Lecture 1 - Cellular Organelles

The body is comprised of trillions of cells that are classified into about how many different cell types?

200

The cell has three major cell divisions:

plasma membrane, nucleus, and cytosol (-plasma)

The selective barrier separating the ICF from the ECF, which is comprised of a lipid bilayer along with many proteins that run completely or partially through it

plasma membrane

Which part of a phospholipid is hydrophilic and polar: head or tail?

head

Which part of a phospholipid is lipophilic/hydrophobic and non-polar: head or tail?

tail

refers to proteins that completely span the plasma membrane

integral

refers to proteins that only partially span the plasma membrane

peripheral

What is the function of general surface proteins on the plasma membrane?

interact with neighboring cells

What is the function of surface receptors on the plasma membrane?

transmit signal into cell

plasma membrane proteins that are open on both ends and important for communication between the inside and outside of a cell

channels

plasma membrane proteins that are open on one end and closed on the other end to allow for the selective passage of materials (ex. carrier proteins)

transporters

the largest single cellular component and contains the genetic material of the cell (DNA) and is surrounded by a double phospholipid bilayer (nuclear envelope)

nucleus

double phospholipid bilayer surrounding the nucleus and allowing substances to move into and out of the nucleus

nuclear envelope

complex, gel-like liquid between the plasma membrane and nucleus, surrounding the organelles

cytosol

cytosol + all distinct membrane-bound organelles

cytoplasm

What are the 6 main types of organelles in nearly all cells?

nucleus, endoplasmic reticulum, Golgi complex, lysosomes, peroxisomes, mitochondria

extensive membranous system distributed throughout the cytoplasm that is primarily involved in protein and lipid synthesis

endoplasmic reticulum

division of the ER that has ribosomes on its surface, responsible for protein synthesis

rough ER

After proteins are synthesized in ribosomes on the rough ER, where are they released? What happens there?

ER lumen, undergoes folding and modifications

After the proteins synthesized in the rough ER are released to the ER lumen and undergo folding and modifications, where are they transported to next?

Golgi complex

division of the ER that does not have ribosomes on its surface, not involved in protein synthesis and serves primarily as a final packaging and discharge site for molecules (proteins & lipids) transported to the Golgi complex

smooth ER

Why do some specialized cells, such as liver, skeletal muscle, and steroid hormone secreting cells, have an extensive smooth ER?

they function in storage of calcium and cholesterol

stack of flattened, membrane-bound sacs that process the raw materials from the ER into finished products and sort/direct these finished molecules into vesicles to their final destinations (another organelle or plasma membrane)

Golgi complex

process in which raw materials from the ER are turned into finished products by attaching a carbohydrate to a hydroxyl or functional group of another molecule, which is important for processing proteins and determining their structure, function, and stability

glycosylation

flattened, membrane-bound sacs in the Golgi complex

cisternae

What are the 6 steps of the protein transport process?

(1) synthesis in RER (2) packaging and budding in SER (3) fusion with Golgi complex (4) processing and sorting in Golgi (5) budding from Golgi and transport to the plasma membrane (6) fusion with the plasma membrane

process in which a secretory vesicle in cytosol travels to and makes contact with the plasma membrane, triggering a fusion reaction between the two membranes so that the contents of the vesicle are released into extracellular fluid

exocytosis

How does the sorting of proteins happen in the Golgi complex? What makes that possible?

each protein has a specific sorting signal attached to it when synthesized

What does the Golgi complex have that binds to the sorting signals on proteins so that those proteins can be organized and localized to certain regions?

specific recognition markers

molecules on the outside of a cell that bind specific cytosolic proteins that are involved in forming a coat around the vesicle, which allows a pulling motion to occur that forms exocytic vesicles that budded from the Golgi

coat protein acceptors

coat protein found inside the cell that is involved in the formation of vesicles for transport

clathrin

specific protein on the surface of a vesicle that budded from the Golgi that serves as a docking marker that binds to and interacts with t-SNARE on the surface of the plasma membrane

v-SNARE

protein on the surface of the plasma membrane that binds with v-SNARE to trigger the fusion between the vesicle and plasma membrane so that exocytosis can occur and contents can be released outside the cell

t-SNARE

membrane-bound organelles that serve as the intracellular digestive system; contain hydrolytic enzymes that break down the organic compounds ingested by the cell via endocytosis; also remove worn-out organelles

lysosomes

1 of the 3 major endocytosis processes "cell drinking", non-selective uptake of small molecules

pinocytosis

1 of the 3 major endocytosis processes: highly selective uptake triggered by a ligand binding to its receptor

receptor mediated endocytosis

1 of the 3 major endocytosis processes: internalization of large, multi-molecular particles like bacteria or erythrocytes (selective to an extent)

phagocytosis

membrane-bound organelles that contain oxidative enzymes and most of the cell's catalase

peroxisomes

enzyme that is important for the conversion of hydrogen peroxide into water and oxygen; found mostly in peroxisomes

catalase

reaction involved in the detoxification of various wastes produced in the cell and foreign toxins ingested by the cell, which occurs in peroxisomes

oxidation

power plants of the cell since they supply the cell with about 90% of its energy in the form of ATP; enclosed by a double membrane, and uses pyruvic acid made from glycolysis to carry out Krebs cycle and ETC

mitochondria

series of infoldings of the inner mitochondrial membrane; forms a labyrinth of sorts inside the mitochondria

cristae

breakdown of glucose by a series of enzymes in the cytosol to produce pyruvic acid

glycolysis

product of glycolysis that goes into the mitochondria and is converted to ATP via a series of enzyme reactions in the mitochondrial matrix (Krebs cycle)

pyruvic acid

In the Krebs cycle, in addition to ATP made from pyruvic acid, excess hydrogen comes in the form of what two molecules?

NADH, FADH2

After the Krebs cycle, the ETC in the inner mitochondrial membrane converts excess hydrogens (NADH, FADH2) into ATP via their movement across the membrane. This generates about how many more ATPs in addition to what has been produced already?

28-32

substance that occupies 55% of total cell volume and is the site of many metabolic processes (i.e. glycolysis); ribosomal protein synthesis; and storage of fat, carbohydrates (glycogen), and secretory vesicles

cytosol

What three things are stored in cytosol?

fat, carbohydrates, secretory vesicles

intracellular scaffolding that gives the cell shape and structure, made of microfilaments, microtubules, and intermediate filaments also serves as an intracellular highway for the trafficking of vesicles to and from the plasma membrane

cytoskeleton

proteins in the cytoskeleton made of many other different proteins, has a relatively middle diameter

intermediate filaments

What makes up microfilaments?

actin

What makes up microtubules?

tubulin

Molecular motors that power the movement of vesicles to and from the plasma membrane are what kind of enzymes?

ATPases

exocytosis molecular motor (carries vesicles from cell body to axon terminal)

kinesin

endocytosis molecular motor (carries vesicles to the cell body)

dynein

maintenance of a relatively stable environment; essential for the survival of each cell, and each cell through its specialized functions contributes as a part of a body system to the maintenance of the internal environment shared by all cells

homeostasis