Cellular Physiology Flashcards
What is the 60-40-20 rule?
- total body water makes up 60% of body’s volume (40 L)
- 40% (2/3) of total body water is ICF (25 L)
- 20% (1/3) of total body water is ECF (15 L)
What cellular components are NOT organelles?
- free ribosomes
- nucleolus
- cytoskeletal filaments
Describe the Krebs cycle.
- occurs in mitochondria
- generates NADH and FADH that carry electrons to inner mitochondrial membrane
What are the 6 functional categories of membrane proteins?
- transporters
- adhesion molecules
- ligand receptors
- surface antigens
- enzymes
- ion channels
What is cell anaplasia?
- de-differentiation
- cells lose identity and revert to stem cells
- usually not reversible
Describe what happens in complex II of the electron transport chain (likely won’t be on test).
- FADH deposits 2 electrons
- Electrons pass through redox centers, energy released but is not used by complex II
- electrons are passed down and go to coenzyme Q
What is the cell membrane made up of? How does protein compare to lipid composition?
- amphipathic phospholipids with polar head group and 2 fatty acid tails
- membrane proteins
- cholesterol (gives cell it’s rigidity and thermal properties)
- membrane proteins and phospholipids may be glycosolated (glycoproteins and glycolipids)
- contains proteins and lipids in equal mass, but lipids usually ~50 X more abundant. Depends on cell/tissue
What is included in the endomembrane system?
Nuclear membrane, endoplasmic reticulum, and Golgi body
What is cell neoplasia?
- Malignancy
- usually a consequence of dysplasia or anaplasia
What can passively diffuse through the cell membrane?
- small, hydrophobic molecules and diatomic gases (e.g. ethanol, O2, N2, CO2)
- small, uncharged polar molecules (e.g. indole, glycerol or fatty acids)
- anything with a high partition coefficient
What is Fick’s Law?
The rate of diffusion across the plasma membrane is
- directly proportional to concentration gradient and membrane surface area
- Inversely proportional to membrane resistance and membrane thickness
How is total body water influenced by age and sex/bodyfat?
- inversely proportional to age and body fat
- body fat has greater affect
Describe what happens in complex III of electron transport chain (will likely not be on test).
- one electron passes through redox centers before reaching cytochrome c
- cytochrome c carries electron to complex IV, where ETC ends
Describe the cytoskeleton and why it is important to the cell.
- dynamic
- microtubules, actin (microfilaments), and intermediate filaments
- involved in intracellular transport of vesicles, give cell shape and organization
- critical for cell integrity and cell division
Endoplasmic reticulum function
- part of the endomembrane system essential for post-translational processing of proteins (folding, transport)
- rough (granular) ER has ribosomes attached to membrane
- smooth ER is important in lipid synthesis
What is the structure and function of mitochondria?
- double membraned organelle
- outer mitochondrial membrane contains multiple porins, channels, and enzymes
- inner mitochondrial membrane is impermeable and contains ATP synthase and complexes I-IV. Has convulsions called cristae
- region bound by inner mt membrane is called the matrix
- contains mtDNA
- site of aerobic cellular respiration (ATP synthesis) via the Kreb’s cycle and oxidative phosphorylation
- stores calcium
What is the location, structure and function of the Golgi Apparatus?
- located near the endoplasmic reticulum
- consists of flattened sacs (cisternae) that further process and package proteins (and some lipids)
ECF is composed of plasma and ISF. Where is ISF found? What percent of ECF and body weight does each make up and what separates them from each other?
- ISF bathes cells outside the vascular system, as well as bone and connective tissue.
- ECF is 20% plasma (15% body weight), 80% interstitial fluid (5% body weight)
- ISF is separated form plasma by endothelium and basement membranes of capillaries
What is the ratio of ICF to ECF?
2:1 (because ICF is 40% TBW and ECF is 20% TBW)
What is the ratio of ISF to plasma?
3:1 (because ISF is 15% TBW and plasma is 5% TBW)
What is the function of peroxisomes?
contain oxidative enzymes important in metabolism of certain fatty acids, bile, and reduction of free radicals or reactive oxygen species (ROS) such as H202, which is degraded by peroxisomes
Describe the flow of protons between the matrix and the inner mitochondrial membrane.
- inner mt membrane always has more protons
- protons flow into complexes III and IV from the matrix (likely wont be on test)
- protons flow into the matrix from inner mt membrane via ATP synthase
What is the function of ribosomes?
translate mRNA into the correct amino acid sequence, either within the ER or dispersed, making them the sites of protein synthesis
What are the cytoskeletal filaments made up of?
