NS1: BBCF Flashcards
Types of nerves
sensory: about sensation; can be either exteroreceptors (respond to stimuli from the outside world) or interoceptors (respond to stimuli generated within the body)
motor: carry information about motions that need to be performed
Both kinds of nerves either connect to the spinal cord (thus called “spinal nerves”) or directly enter the skull (thus called “cranial nerves”)
Types of sensory nerves
PHOTON B mnemonic
Photoreceptors respond to the visible spectrum of electromagnetic waves → vision
Hair cells respond to movement of fluid in the inner ear → hearing
Olfactory receptors respond to volatile compounds in the air → smell
Taste receptors respond to dissolved compounds in substances → taste
Osmoreceptors respond to osmolarity of the blood and maintain water homeostasis
Nociceptors respond to painful stimuli → touch
Baroreceptors respond to changes in pressure
Neural pathway
sensory nerve → afferent neuron → cerebral cortex → spinal cord → efferent neurons → interneurons → motor neurons → muscle tissue
Neural pathways in the peripheral nervous system (PNS) convey information to the central nervous system (CNS) and relay instructions.
Those that take information to the CNS are known as afferent nerves, and those that relay instructions from the CNS are known as efferent nerves.
Important neurotransmitters (4) "anyone's goddess" AN-E GDES mnemonic
Acetylcholine activates muscle contraction at the neuromuscular junction. It is used in all autonomic outputs from the brain to autonomic ganglia, and in the parasympathetic nervous system for post-ganglionic connections.
Norepinephrine is used in post-ganglionic connections in the sympathetic division of the autonomic nervous system. It also increases arousal and alertness and focuses attention.
Epinephrine stimulates the fight-or-flight response
Glutamate is an excitatory neurotransmitter and is the most common, as 90% of brain cells are responsive to glutamate.
- In contrast, GABA is the main inhibitory neurotransmitter of the CNS; alcohol acts as a GABA agonist. Glycine is another inhibitory neurotransmitter found in the spinal cord and brainstem that can work in conjunction with GABA.
Dopamine is used in reward and motor pathways; affected by Parkinson’s
Endorphins suppress pain and can produce euphoria.
Serotonin regulates mood, appetite, and sleep in the brain, with low levels associated with depressive mood disorders; also regulates intestinal movement in the gastrointestinal tract, in addition to its effects in the brain.
Two ions involved with muscle contraction
Muscle activation does require release of Ca2+ from the sarcoplasmic reticulum to cause a mechanical response in the muscle. Depolarization (shown below in the context of the entire action potential) is characterized by a rapid influx of Na+ into the neuron.
Thus, both Ca2+ release and Na+ influx are involved.
why are peptide bonds so stable
A peptide is an amide linkage between the amine group of one amino acid and the carboxylic acid group of another.
Amides are stable because they exhibit resonance stabilization between the lone pair on the nitrogen and the double-bond in the carbonyl group.
differences btwn eukaryotic and prokaryotic DNA replication / transcription
Pro: one point of replication + replication occurs in two opposing directions at once + takes place in cell cytoplasm
Euk: multiple points of origin + unidirectional replication + takes place inside cell nucleus
Pros have less polymerase types than Euk.
Eukaryotic pre-mRNAs must have their ends modified, by addition of a 5’ cap (at the beginning) and 3’ poly-A tail (at the end).
- 5’ cap assists in ribosome binding during translation
- poly A tail protects from enzymatic degradation in the cytoplasm
Many eukaryotic pre-mRNAs undergo splicing. In this process, parts of the pre-mRNA (called introns) are chopped out, and the remaining pieces (called exons) are stuck back together.
steps of transcription
Yields an mRNA copy of a gene that can then be transported to the cytosol for translation into a protein
1) Initiation: RNA polymerase binds to a sequence of DNA called the promoter, found near the beginning of a gene. Once bound, RNA polymerase separates the DNA strands, providing the single-stranded template needed for transcription.
- in euk: binding to a promoter requires the assistance of transcription factors, the most important being the TATA box
2) Elongation: One strand of DNA, the template strand, acts as a template (aka anti-sense) strand for RNA polymerase. As it “reads” this template one base at a time, the polymerase builds an RNA molecule out of complementary nucleotides, making a chain that grows from 5’ to 3’; this resultant chain is referred to as the antiparallel complement strand (aka sense strand).
