midterm 1 Flashcards
Why study Animal Physiology? and what are Physiology’s 2 central questions?
Curiosity!
• Human health and disease
• Evolution
• Understand Behaviour
• Conservation (in terms of climate change we can see how animals respond to changing environments)
• Physiology integrates most of the sciences!
(math-rate functions, chemistry-ATP production, Physics-Locomotion, Psychology-Behaviour)
Physiology’s 2 central questions: how and why (or aka Mechanism and origin)
describe the 4 Important Physiological Concepts
•Homeostasis-physiological processes which maintain
most of the constant states of the organism
- Time- Physiology can change in an animal throughout time (can have programmed changes or changes in response to env)
- Plasticity- The ability of an animal (single genotype) to express two or more genetically controlled phenotypes (the 3 A’s)
- Body Size- Most physiological characteristics are a function of body size (Brain size, Heart rate, Age at sexual maturity, Metabolic rate)
define Regulator, Conformer animals
Relationship between the internal and external environment
• Conformer: internal = external
• Regulator: internal ≠ external, costly
• Animals can use both strategies for different characteristics
define Acclimation, Acclimatization, Adaptation
- Acclimation
• A chronic response to a change in an environment
• Laboratory response - Acclimatization
• A chronic response to a change in a natural environment - Adaptation: happens over multiple generations, evolution
- >When an animal actually evolves to a new environment. Now has a different set of genes.
role of Plasma and intracellular membranes
- Compartmentalize regions of the cells
- Cell signalling
- Transport
describe the membrane bilayer and the flexibility of the structure
Bilayer formed by phospholipids
• Amphipathic (have both hydrophobic and hydrophilic parts)
• Variety of chemical structures
->Phospholipids are flexible and are not set in their structure (Not covalently bound to each other). As the tails become more unsaturated the bonds tend to put a kink in the tail and the membrane becomes more fluid and the cell is more flexible. Butter vs olive oil. Flexibility depends on structure of hydrocarbon tails.
why is membrane fluidity important?
- it allows membrane proteins rapidly in the plane of bilayer.
- It permits membrane lipids and proteins to diffuse from sites where
they are inserted into bilayer after their synthesis. - It enables membranes to fuse with one another and mix their molecules.
- It ensures that membrane molecules are
distributed evenly between daughter cell when a cell divides - it varies with environment
- allosteric modulation of membrane enzymes
Membranes respond to a variety of stimuli? (4)
• Fasting • Dietary changes • Hibernation -temperature (High temperatures cause the fluidization of membranes) • Etc.
describe the 2 Membrane Proteins
integral:
-usually permanent and transmembrane
peripheral:
• Bound non-covalently to one side of the membrane
• Can be added or removed easily
what are the Five functional types of membrane proteins?
Channels- allow things to pass through passively. Simple pore
Transporters/carriers- move things actively (it is facilitated diffusion if metabolic energy is not employed)
Enzymes- catalyze reactions with substrates on membrane (covalent bonds are formed or broken)
Receptors- mediate response of cell to chemical messages arriving outside membrane. (bind to specific molecules and initiate change in membrane permeability or cell metabolism)
Structural proteins- connect one cell to another, creates junctions between cells
what is epithelia?
- Sheet of cells that cover a surface or line a cavity (make up bulk of a lot of animals)
- Cell-cell interactions
why are cellular junctions important and what are the 3 types
Important for:
• Cell-cell interactions
• Cell-cell communication
• Transport across epithelia
- Tight junctions- two cell membranes meet or fuse at ridges
- Desmosomes- block of passage in-between cells and the contact between cells is strengthened
- Gap junctions- block passage between cells but also create tiny pores to allow communication via the two cell’s cytoplasm
two types of Transport across epithelia
- transcellular paths- materials must cross both apical and basolateral epithelia cell membranes
- paracellular path- only small molecules can do this as they have to be able to move past tight junctions between epithelia cells
describe Enzyme Kinetics (what is vmax and km?)
