Biology Chapter 6

Why was it difficult to develop a drug to treat Pompe Disease?

It had to contain a specific delivery system to the lysosome, had to be inactive within the general circulation but active in the lysosome, had to cross the lysosomal membrane

What is unique about the environment in a lysosome?

It is very acidic and contains many hydrolytic enzymes

Why is autophagy important?

It's a recycling program. The cell does not have to synthesize new monomers from scratch (which is very metabolically expensive)

Name two organelles with dramatically different environments within the cell

Lysosomes: acidic environment (pH 4-5) helpful because it digests damaged organelles and recycles monomers Endoplasmic Reticulum: (pH 7.1) neutral environment

Where in the body are lots of cilia found?

The epithelial cells of the lungs

Pancreatic Amylase is made in pancreatic cells and is secreted into the lumen of the small intestine where it acts to digest polysaccharides to disaccharides. Are the ribosomes that direct the synthesis of Pancreatic Amylase most likely found within the cytoplasm or attached to the endoplasmic reticulum (ER)? Why?

The ribosomes that synthesize pancreatic amylase are attached to the ER. Pancreatic amylase is an enzyme that is secreted, and its synthesis must be connected to the endomembrane system of the cell.

What 2 types of cell junctions help form a strong seal between the cells?

Tight junctions Desmosomes

What is the purpose of mechanical signaling pathways?

To relay mechanical info from the outside of the cell to the inside of the cell

In general, what is the cause of Lysosomal Storage Diseases?

a genetic disease where one of the hydrolytic enzymes within the lysosome is not made or does not function

What are dyneins?

motor proteins in cilia that function to move cilia (bend back and forth) which interact with doublet microtubules in the outer ring of a motile cilium

What type of cytoskeletal fiber is found inside microvilli and what specific protein does this fiber contain?

microfiliments that consist of two twisted strands the protein actin

Describe the arrangement of microtubules within a cross section of motile cilium.

-9 doublets of microtubules are arranged in a ring, with 2 microtubules in the center; 9+2 pattern

Describe the arrangement of microtubules within a cross section of a basal body.

-9 triplets of microtubules are arranged in a ring; 9-0 pattern

What is the function of the enzyme GAA? How is it linked to Pompe disease?

-Breaks 1,6 glycosidic bonds in glycogen -necessary for the complete degradation of glycogen, without it the lysosomes become enlarged with glycogen which interfere with normal muscle cell function

What are 2 symptoms associated with onset of Early Onset Pompe Disease? How is it treated?

-Enlarged heart, weak muscles -enzyme replacement therapy

What are 3 functions of peroxisomes in liver cells?

-breakdown of fatty acids into smaller molecules that can enter mitochondria as fuel for cellular respiration -detoxification of alcohol and other harmful compounds in liver cells -formation of H2O2 when hydrogen ions are transferred to water and the conversion of H2O2 (toxic) into water (not toxic)

What is unique about the structure of the nuclear membrane?

-exists as a double membrane -contains pores that allow proteins to easily move into and ribosomes to easily move out of the nucleus

In addition to the synthesis of proteins that are secreted from the cell or embedded within a membrane, what are two other functions of the rough endoplasmic reticulum (RER)?

-glycosylation of proteins (the process by which sugars are attached to proteins) -synthesis of phospholipids that become part of the ER membrane

What are the 3 most common destinations for transport vesicles that bud from the golgi apparatus?

-move to other parts of the cell or plasma membrane -move back to the ER -move back to the cis side of the golgi apparatus

Peroxisomes are small sphere-like structures within the cell. Are these part of the endomembrane system? Why?

-no -they don't bud off from the endomembrane system, they grow by incorporating proteins and lipids found in cytosol or made in the peroxisome itself. They just divide themselves when they become too big.

What are 3 functions of the enzymes attached to the SER?

-synthesis of lipids (oild, steroids) -Carbohydrate metabolism -detoxification of drugs, poison, alcohol, etc.

What are three types of cell junctions that function to connect two adjacent animal cells?

-tight junctions -desmosomes -gap junctions

What is the name of the molecule that attaches integrin to the microfilaments located in the cytoplasm?

Acessory protein

What ion is stored in the lumen of the SER?

Ca2+

What key biological process occurs within mitochondria?

Cellular respiration

What's the difference between the cis and trans sides of the golgi apparatus?

Cis: receiving side (vesicles fuse with golgi membrane) Trans: transport side (vesicles bud off from goldi membrane)

Name 2 proteins found in the extracellular matrix

Collagen Proteins found in the proteoglycan complex (mostly carbs though)

What protein attaches the extracellular matrix to integrin proteins found in the plasma membrane?

Fibronectin

What type of cell junction contains pores that allow molecules and ions to move freely between adjacent cells?

Gap junctions

What type of cytoskeletal fiber is found in the cilia?

Microtubules that contain tubulin

Name 2 other organelle besides the nucleus that contain DNA

Mitochondria and Chloroplast

According to the endosymbiont theory, what 2 organelles may have evolved from prokaryotic species?

Mitochondria and Chloroplasts

What is the major function of chloroplast?

Photosynthesis

What are 2 ways prokaryotes differ from eukaryotes?

Prokaryotes are much smaller and don't have a membrane around their nucleus or organelles

What kind of nucleic acid is synthesized in the nucleolus?

Ribosomal RNA (rRNA)

Structurally, how does the smooth ER differ from the rough ER?

Ribosomes are not attached to the smooth endoplasmic reticulum

What 3 cellular structures are present in both prokaryotes and eukaryotes?

Ribosomes, Chromosomes, plasma membrane

What is the function of the nucleic acid rRNA?

found in ribosomes which function in protein synthesis (translation)

What 2 types of macromolecules are modified as the move through the cisterna of the golgi apparatus?

glycoproteins and phospholipids

Are microfiliment fibers or intermediate fillament fibers larger?

intermediate filament

What is autophagy?

process where a lysosome fuses with a "double-membrane" vesicle containing damaged organelles. Once fused, the lysosome releases its hydrolytic enzymes, which function to degrade the damaged organelles and the "inner" membrane of the vesicle. The monomers will be released from the vesicle into the cytosol where they will be used to make new macromolecules