Biology 30 - Assessment #3

transitional endoplasmic reticulum

where proteins are butted off in vesicles

Where are proteins matured?

golgi apparatus

_____ makes membranes more rigid

cholestero

What parts of a phospholipid are hydrophobic and hydrophilic?

The phosphate heads are hydrophilic and the fatty tails are hydrophobic

Why does oil and water separate?

Oil is no polar and water is polar, so they push against each other.

dipole-dipole

Like dissolves like

cilia

Slender protuberances that project from much larger cells

flagella

lash-like appendage that protrudes from cell body

Amphipathic

Having both hydrophilic and hydrophobic parts (e.g. soap)

What are three types of lipids?

phospholipid, triglyceride, steroid

Difference between saturated and unsaturated fats

Saturated fats can stack and have single bonds between all carbon pairs. Unsaturated fats have kinds or bends in their structure from double bonds between one or more pairs of carbon atoms.

What kind of fatty acids do heat loving organisms have?

They have saturated fats to keep their membranes more solid/keep from dissolving at higher temps

What kind of fatty acids do cold loving organisms have?

They have unsaturated fatty acids to keep their membranes fluid at lower temps

The cytoskeleton is composed of what type of biomolecules(s)?

Mainly proteins

What's the purpose of actin/microfilaments?

They serve as a track for myosin, muscle contraction, cytokinesis after mitosis, highways for cargo transport, assemble and disassemble quickly.

What role do intermediate fibers play in the cytoskeleton?

They are playing a mainly structural role for cells and organelles (e.g. keratin)

what role do microtubules play in the cytoskeleton?

They provide a track for kinesin and dyne in motor proteins; play a structural role and help cells resist compression

What gives bacteria their shape?

cytoskeletal proteins

If you want to maximize surface area to volume, which type of lipids should you use?

cholesterol-rich lipid mix

Where are lysosomes found?

only in animal cells

What can't pass through the cellular membrane easily?

Polar/hydrophilic substances

where do you expect to find receptors for lipid soluable signaling molecules?

Cytoplasmic receptors

Where is the receptor for a water-soluable hormone?

in the plasma membrane

where is the receptor for a lipid-soluable hormone?

in the nucleus or cytoplasm

What is signal transduction?

the transmission of molecular signals from a cell's exterior to its interior

what is the sympathetic nervous system?

"Fight or flight" where heart rate increases and digestive process slows down as blood goes to important organs.

What is the parasympathetic nervous system?

"rest and digest", where heart rate is slow and healthy, body is relaxed.

Is epinephrine hydrophilic or hydrophobic?

Hydrophilic

Where do you expect the receptor for epinephrine to be located?

The cell membrane

Where is epinephrine produced?

the adrenal glands

Process of Signal Transduction

1. Signal molecule binds to receptor and receptor changes shape

2. Alpha subunit dissociates & travels to hit intramembrane amplifier enzyme (GDP replaces DTP)

3. cAMP activates protein kinase A

4. kinases causes phosphorylation

Antagonist

repressor, prevents ligand from binding

Agonist

Same as ligand response but synthetic

G-Protein

Composed of alpha, beta, and gamma subunits. Carry signal transduction from the receptor to the cytoplasm

During Fight or flight what do you want to do?

a) Release free glucose from stored glycogen

b) Stop making more glycogen

c) Store more glucose as glycogen

d) A & B only

D) A & B only

How many transmembrane a helices does epinephrine receptor have?

7

How is epinephrine's interaction with its receptor?

Epinephrine will eventually diffuse away from its receptor

Blocking epinephrine signaling means...?

Less glucose release

cAMP is produced from ______

ATP

Stress response

stress/fear -> epinephrine -> receptor -> G-protein -> adenylyl cyclase -> cAMP (many)

What does phosphorylation do to an enzyme?

Phosphorylation always changes the target enzyme's structure and therefore its function

If you added a toxin that prevented cAMP from changing into AMP, what effect on blood glucose release would you expect?

Glucose levels would increase (continued to be released into the bloodstream for longer)

Telomeres

protective endcaps of DNA that promote DNA stability and integrity

LuxR + autoinducer

transcription factor that induces luciferase production

When would you have the most autoinducer available in the extracellular fluid?

When there are a lot of bacteria around

quorum sensing

The ability of bacteria to sense the presence of other bacteria via secreted chemical signals.

