Hemoglobin
What is the advantage of the O2-Hb dissociation curve's sigmoidal shape?
It allows the body to release oxygen quickly at a steeper slope when needed, as well as allowing less oxygen to be released at higher PO2s.
How does the bird respiratory system differ from mammals?
1. Their gas exchange occurs in the parabronchi instead of the alveoli.
2. Birds have unidirectional air flow, as opposed to bidirectional in animals.
What is the central dogma?
The flow of genetic information: DNA -> RNA -> proteins
How do mutations occur?
Differences in amino acid sequences
What is the role of start and stop codons?
They tell the RNA enzyme when to start producing the mRNA and when to cut it off.
Why does human Hb not work sufficiently at higher altitudes? Relate this to the O2-Hb dissociation curve.
Human Hb doesn't work as well at higher altitudes because the PO2 is much lower and the Hb doesn't bind as willingly to oxygen.
What is the advantage of unidirectional air flow?
The air moving through birds' lungs is mostly "fresh", and their lungs have a higher oxygen content. More oxygen is available to move to the blood.
Which DNA bases bind together? Which RNA bases bind together?
DNA: A-T and G-C
RNA: A-U and G-C
Are mutations harmful, neutral, or beneficial?
They can be all of the above! The most common mutations have little to no effect.
How do bodies protect themselves from mutations?
DNA repair enzymes are able to fix and prevent most mutations.
Explain how cooperative binding in O2 works and how Hb changes shape.
Hb is naturally in a very tense state. As O2 binds to it, it will take on a more relaxed position, which will allow for more O2 molecules to bind to it. As O2 molecules eventually are released, it will be easier for others to leave.
Describe the Hb-O2 dissociation curve when comparing the grey-lag goose to the bar-headed goose.
Both curves are similar to humans at high and low oxygen affinities. The bar-headed goose has a much higher affinity for oxygen than the grey-lag goose.
Translate the following DNA sequence into an RNA strand: A A G G T C A C G T A G C A
U U C C A G U G C A U C G U
Point: one base changes to another
Insertion/deletion: one or more bases are inserted or removed
Duplication: a large chunk of DNA is duplicated within the strand.
Chromosomal: there is a large scale change in the structure of chromosomes.
They Himalayas grew beneath them as they flew and they just flew slightly higher each migration pattern
How do pH, PCO2, temperature, and 2-3-BPG change O2 affinity?
Higher PCO2, higher temperature, lower pH, and the presence of 2-3-BPG will cause a right shift or a lower O2 affinity.
What is the function of air sacs and how does the airflow within birds direct oxygen-rich air through the lungs in both inhalation and exhalation?
Air sacs store both fresh and "used" air for short periods of time that allow for consistently fresh air.
During inhalation: airflow moves into the posterior air sacs, through the parabronchi, and out into the anterior air sacs.
During exhalation: airflow moves from the anterior air sac through the parabronchi.
Walk through the steps of transcription.
1. An enzyme unzips the double-stranded DNA of a gene. One strand of DNA serves as a template to be copied.
2. The enzyme will spit out a complementary strand of RNA that is used later in translation.
3. The RNA strand (now mRNA) will leave the nucleus through a pore and enter the cytoplasm.
Why do loss of function mutations have little to no affect on organisms?
Humans have two alleles of each gene, and if one has a loss of function mutation, the second copy can still do the work necessary.
Why might high-altitude Hb be disadvantageous at low altitudes?
How does the PO2 and PCO2 change from the atmosphere compared to the lungs?
Atmosphere to lungs: There's a higher PO2 in the atmosphere, but a higher PCO2 in the lungs.
Why does the high-efficiency respiratory system of birds not work well at high altitudes?
The primary sequence of amino acids gives a different oxygen affinity, whether higher or lower. The two amino acid differences are proline or alanine.
Walk through the steps of translation.
1. A ribosome will bind to an mRNA base three at a time (a codon).
2. tRNA brings the appropriate amino acid next in sequence based on their anti-codon.
3. The AA sequence will continue to grow until it forms a functioning protein.
NOTE: protein folding occurs while translation is occuring.
What are some causes of mutations?
Radiation, harmful chemicals that mimic the structure of other molecules, errors during RNA replication, and viruses.
Explain the differences between chromosomes, genes, and alleles.
A chromosome is a strand of DNA. Each strand of chromosome contains genes, which are the parts of DNA that are specifically transcribed and translated into proteins. Alleles are different ways these genes are produced/expressed.