BMB 555 Organelles
What is the smallest distance two points can be separated and still be resolved using light microscopy?
0.2um or 200 nanometers
Which is the smallest living unit?
A cell
Prokaryotic cells do not possess
A nucleus (nuclear envelope)
Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called?
Active transport
Lysosomes are found in
Animal and plant cells
Which of the following processes do take place in the peroxisomes?
Breakdown of very long chain fatty acids peroxidation reaction detoxification of toxic molecules production of bile acid
You have generated antibodies that recognize the extracellular domain of the Ca2+ pump. Adding these antibodies to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+?
Ca2+ pumps in the endoplasmic reticulum membrane keep cytosolic calcium levels low. (The pump in the ER is a backup for calcium in case anything goes wrong with the active transport pump)
The overall relationship that links bond-forming reactions to membrane transport processes in the mitochondria is called Chemiosmotic coupling
Chemiosmotic coupling
The nucleus, an organelle found in eukaryotic cells, confines the ___________, keeping them separated from other components of the cell
Chromosomes (genomic DNA)
Vesicles from the ER enter the Golgi at the:
Cis Golgi network (body, face) - (the trans face is the side that get fuels to the plasma membrane or endosomes)
Which of the following processes do take place in the mitochondria?
Citric acid cycle conversion of pyruvate to activated acetyl groups oxidation of fatty acids to acetyl CoA
Which of the following choices BEST describes the role of the lysosome?
Clean-up, Recycling, and disposal of macromolecules
Which component of the electron-transport chain is required to combine the pair of electrons with molecular oxygen?
Cytochrome c oxidase
Most peroxisomal proteins are synthesized in the
Cytosol
Proteins that are fully translated in the cytosol and lack a sorting signal will end up in the?
Cytosol (if a protein does not have any targeting signal or sorting signal it will stay in the cytosol. Proteins that are getting translated in the cytosol but have a nuclear localisation signal they can go to the nucleus because they have the signal for the protein to be targeted to the nucleus)
New membrane phospholipids are synthesized by enzymes bound to the _____ side of the ______ membrane?
Cytosolic: endoplasmic reticulum
Which of the fowling choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels?
ER, Golgi, Plasma membrane
Which of following is a process that delivers material to the lysosome?
Endocytosis (heterophagy, includes pinocytosis and phagocytosis), autophagy
The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted by-products back out. Which term describes the process by which external materials are captured inside transport vesicles and brought into the cell?
Endocytosis (opposite of exocytosis)
Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are?
Endosymbionts
Cells that are specialized for the secretion of proteins are likely to have which of the following features?
Enlarged endoplasmic reticulum
The mitochondrial ATP synthase consists of several different protein subunits. Which subunit binds to ADP +Pi and catalyses the synthesis of ATP as a result of a conformational change?
F1 ATPase head
Stepwise condensation of linear DNA happens in five different packing processes. Which of the following four processes has a direct requirement for histone H1?
Formation of the 30-nm fiber
Which of the following statements describes the mitochondrial inter-membrane space?
It contains proteins that are released during apoptosis
What is the role of the nuclear localization sequence in a nuclear protein?
It is bound by cytoplasmic proteins (receptors) that direct the nuclear protein to the nuclear pore
Which of the following statements describes the mitochondrial outer membrane?
It is permeable to molecules mass as high as 5000 daltons
Which of the following is true of the N-terminal "tail" of the histones?
It is subject to covalent modifications It extends out of the nucleosome core It help DNA pack tightly It binds to DNA in a sequence-nonspecific manner
The cell organelle that contains acid hydrolases is
Lysosome
Phagocytes play an important role in the prey of foreign objects into the cell body, so that the most organelles within phagocytes is/are?
Lysosomes
Cholesterol serves several essential functions in mammalian cells. Which of the following are influenced by cholesterol?
Membrane permeability, Membrane fluidity, and membrane rigidity
Which of the following organelles is not part of the endomembrane system?
Mitochondria Chloroplasts
The mitochondrial proteins found in the inner membrane are involved in the conversion of ADP to ATP, a source of energy for the cell. This process consumes which of the following substances?
NADH, FADH2, oxygen, proton
The ________ is made up of two concentric membranes and is continuous with the membrane of the endoscopic reticulum
Nuclear Envelope
Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran to exchange GDP for GTP. What is the most likely effect of this drug on nuclear transport?
Nuclear transport receptors would be unable to release their cargo in the nucleus.
