Quiz 2/ Chapter 3 Flashcards
What are the 4 concepts of the cell theory?
Cells are the basic unit of life
The activity of an organism depends on the activity of its cells
The biochemical activities of the cell are dictated by their sub-cellular structures
The continuity of life has a cellular basis
What elements are cells primarily composed of?
C, H, N and O
What must a human cell contain?
The plasma membrane, cytoplasm, nucleus
What part of the cell is in a constantly changing fluid mosaic?
The lipid bilayer
What is the extracellular fluid that is in direct contact with the cell membrane called?
The interstitial fluid
What steroid is inside the lipid bilayer and gives the membrane stability?
Cholesterol (20% of the lipid bilayer)
What do integral proteins function as in the membrane?
Transport proteins (channels and carriers)
Enzymes
Receptors
(are usually transmembrane)
What do peripheral proteins usually function as?
Enzymes
Motor proteins (shape change in cell division and muscle contraction)
Cell to cell connections
(loosely attached to integral proteins
What are the 6 functions of membrane proteins?
Transport Receptors for signal transduction Attachment to cytoskeleton and extracellular matrix Cell-cell recognition Intercellular joining Enzymatic activity (TRACIE)
What are CAMs?
They are cell adhesion molecules that provide temporary binding sites that guide cell migration
What type of proteins are considered cell marker and are used in cell-cell recognition?
Glycoproteins (proteins bonded to short chains of sugars)
What do lipid rafts contain?
Phospholipids, sphingolipids, and cholesterol
creates a more stable outermembrane
What are 2 examples of free cells?
Blood and semen
What are the 3 ways cells are bound into communities ?
Tight junctions
Desmosomes
Gap junctions
Explain tight junctions.
Create an impermeable junction
No communication between cells
Isolation
How would you explain desmosomes? Where is 1 place that desmosomes are abundant in the body?
They anchor cells together at plaques
Like velcro
Use linker proteins (cadherins)
Found in the skin (reduces tearing)
Explain gap junctions.
Pores are created called connexons
Open communication between cells (as long as the particles are small)
Found in smooth muscle cells (peristalsis)
What are the two processes that substances cross the membrane?
Passive processes Active processes (use ATP)
How do substances move in passive processes?
Down its concentration gradient (area of high concentration to an area of low concentration)
What are the two types of passive transport?
Diffusion
Filtration
What are the 3 types of diffusion?
Simple diffusion
Carrier and channel mediated facilitated diffusion
Osmosis
Where would you see filtration (passive process) occurring in the body?
Across capillary walls (alveoli in the lungs)
What is the speed of diffusion dependent upon?
Molecule size and temperature
How would you explain diffusion?
Molecules move down their concentration gradient (no energy needed)
What are the 3 ways a molecule can diffuse passively through the membrane?
If the molecule is lipid soluble (the bilayer is made out of phosphoLIPIDS)
Small enough to pass through membrane channels
Assisted by carrier molecule
What kind of passive process would occur in a non polar, fat soluble molecule passed directly through the membrane?
Simple diffusion
What are the two ways facilitated diffusion occurs?
If a LIPOPHOBIC molecule binds to a protein carrier
or if it moves through a water-filled channel
(it is polar/ water soluble)
What kind of molecule would be transported through the membrane by a carrier?
A larger polar molecule
carriers can become saturated
What kind of molecules would be transported across the membrane by channels?
Ions or water (polar small molecules)
What are the two types of aqueous channels used for facilitated diffusion?
Leakage channels (always open) Gated channels
What kind of channels are used in osmosis?
Aquaporins
What is osmosis?
Movement of solvent (like water) across selectively permeable membrane
(area of high concentration of solute to low concentration of solute)
What is the measure of total concentration of solute particles known as?
Osmolarity
If the membrane is permeable to all molecules, does the volume in and out of the cell change during osmosis?
No the volume stays the same since water and ions are moving in opposite directions
When a membrane is impermeable to solutes, what happens to the volume during osmosis?
The volume increases where the concentration of solute is higher (only water is moving across the membrane)
What is tonicity?
Ability of a solution to alter a cell’s water volume
What happens to a cell during an isotonic solution?
Cells retain their normal size and shape
same solute and water concentrations inside the cell and outside
What happens to a cell in a hypertonic solution?
Cells lose water and shrink since the solute concentration is more on the outside of the cell (crenation)
What happens to a cell in a hypotonic solution?
The cell swells as water comes into the cell (hemolysis may occur)
When would active transport need to be used to transport molecules across the membrane?
If the molecule/solute is
too large for channels
not lipid soluble
cannot move down its concentration gradient
What are the two types of active processes?
Active transport
Vesicular transport
What does active transport require and what are the two different kinds of active transport?
Requires carrier proteins (uses ATP to bind specifically and reversibly with substances/ move solutes against concentration gradient)
Primary active transport
Secondary active transport
Where does the energy come from in primary active transport (give an example of a pump that does this)?
Hydrolysis of ATP
Na+-K+ pumps
What is the carrier (pump) called in the sodium potassium pump?
Na+-K+ ATPase
Are membrane channels more permeable to K+ or Na+ leakage/movement?
