Cell Organelles

Question 1

Cell Structure Pic.

Answer 1

Blank on purpose.

Question 2

Nucleus

Answer 2

• Largest organelle
• Two membranes form the nuclear envelope
• Contains the nucleolus

Question 3

What is the nucleolus?

Answer 3

A small dense structure composed largely of:

• RNA
• Most of the cellular DNA;
• Histones: DNA binding proteins, that regulate its activity

Question 4

Primary function of nucleus

Answer 4

The primary functions of the nucleus are

• Cell division and
• Control of genetic information.

Other functions include:

• Replication and repair of DNA
• Transcription of the information stored in DNA.

Question 5

Discuss genetic information transcribed into RNA:

Answer 5

When genetic information is transcribed into RNA it can be processed into:

• Messenger
• Transport
• Ribosomal RNA

It is then introduced into the cytoplasm, where it directs cellular activities.

Question 6

Where does most of the processing of RNA occur?

Answer 6

In the nucleolus

Question 7

What represents about 1/2 the volume of a eukaryotic cell?

Answer 7

Cytosol

Question 8

What is cytosol?

Answer 8

The aqueous solution in the cytoplasm that fills the cytoplasmic matrix.

• 55% of cell volume

Functions:

• Intermediary metabolism
  
  • Enzymatic biochemical reactions
• Ribosomal protein synthesis
• Storage of:
  
  • carbs,
  • fat and
  • secretory vesicles

Question 9

What is the cytoplasmic matrix?

Answer 9

Space between the nuclear envelope and the plasma membrane.

Question 10

What also functions as a storage unit for fat, carbohydrates, and secretory vesicles?

Answer 10

Cytosol

Question 11

What are ribosomes?

Answer 11

• RNA-protein complexes (nucleoproteins) that are synthesized in the nucleolus and secreted into the cytoplasm through pores in the nuclear envelope called nuclear pore complexes (NPCs).
• may float free in the cytoplasm or
• attach themselves to the outer membranes of the endoplasmic reticulum

Question 12

What is the chief function of ribosomes?

Answer 12

Provide sites for cellular protein synthesis

Question 13

What is the endoplasmic reticulum (ER)?

Answer 13

• Membrane factory that specializes in the synthesis and transport of protein and lipid components
• Consists of network of tubular/saclike channels (cisternae) that extend throughout the cytoplams and are continuous with the outer nuclear membrane

Question 14

What two characteristics can the folded membranes that form the cisternae of the endoplasmic reticulum be?

Answer 14

• Rough (granular)
• Smooth (agranular)

Question 15

Why is rough ER (rER) rough?

Answer 15

Ribosomes and ribonucleoprotein particles are attached to it.

Question 16

Why is smooth ER (sER) smooth?

Answer 16

It does not have ribosomes are ribonucleoproteins attached to i.

Question 17

What is the chief function of the endoplasmic reticulum?

Answer 17

• Protein synthesis and folding.
• A new role is sensing cellular stress
• The endoplasmic reticulum communicates with the Golgi complex and interacts with other organelles, particularly lysosomes and peroxisomes.

Question 18

What is the golgi complex?

Answer 18

• Network of flattened, smooth membranes and vesicles frequently located near the nucleus of the cell.
• Proteins from the endoplasmic reticulum are processed and packaged into small membrane-bound sacs or vesicles called secretory vesicles, which collect at the end of the membranous folds of the Golgi bodies—called cisternae.
• The secretory vesicles then break off from the Golgi complex and migrate to a variety of intracellular and extracellular destinations, including the plasma membrane.
• The vesicles fuse with the plasma membrane, and their contents are released from the cell.

Question 19

What is the chief function of the golgi complex?

Answer 19

The Golgi complex is a refining
plant and directs traffic (e.g., protein, polynucleotide, polysaccharide molecules) in the cell.

Question 20

What organelle do many molecules, including lipids, proteins, glycoproteins, and enzymes of lysosomes, pass through at some stage in their maturation?

Answer 20

Golgi Complex

Question 21

What are the coats of best known vesicles from the golgi complex made of?

Answer 21

Coats made largely of the protein clathrin and are called clathrin-coated vesicles.

They bud from the Golgi complex on the outward secretory pathway and from the plasma membrane on the inward endocytotic pathway.

Question 22

What are lysosomes?

Answer 22

• Lysosomes (lyso = dissolution; soma = body) are saclike structures that originate from the Golgi complex.
• They contain digestive enzymes called hydrolases,

Question 23

What is the chief function of lysosomes?

