MCAT BIO Cell Biology Flashcards
Chromosomes have a ___ near the middle to ensure that newly replicated chromosomes are sorted properly during cell divison, one copy to each daughter cell
Centromere
__is a region in the nucleus that functions as a ribosome factory.
Nucleolus
___ consists of loops of DNA, RNA polymerases, rRNA, and the protein components of the ribosome
Nucleolus
What role do the loops of DNA in the nucleolus play?
They serve as template for ribosomal RNA production
The nucleolus is the site of transcription of rRNA by___
RNA polymerase 1
The membrane of the endoplasmic reticulum is at points continuous with the ____
outer nuclear membrane of the nuclear envelope
The lumen of the ER is continuous with the __
space between the two nuclear membranes of the nuclear envelope
Where is pyruvate dehydrogenase and the enzymes of the Krebs cycle located?
In the interior of the mitochondria, the MATRIX
__ is the site of the proton gradient used to drive ATP synthesis by ATP synthase
Inner membrane Matrix of mitochondria
The ___of the mitochondria is impermeable to the free diffusion of polar substances, like protons
Inner membrane of Matrix of mitochondria
The ___ of the mitochondria is smooth and contains large pores that allow free passage of small molecules
outer membrane of the mitochondrial matrix
Why is the inner membrane (matrix) folded into cristae?
To increase surface area and allow for increased electron transport and ATP synthesis per mitochondrion
Where are the enzymes of glycolysis located?
Cytoplasm
Mitochondrion and ____look pretty familiar
Gram-negative bacterium
What difficulty may be encountered in translation of a mitochondrial gene moved to the nucleus?
Coding system of cellular genome is different from that of mitochondrial genome
___is a large system of folded membrane accounting for over half of the membrane of some cells
Endoplasmic Reticulum (ER)
__ contains enzymes involved in steroid hormone biosynthesis or degradation of environmental toxins
Smooth ER
Proteins translated on____ are headed toward peroxisomes, mitochondria, nucleus, or inside cell
Free cytoplasmic ribosomes
Proteins synthesized on the rough ER will end up ___, ___,___
- secreted into the extracellular environment
- Integral plasma membrane proteins
- Membrane or interior of ER, Golgi apparatus, lysosomes
Integral membrane proteins have sections of hydrophobic amino acid residues called __that pass through the lipid bilayer membranes
Transmembrane domains
What are the 3 functions of the Golgi apparatus?
- modification of proteins made in the RER
- Sorting and sending proteins to correct destinations
- Synthesize macromolecules like polysaccharides to be secreted
Vesicles from the ER fuse with the ___ of the Golgi apparatus
Cis track nearest to the rough ER
Proteins leave the Golgi apparatus from the ___
Trans stack farthest from the Rough ER
___is a membrane-bound organelle that is responsible for the degradation of biological macromolecules by HYDROLYSIS
Lysosomes
Process of degradation of organelles by lysosomes
Autophagy
Macriphages of the immune system engulf bacteria and viruses the particles end up in a phagocytic vesicle which will fuse with the __
lysosome
___refers to lysosomal digestion of unneeded secretory products
Crinophagy
Enzyme responsible for degradation in lysosomes is __
acid hydrolases
The pH of lysosome is around __ making its enzyme acid hydrolase active
5
What are functions of peroxisomes?
- Breakdwon peroxide by use of enzyme catalase
- lipid breakdown in many cells
- Asssiste in detox of drugs and chemicals in liver cells
___ is the enzyme in peroxisomes that breaks down peroxide into H20 and O2
Catalase
Integral membrane proteins are held in the membrane by __
hydrophobic interactions
What holds peripheral membrane proteins to integral proteins ( 2 things)
Hydrogen bonding
Electrostatic interactions
What interaction between fatty acid side chains are a major determinant of membrane fluidity?
van derr Waals interactions
Increasing the unsaturated fatty acid content of the membrane will ____
Increase fluidity since they have fewer van derr waals interactions
Why is molality better to use when measuring properties involving temperature?
Molality does not change with temeprature
___ tells us how many ions one unit of a substance will produce in a solution
van’t Hoff (ionizability) factor (i)
__ depend on the number of solute particles in the solution rather than the type of particle
Colligative properties
What are the four major colligative properties tested on the MCAT?
vapor-pressure depression
boiling-point elevation
freezing-point depression
osmotic pressure
__ is the pressure exerted by the gaseous phase of a liquid that evaporated from the exposed surface of a liquid
Vapor pressure
___ is the movement of a molecule down a gradient with the help of a protein
Facilitated diffusion
The ____ established by the Na+/K+ ATPase is the driving force behind secondary active transport of many different molecules, including sugars, and amino acids
concentration gradient of HIGH SODIUM OUTSIDE OF THE CELL
What are thee ways the activity of Na+/K+ ATPase is important?
- To maintain osmotic balance between the cellular interior and exterior
- To establish the resting membrane potential
- To provide the sodium concentration gradient used to drive secondary active transport
___ is a second messenger of the hormones epinephrine and glucagon, chich cause energy mobilization (glycogen and fat breakdown)
cyclic AMP (cAMP)
A___ does not directly transduce its signal but transmits it into the cell with the aide of a second messenger, the most important second messenger being (cAMP)
G-protein linked receptor
The common theme of all G-protein based signal transduction is ___
their reliance on a G-protein, which is a signaling molecule that binds GTP
The animal ____ provides the structural support supplied by the cell wall in bacteria, plants and fungi
Cytoskeleton
What three proteins compose the animal cytoskeleton?
microtubules
intermediate filaments
microfilaments
___is a hollow rod composed of two globular proteins a-tubulin and B-tubulin, polymerized noncovalently
Microtubule
___ radiate out from the centrioles during mitosis
Microtubules
Microtubules radiating out from the centrioles during mitosis are called __ because they are star shaped
Aster
Epithelial cells in the skin are held together tightly but do not form a complete seal; this is accomplished by __
desmosomes
Heart muscle cells are connected by holes called __ that allow ions to flow back and forth between them
Gap junctions
___ also termed occluding junctions because they dont just join cells but form a seal between the membranes of adjacent cells
Tight junctions
___ form pore-like connections between adjacent cells, allowing the two cells’ cytoplasms to mix
Gap junctions
___ in smooth muscle and cardiac muscle allow the membrane depolarization of an action potential to pass directly from one cell to another
Gap junctions
__ phase includes mitosis and cytokinesis
M phase
