General Physiology Exam 1

What is the primary difference between Anatomy and Physiology?

Anatomy refers to the form or what something looks like, while Physiology refers to its function or how it works

What is Homeostasis?

Homeostasis is often defined as the maintenance of an internal constancy. It is a central concept, with perhaps every physiological system aimed at preserving it

Why is Homeostasis necessary in biological systems?

The internal environment needs to be maintained because organisms need to keep aspects of their body constant

How is Homeostasis maintained?

Homeostasis is maintained by adding energy to the system, which fuels physiological machines built to keep aspects of the body constant. Negative feedback is a key mechanism

What are the three time scales of physiological responses to environmental variation?

The three time frames are: Acute response, Acclimatization, and Adaptation

Describe an Acute response.

An Acute response is an immediate, temporary physiological adjustment, occurring within minutes to hours. It is usually reversible

Provide examples of Acute responses.

Examples include movement, inflammation, cell stress responses, and immediate adjustments to ventilation or heart rate. Increased red blood cell volume after traveling to high altitudes is also an acute response. Heavy breathing when carrying bags at a high-altitude resort is an acute response

Describe Acclimatization.

Acclimatization is a reversible physiological adjustment that occurs over several days, weeks, or months within an animal's lifetime. It is not recorded in the DNA sequence

Provide examples of Acclimatization.

Examples include adjusting metabolic rate, adjusting lung capacity, tanning, and adjusting the makeup of cell membranes. Increased ability to obtain oxygen from the air after living at high altitudes for weeks is an example of phenotypic plasticity through acclimatization

Describe Adaptation.

An Arctic fox's physiological adjustments to its environment are an example of Adaptation. Caribbean anole species having shorter legs when they live in trees compared to those on the ground is likely an adaptation. Human skin tone influenced by genetics is often an adaptation

Provide an example of Adaptation

An Arctic fox's physiological adjustments to its environment are an example of Adaptation. Caribbean anole species having shorter legs when they live in trees compared to those on the ground is likely an adaptation. Human skin tone influenced by genetics is often an adaptation

What is the primary distinction between Acclimatization and Adaptation?

Acclimatization occurs within an animal's lifetime and is usually reversible, while Adaptation occurs between generations, is non-reversible, and is present in the DNA sequence

Can Acclimatization look like Adaptation?

Yes, Adaptation is often, but not always, more pronounced phenotypically, and sometimes acclimatization can lead to phenotypes that resemble adaptations. For example, Anolis sagrei can grow shorter legs in response to a predator, which is an irreversible example of plasticity

What is Phenotypic Plasticity?

Phenotypic plasticity is the capacity for an individual of fixed genotype to exhibit two or more genetically controlled phenotypes in response to environmental variation

Can Phenotypic Plasticity be irreversible?

Yes, while some examples are reversible, plasticity during development often leads to irreversible phenotypes

What is an example of an irreversible phenotypic plasticity?

When Anolis sagrei is grown in the lab on sticks, it develops shorter legs than those grown on a flat surface, which is an irreversible example of plasticity

What are the potential costs and benefits of phenotypic plasticity?

Constitutive (always on) expression of a plastic trait can have a big fitness cost (e.g., 5% reduction in fitness for lactase production led to near extinction in 80 days for E. coli). Whether plasticity has other physiological costs or is simply eliminated by genetic drift when not beneficial remains an open question

How can scientists distinguish between acclimatization and adaptation?

Experiments can provide evidence, such as growing animals in different environments and observing different phenotypes. However, demonstrating adaptation can be more difficult

What study regime is most effective for long-term recall, according to an iClicker question?

Testing oneself with flashcards for one hour per week for three weeks before a trip is more likely to lead to recall of the most names during the trip than just reading

What is Metabolism?

Metabolism refers to the chemical processes occurring within a living cell or organism that are necessary for the maintenance of life

What is Metabolic rate?

Metabolic rate is a measure of how fast metabolic chemical reactions occur, often estimated from the rate of oxygen intake

What describes the difference between your neurons and your muscle cells?

Muscle and neuron cells possess all the same alleles, but they express different alleles (i.e., different genes are turned on or off)

Can cells turn genes on and off?

