m1 + 2 lect. - cell biology Flashcards
parts of a cell?
-cell membrane
-nucleus
-cytoplasm
what cell barrier is semi-permeable?
cell membrane
what can go through a semi-permeable barrier?
water-soluble molecules
- hydrophyllic
-polar +/-
electrolytes
proteins
- enzymes
-hormones
-neurotransmitters
what is the RMP?
Resting Membrane Potential
- the polarity across the surface of the cell
RMP is the resting membrane potential generated by regulating what two ions?
extracellur = Sodium (Na+)
intracellur = Potassium (K+)
in what cells does this RMP become a functional process that allows the cells to transmit impulses?
impulses transmitted and received (dendritic endings) — action potential
- neurons
- muscle
how does action potential begin?
- direct stimulation of a nerve ending
- neurotransmitter release at synapse
neurotransmitter release due to ________, stimulates ___ _________ at the post synaptic membrane.
- calcium
- ion channels
what is the level of stimulation called? (needed to activate action potential)
threshold (-55 nerve)
the influx of what ion begins the depolarization wave?
sodium (Na+)
what does an influx of sodium trigger to open?
voltage gated sodium channels,
causing the action potential across the cell in a wave-like fashion
-opens at threshold (-55)
closes at (+30)
how long does depolarization last?
long enough to allow the influx of Na to change the membrane potential to a +30mV
- then Na gates close
the release of what ion causes the repolarization wave?
potassium (K+)
repolarization wave: what happens as soon as the Na gates close?
K gates then open, releasing K from the cell
what happens when potassium is released during repolarization?
it lowers polarity back to a negative charge
+30mV —-> -55mV
what pump is activated when the K gates are opened in the repolarization wave?
sodium/potassium pump
3 Na+ in/ 2 K+ out for every ATP
what happens with hyperpolarization?
what might cause this?
in the presence of other chemicals, that allow the K gates to stay open
ex.) epinephrine/ norepinephrine inhibiting the visceral smooth muscle
what process do cells use to generate energy?
cellular respiration (aerobic respiration)
- needs oxygen
what two compounds are normally required for cellular respiration?
- glucose
- oxygen
Glucose + O2 => 36ATP + H20 + CO2 —-> exhaust
what organelle is necessary for cellular respiration?
mitochondria
where is aerobic respiration used? and for what activity?
in all tissue cells, to produce ATP necessary for all chemical and electrical activity
what happens in glycolysis?
in cytoplasm, glucose is broken down into:
2 ATP
2 Pyruvic acid
2 NADH
after glycolysis, what happens in the mitochondria?
2 ATP are used to turn 2 Pyruvic acids into Acetyl CoA, 2 NADH are produced also
what happens in the kreb’s cycle?
in the mitochondria, the Acetyl CoA and O2 are consumed, producing:
2 ATP,
6 NADH,
2 FADH,
water and
CO2
what happens in the electron transport chain (ETC)? and why?
coenzymes (NADH, FADH) are reduced and 34 ATP are produced
coenzymes are reduced to prevent free radical production —- damages cells and causes disease + cancer
carb metabolism: polysaccharides (starches) are broken down into Di- and Monosaccharides by what enzymes?
-salivary amylase
-pancreatic amylase
-brush border enzymes
all carbs are broken down into monosaccharides, what are the end products?
-glucose
-galactose
-fructose
all are lastly converted to glucose
any excess carbs will be stored as glycogen or fat, due to:
insulin
glycogenesis is:
creation of glycogen
lipogenesis is:
creation of fat
if not enough carbs, glycogenolysis (1) occurs:
the breakdown of glycogen at the liver and skeletal muscle due to glucagon
glucagon–> breaks things down
if not enough carbs, gluconeogenesis (2) occurs:
used by diabetics, starving or those under stress to produce energy from non-carbohydrate sources
in gluconeogenesis, lipolysis is:
the breakdown of fat
produces 2 Acetyl CoA for every fatty acid, then changes to ketones
in gluconeogenesis, transamination/ urea’s cycle is:
breakdown of proteins
produces a kreb’s intermediate and urea –> eliminated in urine
