Cellular Biology

Question 1

What is the Nucleus?

Answer 1

DNA Storage - The control center of the cell which sends messages to grow, mature, replicate or die

Question 2

What is the Mitochondria?

Answer 2

The powerhouse of the cell; responsible for energy production within the cell.

Question 3

What is the Smooth Endoplasmic Reticulum?

Answer 3

• Lipid production
• Phospholipids and cholesterol

Question 4

What is the Rough Endoplasmic Reticulum?

Answer 4

• Embedded with Ribosomes
• Protein synthesis

Question 5

What is the Endoplasmic Reticulum?

Answer 5

1. Provides maximum surface area for physiological function.
2. Divides cytoplasm into compartments and allows different chemical reactions to take place.
3. Protein and fat synthesis

Question 6

What is the Golgi Apparatus

Answer 6

Protein Modification - processes substances from the ER to form lysosomes, secretory proteins and other cytoplasmic components.

Question 7

What is a Ribosome?

Answer 7

Composed of rRNA and protein; site of protein synthesis; free w/I cytosol and bound to RER

Question 8

What is a Lysosome?

Answer 8

Protein Destruction - intracellular digestive system disposing of damaged cellular structures, food particles and unwanted material such as bacteria.

Question 9

Describe the composition of intracellular fluid and the three most common ions?

Answer 9

Fluid located within the cell membrane which contains water, electrolytes, lipids and carbs. Potassium, magnesium, and phosphate are the three most common electrolytes

Question 10

Describe the function of extracellular fluid?

Answer 10

Created and maintained by circulatory function.

Provides micro and macro nutrients

Removes cell waste by carrying toxins to the liver, CO2 to the lungs and Urea to the kidneys

Question 11

What is the structure and composition of the cell (plasma) membrane?

Answer 11

It is a thin, pliable, elastic structure composed almost entirely of proteins and lipids.

55% Protein
25% Phospholopids
13% Cholesterol
4% other lipids
3% Carbhydrates

Question 12

What is the function of the cell membrane?

Answer 12

• semi-permeable
• allows some molecules to diffuse across the lipid bilayer.
• specialized proteins in the cell membrane regulate the concentration of specific molecules inside the cell.

Question 13

What is the function of second messenger mechanisms?

Answer 13

1. Membrane receptor binds a molecule in the ECF
2. Activates inrtacellular enzyme
3. Causes change to the physiology within the cell
4. Cellular response

Question 14

What Ions are found in the Extracellular Fluid (ECF)?

Answer 14

1. Sodium (Na) 142
2. Calcium (Ca) 2.4
3. Chlorine (Cl) 103
4. Bicarb 28
5. Glucose 90

Question 15

What Ions are found in the Intracellular Fluid (ICF)?

Answer 15

1. Potassium (K) 140
2. Magnesium (Mg) 4
3. Phosphate 10
4. Amino Acids 200
5. Protein 16g

Question 16

Describe Transcription.

Answer 16

The process through which DNA replicates into RNA. mRNA carries the code to the ribosome for translation; tRNA transports Amino Acids to Ribosome, and rRNA completes the AA chain which folds into a new protein.

Question 17

What is Mitosis?

Answer 17

The process of cellular division through two phases; interphase and mPhase (Mitosis).

Interphase prepares the cell for division through:

• G1 - (Cellular content duplicate minus Chromosomes),
• Synthesis (Chromosomes Duplicated and DNA Replicated)
• G2 (Cell grows, prepares for Mitosis and checks for errors).

mPhase - Mitotsis - Cell divides into two daughter cells through Prophase, Metaphase, Anaphase, Telophase and Cytokinesis.

Question 18

What is Oxidative Stress?

Answer 18

Free Radicals have an unstable electron, which causes them to attack healthy cells trying to steal electrons. Once started, the process continues until stopped, which causes oxidative stress causing cellular breakdown.

Question 19

What is Reactive Oxygen Species?

Answer 19

Chemically reactive molecules containing oxygen - Peroxide, Superoxide and hydroxyl radical

Question 20

What is Diffusion?

Answer 20

The kinetic movement of molecules or ions through a membrane without interaction with carrier proteins in the membrane.

Question 21

What is Facilitated Diffusion?

Answer 21

Facilitated diffusion requires interaction of a carrier protein. The carrier protein aids passage of molecules through the membrane by binding with them and moving them through.