Autoinducers Common Structure

Biofilms

a thin film of mucus created by and containing a colony of bacteria and other microorganisms

Pseudomonas aeruginosa

Gram negative disease causing bacterium that has very low susceptibility to antibiotics

If you block LuxI, how will this treat bacterial infection?

It will prevent the production of virulence factors

passive transport

open tunnel that anything can pass through without need for energy

Diffusion concentration levels

High concentration means more molecules in the same volume clumped together. Low concentration spreads them around until they're evenly diffused.

transmission depends on movement of _____

ions

Na+/K+ ATPase

3 Na+ out, 2 K+ in (grows less positive when pump is active)

Which ion controls when the pump is phosphorylation in Na+/K+ pump regulation?

Na+

2nd Law of Thermodynamics (Entropy)

an isolated system that is not in equilibrium will tend to increase over time

Antiport

two substances move in opposite directions

Symport

two molecules travel in the same direction

What mV is resting membrane potential at?

-70 mV

Ligand-gated channel

the binding of a specific substance (ligand) to channel leads to transition in the protein causing it to open or close (neurotransmitters act at ligand gated channels at post-synaptic membrane). Starts the process

Voltage gated channel

the gate senses voltage change and opens

Mechanically gated channel

the gate senses pressure and open (can sense muscle stretching)

Dr. Francisco Bezanilla

discovered ball and chain mechanism with voltage gated channels

Action Potential

the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

If you opened Na+ Channels, where would Na+ move?

Into the cell

The Na+K+ ATPase relies on which mechanism to work?

covalent modifications of the pump (phosphorylation)

Luigi Galvani

discovered that muscles of dead frogs' legs twitched when struck with an electric spark

Signal propagation

once depolarization occurs, the signal is propagated down the length of the axon (like a wave)

Why can action potentials go backwards?

Action potentials can't go backwards because ion signal goes inactive after passing on the information

Proprioception

the sense of body position in space

What is the purpose of mouth, tongue, and salivary glands?

Mechanical and chemical digestion through chewing and adding enzymes (lingual lipase and amylase) to make bolus

Why is the stomach acidic?

To denature proteins, keep stomach at the optimal pH for protease pepsin, and to kill any micro-organisms to prevent infection

Why is pepsinogen inactive (pepsin = active)?

Only to have protease activity in the stomach and to minimize destruction of your own cellular proteins

What is the layer closest to the lumen (the cavity) of the stomach?

The mucosa

What parietal cells produce?

Hydrochloric acid (HCl)

Is stomach acid produced all the time?

No, only when there is food in the stomach

When should stomach acid be produced?

When the stomach is stretched

Acetylcholine

activates parietal cells directly and indirectly to produce HCl

Histamine

Stimulates parietal cells to produce HCl

Gastrin

activates parietal cells directly to produce HCl

Which of the following will decrease stomach acid production?

Histamine antagonist

If the parietal cells produce secretes HCl into the stomach lumen, what should happen to parietal cells directly intracellular pH?

The pH increases

How do you protect stomach lining from being eaten up by acid?

Excretion of basic bicarbonate (HCO3-) into mucus layer

How long does it take for the digestive process?

30-40 hours

Peristalsis

series of defined muscular contractions triggered from the nerves in the esophagus

What are the different sections of the small intestine?

duodenum, Jejunum,

and ileum

How much food can the human stomach store?

Up to 4 liters of food

Chief cells

secrete pepsinogen

Mucus cells

release mucin to coat stomach so HCl or pepsin don't degrade the stomach

William Prout

discovered stomachs secrete HCl

What is a major contribution to a rise in intracellular pH?

The Na+/H+ exchange

Who studied the SGLT1 transmembrane protein?

Pia Röder

What is the function of the SGLT1 transmembrane protein?

It is responsible for transporting glucose into epithelial cells.

Can glucose exit epithelial cells after entering through SGLT1?

No, glucose can enter but can't get out.

What role does GLUT2 -/- play in glucose transport?

GLUT2 -/- transports glucose into villi to be picked up by blood capillaries.

What is more difficult to digest: plants or meats?

plants (think of triceratops eating rocks to digest better)

Why do we need invertase?

To cleave sucrose into glucose and frutose

enteroendocrine cells

Can release hormones that can adjust activity in the stomach

When H leaves, the intracellular pH ____

increases

When Na enters, the intracellular pH ____

decreases