Potassium
What does the Sodium potassium pump do?
Pumps against Na+ and K+ gradients to maintain a high intracellular K+ and high extracellular Na+ concentration (maintain electrochemical gradient)
How many K+ are pumped in and Na+ pumped out from one pump?
2 K+ and 3 Na+
use less energy for potassium since the channels are more permeable to it
What catches a ride with Na+ as it is pulled into the cell through electrical and chemical gradients?
Glucose (not directly using ATP)
What kind of transport would be used for large particles, macromolecules, and fluids across membranes?
Vesicular transport
active transport that uses vesicles
What are the 4 functions of vesicular transport?
Endocytosis (enter)
Exocytosis (exit)
Transcytosis (movement across the cell)
Vesicular trafficking
What are the three types of endocytosis?
Phagocytosis
Pinocytosis
Receptor-mediated
What kind of endocytosis uses receptors and engulfs large particles and is important in immune fuction?
Phagocytosis (has receptors so is slightly selective but the large particles do not attach to the receptors)
What kind of endocytosis does the membrane invaginate and take a large gulp from the interstitial fluid?
Pinocytosis (no receptors so is not specific at all)
What type of endocytosis is the most specific and uses clathrin-coated pits?
Receptor-mediated endocytosis (Solute actually binds to the receptor to see if it needs to take it into the cell)
What kind of vesicle is used in exocytosis?
A secretory vesicle
remember secretory means the cell is getting rid of something
What does the vesicle and membrane use for binding and release?
v-SNARES and t-SNARES
vesicle for V and target for T
What do lipid rafts serve as in the lipid bilayer?
They serve as platforms for receptors
What charge does the inner surface of the lipid bilayer carry?
-70 mV (a negative charge)
This is why the Na+ wants to come inside the cell - creates an electrical AND chemical gradient for the secondary active transport
What do CAMs do?
They are glycoproteins that act as attachment sites or signals during embryonic development, wound repair and immunity
What is a membrane potential?
a voltage across the cell membrane that occurs due to a separation of oppositely charged ions
What is resting membrane potential?
Condition where the inside of the cell membrane is negatively charged compared with the outside
What are the 3 major elements of cytoplasm?
Cytosol, cytoplasmic organelles and cytoplasmic inclusions
What do peroxisomes detoxify?
Harmful substances such as alcohol, formaldehyde, and free radicals
What are the parts of the cytoskeleton?
Microtubules
Microfilaments
Intermediate filaments
What is the centrosome?
Region near the nucleus that functions to organize microtubules and organize the mitotic spindle during cell division
What are centrioles?
Small, barrel shaped organelles associated with the centrosome and form bases of cilia and flagella
What are fingerlike extensions of the plasma membrane that increase surface area?
Microvilli
What body cell does not have a nucleus?
Red blood cells
What are the three regions of the nucleus?
Nucleoli, Chromatin, nuclear envelope
What does the nucleus determine?
The kinds and amounts of proteins to be synthesized within a cell
What organelle is continuous with the nuclear envelope?
The rough ER
What are the nucleoli?
Dark-staining spherical bodies within the nucleus that are the sites of assembly of ribosomal subunits and are large in actively growing cells (producing more proteins)
What is the cell cycle?
The series of changes a cell goes through from the time it is formed to the time it reproduces
What are the two main periods of cell cycle?
Interphase and cell division
What is interphase?
the period from cell formation to cell division
What are the three subphases of interphase?
G1 (gap1)-the cell is synthesizing proteins and actively growing
S phase- DNA is replicated
G2- enzymes and other proteins are synthesized and distributed throughout the cell
What are the three main events of cell division?
Mitosis-nuclear division
Cytokinesis-dividing cytoplasm
Control of cell division - depends on surface-volume relationships, chemical signaling, and contact inhibition
What is a gene?
a segment of DNA that carries instructions for one polypeptide chain
What are the 3 forms of RNA?
transfer RNA
ribosomal RNA
messenger RNA
How does transcription occur?
Make an mRNA complement by a transcription factor mediating binding of RNA polymerase
The mRNA that initially results from transcription is called the primary transcript and has introns that must be removed
What is translation?
Process of converting the language of nucleic acids to the language of proteins (nucleotides to amino acids)
What is autophagy?
The process of degrading malfunctioning organelles to prevent excessive accumulation of these structures
What are ubiquitins and what do they do?
They are proteins that attach to and mark unneeded proteins for degredation and recycling
What are the three classes of extracellular material?
Body fluids - interstitial fluid, blood plasma, and cerebrospinal fluid (dissolution)
Cellular secretions - substances aiding in digestion or functioning as lubrication
Extracellular matrix - jellylike substance secreted by cells (consisting of proteins and polysaccharides)
How do chemical signals influence development?
They switch genes on and off
What is cell differentiation?
Process of cells developing specific and distinctive features (becoming unique/ lets you differentiate between them)
What is apoptosis?
Programmed cell death of stressed, unneeded, injured, or aged cells
Why do we have cell division in adulthood if everything is already formed?
To serve to replace cells and repair wounds
What is the wear and tear theory about cell aging?
The cumulative effect of slight chemical damage and production of free radicals
