Cell Structure, Function, and Modifications Flashcards

A comprehensive set of vocabulary flashcards covering cell organelles, their structures, functions, and various cellular adaptations based on the lecture notes.

Organelle

A specialized subunit within a cell that performs a specific function, similar to how organs function within an organism.

Nucleus

The control center of the cell that contains DNA and a dense structure called the nucleolus.

Nuclear Envelope

A double membrane surrounding the nucleus containing pores for materials to enter or leave, connected to the rough ER.

Nucleolus

A structure inside the nucleus that disappears during cell division and is responsible for making ribosomes.

Cell Membrane

A thin, flexible, semi-permeable boundary also known as the plasma membrane that protects the cell from harmful substances.

Classical Model

A cell membrane model proposed in $1930$ by Hugh Davson and James Danielli describing a phospholipid bilayer and proteins.

Fluid Mosaic Model

Proposed in $1972$ by Jonathan Singer and Garth Nicolson, it describes the membrane as a flexible phospholipid bilayer with moving proteins and cholesterol.

Cytoplasm

A viscous, jelly-like fluid where organelles are embedded, providing stability to the cell.

Cytosol

The semi-fluid translucent substance contained within the cytoplasm.

Cell Wall

A protective layer found outside the cell membrane; made of cellulose in plants, peptidoglycan in bacteria, and chitin in fungi.

Mitochondrion

The powerhouse of the cell that converts glucose into energy ($ATP$) through cellular respiration.

Cristae

The folds of the inner membrane within the mitochondria.

Endoplasmic Reticulum (ER)

A system of flattened sacs called cisternae near the nucleus that functions in synthesis and transport of cell products.

Rough ER

A portion of the ER covered in ribosomes that produces and transports proteins to the Golgi apparatus.

Smooth ER

A portion of the ER lacking ribosomes that makes lipids, regulates calcium, and destroys toxic substances.

Ribosomes

The protein factories of the cell made of proteins and $rRNA$ that translate $mRNA$ into proteins.

Golgi Apparatus

A stack of flattened sacs with cis and trans faces that modifies, sorts, and packages molecules for storage or transport.

Lysosomes

Known as suicide bags, they contain hydrolytic enzymes to break down food, bacteria, and worn-out cell parts.

Autolysis

The process where a lysosome ruptures to digest the entire cell if it is damaged or infected.

Cytoskeleton

A network of proteins that provides structural support, mechanical strength, and helps move organelles.

Microtubules

Tube-like structures made of tubulin that form cilia, flagella, and the mitotic spindle.

Intermediate Filaments

The most stable cytoskeleton component, helping maintain cell shape and found in structures like hair and scales.

Microfilaments

Thread-like structures made of actin that help the cell move and form the contractile ring during cytokinesis.

Plastids

Double-membrane bound organelles in plants and fungi that serve as storage for pigments or starch.

Leucoplasts

Colorless plastids primarily used for the storage of starch.

Chromoplasts

Plastids that store colored pigments (red, yellow, orange) that give color to fruits and leaves.

Chloroplasts

Double-membrane organelles in producers containing chlorophyll used for photosynthesis.

Thylakoids

Sacs inside the chloroplast whose stacks are called grana.

Stroma

The gel-like material surrounding the thylakoids within a chloroplast.

Centrioles

Paired structures in animal cells made of microtubules that appear during cell division to form the mitotic spindle.

Vacuole

A storage sac for various substances including water, nutrients, and waste products.

Cell Modifications and Adaptations

Structural and functional changes cells undergo after division to perform specific tasks and aid in survival.

Microvilli

Cytoplasmic extensions that increase the surface area of a cell to enhance nutrient absorption.

Nerve Cells

Elongated cells that facilitate the transmission of impulses between the brain, spinal cord, and body.

Red blood cells (RBCs)

Biconcave-disc shaped cells about $2-3\,\text{um}$ in diameter that lose their nucleus to increase surface area for gas exchange.

Sperm Cell

A specialized cell possessing a flagellum used to propel itself toward the egg for fertilization.

Chromatophores

Star-shaped cells containing bioluminescent pigments that allow organisms like octopuses to change color.

Nematocytes

Stinging cells found in jellyfish and hydra that use a needle-like structure to inject toxins.

Guard cells

Specialized cells that regulate the opening and closing of the stomata in plants.