Bio Exam 4 Eeeek

Phospolipid

Membrane’s major component: comprised of two fatty acids and a phosphate-containing group attached to a glycerol backbone

Hydrophobic

Water fearing

Nonpolar, uncharged

Hydrophilic

Water loving

Able to form bonds with water

Polar, Charged

Mitochondria

• Energy production

• Produces ATP

Structure

• Double membrane

• Many folds

Smooth ER

• Region of the ER with few or no ribosomes

• Synthesizes carbohydrates, lipids, and steroid hormones

• Detoxes certain chemicals

• Stores calcium ions

Diffusion

The movement of small ions and water through micropores along concentration gradients

What are the common nonpolar molecules and how do they cross the membrane?

• CO2 an O

• Cross easily

What are the common polar molecules and how do they cross the membrane?

• Glucose

• Ions

Do not cross easily due to size/charge changes

Rough ER

• Region of the ER that is studded with ribosomes and engages in protein modification and phospholipid synthesis

Endosome

• Compartment formed when the vesicle merges with a lysosome for breaking down material

Osmosis

Transport of water through a semipermeable membrane according to the water’s concentration gradient across the membrane that results from the presence of solute that cannot pass through the membrane

Tubulin

• Alpha and beta tubulin form hollow tubes that form microtubules

Golgi apparatus

• Transport and sorting

• Modification of proteins and lipids

Lysosome

• Break down biomolecules

Structure

• Membranes filled with enzymes in an acidic solution

Cytoskeleton

• Composed of actin filaments, intermediate filaments, and microtubules

• Cell structure, movement, and transport of molecules within cells

Actin filaments

• Made of actin monomers

• Polymerize and depolymerize

Function- structure and aid movement

• Provide rigidity to cell shape

• Important for cell contraction

• Cell motility

• Cell division

Flagella

• Made of microtubules

• Extends from the plasma membrane

• Help the cell swim

  • Ex: Sperm

Intermediate filament

• Can be several different proteins

  • Keratin, desmins, laminin

• Middle size between actin and microtubule

• Slowly dynamic

Function

• Maintain cell shape

• Anchor organelles

• Line nuclear membrane to keep nucleus in shape

Kinesin

• Motor proteins

• Attach to microtubules and the vesicle to deliver the vesicle where it needs to be in the cell

  Require ATP to take a step (change it’s shape)

Ribosomes

• Not membrane bound

• Can be free, or bound in the ER

Function

• Carry out protein synthesis

Free ribosome

• Suspended in the cytoplasm

• Makes proteins that function within the cytoplasm

Bound ribosomes

• Attached to the rough ER
  Makes proteins that go to certain organelles or are exported from the cell

Plasma membrane

Phospholipid bilayer with embedded (integral) or attached (peripheral) proteins, and separates the cell’s internal content form it’s surrounding environment

Centriole

• Rod like structure constructed of microtubules at the center of each animal cell centrosome

Microtubules

• Made of alpha and beta tubulin

• Dynamic and have polarity

  • Alternately grow or shrink

FUNction ;)

• Motility

  • Cilia and flagella swim

• Intercellular transport

  • Vesicles

  • Organelles can use them as tracks to move

Membrane proteins

• Integral membrane proteins

• Receptor proteins

• Lipid anchored proteins

• Peripheral membrane proteins

Integral membrane proteins

• 1. Transport: regulate entry and exit of hydrophilic molecules

  2. Cell-surface identity markers: ID tags and surface attachment sites

  3. Cell-surface receptors: receive commands from extracellular molecules

  4. Cell-to-cell adhesion proteins: attach to ECM or other cells

  5. Enzymes: catalyze a reaction

  6. Attachment: to cytoskeleton

“alpha-helical” transmembrane proteins

• Helix formation maximizes H- bonding between peptide groups

• Hydrophobic side chains (R) interact with fatty acid trails in bilayer

How do Sequences of α-helical transmembrane helices dictate protein structure and function?

Function: Receptors, anchors, transporters

• All side chains are nonpolar

Function: Pores, channels

• Alternating nonpolar and polar side chains

• Multiple alpha amphipathic helices needed

β-barrel transmembrane proteins

• Hydrophobic side chains face fatty acid tails of the bilayer

• Hydrophilic side chains face aqueous pore

Lipid-anchored proteins

Structure

• Soluble protein covalently linked to a phospholipid, lipid, or fatty acid

Function

• Cell-cell communication

• Keep close to membrane

• Stabilize membrane proteins

Peripheral proteins

Structure

• Attached by non-covalent interactions with integral membrane proteins or the membrane

• Ionic, hydrogen bonds

Channel protein

A membrane protein that allows a substance to pass through its hollow core across the plasma membrane

• Facilitated diffusion

• Selective

• Regulated

• Does not require energy

Carrier protein

Membrane protein that moves a substance across the plasma membrane by changing its own shape

• Facilitated diffuction

• Does not require energy

Binding of the substrate causes a conformational change in the protein.

NA⁺/K⁺ ATPase

• Pump for active transport

• Carries sodium and potassium ions

• Pumps out 3 sodium ions out and moves 2 potassium ions in, causing an electrical imbalance

• Requires energy

Active transport

Method of transporting material that requires energy

Endocytosis

• Active transport

• Moves substrates, including fluids and particles, into the cell

Passive transport

Method of transporting material through a membrane that does not require energy

Isotonic solution

Same on both sides

Hypertonic solution

Water leaves the cell

Hypotonic solution

Water enters the cell

Passive diffusion

Passive transport process of low-molecular weight material according to its concentration gradient

Facilitated diffusion

• Materials diffuse across the plasma membrane with the help of membrane proteins

• Concentration gradient exists, however these materials are polar molecule ions that the cell membrane’s hydrophobic parts repel

• Facilitated transport proteins shield the materials from the membrane’s repulsive force

Glycosylation

• Addition of sugars

• Enzymes catalyze addition of carbohydrate groups

• Resulting molecule is a glycoprotein

What does Glycosylation do?

Resulting molecule is a glycoprotein

• Helps with protein folding

• Stabilizes proteins

• Cell-cell recognition

• Direct protein trafficking

• Changes in structure indicator for

shipment to next destination—Golgi apparatus

Glycoprotein

Combination of carbohydrates and proteins

Glycolipid

Combination of carbohydrates and lipids

GPI Anchor

• Lipid anchor for many cell-surface proteins

• Glycosyl Phosphatidyl Inositol

• Soluble protein covalently linked to

  a phospholipid

Antiporter

Transporter that carries two ions or small molecules in different directions

Symporter

Transporter that carries two different ions or small molecules, both in the same direction

Lipid rafts

• Cholesterol organizing clusters of transmembrane proteins into lipid rafts