Membrane Structure
What is the difference between a glycolipid and a glycoprotein?
Glycolipids are carbohydrate chains attached to phospholipids
Glycoproteins are carbohydrate chains attached to proteins.
They both act as signaling and recognition molecules between cells and allow cell adhesion.
What are the two types of transport and which requires energy input and which does not?
Active Transport: Requires energy input
Passive Transport: Requires no direct energy input
Anabolism is the breaking down of complex molcules into simpler ones in which results in a release of energy.
Catabolism is the linking of simple molecules to form complex ones in which require an input of energy.
True or False?
False.
Catabolism is the breaking down of complex molcules into simpler ones in which results in a release of energy.
Anabolism is the linking of simple molecules to form complex ones in which require an input of energy.
Identify the cell structure that serves as the site of protein synthesis, are assembled in the nucleolus, and can be either classified as free or bound.
A. Chromatin
B. Nuclear Pores
C. Endoplasmic Reticulum
D. Ribosomes
D. Ribosomes
This is where the translation stage of protein synthesis occurs.
(Stages: DNA replication, Transcription, and Translation)
What happens when a catalyzed reaction reaches its maximum rate?
A. The reaction has been completed.
B. All the enzyme is bound with the substrate meaning it is working at its maximum, therefore it is saturated.
C.The concentration of the substate has been used all up, therefore it is unsaturated.
D. The reaction rate is reaching its maximum but it can exceed its maximum if it is saturated.
B. All the enzyme is bound with the substrate meaning it is working at its maximum, therefore it is saturated.
If a catalyzed reaction has reached its maximum this means that the enzyme cannot speed the reaction up anymore. It is going as fast as it can and ever will. It has been bounded to all of the substrate. The term for this is saturated (enzyme).
Proteins that are polar/charged and react with integral proteins and the hydrophilic heads of the membrane. What are these proteins called?
A. Integral Proteins
B. Transmembrane Proteins
C. Peripheral Proteins
D. Cholesterol
C. Peripheral Proteins
These types of proteins are embedded near the top or the bottom of the phospholipid bilayer because the hydrophilic heads are there for them to interact with.
What is the difference between Diffusion (Both types) and Osmosis?
Simple Diffusion: Random movement of solutes across a membrane from a greater concentration to a lower concentration to gain a state of equilibrium.
Facilitated Diffusion: Movement of solutes across a membrane down its concentration gradient with the help of facilitating proteins like channel and carrier proteins.
Osmosis: Diffusion of water across a membrane through aquaporins. Happens only depending on the tonicity of the cell.
What do enzymes do during a chemical reaction? Explain using vocabulary catalyze/catalyst, Activation energy, reactants, and products.
Enzymes catalyze (speed up) reaction rates. Activation energy is used to start a chemical reaction whether endergonic or exergonic, but to speed it up an enzyme will be used. In a reaction whether an enzyme is used or not, the reactants go in and the same end result are products.
An example is speeding up the reaction of the disaccharide maltose being broken down into two monosaccharides, glucose.
Identify the cell organelle that is composed of cisternae and vesicles, concentrates, sorts and packs proteins for transport, modifies proteins, and has a cis region, medial region, and trans region.
A. Golgi Apparatus
B. Endoplasmic Reticulum
C. Endomembrane System
D. Mitochondria
A. Golgi Apparatus
The golgi complex is considered the "Amazon of the cell" for packaging and sorting proteins. It comes after the ER in which sends protein filled transport vesicles to the golgi for modification and transport. As an example, lysosomes (which are modified proteins) bud from the golgi and are transported for digestion use.
If a cell with a low salt concentration were placed in an environment with a higher salt concentration than inside the cell, in what direction will water move across the membrane? What will be the tonocity of the cell as well as its result if too much movement?
The tonicity is hypertonic. The water will move out of the cell causing it to shrivel. If a plant cell, the cell membrane will shrink away from its cell wall which is termed plamsolysis.
Proteins that are embedded in and span across the membrane and have both hydrophobic and hydrophilic regions. They act enzymes, aid in signaling, transport, cell recognition, and cell attachment to ECM and cytoskeleton. What are these proteins called?
A. Integral Proteins
B. Phospholipids
C. Peripheral Proteins
D. Cholesterol
A. Intergral Proteins (Transmembrane Proteins)
These proteins span across the membrane because the membrane is amphipathic, meaning they have both hydrophilic and hydrophobic regions just like this type of protein.
ECM = Extracellular Matrix
Breifly describe the three types of endocytosis and exocytosis (one type).
Phogocytosis: Part of the plasma membrane engulfs a cell or large particle (cellular eating)
Pinocytosis: Part of the plasma membrane engulfs fluids or dissolved substances (cellular drinking)
Receptor Mediated: Part of the plasma membrane engulfs specific molecules that specifically will bind to a specific receptor.
