Cell Structure and Function: Biology for Students

Cell

Smallest living unit

Animal Cell

Plant Cell

Bacterial Cell

A single cell

Cell Theory

All living things are made up of cells; All cells come from pre-existing cells; The most basic unit of life.

Robert Hooke

Observed the slice of cork. Saw 'row of empty boxes'. Coined the term cell.

Protoplasm

Cell contents in thick fluids.

Organelles

Structures for cell function.

Prokaryotic

Unicellular; First type on earth; Bacteria and Archaea.

Eukaryotic

Multicellular; Possesses many organelles.

Nucleoid

Region of DNA Concentration.

Bacteria

Have ribosomes.

Cell Membrane

Acts as a barrier separating the inside and outside of the cell. Best described by using the Fluid Mosaic Model.

Phospholipid Bilayer

Hydrophilic head

Contains glycerol/phosphate. Attracts water.

Hydrophobic tail

Contains fatty acids. Repels water.

Selectively Permeable

Lipid Bilayer

Highly permeable to nonpolar (Oxygen, Carbon dioxide); Moderately permeable to small, uncharged, polar (Water, urea); Impermeable to ions and large, uncharged polar.

Membrane proteins

Channels and carriers are very selective.

Active Transport

Energy is required for carrier proteins to move solutes across the membrane. Cellular energy is used.

Antiport

Transport/moves two different substances (in the same or opposite direction).

Symport

Transport/moves two different substances (opposite direction).

Transport in vesicles

Substances move into or out of cells in vesicles.

Endocytosis

Movement of substances into a cell in vesicles.

Exocytosis

Movement of substances out of a cell in secretory vesicles that fuse with the plasma membrane and release their contents.

Transcytosis

Movement of a substance (endocytosis on one side and exocytosis on the opposite side).

Receptor-mediated endocytosis

Cells take up specific ligands.

Phagocytosis

A cell engulfs large solid particles, or 'cell eating'.

Pinocytosis

'Cell drinking'. Tiny droplets of extracellular fluid are taken up.

Cytoplasm

Consists of all the cellular contents between the plasma membrane.

Cytosol

Intracellular fluid. 55% of the cell's volume. 75-90% water.

Cytoskeleton

Passive Process

No input of energy from the cell. Kinetic energy of motion.

Diffusion

Passive movement of molecules along the concentration gradient from regions of higher concentration to regions of lower concentration.

Simple diffusion

Move freely through the lipid bilayer of the cell membrane.

Facilitated diffusion

Integral membrane protein. Faster rate of transport to the Protein channel.

Carrier Proteins

Need to undergo conformational change. Changes its shape to move the bound substance across the membrane and release it on the other side.

Osmosis

Net movement of a solvent through a selectively permeable membrane.

Tonicity

Measure of the solution's ability to change the shape or tone of cells by altering their internal water volume.

Isotonic

Some concentration of solutes outside the cell (cytosol). Normal RBC shape. Where NA goes, H2O follows.

Hypotonic Solution

Lower concentrations of solutes outside than inside the cell. Causes the cells to swell and eventually burst.

Hemolysis (lysis)

Causes the cells to swell and eventually burst.

Hypertonic Solution

Higher concentrations of solutes outside than inside. Water moves out of the cell faster than it enters. Causes the cell to shrink (crenation).

Mannitol

A type of sugar alcohol used in medicine.

Endoplasmic Reticulum

A network of membranes in the form of flattened sacs.

Golgi Apparatus

Modifies, sorts, packages, and transports proteins received from the RER.

Lysosomes

Digest substances that enter a cell via endocytosis and transport the final product of digestion.

Peroxisome

'Microbodies' that oxidize amino acids and fatty acids, and detoxify harmful substances.

Proteasomes

Degrades unneeded, damaged, or faulty proteins by cutting them into smaller pieces or peptides.

Mitochondria

Generates ATP for the energy of the cell and plays an important role in apoptosis.

Cilia

Composed of microtubules, numerous 'hair-like' projections that extend from the surface of the cell and move fluid along the cell surface.

Flagella

Larger than cilia, moves an entire cell.

Centrosome

Microtubule-organizing center located near the nucleus that participates in cell division.

Nucleus

A prominent feature of a cell, spherical or oval-shaped structure.

Smooth Endoplasmic Reticulum

Synthesizes fatty acids and steroids; the outer surface does not have ribosomes.

Rough Endoplasmic Reticulum

Synthesizes glycoproteins and phospholipids that are transferred to cellular organelles.

Ribosomes

Sites of protein synthesis, consisting of two subunits (small and large), can be attached or free.

Apoptosis

A series of cell death; one method to get rid of bad cells.

Microtubules

Composed of protein tubulin; the largest, longest, unbranched hollow tubes from the centrosome.

Microfilaments

The thinnest filaments composed of proteins actin and myosin.

Intermediate filament

Thicker than microfilaments but thinner than microtubules.

Nuclear Envelope

Double membrane that separates the nucleus from the cytoplasm.

Nuclear pore

Controls the movement of substances between the nucleus and cytoplasm.

Nucleolus

Produces ribosomes.

Chromosomes

Genes that control cellular structure and direct cellular functions.

Solute

A substance that is being dissolved in the various fluids.

Solvent

A fluid or gas in which a solute is dissolved.

Concentration

The amount of solute dissolved in a given volume of solvent.

Concentration Gradient

The difference in concentration of a substance between two areas.