Cell Structure & Function Flashcards

biology

Cell

The basic structural unit of all life forms; the smallest unit capable of performing life functions.

Cell Theory

All living things are made of one or more cells, and all cells come from pre-existing cells through cell division.

Examples of Cells

Amoeba Proteus, Nerve Cell, Plant Stem, Red Blood Cell, Bacteria

Plasma Membrane (cell membrane)

Outer membrane of a cell that controls the movement of substances in and out; it is a double layer.

Function of Plasma Membrane

Protects the cell from its surrounding environment; it is semi-permeable and regulates the materials that enter and exit the cell.

Cell Wall

Outer membrane in plant cells and bacteria that supports and protects the cells; made of cellulose in plant cells.

Long tube-like cells in tree trunks that transport water and provide strength.

Xylem

Cell Parts

Organelles

DNA (deoxyribonucleic acid)

Information molecule that is the universal basis of an organism’s genetic material; contains instructions for protein production.

Cytoplasm

Gel-like fluid inside the cell surrounded by the cell membrane; it includes cystosol and organelles.

Nucleus

Directs cell activities; contains genetic material (DNA) and a structure called the nucleolus.

Nucleolus

Site of ribosome synthesis; made of densely packed protein and ribonucleic acid (RNA).

Mitochondria

Site of aerobic cellular respiration; produces energy through chemical reactions; contains mitochondrial DNA (mtDNA).

Ribosomes

Site of protein synthesis; found on rough endoplasmic reticulum (ER) and floating throughout the cell.

Endoplasmic Reticulum (ER)

Moves materials around in cell; can be smooth (lacking ribosomes) or rough (ribosomes embedded in surface).

Rough Endoplasmic Reticulum

Intracellular transport system studded with ribosomes that delivers proteins to all parts of the cell.

Smooth Endoplasmic Reticulum

Transports proteins, synthesizes lipids and assists in the manufacture of the plasma membrane, no ribosomes.

Golgi Apparatus (Golgi Bodies)

Protein packaging plant; moves materials within and out of the cell.

Lysosome

Specialized vesicles containing enzymes that digest (break down) waste or unwanted materials.

Cytoskeleton

3-dimensional structure in the cytoplasm that provides shape to the cell; made of microtubules and microfilaments.

Plastids

Found in plants and algae; responsible for manufacturing and storing food (photosynthesis) and synthesis of colored pigments.

Chloroplast

Where photosynthesis takes place; contains green chlorophyll; converts light energy to chemical energy (sugars).

Vacuoles

Membrane-bound sacs for storage of sugars, minerals, proteins and water; plants have large vacuoles, animal cells contain small vacuoles.

Two Types of Cells

Prokaryotic (no nucleus) and Eukaryotic (contains a nucleus)

Prokaryotic Cells

Simpler, smaller cells with single circular DNA and no membrane-bound organelles; found in kingdom Eubacteria and Archaebacteria.

Eukaryotic Cells

More complex, larger cells with DNA organized into chromosomes in the nucleus and membrane-bound organelles; found in Animal, Plant, Fungi and Protista Kingdoms.

Prokaryotic cells

Cells with the simplest structure; found in kingdom Eubacteria and Archaebacteria.

Eukaryotic cells

Contain membrane-bound organelles; DNA enclosed by a nuclear envelope.

Cell size

Having many small cells is more efficient for transporting nutrients and removing wastes compared to one big cell.

SA:V Ratio

Ratio of surface area to volume; smaller cells have a higher ratio, which allows more molecules and ions to move across the cell membrane.

Plasma Membrane

A network of lipids and proteins that forms the boundary between a cell’s contents and the outside of the cell.

Phospholipid Bilayer

Double layer of phospholipids spontaneously arranged with hydrophilic heads on the outside and hydrophobic tails on the inside.

Phospholipid molecules

Head: hydrophilic (water-loving). Tail: hydrophobic (water-hating/ repels water).

Fluid Mosaic Model

Describes the plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins; gives the membrane a fluid character and flexibility.

Key features of the fluid mosaic model

Phospholipid bilayer, proteins, carbohydrates, and cholesterol

Integral proteins

Proteins whose position is permanently fixed in the cell membrane (full-time employees)

Transmembrane proteins

Proteins that span both layers of the phospholipid bilayer

Super Important Transmembrane Protein Functionality

Provide a direct travel route between the intracellular and extracellular environment of cells

Transmembrane Proteins - Critical Functions

Act as transport channels, act as enzymes, signal transduction, cell-cell recognition, intercellular joining, attachment to the cytoskeleton and extracellular matrix

Diffusion

Movement of particles from a region of high particle concentration to a region of lower particle concentration.

Diffusion

Passive form of movement as no energy is required

3 factors that affect the rate of diffusion

Concentration, temperature and particle size

Channel proteins

Act like pores in the membrane; open and close to encase specific substances – usually water-soluble (hydrophilic) polar particles, such as ions.

Carrier proteins

Change their shapes to conform and bind to molecules to move across the membrane. They then return to their original shape

Osmosis

Passive movement of water through a semi permeable membrane to establish equilibrium (same on both sides)

3 Types of Solutions

Isotonic, hypotonic, and hypertonic

isotonic

Water concentration is the same inside the cell and outside the cell. The amount of water entering and leaving will be the same

hypotonic

Higher water concentration outside the cell (lower solute concentration) than inside the cell

hypertonic

Lower water concentration outside the cell (higher solute concentration) than inside the cell

Haemolysis

animal cells swell and burst when placed in a hypotonic solution

Crenation

Animal cells shrink and crinkle when placed in a hypertonic solution

Turgid

Plant cell placed in a hypotonic solution and water moves into the cell

Plasmolysis

Plant cell is placed in a hypertonic solution and water moves out of the cell. The plasma membrane then moves away from the cell wall

The cell becomes turgid

Plant cell placed into a hypotonic solution.

What happens to a Hypotonic Plant Cell

Plant cell placed into a hypertonic solution. The cell becomes flaccid. Plasmolysis occurs if the plasma membrane pulls away from the cell wall

What happens if Diffusion and Osmosis require no energy

However, sometimes energy is needed to move substances across the membrane. This is active transport

Endocytosis

Formation of vesicle containing molecules from outside the cell

Phagocytosis

Engulfing of solids/food by phagocytes or amoeba

Pinocytosis

Bulk transport of extracellular fluid such as fat droplets in the small intestine

Exocytosis

Process by which large molecules produced in the cell are transported from the cytoplasm to the external environment

Integral proteins

Go all the way through the lipid bilayer. These are also called channel proteins

Peripheral proteins

Are only on one side of the bilayer. They are involved in cell to cell communication

What can Pass Through the Membrane

Small, Non-Polar; Water, CO2