Yes, cells can turn genes on and off. Stress can also regulate gene activity

If one gene has four exons, how many different transcripts could it potentially produce through transcriptional splicing?

One gene with four exons could potentially produce 16 different transcripts

How many proteins can a human cell with 20,000 genes produce?

A human cell with 20,000 genes can produce 100,000 proteins due to transcript diversity from processes like splicing

Can an enzyme have more than one active site?

Yes, an enzyme can have multiple active sites

What most directly determines the sequence of the polypeptide produced during translation?

The sequence of the mRNA being transcribed directly determines the polypeptide sequence

What are the various levels at which gene expression can be regulated?

Gene expression can be regulated at many levels, including: 1) Regulation of transcription, 2) RNA modification (e.g., splicing), 3) mRNA export, 4) mRNA degradation, 5) Translation, 6) Modification and sorting of proteins, 7) Protein degradation, and 8) Protein activation state (for enzymes)

What are the directly usable forms of energy in a cell?

Directly usable energy molecules include ATP (adenosine triphosphate) and GTP, NADH, and Phosphogens

What are the short-term and long-term stored forms of energy in an animal?

Short-term stored energy includes glucose, pyruvate, amino acids, and ketones. Long-term stored energy includes carbohydrates (like glycogen) and lipids (like triglycerides)

Which molecule is the most common high-energy molecule in living cells?

ATP (Adenosine TriPhosphate) is the most common high-energy molecule

How does ATP transfer its energy to cellular molecules to do work?

ATP transfers its energy by donating its third phosphate directly to the enzyme, a process called phosphorylation

If you add up all the energy an animal uses for growth, activity, and defecation, will it equal the total energy ingested?

No, it will not, because some energy is always lost as heat

What is an Enzyme?

Enzymes are proteins that speed up (catalyze) chemical reactions by reducing the activation energy. Their function is extremely reliant on their shape

How do enzymes affect activation energy?

Enzymes reduce the activation energy required for a reaction to occur, but they do not eliminate it

What is Vmax in enzyme kinetics?

Vmax is the maximum reaction velocity. It is affected by the number of enzymes present

What is the Michaelis constant (Km)?

The Michaelis constant (Km) is a measure of enzyme-substrate affinity. A lower Km indicates higher affinity

What are the four main ways enzyme activity is regulated?

Enzyme reaction rates are regulated by: 1) Protein synthesis rates, 2) Protein degradation, 3) Substrate concentration (Michaelis-Menton kinetics), and 4) Allosteric modulators

What is Allosteric regulation?

Allosteric regulation involves a modulator binding to an enzyme at a site other than the active site (a noncovalent site), which changes the enzyme's shape and thus its activity (either activating or inhibiting it)

What is Metabolic flux?

Metabolic flux is the overall rate of reaction in a biochemical pathway (e.g., glycolysis)

If allosteric inhibition results in a 50% decrease in the velocity of one reaction within a three-enzyme pathway, what would be the effect on total metabolic flux?

It would result in the halving of the total flux rate

What are 'omics'?

'Omics' refers to comprehensive studies of biological molecules: Genomics (entire genome), Proteomics (entire proteome/protein pool), and Metabolomics (entire metabolome/metabolite pool)

What is Genomics?

Genomics is the study of the entire genome (all the genes)

What is the biggest impact of Genomics?

The biggest impact of Genomics has been permitting us to generate hypotheses about physiological function by comparing DNA sequences

What is Transcriptomics?

Transcriptomics is the study of the entire populations of mRNA (gene expression)

What tool is used to investigate entire populations of mRNA in Transcriptomics?

A DNA microarray is a tool capable of estimating the expression of mRNA for thousands of individual genes simultaneously

Provide an example of a Transcriptomic approach.

Quantifying mRNAs present in pH-stressed sea urchins compared to those present in unstressed urchins is a transcriptomic approach

What is Proteomics?

Proteomics is the study of the entire proteome, meaning a cell's entire protein pool. It involves measuring the levels of all proteins in a tissue, which is theoretically one step closer to the phenotype

What tool is commonly used in Proteomics to investigate the entire pool of proteins?

2D protein gel electrophoresis is a good example of a proteomic approach, separating proteins by size and isoelectric point

What is Metabolomics?

