Ch. 3 The Cell Flashcards
What is the energy source for facilitated diffusion?
The kinetic energy of the diffusing solute provides the energy allowing them to move down concentration gradient.
How would CO2 likely diffuse across cell membrane?
Small non-polar molecules readily dissolve in lipids and may therefore diffuse across.
What energy source is used most directly during the secondary active transport of glucose into the cell?
The facilitated diffusion of Na+ ions across the membrane; “Co-transporter”/Symport to power the secondary active transport.
What is true regarding extracellular Na+ and K+ ion concentrations?
Na+ ion concentrations are high outside the cell relative to the inside of the cell.
What explains why the interior of the plasma membrane is more negatively charged than the exterior of the membrane?
Significant amounts of K+ diffuse out of the cell. The membrane is more permeable to K+ than Na+. Because of the concentration gradient, significant amounts of K+ diffuse out through leakage channels, leaving a negative charge inside.
True or False? Membrane-bound receptors act as carriers that allow the diffusion of ligands into cells.
FALSE; ligands function to activate receptors but are not transported into the cell as part of a signaling event.
Accurately track a glycoprotein from its site of initial synthesis to its arrival at the plasma membrane:
ER – transport vesicle – Golgi – secretory vesicles – plasma membrane
What structure functions to increase the absorptive ability of kidney and intestinal cells?
Microvilli: tiny, fingerlike extensions of the plasma membrane that aid in absorption by increasing surface area.
True or False: The products of DNA replication include one double helix consisting of two original strands and one double helix consisting of two newly synthesized strands.
FALSE; each new molecule consists of one old and one new nucleotide strand, known as “semi-conservative replication”.
What happens in Telophase?
The nuclear envelope reforms.
What is not a function of the ribosome during polypeptide synthesis?
Removing introns from pre-mRNA. RNA splicing is performed by “spliceosomes”.
Is mRNA synthesized in the cytoplasm or the nucleus?
RNA is synthesized during transcription of chromosomal DNA in the nucleus.
What is the main component of the cell membrane?
Phospholipid bilayer
What is not a function of proteins in cell membrane?
Forming the entire glycocalyx
What part of the cell membrane is usually in contact with the interstitial (extracellular) fluid?
Phosphate head of phospholipids
What is most likely to move through the cell membrane by facilitated diffusion?
Na+; cell membrane largely non-polar, so gases can easily pass through.
Polar molecules, like Na+, K+, and Glucose need to go through protein channels.
What is not required for osmosis to occur?
Cellular energy
If a person is severely dehydrated, their extracellular fluids will become hypertonic to the intracellular fluid. What do you predict will happen to the person’s cells?
The cells will lose water and shrink.
Three examples of Active Transport
Endocytosis, Exocytosis, Primary active transport (uses ATP)
What is another name for secondary active transport?
Symport
Three examples of Passive Transport
Simple diffusion, Facilitated diffusion, Osmosis
What is characteristic of cilia?
They are whiplike, motile cellular extensions that occur in large numbers on the exposed surfaces of certain cells.
What happens in G1 subphase?
The cell synthesizes proteins rapidly and grows vigorously.
What happens in S phase?
DNA is replicated.
What happens in G2 subphase?
Protein needs for division are synthesized and moved to their proper sites.
Prophase
First stage of Mitosis, Chromosomes become visible, Spindle forms.
Metaphase
Second stage of Mitosis
Anaphase
Third stage of Mitosis in which chromosomes move toward each pole of a cell.
Telophase
Final stage of Mitosis, Chromosomes complete migration to poles of cell.
Cytokinesis
Division of cytoplasm after the nucleus has divided
Sequence of events in Translation
Initiation, Elongation, and Termination
Apoptosis
A process of controlled cellular suicide
Does Apoptosis use lysosomes?
No, unlike autophagy, apoptosis does not use lysosomes.
Pinocytosis
Engulfing of extracellular fluid by cells.
Codon
Three base sequence on mRNA that provides genetic information for protein synthesis
The smallest unit capable of life is ?
The Cell
The major types of lipids found in plasma membranes.
Cholesterol and Triglycerides
Membrane junctions that allow nutrients or ions to flow from cell to cell are called ?
Gap junctions
Osmosis always involves ?
A selectively permeable membrane, difference in solute concentration, and diffusion.
The endocytotic process in which a sampling of particulate matter is engulfed and brought into the cell:
Phagocytosis
The nuclear substance composed of histone proteins and DNA is:
Chromatin
The information sequence that determines the nature of a protein is:
Gene
The phase of mitosis during which centrioles reach the poles and chromosomes attach to the spindle:
Prophase
The RNA synthesized on one of the DNA strands:
mRNA, tRNA, and rRNA
The RNA species that travels from the nucleus to the cytoplasm carrying the coded message:
mRNA
A nerve cell and lymphocyte are presumed to differ in their:
Specialized structure and genetic information
A physiologist observes that the concentration of Na+ inside a cell is decidedly lower than outside. She also observes that there is a small leakage of Na+ into the cell. What process prevents the concentration gradient from disappearing?
