BABS Week 4 (Cell Integrity, Transport, Metabolism I)

Cell Membranes

Form boundaries between life and it’s surrounfings. They are selectively permeable and able to control traffic in and out of the cell.

Membrane Structure (Amphipathic)

Membranes are amphipathic; hydrophilic portions protrude while hydrophobic proteins remain in the membrane

Sidedness of Membranes

Membrane proteins are distributed asymmetrically and specific types may cluster together in some areas

Membrane Components:

Lipids (PC)

Proteins (PI)

Carbohydrates (GG)

phospholipids, cholestorol

peripheral, integral

glycolipids, glycoprotein

The _______ face of a cell is topologically _______ to the _____ face of the ER, GA, lysosome and vesicle.

cytoplasmic (inside), equivalent, extracellular face

Phospholipid Bilayer

Pemeability barrier to most molecules and is comprised of phospholipids

Phospholipid Bilayer Processes

• Hydrophobic molecules ______ in hydrophobic core and _____ across the membrane.

• Small molecules cross the membrane via ________

• Ionized/polar/large molecules need to cross the membrane through a protein ______.

dissolve, diffuse

diffusion

transporter

Red Blood Cells

• Deliver _____ to the bodies _____ through the _________ system

• They take up oxygen in the _____ and release it in the _______ while squeezing through it

oxygen, tissues, circulatory

lungs, capillaries

Diffusion

Transport of a solvent from an area with high concentration to an area with lower concentration until an equillibrum is reached. No energy is expended in the cell when this occurs.

Osmosis

Passive transport of water

Hypotonic

Lower solute concentration

• RBC lysed

• Plant Cell turgid

Isotonic

Equal solute and solvent concentration

• RBC nomal

• Plant Cell flacid

Hypertonic

Higher solute concentration

• RBC Shrivelled

• Plant Cell plasmolysed

Passive Transport (FD, O)

Movement of substances without energy

• facilitated diffusion, osmosis

Active transport (P,S)

Movement of substances against the concentration gradient which requires energy

• Primary active, Secondary Active

Vesicular Transport (E, E)

Movement of substances through a vesicle

• Endocytosis, exocytosis

Channel Proteins

Direct passage for solutes to move between the membrane’s sides. It is specific and able to take up what is wanted and exclude what is unwanted

Gated Channel Proteins

Channel proteins which open or close in response to a stimulus such as a binding to a specific molecule

Carrier Proteins bind to a _____ _____ before changing _____, allowing it to ______ the _____on the ____ ____ of the membrane.

target solute, shape, release, solute, other side

Active transport

Pumping solutes across the membrane against the concentration gradient through carrier proteins. Energy is required for this process.

Transporter Proteins

Proteins which use active transport to move solutes between membrane sides. Energy is released through ATP hydrolysis.

Proton Pumps

Transports H+ ions

Proton Pump Process

_____ is stored by generating ______ across the membrane. The voltage and H+ ions create a __________ ______ which helps drive other processes

energy, voltage, concentration gradient

Proton Pump Additional Processes (AS, PR)

ATP synthesis

pH regulation

Simple vs Facilitated vs Active

Simple Diffusion: no, concentration gradient, no, no

Facilitated Diffusion: no, concentration gradient, yes, yes

Active Transport: yes, atp hydrolysis, yes, yes

Ion ________ differ inside and outside of cells. However they ______ over time if they are not maintained through _____ _______

concentrations, disappear, active transport

Membrane Potential

The voltage difference across the membrane. It serves as an energy source to move charged molecules

Voltage Difference

Voltage created by the difference between positive and negative ions

Endocytosis + (PPR)

Vesicles detatch from the plasma membrane. These vesicles have enclosed substances which are being imported into the cell.

(pinocytosis, phagocytosis, receptor-mediated)

Pinocytosis

Fluids are dissolved in a vesicle and taken into the cell

Phagocytosis

Cell engulfs a particle, packaging it into a large vesicle. Macrophages then destroy bacteria and other foreign substances.

Receptor-mediated

highly specific uptake down through the recognition of molecules through receptors.

Exocytosis + (CRL)

Vesicles fuse with plsma membrane to export contents out of a cell

(Constitutive, Regulated, Lysosomal)

Constitutive Endocytosis

continuous release of molecules without external signals

Regulated Endocytosis

release of molecules triggered by signals

Lysosomal Endocytosis

Lysosomes fuse with a membrane in order to release or repair damage.

Catabolism

Break down of complex molecules into simpler molecules which release energy.

Anabolism

Building complex molecules from simpler molecules which consumes energy.

Adenosine Triphosphate (ATP)

Provides energy for living cells

ATP Structure

Adenine is bonded to a ribose sugar which is bonded to a phosphate group

ATP Chemical formula

ATP + H2O → APD + Pi

Hydrolysis Energy Release Rate

7.3kcal/mol released for cellular work

Cellular work (CMT)

Chemical, Mechanical, Transport

Recycling ATP

• ATP undergose ________ which releases a ______ group and _____ which is used by cells, turning it into ADP.

• ADP then undergoes ______ where it gains _____ from food and a ______ group which turns it back into ATP.

catabolism, phosphate, energy

anabolism, energy, phosphate

Utilization of Macronutrients (DUTUC)

1. _______ (polymers → monomers)

2. _____ by epithelial cells

3. ______ around the body

4. _____ by cells from different tissues

5. ______ (cell storage)

Digestion

Uptake

Transport

Uptake

Catabolism

Enzymes

A macromolecule which catalyzes specific biochemical reactions

Enzyme Properties (S,A,R)

1. Substrate specificity

2. Activation energy

3. Regulation

Influences on Activation Energy

Activation energy is influenced by factors such as pH, temperature, cofactors and inhibitors

Enzyme Process

Substrates ____ to an enzyme. The enzyme _____ the hydrolysis process of ______

bind, catalyzes, catabolism

Cofactors

Non-protein components of enzymes which may be required for some catalysis processes

Allosteric regulation

Binding of a regulatory molecule at one site affects the function of another site

Stabilizing Enzyme Active Form

active site and activator

Stabilizing Enzyme Inactive Form

inhibitor and non-functional active site

Cooperativity

binding of substrate to one active site which enhances the binding of the substrate to another site

Feedback Inhibition

the end product of a reaction interferes with an earlier enzyme, causing deactivation of the enzyme, stopping it’s process.

Feedback Inhibition Purpose

Stops enzymes from making too much products or using too much energy

Fermentation

Partial degradation of sugars without oxygen. It occurs in skeletal muscles or red blood cells and allows for the conversion of glucose into lactate.

Aerobic Respiration

The complete oxidisation of sugars which require energy. It is more efficient than formentation in ATP production and uses amino acids to breakdown macromolecules.

Oxidation

Loss of electrons or bonds to more electronegative atoms

Reduction

The gaining of electron or bonds to less electronegative atoms