Histology 1 (Exam 1) Flashcards
What is the plasma membrane composed of
Phospholipid bilayer with proteins embedded in the membrane
How are the molecules of the phospholipid bilayer arranged
Polar-hydrophilic heads facing outwards
non-polar hydrophobic tails facing inwards
What are the different types of membrane proteins associated with the lipid bilayer
Peripheral proteins
Integral proteins
What are peripheral proteins
proteins that are embedded in just one of the membranes
integral proteins span the membrane completely
What lipid helps maintain fluidity of the lipid bilayer
cholesterol
What are the two faces of the plasma membrane
extracellular (e-face)
protoplasmic (p-face)
Are the p-face and e-face identical
no, they have different proteins on each face
What are the types of integral membrane proteins
Channels Pump Enzymes Receptors Linker
What is the function of Channel proteins
opens a gate and allows molecules to flow through, down its gradient
What is the function of pump proteins
spans entire plasma cells and moves things between internal and external environments
What is the function of receptor proteins
ligand binds to receptor and creates and intercellular conformation change that activates a signaling cascade
What is the function of enzyme proteins
to speed up reactions
What is the function of linker proteins
associated with plasma membrane and interact with proteins that span plasma membrane
What are the different methods of transport across a plasma membrane
Channel
Carrier
Diffusion
What is the method of channel transport
small molecules (usually ions) flow through, down its gradient
What is the method of carrier transport
Molecules are carried across a membrane, can be active or passive, is highly selective
What is active transport
requires the use of ATP or energy
What is passive transport
does not need energy to proceed
What is the method of diffusion
small, hydrophobic molecules can diffuse through the plasma membrane without the help of a protein
What are the types of vesicular transport
Endocytosis
Exocytosis
What is endocytosis
bringing things from outside the cell in
What is exocytosis
bringing things from inside the cell out
What are the types of endocytosis
Pinocytosis
Phagocytosis
Receptor-mediated
What are the types of exocytosis
constitutive
regulated
What is pinocytosis
“cell drinking”
cell nonspecifically takes up molecules through invaginating the plasma membrane
What is phagocytosis
performed by certain cells (neutrophils, macrophages) that engulf bacteria or pathogens and bring them into the cell to be killed
What is receptor-mediated endocytosis
ligand binds to receptor, activates adaptin to make a vesicle from the plasma membrane (may require use of clathrin),
receptors and ligand are brought inside the cell
sorted before sent to lysosome
What is constitutive exocytosis
cell releases products as they are made, constant fusing of vesicles with the plasma membrane
What is regulated exocytosis
there must be a signal to tell the cell to secrete product at a certain time
For phagocytosis, what must be rearranged in order for phagocytosis to occur
actin cytoskeleton of the cell
How does clathrin coated pits form
during receptor-mediated endocytosis
ligand binds to receptor will activate adaptin
adaptin will then recruit clathrin to plasma membrane to form clathrin coated pit that will generate vessicle for endocytosis
Clathrin dependent is what
requires clathrin for vesicle formation
What is clathrin independent
does not require clathrin for vesicle formation
What is an endosome
larger vesicle within the cell that becomes more acidic as it matures
(becomes lysosome)
What is the function of early endosomes
sort and recycle proteins
What is the pH of early endosomes
pH 6.2-6.5
What is the function late endosomes
pre-lysosomes
What is the pH of late endosomes
pH of 5.5
What is the function of lysosomes
degrade molecules from endocytic pathways and autophagy
What is the pH of lysosomes
4.7
What is contained within a lysosome
diverse array of acid hydrolases that become active when the pH reaches 5
What are the types of acid hydrolases/ enzymes in a lysosome
proteases nucleases lipases phospholipases glycosylases sulfatase phosphatases
What type of proteins are seen in lysosomal membranes
lysosome-associated membrane proteins,
glycoproteins, other integral membrane proteins
Why is the pH of lysosomes important
that is when the enzymes will work, if they spill into cell they won’t work
What are the four pathways that can lead to intracellular digestion
pinocytosis
phagocytosis
receptor-mediated endocytosis
autophagy
What is autophagy
when cells self eat material, recycles component within the cell
Other than lysosomes, how might single polypeptides and proteins be degraded within a cell
non-membraneous structures in cytoplasm called proteasomes
What are the features of Tay-Sach’s disease
Cherry red macula
loss of vision and hearing
muscle atrophy due to loss of nervous tissue
early death by 5y
What is deficient in Tay-Sach’s disease
Hexosaminadase deficient
What accumulates in Tay-Sach’s disease
Ganglioside GM2 accumulates in neurons
What are the characteristics of I-cell disease
skeletal abnormalities
hepatomegaly
mental retardation due to abnormal cellular architecture
early death by 5 y
What is deficient in I-cell disease
N-acetylglucosaminyl-1-phophotransferase
What accumulates in I-cell disease
lysosomal hydrolases not phosphorylated in Golgi, get secreted instead
What are the characteristics of Niemann-Pick disease
hepatosplenomegaly
neurodegeneration
progressive wasting due to sphingomyelin accumulation in all cells
early death often by 3y
What is deficient in Niemann Pick disease
Sphingomyelinase
What accumulates in Niemann Pick disease
Sphingomyelin
What are characteristics of Gaucher disease
affects the spleen, liver, lungs, bone marrow due to accumulation of glucosylceramide in cells of the macrophage-monocyte system
What is deficient in Gaucher disease
Beta-glucocerebrosidase
What accumulates in Gaucher disease
glucosylceramide
What enzymes are contained within peroxisomes
catalase and peroxidase
What is the function of peroxisomes
break down peroxide
What cells are peroxisomes abundant in
liver and kidney cells
What processes are peroxisomes involved in
beta oxidation of fatty acids (long chain)
detoxification of ethanol
synthesis of plasmalogens: maintain membrane integrity in CNS
What causes Zellweger syndrome
Nonfunctional peroxisomes
What are the features of Zellweger syndrome
CNS demyelination
early death
What occurs due to nonfunctional peroxisomes
inability to import proteins to peroxisomes and accumulation of long-chain fatty acids;
mutation in gene encoding the integral membrane protein Pex2; demyelination in CNS
When will constitutive endocytosis occur
antibodies
When will regulated endocytosis occur
endocrine, neurons
Which is seen more, constitutive or regulated endocytosis
regulated
How will secreted proteins be handled
become integral membrane proteins , or will be membrane bound/part of an organelle, are synthesized on rough ER ribosomes and then trafficked to the proper location based on signal sequence within the polypeptide chain
What will result from an a1-antitrypsin (A1AT) deficiency
a single amino acid substitution renders the rER unable to export (A1AT). Leads to decreased activity of A1AT in the blood and lungs and abnormal deposition of defective A1AT within the rER of liver hepatocytes, resulting in emphysema and impaired liver function
What is the function of rER
synthesize proteins and secretion
What cells are rER prominent in
Secretory cells
What cells are sER abundant in
hepatocytes
What is the function of sER
cells that function in lipid metabolism, detoxification, and steroid synthesis
What is the function of the golgi apparatus
post translational modification, sorting, packaging proteins
Where are the two faces of the golgi apparatus found
cis- closest to nucleus
trans- towards outside, further from nucleus
How does mitochondria generate ATP
oxidative phosphorylation
TCA
beta oxidation of fatty acids
What cells will lack mitochondria
RBCs and terminal keratinocytes