Primary active transport
Three ways cells can be bound to each other
Tight junctions, Desmosomes, Gap junctions
Concentration Gradient
Difference in the concentration of a chemical between one side of the plasma membrane and the other
Electrical Gradient
Difference in concentration of ions between one side of the plasma membrane and the other
Brownian Motion
The erratic random movement of microscopic particles in a fluid, as a result of continuous bombardment from molecules of the surrounding medium
Diffusion is influenced by ?
Concentration, Size, and Temperature
Osmolarity
Measures the concentration of the total number of solute particles in a solvent
Hydrostatic Pressure
Outward pressure exerted on cell side of membrane
Osmotic Pressure
Inward pressure due to tendency of water to be pulled into cell
Tonicity
Ability of a solution to change the shape or tone of the cell by altering cell’s internal water volume
Phagocytosis
Bringing into the cell in bulk
Pinocytosis
“Drinking” a small sample of extracellular environment
Cytoplasm consists of?
Cytosol and Organelles
Cytoskeleton consists of 3 protein filaments called ?
Microfilaments, Intermediate Filaments, and Microtubules
What does Rough ER synthesize?
Glycoproteins and Phospholipids
What does Smooth ER synthesize?
Fatty Acids and Steroids
Which ER deactivates or detoxifies drugs?
Smooth ER
What best describes the fluid mosaic model of the plasma membrane?
A lipid bilayer with protein molecules dispersed within it
What is NOT a function or role performed by proteins found in the plasma membrane?
Synthesis of proteins
In which stage of mitosis do the chromosomes align along the cell equator?
In metaphase, the chromosomes cluster around the middle of the cell, with their centromeres aligned on the cell equator.
Lysosomes perform what cellular functions?
Lysosomes are spherical membrane-bound sacs that contain many different digestive enzymes utilized within the cell.
Which organelle produces secretory vesicles?
Secretory vesicles bud off of the trans-Golgi network of the Golgi apparatus and travel to the plasma membrane, where their contents are secreted.
Which organelle maintains cell shape, supports cellular structures, and generates cell movements?
The cytoskeleton is an elaborate network of rods running throughout the cytosol, maintaining cell shape, supporting cellular structures, and generating cell movements.
Which organelle possesses oxidase enzymes that function in neutralizing harmful free radicals?
Peroxisomes contain a wide variety of enzymes, including oxidases, which function in neutralizing harmful free radicals in the cells.
Which nucleic acid molecules are involved in transcription but not translation in the synthesis of a particular polypeptide?
DNA is copied into mRNA in transcription within the nucleus in the synthesis of a particular polypeptide.
Cells may be said to be “sugar-coated” because of the presence of __________.
The glycocalyx is made up of glycoproteins, which are proteins with carbohydrate side chains located on the outside surface of the cell membrane, thus causing the cell to appear sugar-coated.
Proteins in the cell membrane that bind hormones and relay messages into the interior of the cell __________.
perform a function known as signal transduction.
Definite changes in the __________ of the cell membrane can be seen in a cell that is becoming cancerous.
The glycocalyx shows definite changes when the cell becomes cancerous and changes continuously to keep the immune system from recognizing it.
Crenation takes place when a cell is placed in a(n) __________.
Hypertonic solution. Cells placed in a hypertonic solution shrink from loss of water and are said to be “crenated.”
The resting membrane potential is mainly determined by __________.
the differential permeability of the plasma membrane to K+ and other ions.
Cristae are found in which of the following cell organelles?
The mitochondria contain cristae produced by the inward folding of their inner membrane.
The underlying cause of Tay-Sachs disease is __________.
Lysosomes swollen with undigested lipids in nerve cells from the lack of the enzymes needed to digest a certain glycolipid are the cause of Tay-Sachs disease.
Which of the following types of RNA contains regions that act as a switch to turn protein synthesis on and off for the protein they code for?
Riboswitches contain regions that act as a switch to turn protein synthesis of the protein they code for on or off.
Cells of the body mainly use __________ for the selective endocytosis of most macromolecules.
receptor-mediated endocytosis
DNA is replicated during the __________ phase of the cell cycle.
S
A gene is best defined as __________.
a segment of DNA that carries instructions for the production of one polypeptide chain
In the immune system, some components are able to recognize sugar groups attached to the outside of a bacterium. These immune components must be recognizing which membrane lipids?
Glycolipids
Cells may be said to be “sugar-coated” due to the presence of ?
Glycocalyx
What is the plasma-membrane lipid that stiffens the plasma membrane?
Cholesterol
What are mechanical couplings scattered like rivets along the sides of adjacent cells to prevent their separation?
Desmosomes
Definite changes in the ________ of the cell membrane can be seen in a cell that is becoming cancerous.
Glycocalyx
