EPHE 242 Organelles & Intro

what are the four characteristics of living matter

1. complicated and highly organized

2. each constituent has a specific function

3. extracts raw energy from the environment and synthesizes own complex structures from simple raw materials

4. capable of precise reproduction

describe the six life processes

1. metabolism: the sum of all chemical reactions in the body (comprised of catabolism and anabolism, the formation and breakdown of complex chemical substances)

2. responsiveness: body’s ability to detect and respond to internal and external environmental changes

3. movement: motion of the whole body, individual organs, single cells, and structures inside cells

4. growth: increase in body size resulting from an increase in size or number of cells

5. differentiation: development of a cell from an unspecialized to a specialized state

6. reproduction: formation of new cells for tissue growth/repair/replacement, OR the production of a new individual

what are the four key themes of physiology

1. homeostasis - maintenance of the internal environment

2. integration - all components of the body working together at various levels to keep the body alive

3. mechanism of action - explaining how the body works through a mechanistic approach

4. communication - understanding the body’s messengers that allow the body to function

what are emergent properties

at each level of organization in the body, new properties emerge that are not present at the levels below (eg: memories, GI tract peristalsis)

what is integration

a process by which several components work together for a common, unified purpose (the body is much more than the sum of its parts)

homeostasis is controlled by

feedback systems and feedforward control

how are most variables in the body controlled

negative feedback systems

what’s the difference between positive feedback and feedforward control

positive feedback strengthens or reinforces a change in a controlled variable, while feedforward control is when events occur in anticipation of a change in a controlled variable

what is the difference between disorder and disease

disorder: abnormality in function or structure

disease: illness characterized by a recognizable set of signs and symptoms

what is the difference between signs and symptoms

signs are objective changes a clinician can observe, and symptoms are subjective changes in body function that are not apparent to an observer

what is the difference between the cytoplasm and the cytosol

cytoplasm = cytosol + organelles

• cytosol is the fluid itself, cytoplasm is all the internal components of the cell excluding the nucleus

what is the role of membranes

• separate the cytoplasm and the ECF

• regulate the passage of substances in and out of the cell, and between organelles

• detect chemical messengers arriving at the cell

• link adjacent cells together

• anchor cells to the ECM

• protect the contents of each organelle from each other and from the cytosol

phospholipids have ___ heads and ___ tails, making them ____

hydrophilic; hydrophobic; amphipathic

what is the difference in the plasma membrane structure of a molecule that isn’t very metabolically active

it won’t have as many membrane proteins because it won’t engage in membrane transport and cell signaling as often

what are the three types of lipids in the plasma membrane

phospholipids, sphingolipids, cholesterol

the amphipathic property of the plasma membrane is important because it

creates a barrier against the passage of water-soluble particles

what is the main similarity and difference in structure between a phospholipid and a sphingolipid

similarity: both have fatty acid tails, and are of a similar chemical structure in general

difference: sphingolipids have longer tails, making the plasma membrane appear bumpy

what is the function of sphingolipids

support the CM in areas containing proteins associated with:

• developing tissue

• cell recognition

• adhesion to ECM / other cells

• receptors for toxins

besides making the membrane more fluid, cholesterol __

prevents crystallization of phospholipids

structure of lipid rafts

• cholesterol

• sphingomyelin

• glycolipids

• peripheral proteins

function of lipid rafts

important site for entry and exit of viruses

glycolipids and glycoproteins attach to the CM via __ bonds on the extracellular surface

covalent

what are the function of membrane carbohydrates

glycocalyx (protection and cell adhesion)

cell recognition (immune response and tissue growth)

what is glycocalyx (structure and function)

structure: dense gel mesh containing CHOs

functions:

• protective barrier for the cell

• differing CHOs in the glycocalyx of different cells allows for cell recognition

• acts as a mechanosensor on endothelial cells, triggering vasodilation when BP increases

• storage for proteins that may be used by the cell

what are blood tyeps determined by

the # and composition of sugars attached to sphingolipids

functions of the cytosol

• location of specific chemical reactions

• storage of fat and carbs

• storage of secretory vesicles

• ionic composition → maintaining resting membrane potential (nerve & muscle cells)

apart from the PM, what else are double membrane organelles

mitochondria, nucleus

what can cause a change in blood type

• infection

• malignancy

• autoimmune disease

• bone marrow transplant

ribosomes on the ER produce proteins for __, versus free ribosomes produce proteins for __

secretion from the cell or distribution to other organelles; release into the cell

compare the function of the rough and smooth ER

rough ER:

• synthesis of proteins (ribosomes) and lipids for packaging in vesicles for transport out of the cell

smooth ER:

• lipid synthesis (triglycerides and steroids)

• liver: detoxification enzymes (can develop the structure further if this function is used in large amounts)

how do people build up a tolerance for opiates

repeated use of a substance considered toxic can cause an increase in sER development in the liver, to allow for adequate detoxification in the cells

what is the function of the golgi apparatus

• modification of macromolecules made in the ER (lipids, proteins)

• packages macromolecules made in the ER

• secretory vesicles transport the macromolecules to the cytosol or membrane

describe the location of the cis and trans faces of the golgi apparatus relative to the ER

cis face: faces the ER

trans face: faces the cytosol

describe the relationship between covid and function of the golgi apparatus

covid causes the golgi to assemble virus proteins and more virus

dysfunction of what organelle relates to Parkinson’s, Alzheimers, and ALS

fragmentation of the golgi apparatus (early warning sign)

• consider its function - will have incomplete or dysfunctional molecules if the golgi isn’t working properly

what is the function of the mitochondria

production of ATP via aerobic metabolism

• kreb’s cycle in the matrix

• ETC on the inner membrane

what organelle triggers apoptosis

the mitochondria

what is unique to mitochondria regarding replication

• can replicate by budding even when the cell is not dividing because they have their own DNA

what is the function of vaults

may help transport molecules between the nucleus and the cytoplasm (eg: bringing mRNA out of the nucleus and joining it with ribosome subunits)

what organelle contributes to chemotherapy resistance and how

vaults:

• chemotherapy drugs accumulate in the nuclei of cells in attempt to destroy it so the cell dies

• therapy resistant cells respond and create more vaults, transporting the chemo drug through the PM via exocytosis

function of the cytoskeleton

• provides mechanical support and structure

• suspends organelles in the cytosol

• motor proteins use it to transport materials throughout the cell

what are the three major components of the cytoskeleton

• microfilaments: actin

• intermediate filaments: myosin, neurofilaments, keratin

• microtubules

function of microfilaments

• muscle contraction (actin)

• separation of cytoplasm during cell division

• structural support for cell projections (microvilli, hair cells)

function of microtubules

• provides a dynamic structure

• transport of secretory vesicles etc

• major component of cilia and flagella

function of kinesins (motor protein)

movement of vesicles - take things towards the plasma membrane, away from the center of the cell (opposite of dyneins)

function of dyneins (motor protein)

• movement of vesicles

• walk towards the center of the cell (opposite of kinesins)

function of lysosomes

• breaks down molecules into monomers that are useful to the cell, via digestive enzymes

• important role in immune cells

function of proteasomes

• breaking down damaged, misfolded, or unwanted proteins that are flagged with a “death tag”

• specialized type called the immunoproteasome assists in the breakdown of viral proteins

function of peroxisomes

• detoxification

• oxidative reactions

• turn hydrogen peroxide (2x h202) into two water molecules and one oxygen gas molecule