What is the final result of the electron transfers in Stage 1 of the membrane-based processes that drive ATP synthesis in the mitochondria
O2 is reduced to H2O
The chromosomes we typically see in images are isolated from mitotic cells. These mitotic chromosomes are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed and _______
Occupy discrete territories in the nucleus
Different glycoproteins can have a diverse array of oligosaccharides? Which of the statements below about this diversity is true?
Oligosaccharide diversity comes from modifications that occur in the ER and the Golgi of the 14-suagr oligosaccharide added to the protein in the ER (You get glycosylation in the er and golgi)
_________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location.
Peroxisomes
Which of the following statements about peroxisomes are true?
Peroxisomes synthesise phospholipids for the myelin sheath Peroxisomes contain enzymes that help inactivate toxins Proteins do not need to unfold to enter the peroxisome
Which type of lipids are the most abundant in the plasma membrane?
Phospholipids
After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic reticulum to encode?
Plasma Membrane Proteins ER membrane proteins Soluble secreted proteins
Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?
Potassium (K+)
Ca2+ pumps in the plasma membrane and endoplasmic reticulum are important for?
Preventing Ca2+ from altering the activity of molecules in the cytosol (if we have to much calcium, we are going to have a problem)
The major functions of autophagy are:
Recycling of unnecessary or dysfunctional organelles
Which of the following sequences is a peroxisomal target signal?
Serine-lysine-leucine
Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant outside a typical mammalian cell?
Sodium (Na+)
A large protein that passes through the nuclear pre must have an appropriate:
Sorting sequence (NLS), which typically contains the positively charged amino acids lysine and arginine
Which of the following channels would be expected to generated a change in voltage by movement of its substrate across the membrane where it is found?
The proton channel sodium channel calcium channel hydrogen pump (found in the mitochondrial membrane) charged ions
The sodium potassium pump is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. What happens immediately after the pump hydrolyses ATP?
The pump is phosphorylated The pump undergoes a confirmation change which deposits the sodium outside the cell and takes potassium into the cell
Where does most new membrane synthesis take place in a eukaryotic cell?
The smooth ER
Proteins that are fully translated in the cytosol do not end up in:
Transport vesicles
Which of the following components of the electron-transport chain does NOT act as a proton pump?
Ubiquinone, cytochrome C
Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodelling complexes provided this access by?
Using the energy of ATP hydrolysis to move nucleosomes
Diversity among the oligosaccharide chains found in the carbohydrate coating of the cell surface can be achieved in which of the following ways? (diversity in the glycoproteins)
Varying the types of sugar monomers used varying the types of linkages between sugars varying the number of branches in the chain
Which of the following statements about nuclear transport is true? a. mRNAs and proteins transit the nucleus through different types of nuclear pores b. Nuclear import receptors bind to proteins in the cytosol and bring the proteins to the nuclear pores, where the proteins are released from the receptors into the pores for transit into the nucleus c. Nuclear pores contain proteins with disordered segments that fill channel and allow small water-soluble molecules to pass through in a non-selective fashion d. Nuclear Pores are made up of many copies of a single protein
c. Nuclear pores contain proteins with disordered segments that fill channel and allow small water-soluble molecules to pass through in a non-selective fashion
During Stage 2 of oxidative phosphorylation, ATP synthesis is powered by movement of ________ ions through the ________
H+, ATP synthase
Which of the following histone proteins does NOT form part of the octameric core?
H1
In which cellular location would you expect to find ribosomes translating mRNAs that encode ribosomal proteins?
In the cytosol
The concentration of H+ ions inside the mitochondrial matrix is lower than it is in the cytosol or the mitochondrial inter-membrane space. What would be the IMMEDIATE effect of a membrane-permeable compound that carries and releases protons into the mitochondrial matrix?
Inhibition of ATP synthesis
Which of the following statements describes the mitochondrial matrix?
It contains its own DNA and enzymes required for the citric acid cycle and the oxidation of fatty acid
Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of the material "burned" and form of energy produced during cellular respiration?
Sugar, ATP, fatty acids, ATP (lipid oxidation)
Which of the following statements about the ER is true? The ER is the major site for new membrane synthesis in the cell. Proteins to be delivered to the ER lumen are the synthesised on the rough ER; Steroid hormones are synthesised on the smooth ER; The ER membrane is contiguous with the outer nuclear membrane.
The ER is the major site for new membrane synthesis in the cell