- actin (microfilaments) is made of proteins in a helix
- intermediate filaments are keratin in the integument and most types of neurofilament
- microtubules are made up of tubulin dimers
Describe glycolysis.
- occurs anaearobically in the cytoplasm
- produces 4 ATP from one glucose
What is cell hyperplasia?
increase in number of cells
Describe what happens in complex I of the electron transport chain (likely not on test).
- NADH deposits 2 high energy electrons
- Electrons release energy when passing through redox centers
- Complex I uses energy to pump protons into inner mt membrane
- Last redox center transfers 2 electrons to Coenzyme Q
Name 6 things ATP is used for.
- membrane potential (important for neurotransmission)
- ATPases
- intracellular and membrane (secondary active) transport
- anabolic reactions and processes (27% for protein synthesis)
- driving certain chemical reactions (e.g. gluconeogenesis)
- Mechanical activity of cells (e.g. muscle contraction)
What is a lysosome and what is its function?
- an acidic organelle containing hydrolytic enzymes that degrade or recycle cellular components
- involved in apoptosis and protective against viruses and bacteria
Describe how energy is released from ATP.
- transfers and delivers energy. Does not store.
- energy is released from hydrolysis of the Pi linkage
- PO4- is subsequently transferred to another molecule via enzyme catalysis
What affects membrane resistance?
- size of diffusing molecule
- solubility of molecule in lipids
- composition of lipid membrane
What is cell metaplasia?
- replacement of one cell type for another
- implies change in function
- e.g. Barrett’s esophagus
What is cell dysplasia?
- Abnormal division or nuclear regulation
- suggestive of pathology
Mitochondrial disease is characterized by what?
Muscle weakness and neurological problems
State 3 processes to which diffusion is essential.
- cell nutrition (e.g glucose)
- removal of cellular wastes (e.g. CO2)
- general metabolism
What are the 3 main functions of the nucleus?
- contains DNA
- regulate gene expression
- site of ribosome assembly
Describe the post-translational processing of proteins.
- TRANSPORT vesicles carry proteins from endoplasmic reticulum to cis-face of Golgi body
- processed proteins may leave trans-face of Golgi to be secreted by exocytosis (by SECRETORY vesicles) or remain in the cell.
What affects the diffusion coefficient of a particle?
- Temperature (directly proportional)
- Size (inversely proportional)
- Solubility
- Viscosity (rate of flow) of medium
How does water pass through the plasma membrane?
- through aquaporins (facilitated or passive diffusion)
- through osmosis (large concentration gradients)
What conditions must be met for passive transport?
- favorable concentration gradient
- must be a small unchanged molecule to diffuse through membrane
- if not small, hydrophobic, and uncharged, must receive assistance from a membrane protein
What are the two types of proteins involved in PASSIVE transport?
- ion channel proteins
- carrier proteins
What are the 3 types of passive transport?
- diffusion
- osmosis
- specific and nonspecific facilitated diffusion
Describe the importance of ion channels.
- your entire sensorium depends on them
- your brain and heart needs them
- malfunction of ion channels, usually due to genetics, is can lead to epilepsy, migraines, arrhythmias, and chronic pain
Describe the characteristics of ion channels.
- a type of passive transport (do not require ATP to function and do not pass ions across their concentration gradient)
- somewhat specific
- can be receptors (ligand-gated channels)
- transport faster than carrier proteins
- are commonly gated and closed, but there are “leak channels” that remain open most of the time
What are 3 types of ion channels and how are they regulated?
1) voltage-gated, by change in membrane potential
2) ligand-gated, by binding of a ligand
3) mechanically-gated/ stretch-gated, by mechanical deformation of membrane
Describe how membrane carrier proteins work.
- transport molecules much slowly than ion channels
- transport larger molecules (e.g. glucose, amino acids)
- stereo-specific
- Substrate binds to it then it changes confirmation and releases substrate to other side
- subject to inhibition (blocking)
In facilitated diffusion, what factors does the maximum rate (Vmax) of transport across membrane depend on?
- availability/ number of transporters
- concentration gradient
- in the case of carrier proteins, the time it takes for substrate to bind and the time it takes for carrier protein to make conformational changes
Describe active transport.
- moves molecules against their concentration gradient; this requires ATP. Active transporters hydrolyze ATP.
- Active transporters are often called “pumps” (ATPases)
Describe the importance of the sodium-potassium pump
- essential for cell metabolism
- alters cell osmotic (fluid) balance
- alters membrane charge gradient, which is important for generation of never impulses