Question 22

What is Active Transport?

Answer 22

Movement against a concentration gradient, which involves a carrier protein moving a substance all the way through a membrane.

Primary - Energy comes form ATP breakdown

Secondary - Energy was stored in the concentration gradient

Question 23

What is Osmotic Pressure?

Answer 23

Osmotic pressure is the exact amount of pressure required to stop osmosis across a semipermeable membrane

Question 24

What is Oncotic Pressure?

Answer 24

Osmotic pressure caused by proteins - dependent on the number of particles, not the size.

Question 25

What is hydrostatic Pressure?

Answer 25

The force exerted by a column of fluid on the walls of the container (think of the human body)

Question 26

What is Tonicity?

Answer 26

Tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a semipermeable cell membrane.

Question 27

What is Resting Membrane Potential?

Answer 27

Resting Membrane Potential is the electric potential of the cell, which is a result of ions moving in and out.

Question 28

What are the stages of depolarization?

Answer 28

The muscle receives nerve stimulous suddenly becomes permeable to sodium ions. Once the threshold has been met, sodium gated ion channels open allowing rapid diffusion of positively charged Na+ ions into the cell. The normal polarized membrane rapidly gains a positive charge until sodium levels reach +35 at which time Na+ Ion channels close.

Question 29

What are the stages of repolarization?

Answer 29

Within a few 10,000ths of a second after the membrane becomes highly permeable to sodium ions, the sodium channels begin to close (+35) and the potassium channels open to a greater degree than normal. Then, rapid diffusion of potassium ions to the exterior establishes the normal negative resting membrane potential, which is repolarization.

Question 30

How does action potential propagate from a nerve to a muscle?

Answer 30

Acetylcholine is released from the axon terminal of the nerve cell at the neuromuscular junction and binds to acetylcholine receptors on the muscle cell. This binding allows the cell membrane to become more permeable to sodium. As sodium enters the cell, the cell reaches its threshold level of -70 mV and begins to depolarize. Due to the fact that muscle cells can be thick, t-tubules which are invaginations of the sarcolemma help to propagate the action potential to many myofibrils within the cell allowing for simultaneous depolarization throughout the cell.

Question 31

Explain the pathophysiology associated with the blockage of neuromuscular junctions?

Answer 31

The neuromuscular junction (NMJ) is a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/ smooth/ cardiac). It is the site for the transmission of action potential from nerve to the muscle.

Question 32

Compare and contrast slow and fast oxidative and glycolytic muscle.

Answer 32

**Contraction Speed**: Slow - Fast - Fast **Myosin ATPase Activity**: Slow - Fast - Fast **Major Pathway for ATP synthesis**: Aerobic Respiration - Aerobic Respiration - Glycolysis **Rate of Fatigue**: Slow - Intermediate - Fast **Mitochondria**: Many - Many - Few **Color**: Red - Red to Pink - White

Question 33

Describe the functional anatomy and physiology of skeletal muscle contraction.

Answer 33

- RMP of -90mv; duration is 5x longer than nerve APs and1/13th the velocity - contractions require nervous signal input, the NMJ and the release of Ach - able to contract 30% of length; - energy required to maintain contraction; contraction stops when nerve impulse stops - all contractions are voluntary and rather quick - skeletal muscle has a greater store of calcium in its sarcoplasmic reticulum

Question 34

Describe the functional anatomy and physiology of smooth muscle contraction.

Answer 34

- contraction activated via nervous, hormonal or other ligand signal - requires extracellular calcium and no troponin – binds to calmodulin - mostly prolonged, involuntary tonic contractions - able to contract 80% of length (sphincter; movement through intestines) - low energy requirement to maintain contractile state (latch phenomenon) - unitary muscle responds to sudden ‘stress-relaxation’ response - maximum contraction force greater than skeletal.

Question 35

Compare and contrast action potential generation in different muscle types.

Answer 35

**Skeletal:** activated via Ach release from a nervous signal only **Smooth:** can be activated by the following signals/stimuli: nervous / hormonal / Ligand / Stretch of a hollow organ **Cardiac:** Na+ influx for *depolarization*, *short repolarization* via exfil of K+, *plateau phase* Ca++ influx, **repolarization** through K+ exfil, *Resting*