Metabolism
What is the chemical equation for cellular respiration?
C6H12O6 + 6O2 --> 6CO2 + 6H2O + 36 ATP
Give an example of how passive immunity can be acquired.
1. Antibodies in baby acquired from mother through placenta or milk.
2. Direct antibody injections (ex. rabies shot after bite)
3. Direct intravenous antivenom with antibodies (ex. after snake bite)
Do female mammals, including women, produce testosterone?
Yes, both males and females produce testosterone. Males typically produce testosterone at a much higher concentration than females.
What does isogamous and anisogamous mean?
Isogamous: gametes are not differentiated into "male" and "female" types, similar size
Anisogamous: gametes are not the same size
What is 1 and 2 on the figure?
1: dendrites
2: axon
What are the three major metabolic pathways? Give a brief description of each one.
Glycolysis: 6 carbon glucose → two 3 carbon pyruvates
Krebs Cycle: reduce electron carriers (stored energy), produce CO2 as byproduct
Electron Transport Chain: generate ATP from electrons from NADH and FADH2, primary source of ATP
What is the main role of B cells in humoral immunity?
B cells produce and secrete antibodies that target and neutralize pathogens in body fluids.
Where is leptin secreted from, and where does it bind to?
Secreted from adipose (fat) tissue, binds to receptors in hypothalamus.
What is the difference between internal and external fertilization? Give some examples of animals for each case of fertilization. Do birds have internal or external fertilization?
External fertilization: sperm and egg fuse outside of the parents' bodies, typically in aquatic environments. Both gametes are released into the environment separately, and you just have to hope that they cross each other in the water. Animals that do external fertilization include fish and frogs.
Internal fertilization: the male's sperm fertilizes the female's egg inside the female's body, common for most land animals. Animals that do internal fertilization include mammals and reptiles.
Birds have internal fertilization using cloacas. Physical contact between the two allows for sperm to be transferred from the male to the female body.
Which is the presynaptic and postsynaptic neuron? Where is the synaptic cleft? What is the function of all of them?
Top: presynaptic, sends the message
Bottom: postsynaptic, receives the message
Synaptic cleft: space between the two neurons
What are the inputs and outputs of each of the three metabolic pathways?
Glycolysis: 1 glucose (6C) --> 2 pyruvate (3C)
Transition step: 1 pyruvate (3C) --> 1 Acetyl-CoA (2C)
Krebs Cycle: 2 Acetyl-CoA, 2 ADP + Pi, 6 NAD+ + H+, 2 FAD + H+ --> 4 CO2, 2 ATP, 6 NADH, 2 FADH2
Electron Transport Chain: 6 NADH + 2 FADH2 + 6 O2 + 26 ADP + 26 Pi --> 6 NAD+ + 2 FAD + 6 H2O + 26 ATP
Label the figure!
Red: antigen
Blue: antibody
Classify the hormones in the figure as hydrophilic, hydrophobic, peptide, or amine, or steroid. Some categories overlap!
Insulin: peptide, hydrophilic
Cortisol: steroid, hydrophobic
Epinephrine: amine, hydrophilic
Thyroxine: amine, hydrophobic
Label the figure!
See slides
What happens if there is not enough myelin insulating a neuron?
Sufficient myelin is required to insulate neurons so that electrical impulses can travel efficiently. Without enough myelin, these impulses slow down or stop. This could result in loss of sensation, movement problems, vision problems, and cognitive decline. Multiple sclerosis is associated with myelin deficiency.
Given the picture of the mitochondria, label where glycolysis, the transition step, the Krebs cycle, and the electron transport chain takes place.
Glycolysis: cytosol
Transition step: mitochondrial matrix
Krebs cycle: mitochondrial matrix
Electron transport chain: inner mitochondrial membrane
Explain how fever contributes to innate immunity and why it is beneficial despite being energetically costly.
In the hypothalamus, cytokines (messenger proteins) trigger a rise in body temperature. This elevated body temperature then inhibits pathogen replication, increases leukocyte (white blood cell) mobility, enhances phagocytosis, and speeds up enzymatic reactions involved in immune defense. Although costly, the metabolic increase is outweighed by the improved immune efficiency.
What are two things that could be wrong with this mouse?
1. The mouse has defective leptin production in the adipose tissue, so it doesn't produce appetite suppressant signals and continues eating, causing it to be overweight.
2. The mouse has defective leptin receptors in the hypothalamus, so it doesn't receive the appetite suppressant signals and continues eating, causing it to be overweight.
What hormone does the hypothalamus release at the start of the ovarian cycle, and what is its function? What glands release LH and FSH, what is their function?