Reaction rate is dependent on substrate concentration (no substrate = no reaction) and enzyme affinity
- > At some point the enzymes will become saturated and cannot process the substrate any faster (this value is Vmax). Increasing the number of enzymes can increase the Vmax
- > Can use the graphs of different enzymes to determine its Km (not all work at the same speed or have the same affinity for their substrate). Km found at half maximum velocity (Km is the conc of substrate that you need to reach 50% of enzymes Vmax) Km= 1/2(vmax)
- Lower affinity enzymes need more substrate present to get going (high Km) even if they have the same Vmax as a high affinity enzymes
how is The function of an enzyme regulated by allosteric modulation
Allosteric modulation:
Anything that’s not covalently bound to enzyme
Inhibited or up-regulated
Other non-substrate ligands
Membrane fluidity (for transmembrane enzymes)
how is The function of an enzyme regulated by covalent modulation
regulated by covalent modulation:
Phosphorylation and dephosphorylation (Protein kinases )
Allows enzyme to function or not function
what are enzyme isoforms and what is their significance
similar functioning enzymes that are slightly structurally different and may function a bit differently but catalyze the same reaction
- Isoforms allow animals to live in new environments or have new functions
- Inter- and intraspecific isoforms (different isoforms within a species and between different species)
- Enzymes can evolve quite easily. Each animal is related in terms of the LDH allele they express.
describe how Enzymes are instruments of change at all time frames
- Acute: allosteric or covalent modulation
- Chronic: expression of genes for different enzymes or isoforms
- Evolution: mutations to genes over time, acted on by natural selection selection (results in mutations and altered genes)
- Development: programmed enzyme expression
- Circadian rhythms: internally programmed enzyme function
• In all cases, cells require what to communicate to each other?
cells require a receptor for the signal and a transducer to
act on the signal (a way to turn signal into an actual message)
how do receptors work? what are the 4 types
Receptors bind extracellular ligand and usually rely on second messengers to transmit signals (ligands are first messengers)
- ligand gated channel
- G protein coupled receptor and associated G protein system (after binding to ligand, receptor binds second messengers- g protein and enzyme)
- enzyme/enzyme linked receptor
- intracellular receptor (ligand diffuses across membrane before binding with receptor)
what is Signal Transduction
the transmission of molecular signals from a cell’s exterior to its interior. Signals received by cells must be transmitted effectively into the cell to ensure an appropriate response
• Receptors activate second messengers: often amplify message to cell
• Cyclic AMP
• Cyclic GMP
what can the cone snail do to fish receptors?
it poisons the fish and paralyzes it by binding its alpha-conotoxin to the fishes receptors and preventing acetylcholine to bind (channels stay closed and muscle cannot contract)
what are Genomics, proteomics and metabolomics ?
Genomics
- study of the genome
Epigenetics: modifications of gene expression that are transmitted
Proteomics
- The study of proteins synthesized by the cell
- 2D-Gel Electrophoresis for protein screening and Western-blotting for protein expression
Metabolomics
- The study of organic compounds in the cell, the biochemical phenotype
what are the two main goals of genomics
2 main goals:
o Evolution of genes
o Function of genes
describe what is looked at for the evolution of genes in genomics
Mechanism of gene modification
• Base substitutions
• Duplication
• Partial or full deletions, mutations that block transcription
and
Timeline of evolution
• When did modifications, loss, duplications, etc. take place? And why did it happen at that particular point in evolution time
why doesnt the Antarctic ice fish produce hemoglobin
Evolved in harsh/cold environments. Only vertebrates that don’t have hemoglobin in their blood which is important for the transport of oxygen. How do these fish survive and why did they end up that way? Is the gene for hemoglobin lost or is it there and just not expressed? In ice fish, they completely lost the beta part of the gene and there is no way for them to produce hemoglobin.
Graph: The loss of hemoglobin gene happened only once, bc everyone after that point doesn’t have hemoglobin either.
Was the loss of hemoglobin in the icefish a disadvantage or an advantage acted on by natural selection?
Less oxygen into the body is usually a disadvantage -> especially if the fish is active. Therefore they probably didn’t lose it on purpose. The ventricles became very big in the fish to pump around more oxygen. Natural selection for the fish without hemoglobin selected for bigger and bigger hearts but now are restricted to living in cold waters because oxygen concentration is higher/more saturated in cold water.
describe what is looked at for the function of genes in genomics
• Newly sequenced genes can be related to previously sequenced similar genes of known function
• This is only a hypothesis and must be tested
• The function might not be the same in a different animal
• The gene might not be expressed at the same time and in the same tissues
• Patterns of transcription
• Patterns of translation
(screening)
Transcription ≠ Translation
how can we can look at physiology from the top down and bottom up?
Top down:
Here is an animal living in this context, how is it doing that? What are the tissues doing? What are the genes?
Bottom up:
Sequenced the genes of a cool animal, don’t know what the genes do? what proteins do the genes code for?
what are Microarrays
example of gene screening where you take a snapshot of changes of gene expression in two different conditions. Under certain conditions, expresses certain genes.
- Allow mRNA to bind to DNA and gives an idea of expression. Less mRNA will result in a change in color.
- You can tell from this if transcription went up, went down or stayed the same