Origin of Life Theories and Experiments

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following theories posits that life originated from inorganic molecules under early Earth conditions?

  • The spontaneous abiotic origin theory (correct)
  • The extraterrestrial forces theory
  • The intelligent design theory
  • The supernatural divine force theory

What did Oparin and Haldan propose about the early Earth's atmosphere?

  • It was similar to today's nitrogen-rich atmosphere.
  • It was devoid of any gases.
  • It was primarily composed of free oxygen.
  • It had a reducing atmosphere rich in hydrogen. (correct)

Which of the following was NOT an energy source utilized in the formation of life on early Earth?

  • Volcanic energy
  • UV radiation
  • Solar energy (correct)
  • Lightning

What experimental setup did the Miller Urey experiment simulate?

<p>Conditions of early Earth to test life formation (D)</p> Signup and view all the answers

Which statement best describes protobionts?

<p>They are grouped substances capable of metabolism and reproduction. (B)</p> Signup and view all the answers

What distinguishes tight junctions from desmosomes in animal cells?

<p>Tight junctions fuse the membranes of two cells. (A)</p> Signup and view all the answers

Which of the following statements about prokaryotes and eukaryotes is true?

<p>Both can perform photosynthesis. (D)</p> Signup and view all the answers

What is the primary role of centrosomes in animal cells?

<p>To initiate the process of cell division. (A)</p> Signup and view all the answers

Which statement correctly describes microtubules in the cytoskeleton?

<p>They facilitate the movement of cilia and flagella. (C)</p> Signup and view all the answers

What defines selective permeability in the context of the cell membrane?

<p>The ability to regulate the passage of certain substances while restricting others. (A)</p> Signup and view all the answers

Which type of junction specifically allows for the passage of ions and small molecules between animal cells?

<p>Gap junctions (C)</p> Signup and view all the answers

What is the significant characteristic of large nonpolar molecules regarding their passage through the plasma membrane?

<p>They pass through at a slower rate than ions. (C)</p> Signup and view all the answers

During the process of endocytosis, what occurs?

<p>Cells incorporate substances from their environment into the cytoplasm. (D)</p> Signup and view all the answers

Which of the following statements about prokaryotic cells is true?

<p>They do not possess membrane-bound organelles. (D)</p> Signup and view all the answers

Which component of the cell membrane is primarily responsible for its fluidity?

<p>Phospholipids (C)</p> Signup and view all the answers

What is the main function of ribosomes in a cell?

<p>Protein synthesis (D)</p> Signup and view all the answers

Which process describes the movement of water across a selectively permeable membrane?

<p>Osmosis (A)</p> Signup and view all the answers

What role do lysosomes play in a cell?

<p>Digesting waste materials (D)</p> Signup and view all the answers

What distinguishes eukaryotic cells from prokaryotic cells?

<p>Containment of DNA in a nucleus (A)</p> Signup and view all the answers

Which type of endocytosis involves the intake of liquid substances?

<p>Pinocytosis (C)</p> Signup and view all the answers

What is the role of the Golgi apparatus in a cell?

<p>Modifying and packaging proteins (C)</p> Signup and view all the answers

What type of cell organelle is responsible for photosynthesis?

<p>Chloroplast (D)</p> Signup and view all the answers

How do integral proteins differ from peripheral proteins in the cell membrane?

<p>Integral proteins are embedded and span the membrane. (A)</p> Signup and view all the answers

In which type of solution does a cell experience lysis due to water intake?

<p>Hypotonic (D)</p> Signup and view all the answers

What mechanism allows certain substances to be transported against their concentration gradient?

<p>Active transport (D)</p> Signup and view all the answers

Which of the following is NOT a function of the cell membrane?

<p>Energy production (C)</p> Signup and view all the answers

Which organelle is primarily involved in the synthesis of lipids and calcium storage?

<p>Smooth ER (C)</p> Signup and view all the answers

Flashcards

Abiotic Origin of Life

A hypothesis stating that life on Earth arose from non-living substances, gradually over time, in a series of steps.

Reducing Atmosphere

The early Earth’s atmosphere, primarily composed of gases like methane, ammonia, and hydrogen, lacked free oxygen.

Protobionts

Early life forms are called protobionts. These 'pre-cells' were clusters of organic molecules enclosed in a membrane-like structure. They could perform basic metabolic processes and reproduce.