- in RNA, thymine is replaced by uracil
- Termination: Sequences called terminators signal that the RNA transcript is complete. Once they are transcribed, they cause the transcript to be released from the RNA polymerase.
what is (RNA) splicing and why is it important
only in euk
In splicing, noncoding sequences (introns) are removed and coding sequences (exons) are ligated together.
- carried out by spliceosomes (a combination of small nuclear RNAs (snRNAs) and protein complexes.)
Splicing explains why there are over 200,000 proteins in the human body, but only approximately 20,000 genes → greater diversity!
what forces keep DNA double helixes together?
hydrogen bonding btwn the two complementary strands of DNA
define the following
- DNA
- RNA
- cation
- anion
dna = deoxyribonucleic acid rna = ribonucleic acid
cation = ion w positive net charge anion = ion w negative net charge
what is the immune system made of
The immune system is comprised of the innate IS (quick but general response to threats) and the adaptive IS (slower but specific response to threats; “remembered” by the body via memory cells).
what is the innate immune system comprised of
Non cellular: anatomical barriers and signaling molecules (ie cytokiens and complement proteins)
Cellular: range of leukocytes (white blood cells, incl neutrophils, lymphocytes, monocytes and their differentiation into macrophages or dendritic cells, eosinophils, basophils, and mast cells)
what is the adaptive immune system comprised of
incl B and T cells (both of which are lymphocytes produced in the bone marrow but mature in the lymphatic system)
B cells: aka humoral immunity; recognize antigens and secrete large amounts of antibodies (immunoglobulins; Ig) in responses → Ig-A/D/E/G/M
T cells: mature in the thymus; recognize non-self or damaged self cells via interactions with major histocompatibility complex (MHC) Class I and II
what are erythrocytes
red blood cells
Responsible for carrying oxygen to the different tissues of the body + aid in carrying CO2 to the lungs for exhalation → function arises due to them holding hemoglobin (polymer of 4 proteins and iron that binds oxygen)
Created in the bone marrow in response to erythropoietin (EPO), a hormone that is released from the kidney whenever erythrocyte levels are low → during their development, they will lose their membrane-bound organelles, including their mitochondria and nucleus
- As such, they only engage in anaerobic metabolism and have a limited lifespan of only about 100 days
- Their lack of internal organelles contributes to their characteristic biconcave shape, which helps them travel more efficiently through capillaries and maximizes their surface area, which assists in gas exchange
Erythrocytes are degraded by the spleen, which is located in the left upper quadrant of the abdomen.
at blood pH (7.4), which AA’s would be most likely:
- phosphorylated
- negatively charged
The residues most prone to phosphorylation are serine (S), tyrosine (Y), and threonine (T).
Both aspartate / aspartic acid (D) and glutamate / glutamic acid (E) are acidic residues and thus likely to be negatively charged.
what makes up an AA
give examples of the interactions AA’s can have based on their R groups
The central α-carbon has four substituents: –NH2 (amino), – COOH (carboxylic acid), –H, and –R.
The –R group, or side chain, is the only part that differs between amino acids and determines their individual properties.
Polar amino acids tend to be located on the exterior of globular proteins, facing the watery environment. In contrast, nonpolar amino acids are generally buried in the interior of these proteins, protected from the aqueous cytosol or extracellular fluid.
Disulfide bonds can form between cysteine side chains, which are important for the protein’s tertiary structure. Disulfide bonds arise when one cysteine’s sulfur atom connects to another, losing the attached hydrogen atoms in the process
important bio/biochem enzymes and their functions
“KAPPA MD” mnemonic for KPPMD
Kinases transfer phosphate groups from a high-energy source (usually ATP) to their substrates, while phosphorylases transfer phosphate from an inorganic phosphate source.
Phosphorylase enzymes also add phosphate groups to their substrates, so the “general effect” of a phosphorylase on its substrate is similar to that of a kinase.
Phosphatase enzymes are involved with the removal of phosphate from a substrate.
Mutases is a specific type of isomerase. These enzymes neither add nor remove phosphate groups.
Dehydrogenase enzymes are oxidoreductases, or enzymes that catalyze oxidation- reduction reactions.
