Biology Cell Structures and Functions Quiz

Introduction to Cells

• Cells are the basic units of structure and function in all living things.

Discovery of Cells

• Anton van Leeuwenhoek (1632-1723): Dutch biologist, first person to observe living cells through a simple microscope.
• Robert Hooke (1635-1703): Examined cork cells, and coined the term "cell" describing the compartments.
• Robert Brown: Observed a dark circle in the center of the cell, which was later named the nucleus.

Development of Cell Theory

• Matthias Schleiden (1838): German scientist, observed plant parts using a microscope; concluded that all plants are made of cells.
• Theodor Schwann (1839): German scientist, observed many different animal cells; concluded that all animals are made of cells.
• Rudolph Virchow (mid-1800s): German physician; hypothesized that new cells are formed from pre-existing cells.

Cell Theory

• All living things are composed of one or more cells.
• Cells are the basic units of structure and function in living organisms.
• New cells are produced from pre-existing cells.

Developments in Cell Biology

• Microscopes clarified the definition of life.
• All living things consist of organized parts, obtain and use energy, perform chemical reactions, change over time, maintain homeostasis, respond to their environment, reproduce, and share a common history.

Cell Diversity

• Not all cells are identical.
• Cells within an organism exhibit diverse size, shape, and organization variations.
• This diversity is related to the variety of cell functions.

Cell Organization

• Tissues: groups of cells that carry out specific functions (e.g., epithelial tissue, muscle tissue).
• Organs: several types of tissues interacting to perform a specific function (e.g., stomach).
• Organ systems: groups of organs working together to perform a set of related tasks (e.g., digestive system).

Prokaryotic Cells

• Unicellular organisms.
• Lack a nucleus and membrane-bound organelles. The genetic material is concentrated in a nucleoid region.
• Can be concentrated in one part of the cell.
• Can have flagella for movement or pili/fimbriae for attaching to surfaces.
• Reproduce by binary fission. Examples: E. coli, Streptococcus.

Eukaryotic Cells

• Contain a membrane-bound nucleus and organelles.
• Examples include plant and animal cells.

Cell Facts

• Cells cannot survive if isolated from their environment.
• Cells need nutrients to survive.
• Cells eliminate waste.
• Most cells are only visible using a microscope.

Organelles

• Organelles are cell components that perform specific functions.

Cell Structures

• All cells have
  • Cell membrane: outer boundary of the cell.
  • DNA: genetic information
  • Cytoplasm: watery material inside the cell membrane; contains dissolved substances, enzymes, organelles, and structures.

Prokaryotic vs. Eukaryotic Cells

• This is a comparison highlighting the key structural differences.

Cell Wall

• Found in plants, algae, some bacteria, and fungi.
• Surrounds the cell membrane.
• Protects and supports the cell
• Made of cellulose in plants.
• Has primary and secondary layers.

Nucleus

• One of the largest organelles.
• Surrounded by a nuclear envelope with nuclear pores, a membrane.
• Contains a nucleolus, a dense region with RNA and proteins, which are essential for ribosome production.
• Contains the chromosomes that hold the genetic information.
• Is the information center of the cell, directing most of the cell activities.

Cytoplasm

• Contains structures called organelles.
• Primarily composed of water.

Mitochondria

• Has two membranes.
• Used to generate cellular energy (ATP) through cellular respiration.
• Inner membrane has folds called cristae.
• Contains their own DNA and ribosomes.

Plastids

• Found in plant cells
• Store food and pigments.
  • Amyloplasts: store starch
  • Leucoplasts: store food
  • Chromoplasts: store pigments like carotenoids (orange).
  • Chloroplasts: conduct photosynthesis.

Chloroplast

• Photosynthetic organelle (found in plant cells).
• Has two outer membranes and one inner thylakoid membrane
• Interior fluid is called stroma
• Changes energy from sunlight into stored chemical energy.
• Contains pigment chlorophyll.

Vacuoles

• Sac-like storage structures.
• Store enzymes and waste products.
• Very large in plant cells; aid in plant growth and support.

Cytoskeleton

• Network of filaments and fibers that support cell structure and movement.
• Types: microtubules, microfilaments, and intermediate filaments.
• Includes cilia and flagella.

Centrioles

• Cylindrical organelles found only in animal cells.
• Involved in cell division.
• Starting place for microtubules.
• Always occur in pairs

Endosymbiotic Theory

• eukaryotic cells evolved from prokaryotic cells through engulfing of prokaryotes, particularly mitochondria and chloroplasts.