Basic Principles Flashcards
What are Niko Tinbergen’s 4 levels of analyses?
Mechanisms
Development
Evolution
Adaptation
What is Krogh’s principle?
A Physiological problem of one species is likely to occur in another
What is the SENSOR in positive and negative feedback/
The hypothalamus
What happens when the physiological system of homeostasis fails?
Behaviour changes and behavioural homeostasis occurs
What does it mean to be POIKILOTHERMIC?
Cold-blooded
What % saline concentration does the body attempt to maintain? What does this equate to in g NaCl / L?
0.9% Saline Concentration
= ~8.5g NaCl / L
What stimulates the secretion of vasopressin?
Dehydration in osmoreceptors
Why does vasopressin target the kidney?
In order to gain maximal reclamation of H2O
What inhibits vasopressin?
Alcohol
What does PVN stand for?
Paraventricular Nuclei
What does SON stand for?
Supraoptic Nuclei
Where is vasopressin found?
Paraventricular Nuclei & Supraoptic Nuclei
What is ADH?
ADH = Antidiuretic Hormone = Vasopressin
What is thirst?
How many kinds of thirst are there?
What are they?
Thirst is the motivation to seek and ingest H2O;
There are two kinds;
Osmotic thirst & hypovolemic thirst.
What is the difference between osmotic thirst and hypovolemic thirst?
Osmotic thirst:
Increase in osmotic pressure of interstitial fluid relative to intracellular fluid (cellular dehydration)
Hypovolemic thirst:
A decrease in blood volume without a decrease in intracellular fluid
What are two reliable hormone indicators of body fat?
Insulin & Leptin
What does it mean to be OREXIGENIC?
To be hungry - an increase of food intake
Hormones associated: Neuropeptide Y & Agouti-Related Protein
What does it mean to be ANOREXIGENIC?
(Satiety) - a decrease in food intake
Hormones associated: Pro-opiomelanocortin (POMC) & Cocaine&hetamine regulated transcript (CART)
Which of the (5) nucleic acids are purines and which are pyrimidines?
Adenine & Guanine are PURINES
Cytosine, Thymine & Uracil are PYRIMIDINES
What is DNA?
A polynucleotide chain consisting of pentose residues linked with phosphodiester bonds
What facilitates the binding of polymerases in RNA?
An increased temperature (~92˚C) and or the addition of enzymes reduce the hydrogen bonds between nucleotides and facilitate the binding of polymerases
What is an example of a single-stranded RNA virus? (ssRNA)
Norovirus - causes vomiting and diarrhea
What is an example of a double-stranded RNA virus? (dsRNA)
Rotavirus - Severe diarrhea in infants and young children - immunity develops with each infection
What are two commonly studied epigenetic modifications?
DNA Methylation & Histone acetylation
Describe DNA Methylation
DNA methylation is an epigenetic modification that occurs at the promoters of DNA and silences transcription.
Around 1-5% of the cytosine residues are modified by the addition of a methyl group (-CH3) to the 5’ Carbon to form 5’-methyl-cytosine.
The action is catalysed by the enzyme DNA methyltransferase
It usually occurs in CpG sites, regions rich in CpG sites are called CpG islands and are abundant in promoters.
When the DNA is replicated, the new strand is unmethylated, maintenance methylase catalyses the methylation to create 5’-methyl-cytosine in the new strand.
Demethylase (TET) can reverse the methylation and once methylated, strands can be transcribed.
Heavily methylated strands tend to be inactive.
What is TET? What does it do?
Ten eleven translocation - Demethylases DNA
Describe histone acetylation
Histone acetylation is another form of epigenetic modification.
Each DNA histone has a tail at it’s N-terminus containing around 20 amino acids (mainly lysine), which is positively charged and sticks out.
Because of its positive charge and the negative charge of DNA, there is usually a strong ionic attraction between the tail and DNA.
However, histone acetylases add acetyl groups and change the charge of the amino acid tail. As a result of this, the compact nucleosome opens. Acetylated histones (COCH3) result in euchromatin.
Additional chromatin remodeling proteins, histone deacetylase can remove acetyl groups from histones and repress transcription. Deacetylated histones result in heterochromatin.
Histone deacetylases are being targeted as possible drugs for the treatment of some cancers.
A combination of DNA Methylation and histone deacetylation means what for transcription?
Transcription is repressed
A combination of DNA un-methylation and histone acetylation means what for transcription?
Transcription is enhanced
DNA methylation and histone acetylation act during both embryonic and foetal stages with permanent effects. How is it transmitted?
Transmitted through maternal lineages and establishes in germline cells. Resulting in permanent effects on physiology can mean phenotypic variation despite identical genomes.
DNA methylation and histone acetylation are rhythmic, what does this mean?
