Cellular Structure and Function 1, 2, 3

W1 Huckle

Describe the scope of physiology and its relationship to other basic medical sciences

physiology studies the function at all levels from molecules to the whole body

provides a basis for understanding endogenous responses to disease, mechanisms of tissue repair, and approaches to diagnostics and therapies

• relations to biology, anatomy, chemistry, and physics

Define the physiological principle of homeostasis and recognize its role in maintaining living organisms

Homeostasis: an organism's ability to modulate its biological components and return to a stable functional state

• when faced with environmental changes/conditions:

  • internal (endogenous)

  • external (exogenous)

Homeostatic feedback control

1. Sensor monitors activity levels

2. integrator receives that information and communicates adjustments to be made

3. Effector makes the adjustments

Negative Feedback

Most functions are controlled through negative feedback mechanisms

Provides an upper limit to system activities → prevents over-compensation to changes in conditions

Negative feedback example: control of arterial blood pressure

• Sensor: baroreceptors

  • Action: sense hydrostatic pressure of blood downstream of heart

• Integrator: cardiovascular control center in medulla of brain

• Effector: autonomic nervous system wired to mechanical control elements in heart and blood vessels

  • Action: change in blood pressure (force/rate of contraction)

Positive Feedback

Biochemical entity or event that feeds back/forward to increase the level of activity of a process leading to its own occurrence or formation

occurs either in the same pathway or a functionally related sequence of events

Recognize the iterative nature of how the scientific method increases our understanding of biological systems

Observation → Hypothesis → Experiment → Observation....

Explain the role of energy expenditure in driving processes needed to maintain living systems

energy expenditure is needed to keep biological systems operating a manner of compatible with life. Schemes need for capture, storage, and retrieval of chemical energy

Major classes of biomolecules

proteins, nucleic acids, carbohydrates, and lipids

Proteins

monomers: α- amino acids

polymers: proteins and polypeptides

components: carboxyl group, amino group, a side chain

function: structural/mechanical, catalysts, chemical messengers, sensors, fuel

Nucleic Acids

monomers: nucleotides

polymer: nucleotide chains

components: nitrogenous base coupled to the sugar ribose (RNA) or deoxyribose (DNA)

function: chemical energy intermediates, information storage, information retrieval, structural, catalytic/regulatory

Lipids

relatively low aqueous solubility

fatty acids, phospholipids, sterols, gangliosides

functions: solubility barrier, structure, chemical messenger, fuel

Carbohydrates

monomers: monosaccharides

polymers: polysaccharides

functions: fuel, energy storage, structure, cellular recognition, communication

Describe the shared and distinguishing features of animal cells

1. sense and respond rapidly to surrounding conditions

2. access stored information for longer-term changes in characteristics

3. generate and utilize forms of chemical energy

4. interact appropriately with their surroundings

stem cells: have the ability to self-renew unchanged and to differentiate into multiple different specialized cell types

Cell Organelles

nucleus, rough ER, ribosome, proteasome, mitochondria, golgi vesicle, golgi apparatus, smooth ER, mitochondrial membrane, lysosome, peroxisome

Mitochondria

major site of energy metabolism, contain their own DNA

Nucleus

information storage and retrieval. Contains all apparatus for DNA replication and transcription

Ribosomes

site of protein synthesis for protein that will remain in the cell. Composed of specialized RNA and protein molecules

Golgi Apparatus

protein sorting, modification export

Proteasomes

degradation of non-functional or mis-folded proteins. Essential for cell cycle, the regulation of gene expression, and responses to chemical stressors

Lysosomes

degradation of internal and ingested material. Roles in defense against invading organisms and disposal of organelles

Plasma Membrane

defines cell boundary

Primary Active

indicates that the ATP hydrolysis occurs during the transport event

• i.e. Na/K ATPase and hydrolysis of ATP

Secondary Active

indicates that a gradient has already been established and an additional molecule is transported alongside the primary

• Antiport

  • Na+/Ca+ energy coupling

• Symport

  • AA, Na+, Na+ gradient serving as form of energy

Simple Diffusion

passive dissolution through membrane (concentration dependent)

Facilitated Transport

aided by a transporter protein, but still concentration dependent

L2,3 Q1: Diversity of protein properties attributable to the various amino acid side chains and their modifications

L3 Q2: The replication and encoding of info made possible by nucleotide pairing

L3 Q3 Self associating and hydrophobic nature of lipids as a contributor to membrane function