The hormone releases GnRH (gonadotropin releasing hormone), which stimulates the anterior pituitary to secrete FSH (follicle stimulating hormone) and LH (luteinizing hormone), initiating activity in the ovaries. FSH stimulates the ovaries to begin maturing a follicle, which contains the egg. LH triggers ovulation, which releases the mature egg from the ovary.
What happens when acetylcholine (a neurotransmitter) is stuck or remains in the synaptic cleft?
Acetylcholine is a neurotransmitter that enables muscle contraction (movement). Typically, the vesicle containing the neurotransmitters is released from the presynaptic neurons into the synapse. The neurotransmitters then bind to the receptor on the postsynaptic neuron, producing the desired effect (acetylcholine produces movement). After the desired effect is produced, the neurotransmitter will either be reuptaken by the presynaptic neuron or degraded by enzymes.
However, if this does not occur, the acetylcholine will remain in the synapse and can continue binding to the receptor, causing the neuron to fire another unintentional action potential. Repeated action potential firing due to lack of acetylcholine reuptake or degradation will result in seizures.
In the electron transport chain, describe the movement of electrons and the movement of protons and draw it on the whiteboard. Include locations in terms of the mitochondria.
Electrons come from NADH and FADH2 (electron carriers) produced in the mitochondrial matrix, and are donated to the ETC complexes embedded in the inner mitochondrial membrane. The electrons flow through the ETC complexes until they reach oxygen, which is the terminal electron acceptor and is reduced to water.
As the electrons move through the ETC, they provide energy for active transport of protons from the mitochondrial matrix to the intermembrane space, pumped through the ETC protein complexes. This creates a proton gradient (aka proton motive force): there is a high H+ concentration in the intermembrane space, and a low H+ concentration in the matrix. Protons then flow back into the matrix through ATP synthase, driving ATP production.
A person is exposed to the same pathogen twice. Explain why the second exposure results in higher antibody levels despite the same antigen concentration.
During the second exposure, memory B cells respond immediately and proliferate rapidly. Because there are more memory B cells than naïve B cells and they activate more quickly, the antibody response is stronger and faster. These cells also differentiate into plasma cells more efficiently, producing much higher levels of antibodies for the same amount of antigen.
Explain the role that anti-diuretic hormone (ADH) has in kidney function. Where is it produced? Secreted? What is the target organ?
ADH is produced in the hypothalamus and released from the posterior pituitary, and will travel through the bloodstream to act on the kidney.
When the blood is too concentrated (has too many solutes), the hypothalamus and posterior pituitary will produce and release (respectively) more ADH, which will then act on the kidney. The kidney will then reabsorb more water from waste into the blood, and as a result, the excreted urine is more concentrated while the salt concentration in the blood decreases.
When the blood is too dilute, the hypothalamus and posterior pituitary will produce and release (respectively) less ADH. Without ADH, the kidneys will not reabsorb more water black into the blood, and therefore eliminate more water in the urine. The salt concentration in the blood will then increase back to normal.
What are the components in the milk produced by female mammals while nursing? Why are they important?
Initial milk produced (colostrum) contains antibodies (immunoglobulin IgA), lactoferrin (protein, acts as bactericide and fungicide), and white blood cells. Mature milk is composed of macronutrients: protein, fat, lactose. These components all help babies have stronger immune responses.
Explain what is happening regarding the Na+/K+ ion channels in the neuron at each step of the action potential graph.
The neuron's resting potential is at -70 mV. The voltage-gated Na+ and K+ channels are closed, and the Na+/K+ pump is actively pumping 3 Na+ out and 2 K+ in to maintain the gradient. At this state, the neuron is ready to respond
The threshold potential is around -55 mV, where a stimulus causes a small depolarization. If the membrane reaches the threshold, voltage-gated Na+ channels open rapidly, allowing for depolarization and triggering the action potential. Na+ ions will enter the neuron, causing the depolarization.
At depolarization, the voltage-gated Na+ channels are fully open. There is a massive influx of Na+ down its electrochemical gradient, making the cell more positive.
At the peak of the action potential (about 30 to 40 mV), Na+ stops entering the neuron and voltage-gated K+ channels open, driving the voltage back down.
In repolarization, the large outflow of K+ through the open channels brings the membrane potential back down into the negative values, returning to resting potential.
Hyperpolarization is when the neuron dips below resting potential (about -80 mV).
Finally, the neuron returns to resting potential. Both voltage-gated ion channels are closed, and the Na+/K+ pumps re-establish the ion gradient. The neuron is now reset and ready to fire again.