Answer 23

• Lysosomes function as the intracellular digestive system
• Lysosomal enzymes are capable of digesting most cellular constituents completely to their basic components:
  
  • such as amino acids,
  • fatty acids, and
  • carbohydrates.

Question 24

Name one genetic defect affecting lysosomal storage:

Answer 24

Pompe Disease

Question 25

Discuss Pompe Disease

Answer 25

* Glycogen accumulation in lysosomes * Lack of: * lysosomal a-1, 4-glucosidase * Clinical Presentation: * Predominant sign is usually progressive muscle weakness, generally beginning with the trunk and proximal muscles of the lower limbs.[1], [2] * Clinical manifestations can first appear at any age, from early childhood to late adulthood. * In children, the first signs may be delayed motor milestones.[ * Similarly, adults may first notice difficulty walking or climbing stairs and exhibit gait abnormalities. * Early respiratory involvement resulting from degeneration of the diaphragm and other respiratory muscles may manifest as respiratory insufficiency, including orthopnea and indications of sleep-disordered breathing such as morning headaches and daytime fatigue. * Feeding and swallowing difficulties Poor weight gain/maintenance

Question 26

What is Tay-Sachs disease?

Answer 26

* Lysosomal storage disease * Accumulation of GM2 ganglioside (lipid) in lysosomes * b/c of deficiency or absence of lysosomal hexosaminidase * Inherited if both parents have Hex-a gene * A defective gene on chromosome 15 (HEX-A) causes Tay-Sachs disease. This defective gene causes the body to not make a protein called hexosaminidase A. Without this protein, chemicals called gangliosides build up in nerve cells in the brain, destroying brain cells. * Symptoms: muscle weakness, coordination issues, rhythmic muscle contractions, stiff muscles, faint feeling, dysphagia, hearing loss, seizures, vision loss and/or impaired voice.)

Question 27

Brief discussion of gout's patho:

Answer 27

* In gout, undigested uric acid accumulates within lysosomes, damaging the lysosomal membrane. * Subsequent enzyme leakage results in cell death and tissue injury.

Question 28

What are peroxisomes (microbodies)?

Answer 28

* Membrane-bound organelles that contain several oxidative enzymes such as catalase and urate oxidase. * Peroxisomes contain enzymes that use oxygen to remove hydrogen atoms from specific substrates in an oxidative reaction that produces H₂O₂. * **Peroxisomes also have an important role in the synthesis of specialized phospholipids necessary for _nerve cell myelination_.**

Question 29

What are mitochondria?

Answer 29

* Mitochondria (mito = thread; chondros = granule), organelles * **Responsible for cellular respiration and energy production.** * Metabolic pathways involved in the metabolism of carbohydrates, lipids, and amino acids and special pathways involving urea and heme synthesis are located in the mitochondrial matrix. * The outer membrane is permeable (passable) to many substances, but the inner membrane is highly selective and contains many transmembranous transport systems. * The inner membrane contains a transporter to move electrically charged calcium (calcium ions). * Mitochondria contain their own DNA that codes for enzymes needed for oxidative phosphorylation.

Question 30

What is a vault?

Answer 30

An octagonal barrel-shaped organelle believed to transport messenger RNA from the nucleus to the cytoplasmic ribosomes.

Question 31

What is the cytoskeleton?

Answer 31

* "bones and muscles" of the cell * Maintains shape and internal organization * Permits movement of substances within the cell and movement of external projections (cilia, flagella)

Question 32

What is mechanotransduction?

Answer 32

Cellular process that translates mechanical stimuli into biochem signals, allowing to adapt to surroundings.

Question 33

What is the plasma membrane?

Answer 33

Surrounds the cell or intracellular organelle. Allow or exclude various molecules - selective transport allows for in/out molecule movement.

Question 34

5 functions of cell membrane (PP)

Answer 34

* 1. Structure * 2. Protection * 3. Activation * 4. Transport * 5. Cell to Cell interaction

Question 35

Structure of phospholipid molecule

Answer 35

Blank on purpose.

Question 36

Channel Receptor Example (Na/K pump)

Answer 36

Channel Receptors-Respond to receptor “stimuli”-transport proteins like channels from one side of membrane to anotherInactive and Active state EXP: sodium-potassium ATPase -thousands in every membrane which * use 1/2 of body’s energy every day * shuttles 3 positive-charged sodium atoms out of the cytoplasm * and simultaneously admits 2 positive-charged potassium atoms into the cytoplasm * Each revolution throws off more + charges out of cell than it lets in leaving the cell negatively charged with outside cell positively charged creating a “membrane potential”