They are reversible; both methylation and acetylation regulate a range of physiological processes that change throughout the day.
What is the basic structure of a protein?
Amino acid
amine, carboxylic acid, hydrogen and “R” group
What is the primary structure of a protein?
A linear sequence of amino acids
What is the secondary structure of a protein?
Alpha helices or Beta-pleated sheets
Briefly describe alpha helices
A right-handed coil. The R groups extend outward from the peptide backbone of the helix. Coiling is a result of hydrogen bonds forming between the hydrogen of N-H of one amino acid and the oxygen of C=O of another.
The coil is stabilised when this pattern is repeated over a segment of the protein.
Briefly describe beta-pleated sheet
Formed when two or more polypeptide chains are almost completely extended and aligned. The sheet is stabilised by hydrogen bonds between the N-H of one chain and the C=O groups of another.
A Beta-pleated sheet can form between separate polypeptide chains or between different regions of a single polypeptide chain that is bent back onto itself.
What is the tertiary structure of a protein?
Polypeptides fold, forming specific shapes. Folds are stabilised by bonds, including hydrogen bonds and disulfide bridges.
In many proteins, the polypeptide chain is bent at specific sites and then folded back and forth, resulting in the tertiary structure. Although alpha helices and beta-pleated sheets contribute to tertiary structure, usually only portions of the macromolecule have these secondary structures and large regions consist of tertiary structure unique to a particular protein.
Briefly describe how disulfide bridges are formed
Two cysteine molecules in a polypeptide chain can form a disulfide bridge (-S-S-) by oxidation (removal of hydrogen atoms).
What is the quaternary structure of a protein?
Many functional proteins contain two or more polypeptide chains, called subunits, each of them folded into its own unique tertiary structure. The protein’s quaternary structure results from the ways in which these subunits bind together and interact.
Quaternary structure can be dimers, trimers, tetramers etc.
What is the central DOGMA?
DNA –> RNA –> Proteins
What are some challenges to the central DOGMA?
Non-coding RNA (ncRNA) - They do not make proteins, but still have a function.
What are the two kinds of non-coding RNA?
What is the difference between them?
microRNA:
20-50 base pairs long; can function as ligands for proteins and mediate base-pairing interactions to specific RNA or DNA sites
long ncRNA:
>200 base pairs long; similar to microRNA; can fold into higher structures for versatility in proteins and target sequence recognition.
What is the structure of fatty acids?
A carboxyl head with a hydrocarbon tail (between 4-28 Carbons)
What is the difference between saturated and unsaturated fats?
Unsaturated fats have a double bond between two carbon molecules, meaning there is a “kink” in the hydrocarbon tail
Saturated fats do not have a double bond between two carbon molecules and therefore have a straight hydrocarbon tail.
Glycerides have what kind of molecule attached to a fatty acid?
Monoglycerides, diglycerides, and triglycerides are all dependent on what?
A Glycerol molecule.
The number of fatty acids attached to a single glycerol molecule
What would be the result if a phosphate group were to replace the glycerol molecule of a triglyceride?
A phospholipid
What is cholesterol?
How many types are there?
What are they?
What are their functions?
Cholesterol is a lipid sterol
There are two kinds,
Low-density lipoprotein: causes the formation of plaque
High-density lipoprotein: removes the build-up of low-density lipoprotein and takes it to the liver for degradation
What are monosaccharides?
Sugar molecules (either pentose or hexose) that are the building blocks for carbohydrates
What is a disaccharide?
Two monosaccharides joined together.
Most common examples are sucrose and lactose
Briefly describe sucrose
A glucose molecule with an alpha-glycosidic bond to a fructose molecule
Briefly describe lactose
A glucose molecule with a beta-glycosidic bond to a galactose molecule
What is a polysaccharide? Give examples
A polysaccharide is a linked number of monosaccharides.
Glycogen is the primary form in animals and starch is the primary form in plants. Polysaccharides are stored in the liver and muscle cells of animals.
What is the 1st law of thermodynamics?
Energy can neither be created or destroyed, only changed from one form to another
What are the functions of calories?
- Maintain vital organs
- Build, maintain and repair cells and body tissues
- Drive metabolic processes
- Maintain body temperature
- Support external activites
What is a calorie?
The amount of heat required to raise the temperature of 1g of water by 1˚C
How many Joules of energy in 1 calorie?
1Kcal = 4.18J
How many calories in 1 Joule?
1 J = 0.239Kcal
What is digestive efficiency?
How do we calculate it?
The amount of ingested energy absorbed
DE = (GEI-(Loss/GEI))x100%
What is GEI?
How do we calculate it?
GEI = Gross Energy Intake
GEI = Food intake x Energy content in food
How do we calculate energy loss?
Loss = Faeces weight x Energy content in faeces