Cell Structure and Function

Cell Membrane

Outer boundary that separates cell from exterior

Phospholipid Bilayer

Double layer of phospholipid molecules in the cell membrane

Hydrophilic Heads

Water-loving part of phospholipid molecules in the cell membrane

Hydrophobic Tails

Water-fearing part of phospholipid molecules in the cell membrane

Plasma Membrane

Outer boundary that separates cell from exterior

Fluid Mosaic Model

Arrangement of components in the cell membrane to form a continuous sheet

Rafts

Pinches into two cells during cell division; pinch inward to bring material into cell

Cholesterol

Scattered through hydrophobic portion of the cell membrane, contributes to structural integrity

Integral Membrane Proteins

Proteins attached to the hydrophilic portion of the cell membrane with various functions

Pores or Channels

Controlled transport of hydrophilic molecules across the cell membrane

Cell Identity Markers

Glycoproteins or proteins that identify cells

Receptor Molecule

Binds to chemicals and causes changes inside the cell

Enzyme

Stimulates chemical reactions and metabolic pathways

Cytoplasm

Gel-like internal substance of cells

Cytosol

Watery intracellular fluid within the cell

Organelles

Specific structures within the cell that perform various functions

Endoplasmic Reticulum

Membranous walled canals and flat curving sacs in parallel rows

Rough ER

Endoplasmic reticulum with ribosomes on its outer surface for protein synthesis and intracellular transport

Smooth ER

Endoplasmic reticulum that synthesizes certain lipids and carbohydrates and removes excess calcium from the cell's interior

Ribosomes

Non-membranous structures involved in protein synthesis

Mitochondria

Organelles involved in energy production

golgi apparatus

Membranous organelle involved in processing and packaging proteins, is then released out of cell through secretory vesicle

Cytoskeleton

Internal support framework that moves the cell or its parts, made up of tiny flexible fibers, detects changes inside or outside of cell

Cell Fibers

Tiny flexible fibers that extend from the plasma membrane and provide internal support, 3 different types

microfilaments

thin twisted proteins, can slide past each other to cause cell to shorten

intermidiate filaments

slightly thicker twisted proteins, acts like tendons and ligaments

Microtubules

Thickest cell fibers made of hollow tubes or protein subunits that move things around inside the cell

cell extensions

extend plasma membrane outward to form tiny fingerlike processes, 3 different types

Microvilli

Tiny fingerlike processes on epithelial cells that line areas to increase surface area, in digestive tract

Cilia

Cylinders made of microtubules in the respiratory tract that brush material past the cell's surface and have sensory functions

Flagella

Tail-like structure on sperm cells that propels them forward

Cell Connections

Structures that allow cells to connect closely with each other

Desmosomes

Interlocked fibers that provide strong adhesion between cells, spot or belt

Gap Junctions

Membrane channels that form gaps/tunnels between cells, allowing cytoplasm to join together forming 2 plasma membranes into single structure, heart or nervous tissue

Tight Junctions

Collars of tightly fused material that prevent movement of material across a sheet of cells, intestines and bbb

Lysosomes

Membranous sacs throughout the cell that contain powerful digestive enzymes for anything that shouldn’t be in cell

Proteasomes

Hollow cylinders throughout the cell that break down abnormal or defective proteins

peroxisomes

in kidney or liver cells, has enzymes that detoxify harmful substances in cell

Active Transport

Movement of substances against the concentration gradient, requiring energy

Endocytosis

Bulk movement of substances into the cell through vesicles

Exocytosis

Bulk movement of substances out of the cell through vesicles

Pumps

Membrane proteins that move substances against the concentration gradient

Calcium Pump

Pump that transports calcium ions in and out of muscle cells, atp breaks down into adp for this to happen

Sodium Potassium Pump

Pump that transports sodium and potassium ions in and out of cells, 3 sodium for every 2 potassium

Vesicle Mediated Transport

Transport of substances into or out of the cell through vesicles

Phagocytosis

Type of endocytosis where large particles are engulfed by the plasma membrane, cell eating

Pinocytosis

Type of endocytosis where fluid is brought into the cell, cell drinking

Receptor Mediated Endocytosis

Type of endocytosis where specific substances are brought into the cell detected through receptors, plasma membrane is pulled inward to pinch around substance

Passive Transport

Movement of substances down the concentration gradient, not requiring energy

Osmosis

Movement of water through a semi-permeable membrane

Simple Diffusion

Movement of substances without the need for special channels or carriers

Facilitated Diffusion

Movement of substances through pores or channels

Channel Mediated Diffusion

Movement of substances through specific channels

Carrier Mediated Diffusion

Movement of substances through membrane proteins

gated ion channels

controls movement of ions, can be open,closed, or inactive

Aquaporins

Channels that facilitate the movement of water, very selective

Diffusion

Movement of particles from an area of high concentration to an area of low concentration

Solution

Mixture of solute and solvent

water pressure developing from osmosis

osmotic pressure

Tonicity

Relative osmotic pressure of two fluids or osmotic pressure outside the cell relative to inside the cell

• greater amount of solute, greater amount of tonicity

Hypertonic Solution

Solution with a higher tonicity than inside the cell, water flows out of cell to dilute solution and cell may shrivel or shrink

Hypotonic Solution

Solution with a lower tonicity than inside the cell, water flows into cell to dilute solution inside cell and cell may swell or get bigger

isotonic solution

Same tonicity inside and outside of cell, so no net movement

State of balance where there is no net change in the amount of water and solute on each side of the membrane

equilibrium

Anabolism

Process of building larger molecules from smaller ones

Dehydration Synthesis

Anabolic reaction that forms larger molecules by removing water

Catabolism

Process of breaking down large molecules into smaller ones

Hydrolysis

Catabolic reaction that breaks down large molecules by adding water

Enzymes

Proteins that act as catalysts to speed up chemical reactions, reaction uses less energy

Substrate

The raw material before a reaction occurs, what the enzyme attaches to

The result of a chemical reaction

Product

The part of the enzyme that binds to the substrate

Active Site

Allosteric Effector

Chemical or physical agent that changes the shape of the enzyme and can activate or inhibit it

eg. temp- enzymes have to be a certain temp for it to function

Process that converts glucose into ATP

cellular respiration

glycolysis

Initial step of cellular respiration that forms NADH and ATP, in cytosol

citric acid cycle

Generation of energy in the form of NADH, ATP, and reduced form of FADH2, in mitochondria

ETC

Generation of energy from energized electrons to ATP, in mitochondria