NS 3410 Cellular Organelles

The Nucleus is comprised of what 4 things?

1. Nuclear envelope

2. Chromatin

3. Nucleoli

4. Distinct compartments rich in specific proteins

The nucleus contains ____ and its the ____ center of the cell

genes; control

The nucleus dictates the kinds and amounts of ____ to be synthesized

proteins

Cells and be either?

anucleate or multinucleate

mRNA’s (made in the nucleus) are directed to certain locations before proteins are made. Why?

it helps save energy and help prevent interactions as proteins trafficked

RNA’s may have ___ to position them within cell

“zip codes”

What two functions do Nucleolus’ serve?

1. Synthesize rRNA

2. Assemble Ribosomes

What are the 5 functions for the Smooth Endoplasmic Reticulum (SER)?

1. Synthesize lipids and steroids

2. Detoxify drugs

3. Metabolize carbohydrates

4. Metabolize steroids

5. Regulate Ca concentrations

What does the prefix sarco mean?

muscles

What is the Smooth Endoplasmic Reticulum of muscles? What does it do?

Sarcoplasmic reticulum (SR); Regulates Ca concentrations which is integral to muscle contraction

What are the 3 main functions of the Rough Endoplasmic Reticulum (RER)

1. Protein Folding

2. Quality Control- Identify misfolded proteins so they are degraded in cytoplasm (ERAD= ER- associated protein degradation)

3. Can regulate pace of protein folding via process called UPR= unfolded protein response

Polypeptides translated from ____ into the ER

ribosome

What two things do ER do to achieve correct confirmation?

1. Glycosylates

2. Modifies

Where are proteins exocytosed out to?

cis side of Golgi apparatus

What is the main function of ribosomes?

synthesize proteins

What are the two subunits of ribosomes

1. Small ribosomal subunit

2. Large ribosomal subunit

   each subunit contains ribosomal RNA (rRNA)

For protein synthesis to begin what needs to happen?

Small and large subunits join together with a strand of

messenger RNA (mRNA; made in the nucleus)

What are the two types of ribosomes?

1. Free floating→ scattered throughout cytoplasm

2. Fixed → attached to Endoplasmic Reticulum ER

What is the main function of golgi apparatus?

packaging proteins into vesicles

What is exocytosis?

proteins destined for release outside of the cell

What is the function of secretory vesicles?

proteins stored in vesicle within the cell until signal given for their release

What are lysosomal enzymes?

proteins targeted for lysosome; hydrolases, digestive enzymes, membrane proteins

What are lyosomes “cellular stomach”?

Spherical membranous bags containing powerful digestive enzymes – cleanup and recycling within the cell

Lysosomes digest ingested?

Bacteria, viruses, and toxins

Lysosomes degrade what?

nonfunctional organelles and macromolecules

What is autolysis?

to destroy cells, proteins, and organelles

Products of digestion can be _____ by the cell or removed by _____

reutilized; exocytosis

The interal pH of lysosomes is ~5; How is this maintained?

through proton pumps and chloride ion channels

Many lysosomal enzymes exist what are some examples?

– Polysaccharide hydrolyzing enzymes

– Protein hydrolyzing enzymes

– Nucleic acid hydrolyzing enzymes

– Lipid hydrolyzing enzymes

– Phosphatases / Sulfatases

What do peroxisomes do?

Detoxify harmful or toxic substances

Peroxisomes function in the breakdown of what?

fatty acid (beta oxidation of very long chain FA; those too long to be broken down in mitochondria)

Peroxisomes produce what?

hydrogen peroxide (H2O2)

Peroxisomes contain enzymes (catalase) that do what?

breakdown H2O2 into water and oxygen; and enzymes that utilize peroxide in same compartment to help prevent toxicity of H2O2

Peroxisomes contain over 50 enzymes depending on tissues; they are numerous peroxisomes in what two organs?

liver and kidney (detoxification)

Mitochondria converts organic material into cellular energy ATP; it is the powerhouse of the cell; It what type of metabolism?

aerobic metabolism; requires oxygen

The Mitochondria produces 95% of ATP needed to keep cell alive; Urea/heme synthesis; Mitochondiral DNA is unique from ______

nuclear DNA

What are the two cytoplasmic organelles that are non-membraneous?

1) Ribosomes

2) Cytoskeleton (microtubules, microfilaments, intermediate filaments)

The cytoskeleton is the “skeleton” of the cell; it is dyanmic, elaborate series of rods running through the cytosol; It consists of what 3 things?

1) Microtubules

2) microfilaments

3) intermediate filaments

What are microfilaments?

involved in cell motility and changes in cell shape

What are intermediate filaments?

do not bind ATP or serve as “tracks” main job to resist pulling forces

What are microtubules?

attach to organelles and can move these using motor proteins

Determine the overall shape of the cell and distribution of organelles

Take home messages: Plasma membrane

dynamic structure to all cells

Take home messages: Nucleus

control center, double membrane; a or multinucleate

Take home messages: ER

continuous with nuclear membrane, site of protein synthesis, protein folding, UPR, ERAD, Ca storage (SER), RER

Take home messages: Golgi apparatus

responsible for modifying, packaging and sorting proteins for subsequent cellular use or exocytosis

Take home messages: Lysosomes

responsible for enzymatic degradation of many cellular products

Take home messages: Proteosome

degragde mis-folded proteins

Take home messages: Peroxisomes

oxidation of very long chain fatty acid

Take home messages: Mitochondria

double membrane, ATP production, ETC, oxidative phosphorylation

Take home messages: Cytoskeleton

microfilament, intermediate, microtubule

Take home messages: Cellular organelle composition facilities?

tissue/organ function