring.
  2. Law of Segregation: Alleles separate during gamete formation.
  3. Law of Independent Assortment: Different characters are inherited independently.

Origin of Biomolecules

Oparin’s Theory: Formed from reactions between gases in the primitive atmosphere (H2O, H, CH4).

Current Theory: Reactions occurred in volcanoes (N2, H2O, CO2 atmosphere).

Evidence of Evolution

  • Adaptation: Inherited variations that spread through populations.
  • Paleontology: Fossil evidence.
  • Biogeography: Geographical distribution of species.

Ecological Succession

A dynamic process where populations are replaced by new ones, creating more complex and stable ecosystems.

  • Primary Succession: Occurs in virgin territory (e.g., mountains, dunes).
  • Secondary Succession: Occurs in a disturbed ecosystem.

Precambrian

  • Geography: Supercontinent Pangea.
  • Climate: Formation of the hydrosphere.
  • Life: First life forms, increase in atmospheric oxygen, first extinction.

Cenozoic

  • Geography: Alpine Orogeny, sea level changes.
  • Climate: Ice ages, marine transgressions and regressions.
  • Life: Nummulites, mollusks, echinoderms, sharks, grasses, birds, mammals, humans.

Wilson Cycle

Describes the cycle of ocean basin formation, expansion, and closure.

Earthquakes

Ground vibrations caused by the release of energy (elastic rebound).

  • Surface Waves: L-waves (horizontal), R-waves (rolling).
  • Internal Waves: P-waves (longitudinal), S-waves (transverse).

Discontinuous Deformation

  • Joints: Fractures with no relative movement.
  • Fault-Fold: Fractures in folds.
  • Thrust Sheets: Faults with large displacement.
  • Faults: Fractures with movement.

Volcanoes

Magma reaching the surface through openings.

Characteristics of Rivers

  • Upper Course: Steep, high velocity, V-shaped valleys.
  • Middle Course: Moderate slope, meandering path.
  • Lower Course: Flat terrain, low velocity, meanders.

Coastal Modeling

Shaped by waves, tides, and currents.

Karstic Landscapes

Formed by water dissolving limestone.

Definitions

Various terms related to biology, genetics, and geology are defined.