Metabolomics is the study of the entire metabolome, meaning a cell's entire pool of metabolites (molecules not coded in genes)

What tool is used to investigate the entire pool of metabolites in Metabolomics?

Nuclear magnetic resonance spectroscopy (NMR) can detect the presence of different compounds via their unique resonance signatures

What is a potential weakness of the "omics" approaches?

A potential weakness is that they often fail to clarify causal relationships between molecules and functions when many molecules are involved

What is Gene knockout?

Gene knockout is a technique where a specific gene is inactivated, often used to test hypotheses about gene function

What does Physiological Development refer to?

Physiological Development refers to the physiology of immature individuals, which always differs from that of adults

Provide an example of physiological development in animals.

As sea lions develop into adults, their mass, dive duration, and oxygen storage capacity increase, with a dramatic increase in muscle myoglobin and blood hemoglobin

Distinguish between Phenotype forced by the environment and Phenotype produced by organism in response to environment.

Phenotype forced by the environment (environmental forcing) is a physical or chemical necessity, like bleeding from a puncture wound. A Phenotype produced by the organism in response to environment is phenotypic plasticity or an adaptive response, like a callus developing on a hand from manual labor

Is increased skin pigmentation (tanning) when exposed to sun an adaptive response or environmental forcing?

It is an adaptive response (phenotypic plasticity)

What is Polyphenic development?

Polyphenic development is a very striking example of phenotypic plasticity in insects, characterized by categorical, non-continuous variation, often leading to distinct phenotypes based on environmental cues

Provide an example of Polyphenic development.

The wet season and dry season developmental female forms of insects, where each color matches the environment better during their season, are examples of polyphenic development

In locusts, is the transition from solitary to gregarious (swarming) genetically or environmentally triggered?

It is environmentally triggered

What is the adaptive advantage of gregarious swarming in locusts?

The adaptive advantage of gregarious swarming is thought to be that it enables the locusts to find food

What is Epigenetics?

Epigenetics refers to heritable changes in transcriptional states (gene expression) due to modification of DNA, but without any change in the gene sequence

Are epigenetic changes heritable between generations?

Yes, epigenetic changes can be passed down through several generations, a phenomenon known as transgenerational epigenetics

What are the two main mechanisms for epigenetic marking?

The two main mechanisms are DNA methylation and Histone modification

What is DNA methylation usually associated with?

DNA methylation is usually associated with decreased gene expression

Do epigenetic marks made during development affect physiology throughout an animal's life?

Yes, epigenetic marks made during development are transmitted through cell lines and can affect physiology throughout an animal's life

What is Diffusion?

Diffusion is a type of passive transport achieved by random physical kinetics, where molecules move from an area of higher concentration to an area of lower concentration

What is the net direction of diffusion when there is a concentration gradient?

The net direction of diffusion is from higher to lower concentration

Do molecules stop moving in a system at equilibrium?

No, at equilibrium, molecules still move, but the net movement in any particular direction is zero

How do concentration gradients affect diffusion rates?

Solutions with larger concentration gradients should have faster diffusion rates

How fast is diffusion over long distances?

Diffusion is very slow over long distances. For example, it could take 30 years to change the sodium concentration by half in a sciatic nerve at the big toe by diffusion alone from the spinal cord

List the factors that affect diffusion rates across a membrane.

Factors affecting diffusion rates across a membrane include the thickness of the membrane, the permeability of the membrane, and the concentration inside and outside the membrane

What factor does not affect diffusion rates across a membrane?

The levels of available ATP do not affect passive diffusion rates, as diffusion does not directly consume ATP

What is the Fick equation for flux rate?

J = D ((C1 - C2) / X), where J is flux rate, D is the ease of diffusion (permeability coefficient for membranes), C1-C2 is the difference in concentration, and X is the distance to diffuse

How do non-polar molecules diffuse across membranes compared to ions?

Non-polar molecules (e.g., steroid hormones) can dissolve in fats and readily diffuse across membranes. Ions cannot and therefore require specialized protein channels

What is Facilitated diffusion?