Miller-Urey Experiment

A famous experiment simulating early Earth conditions, using gases, water, and electrical discharge, resulting in the formation of amino acids, demonstrating how life's building blocks could have arisen from inorganic matter.

Signup and view all the flashcards

Oparin-Haldane Hypothesis

The idea proposed by Oparin and Haldane that life originated from non-living matter in a series of gradual steps, starting with simple organic molecules.

Signup and view all the flashcards

Abiotic Synthesis

The process of non-living materials forming organic compounds like amino acids, which are fundamental building blocks of life.

Signup and view all the flashcards

Prokaryotic Cell

A cell lacking a nucleus and other membrane-bound organelles, with its DNA located in a region called the nucleoid.

Signup and view all the flashcards

Eukaryotic Cell

A cell with a true nucleus enclosed by a membrane and containing other membrane-bound organelles.

Signup and view all the flashcards

Endosymbiotic Theory

The process by which a larger cell engulfs a smaller cell, resulting in a symbiotic relationship where both cells benefit.

Signup and view all the flashcards

Cell Membrane

A flexible and selectively permeable barrier that encloses the cell, regulating the movement of substances in and out.

Signup and view all the flashcards

Cell Wall

A rigid structure that provides support and protection to the cell, particularly important in plant cells to maintain shape and prevent bursting.

Signup and view all the flashcards

Nucleus

The control center of the cell, containing DNA and responsible for regulating cellular activities.

Signup and view all the flashcards

Nucleolus

The site of ribosome production within the nucleus.

Signup and view all the flashcards

Ribosomes

Small organelles responsible for protein synthesis, reading instructions from mRNA to create proteins.

Signup and view all the flashcards

Rough Endoplasmic Reticulum (ER)

A network of interconnected membranes responsible for protein synthesis and modification, with ribosomes attached to its surface.

Signup and view all the flashcards

Smooth Endoplasmic Reticulum (ER)

A network of interconnected membranes involved in lipid synthesis, detoxification, and calcium storage.

Signup and view all the flashcards

Golgi Apparatus

A stack of flattened membrane-bound sacs involved in processing, modifying, and packaging proteins and lipids.

Signup and view all the flashcards

Lysosomes

Membrane-bound organelles containing hydrolytic enzymes responsible for breaking down macromolecules and waste.

Signup and view all the flashcards

Mitochondria

The powerhouse of the cell, responsible for generating energy in the form of ATP through cellular respiration.

Signup and view all the flashcards

Chloroplasts

Organelles found in plant cells that perform photosynthesis, converting light energy into chemical energy.

Signup and view all the flashcards

Plasmodesmata

Channels between plant cells that allow the passage of molecules. This connection facilitates communication and transport between adjacent cells.

Signup and view all the flashcards

Centrosomes

A region in animal cells where microtubules grow, crucial for cell division and chromosome separation.

Signup and view all the flashcards

Cytoskeleton

A network of protein fibers that provides structural support, aids in cell movement, and helps maintain cell shape.

Signup and view all the flashcards

Passive Transport

The movement of substances across a cell membrane from a region of higher concentration to a region of lower concentration. No energy is required for this type of transport.

Signup and view all the flashcards

Selective Permeability

The ability of a cell membrane to control the passage of molecules in and out of the cell. It allows some substances to pass through while blocking others.

Signup and view all the flashcards

Heterotroph

A type of cell that cannot produce its own food and relies on consuming other organisms or organic matter.

Signup and view all the flashcards

Autotroph

A type of cell that can produce its own food through photosynthesis, converting inorganic substances into organic molecules.

Signup and view all the flashcards

Endocytosis

A process where the cell engulfs substances from its environment by forming a vesicle around them.

Signup and view all the flashcards

Study Notes

Origin of Life Theories

  • Life on Earth may have been created by a supernatural divine force.
  • Life may have originated from extraterrestrial forces.
  • Life likely arose spontaneously from inorganic molecules (main theory).

Oparin and Haldan Hypothesis

  • Proposed life arose gradually from inorganic molecules.
  • Suggested a reducing atmosphere on early Earth.
  • Their ideas led to the Miller-Urey experiment.

Conditions of Early Earth

  • Reducing atmosphere (lacks free oxygen).
  • Abundant hydrogen (H).
  • Absence of free oxygen.
  • Energy sources included lightning, volcanic energy, and UV radiation.

