Biochemistry

Question 1

List chemical elements of life

Answer 1

Oxygen
Carbon
Hydrogen
Nitrogen
Phosphorus
Sulfur

Question 2

List the 4 types of macromolecules

Answer 2

Proteins
Polysaccharides
Lipids
Nucleic Acids

Question 3

Troponin

Answer 3

Component of the heart’s muscle fibers
Leaks into the bloodstream when the heart is deprived of oxygen and the muscle fibers are
damaged
Two types of troponin (cTnI and cTnT) begin to increase within a few hours after a heart attack and
stay elevated for up to 2 weeks

Question 4

Myoglobin:

Answer 4

Protein found in both skeletal and heart muscle

Not specific for heart damage but does rise early in a heart attack

Question 5

structure and function of hemoglobin

Answer 5

A tetrameric, heme-containing globular protein in red blood cells that carries oxygen to other cells
and tissues
Contains 2 alpha and 2 beta polypeptide chains
Each hemoglobin can bind 4 oxygen molecules
Average normal adult hemoglobin level is 12-16 gm/dl
Oxygen is primarily transferred in the “bound” state in which 1 gram of HgB carries 1.34ml of O2
A minimal amount of oxygen is carried in the “dissolved” state

Question 6

Isotonic Solution

Answer 6

Concentrations of solutes that cannot cross the plasma membrane are the same on both sides Maintains normal shape

Question 7

Hypotonic Solution

Answer 7

Lower concentration of solutes than the cytosol inside the cell
Water molecules enter the cell causing swelling and rupture, or hemolysis

Question 8

Hypertonic Solution

Answer 8

Higher concentration of solutes than the cytosol

Water molecules move out of the cells causing cells to shrink, called crenation

Question 9

1 of 2 .Passive Transport

Answer 9

Solutes move from an area of higher concentration to an area of lower concentration
No energy required

Question 10

2 of 2.Active Transport

Answer 10

Carrier protein move solutes across the membrane against a concentration gradient
Energy is required!!!

Question 11

K

Answer 11

The major intracellular ion
Necessary for cardiac muscle to perform normal contractions
Normal K+ levels are 3.5 to 5.3 mEq/L
Insulin may be necessary to lower the K+ and maintain a normal sinus rhythm, however, if urine
production is minimal, lasix should be used 1st to see if promoting urine production will aid the excretion of k+

Question 12

Na

Answer 12

The major extracellular ion
Many roles in the distribution of body fluids
Its relationship with K+ keeps sodium out of cells in order for potassium to stay intracellular
Normal Na+ levels are137-145

Question 13

An action potential occurs in the contractile fiber in 3 steps
1.
2.
3.

Answer 13

1. Depolarization
2. Plateau
3. Repolarization

Question 14

Depolarization

Answer 14

Contractile fibers have a stable resting membrane potential close to -90mV
When a fiber is brought to threshold, its voltagegated fast Na+ channels open allowing Na+
inflow because the cytosol is electrically more negative and concentration is lower inside the cell
This rapid inflow of Na+ creates rapid depolarization and within a few milliseconds, the channels deactivate and Na+ flow decreases

Question 15

Plateau

Answer 15

A period of maintained depolarization due to the opening of voltage-gated slow Ca++ channels and
the opening of K+ channels allowing K+ to leave the
cell and sustain depolarization
 Ca++ moves inside the cell and the increased Ca++
concentration ultimately triggers contraction
 Lasts for about 0.25 seconds and the membrane
potential is close to 0 mV

Question 16

Repolarization

Answer 16

The recovery of the resting membrane potential
Additional voltage gated K+ channels open and flows into the cell as the Ca++ channels close
Membrane potential returns back to -90 mV