Facilitated diffusion is a type of passive transport where polar molecules diffuse across membranes aided by transporter proteins. It involves reversible binding to these transporters, occurs in the direction of electrochemical equilibrium, and requires no energy

How do electrical gradients influence diffusion?

Electrical gradients provide potential energy that, in addition to chemical gradients, influences both the rate and direction of passive transport. Ions move towards areas with opposite charge.

In a scenario where Na+ ions are in equal concentration across a permeable membrane, but the left side is positively charged, what happens to Na+?

Na+ should diffuse to the right, towards the negatively charged side, until the electrical gradient is balanced by the chemical gradient at electrochemical equilibrium

When is the diffusion of an ion fastest across a membrane?

Diffusion is fastest when both the chemical force (concentration gradient) and the electrical force (electrical gradient) push the ion in the same direction across the membrane

What is Osmosis?

Osmosis is the movement of water down its own concentration gradient across a selectively permeable membrane

What is Osmolarity?

Osmolarity is the total concentration of solutes in a solution

How do freshwater fish deal with osmotic stress?

Freshwater fish constantly battle the osmotic uptake of water through their gills and must continually rid their bodies of excess water

What is Active transport?

Active transport is a process capable of transporting ions or molecules across a membrane against their concentration gradient, which requires energy (ATP directly or indirectly)

What is Primary active transport?

Primary active transport occurs when a transporter protein directly consumes ATP (and is thus called an ATPase) to move a molecule against its gradient

What is Secondary active transport?

Secondary active transport occurs when a transporter protein does not use ATP directly. Instead, the energy for transport is generated from the cotransport of an ion down its gradient, with that driving ion's concentration gradient being upheld by primary active transport.

What is Cell Signaling?

Cell Signaling is the process by which cells tell other cells what to do, enabling communication and coordination within an organism

What is a Ligand in cell signaling?

A Ligand is the molecule that binds specifically and non-covalently to a receptor protein, initiating a signal

What is a Receptor in cell signaling?

A Receptor is a protein, usually located on the cell surface, that cell signals (ligands) bind to

What is Signal transduction?

Signal transduction is the process by which cells carry out the instructions of a signal. It often involves a series of chemical reactions, commonly through phosphorylation events that activate enzymes

What are Secondary messengers in cell signaling?

Secondary messengers are small, intracellular molecules (e.g., cyclic AMP, Ca2+) that relay and amplify signals from receptors to target molecules within the cell, often initiating phosphorylation cascades

What are the three major types of receptor molecules involved in signal reception?

The three major types include Ligand-gated channels, G-protein-coupled receptors, and Enzyme-linked receptors. Intracellular receptors are also a key type

Which cell signaling mechanism is most likely to alter rates of gene expression?

Intracellular receptors are most likely to alter rates of gene expression, as they bind ligands (like steroid hormones) and often directly regulate transcription

Which cell signaling mechanism is most likely to initiate a phosphorylation cascade via secondary messengers?

G-protein-coupled receptors are most likely to initiate phosphorylation cascades via secondary messengers

What is Signal amplification in cell signaling?

Signal amplification occurs when a single signaling molecule can trigger a large response, often through a cascade where one activated enzyme (like a protein kinase) phosphorylates and activates multiple copies of the next enzyme in the pathway, leading to a dramatic increase in the signal's effect

Provide an example of Signal amplification

In epinephrine signaling, many more glucose molecules are released into the blood than the number of epinephrine molecules that initially bound to receptors, demonstrating signal amplification

What is a Conformer in the context of maintaining internal constancy?

A Conformer allows its internal conditions to match the external environmental conditions (e.g., temperature conformers)

What is a Regulator in the context of maintaining internal constancy?

A Regulator actively keeps its internal conditions constant, despite variations in the external environment, often requiring energy

What is Negative feedback?

Negative feedback is a control system mechanism that opposes a deviation from a set point, working to return a physiological variable to its normal range. It is a primary means of maintaining homeostasis

What is Positive feedback?

Positive feedback is a control system mechanism that reinforces a deviation from a set point, often driving a physiological change to completion rather than maintaining stability

What are the five time frames of physiological changes recognized in animals?

The five time frames are: Acute changes, Acclimatization, Adaptation, Developmental changes, and Changes controlled by periodic biological clocks