Protobionts

  • Protobionts were precursor forms of living organisms.
  • These were collections of inorganic and organic substances enclosed by a layer (similar to a cell membrane).
  • Water played a role in grouping these molecules.
  • The lipid layer enclosed protobionts.
  • Protobionts exhibited metabolism and reproduction.

Miller-Urey Experiment (summary)

  • Simulated early Earth conditions to study the formation of life from inorganic molecules.
  • Water vapor, gases, and lightning were used to simulate early Earth conditions.
  • The experiment produced amino acids and other organic compounds.

Prokaryotic vs. Eukaryotic Cells

Feature Prokaryotic Eukaryotic
Cell type Unicellular Uni and multicellular
Organelles Few or no membrane-bound organelles Membrane-bound organelles (nucleus, mitochondria, etc)
DNA Free-floating, circular DNA (plasmid) Linear DNA contained within a nucleus
Size Small Larger and more complex
Examples Bacteria, Archaea Plants, animals

Endosymbiotic Theory

  • Eukaryotic cells evolved from prokaryotic cells.
  • Aerobic bacteria were engulfed but not digested, forming a mutually beneficial relationship (mitochondria).
  • Photosynthetic bacteria were engulfed to form chloroplasts.
  • Evidence includes double membranes, ribosomes, and independent reproduction in mitochondria and chloroplasts.

Cell Membrane Structure and Function

  • Fluid Mosaic Model: The cell membrane is a fluid structure composed of phospholipids, proteins, and carbohydrates; held together by weak bonds.
  • Structure: Hydrophilic heads and hydrophobic tails.
  • Selective Permeability: Allows certain substances to pass through.
  • Fluidity: Affected by temperature, lipid saturation, and cholesterol.
  • Proteins: Integral (transmembrane) and peripheral proteins embedded in or attached to the membrane.
  • Functions: Regulation of transport, communication, and protection.

Transport Across Cell Membranes

  • Osmoregulation: Control of solute and water balance.
  • Contractile Vacuoles: Remove excess water from cells.
  • Bulk Transport: Transport of large molecules.
    • Endocytosis: Taking material into the cell. (Phagocytosis, Pinocytosis, Receptor-Mediated Endocytosis)
  • Exocytosis: Release of material from the cell.
  • Diffusion: Movement of molecules from high to low concentration.
  • Facilitated Diffusion: Diffusion with the help of transport proteins. (Aquaporins for water)
  • Active Transport: Movement against the concentration gradient, needing energy (e.g., Na+/K+ pump).
  • Cotransport: Coupled transport of different molecules.
  • Osmosis: Movement of water.
    • Hypotonic: Water enters the cell.
    • Isotonic: Equal water movement in and out of the cell.
    • Hypertonic: Water leaves the cell.

Cell Organelles and Functions

  • Cell Membrane: Regulates transport, provides protection, and facilitates communication.
  • Cell Wall: Provides structure and protection (in plants).
  • Nucleus: Stores DNA, controls gene expression, and directs protein synthesis.
  • Nucleolus: Produces ribosomes.
  • Ribosomes: Synthesize proteins; bound or free.
  • Rough ER: Modifies proteins and transports products.
  • Smooth ER: Synthesizes lipids, stores Ca2+.
  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
  • Lysosomes: Breakdown macromolecules and waste.
  • Mitochondria: Produces ATP via cellular respiration.
  • Chloroplast: Site of photosynthesis in plant cells.
  • Central Vacuole: Stores water, waste, and nutrients; maintains turgor pressure (plant cells).
  • Peroxisomes: Break down fatty acids and other toxins.
  • Flagella: Movement (in some cells).
  • Cilia: Movement and other functions (in some cells).
  • Plasmodesmata: Channels between plant cells.
  • Intercellular Junctions (Animal Cells): Tight junctions, desmosomes, gap junctions.
  • Centrosomes (Animal Cells): Microtubule organizing centers for cell division.
  • Cytoskeleton: Support and movement. (Microtubules, microfilaments, intermediate filaments)
  • Apoptosis: Programmed cell death; regulated process.

Biological Concepts

  • Hypertonic, Hypotonic, Isotonic
  • Osmosis
  • Proteins, Nonpolar, Hydrophilic, Hydrophobic
  • Selective Permeability
  • Transport Across Cell Membrane
  • Diffusion and Facilitated diffusion

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser