cytoplasm biochem

What are the 4 main parts of the cytoplasm?

Cytosol, organelles, inclusion bodies, and cytoskeleton

What is cytosol?

The fluid component of the cytoplasm

What organelles are listed in the cytoplasm?

Ribosome, rough ER, smooth ER, Golgi, lysosome, and mitochondria

What are the 3 cytoskeleton components?

Microtubules, microfilaments, and intermediate filaments

Are ribosomes membrane bound?

No, ribosomes are non membrane bound organelles

What are the ribosomal subunits?

60S large subunit and 40S small subunit

What are ribosomal subunits made of?

rRNA and ribosomal proteins

What is the main function of ribosomes?

Translate mRNA into a polypeptide chain

Where does translation occur?

In the cytoplasm

What is a functional ribosome?

The 60S and 40S subunits together form an 80S ribosome

What do free ribosomes make?

Proteins for use within the cell

What is a polyribosome or polysome?

Multiple ribosomes translating one mRNA at the same time

What do ribosomes attached to ER form?

Rough endoplasmic reticulum

What do bound ribosomes make?

Secreted proteins, lysosomal proteins, and integral membrane proteins

What is the endoplasmic reticulum?

A network of membranous tubules and flattened sacs with a lumen

What makes rough ER look rough?

Ribosomes attached to its surface

What is a main function of rough ER?

Protein synthesis and early protein processing

What happens to proteins in rough ER?

They begin folding into their tertiary structure

Does smooth ER have ribosomes?

No

Is smooth ER continuous with rough ER?

Yes

What are the major functions of smooth ER?

Calcium storage, glycogen metabolism, detoxification, protein transport, and lipid synthesis

What does smooth ER do with calcium?

Stores and releases calcium in skeletal and cardiac muscle

What does smooth ER do with glycogen?

Stores and metabolizes glycogen in hepatocytes

What detoxification occurs in smooth ER?

Detoxification of drugs and harmful metabolic by products

What does smooth ER transport?

Protein material from rough ER toward the Golgi

What does smooth ER synthesize?

Lipids

What is smooth ER called in muscle cells?

Sarcoplasmic reticulum

What smooth ER problem contributes to neonatal jaundice?

Underdeveloped smooth ER in the newborn liver

Why does neonatal jaundice cause yellow coloring?

Bilirubin is not cleared efficiently from the blood

What is the main function of the Golgi apparatus?

Mature, modify, sort, and package proteins

What is the Golgi made of?

Stacks of flattened curved membrane bound cisternae

What are the 3 Golgi regions?

Cis face, medial compartment, and trans face

What is the cis face of the Golgi?

The forming or entry face closest to the rough ER and nucleus

What arrives at the cis face?

Transfer vesicles containing immature proteins

What is the medial Golgi?

The intermediate processing compartment

What is the trans face?

The exit face where mature proteins leave the Golgi

What happens at the trans Golgi network?

Proteins are sorted for their final destinations

What is glycosylation?

Addition of an oligosaccharide to a protein

Why is glycosylation important?

It can help proteins fold, remain stable, and avoid degradation

What are the 3 destinations from the trans Golgi?

Secretory vesicles, plasma membrane, and lysosomes

What happens to proteins in secretory vesicles?

They leave the cell by exocytosis

What are examples of secreted proteins?

Hormones, neurotransmitters, and collagen

What happens to Golgi proteins sent to the plasma membrane?

They become integral membrane proteins

What does the Golgi send to lysosomes?

Enzymes that are stored in lysosomes

What is a lysosome?

A membrane bound organelle containing degradative enzymes

What pH do lysosomal enzymes work best at?

About pH 5

How is lysosomal pH kept acidic?

ATP powered proton pumps

What are major lysosomal enzymes?

Proteases, lipases, and nucleases

What is autophagy?

Lysosomal breakdown of old or nonfunctioning cell structures

What is heterophagy?

Breakdown of material that came from outside the cell

Which cells commonly perform heterophagy?

Macrophages and neutrophils

Where do lysosomes and secretory vesicles originate?

The trans face of the Golgi

Where is a secretory vesicle's final destination?

Outside the cell after exocytosis

Where is a lysosome's final destination?

Inside the cytoplasm

What is the main function of mitochondria?

Aerobic respiration and ATP production

What are the major parts of a mitochondrion?

Outer membrane, intermembrane space, inner membrane, cristae, and matrix

What are cristae?

Folds of the inner mitochondrial membrane

What is the mitochondrial matrix?

The material filling the inner mitochondrial cavity

How are mitochondria moved through the cell?

They are transported along microtubules

How can mitochondria increase or decrease in number?

Increase by division and decrease by fusion

What are cytoplasmic inclusions?

Accumulated metabolites or other substances in the cytoplasm

What are the main inclusion bodies?

Glycogen, lipid droplets, lipofuscin, and melanin

Are most inclusion bodies membrane bound?

No, most are temporary non membrane bound bodies

Where is lipofuscin commonly found?

Non dividing cells such as cardiac muscle cells and neurons

What must you know about each cytoskeleton element?

Its subunit, location, function, and organization

What are microtubules made of?

Alpha tubulin and beta tubulin

What is the shape of a microtubule?

A hollow tube

How many tubulin dimers make one microtubule circle?

13 dimers

What is a major function of microtubules?

Maintain cell shape and provide tracks for intracellular transport

What cellular appendages contain microtubules?

Cilia and flagella

What motor proteins move on microtubules?

Dynein and kinesin

What do dynein and kinesin do?

Move organelles along microtubules

Where do microtubules originate?

The MTOC associated with the centriole in the centrosome

What is the microtubule arrangement in cilia?

9 plus 2 arrangement

Are cilia organelles?

No, their core is made of microtubules

What are microfilaments also called?

Actin filaments

What are microfilaments made of?

Actin

What is G actin?

The globular actin monomer

What is F actin?

The filament formed when G actin monomers polymerize

How is a microfilament organized?

Two F actin strands twist around each other

Where are actin microfilaments found?

Microvilli and prominently in smooth muscle cells

What role do microfilaments have in cytokinesis?

They form the contractile ring with myosin

What is the main function of intermediate filaments?

Structural support and stabilization

What do intermediate filaments connect?

Intracellular structures to each other and to plasma membranes

What intermediate filament identifies epithelial origin?

Cytokeratin

What intermediate filament identifies mesodermal origin?

Vimentin

What intermediate filament identifies muscle cells?

Desmin

What intermediate filament identifies nerve cells?

Neurofilament proteins

What intermediate filament identifies glial cells?

GFAP

Where is lamin found?

Along the inner side of the nuclear membrane