Exocytosis: When cells secrete a substance out of the plasma membrane. (Exiling a substance)
Why do enzymes work at certain temperatures only? What do you call this functioning temperature?
Enzymes can only work at a designated functioning temperature. This temperature is called an optimum. For humans, that temperature is 37 degrees celsius (Our body temperature). If the temperature were to be outside of the enzymes optimum, like too hot, this could denature the protein. This ruins the active site shape in which a substrate can no longer bind to. (Not functioning)
Describe the function of the mitochondria and chloroplast and how they relate to endosymbiosis theory.
Chloroplast: Converts light energy to chemical energy for the cell. The chemical energy is then used to make carbohydrates for the cell (food) Photosynthetic structure.
Both the chlorplast (in plants only) and the mitochondria have been theorized as previous prokaryotic cells. Evidence is they have their own DNA, ribosomes, and can divide on their own. (Endosymbiosis Theory)
Describe the difference between irreversible and reversible inhibition.
Reversible: A molecule that binds to the active site non-covalently. When this molecule is bound the enzyme cannot function, but it can be removed and the function will return.
Irreversible: A molecule binds to an active site covalently, in which stops the enzyme from functioning permanently for the molecule cannot be removed.
What is the term used to describe a membrane that only allows certain molecules to pass through its membrane or in and out of the cell?
A. Semi-conservative
B. Selectively Equal
C. Diffusion
D. Selectively Permeable
D. Selectively Permeable (Semi-Permeable)
Identify and explain the two types of facilitated diffusion (Gated Channel).
Ligand Ion Channel: Ligand binds to a receptor on a channel protein causing it to open on that side for a molecule to pass through.
Voltage Ion Channel: An electrical signal is sent to a channel protein causing it to open on that side for a molecule to pass through.
Desccribe the difference between a regular metabolic pathway and a feedback inhibition.
Metabolic Pathway: A substrate binds to an active site to produce a product. That product binds to another enzyme as a substrate and then gets turned into a product. This happens over and over as long as it needs to with multiple enzymes. The product of one reaction becomes the substrate for the next.
Feedback Inhibtion: When the end product of a metabolic pathway turns and binds to an enzyme earlier in the pathway to stop the pathway from continuing. This could be in the situation of too much product being accumulated.
List at least two function of the smooth endoplasmic reticulum and the rough endoplasmic reticulum.
SER:
1. Detoxification.
2. In animal cells glycogen is broken down here.
3. Lipids and steriods are formed here.
4. Serves for storage of calcium ions (Ca+)
RER:
1. Modifies Proteins
2. Transports proteins to other areas of the cell (golgi complex) through transport vesicles.
What is the make up of the endomembrane system? *Bonus: What is the purpose of the endomembrane system?
A. Transport Vesicles, Golgi Apparatus, Lysosomes, Cell membrane
B. Nuclear Membrane, Endoplasmic Reticulum, Golgi Apparatus, Lysosomes, Transport Vesicles, Cell Membrane
C. Mitochondria, Chloroplast, Vacuole, Cell membrane, Cell Wall
D. Flagellum, Cilia, ECM, Cytoskeleton, Plasma Membrane, Cytoplasm
B. Nuclear Membrane, Endoplasmic Reticulum, Golgi Apparatus, Lysosomes, Transport Vesicles, Cell Membrane
*Bonus: Protein trafficking in cells. It equals the flow of protein transport.
Describe the function of cholesterol in the cell membrane. (If it were to get too hot or too cold what will cholesterol do in the membrane?)
Cholesterol helps the cell membrane maintain fluidity. If the cell were in a hot environment, naturally the membrane phospholipids will spread out too much (too much fluidity). Cholesterol will keep the phospholipids from moving too far apart.
If the cell were in a cold environment, naturally the membrane phospholipids will get close together (not enough fluidity). Cholesterol will keep the phospholipids from getting too close to each other so the membrane stays fluid.
Explain the process of the Sodium-Potassium Pump (Electrogenic Pump).
When the Na+ concetration is high and the K+ concentration is low outside the cell and vice versa on the inside of the cell, a channel protein will take in Na+ from the inside of the cell (low concentration region) bind ATP and then expel it to the outside of the cell (high concentration region). Then as the Na+ exits the K+ enters the channel protein (from the low concentration region) and will be brought into the cell as the protein opens on the inside of the cell (to the high concentration region). Both molecules are being transported against their concentration gradient using ATP. This counts as active transport.
Which best explains competitve inhibitiion?
A. A competitive inhibitor binds to an active site before the correct substrate can bind to it, stopping the reaction.
B. A substrate binds to an active site on an enzyme.
C. A regulatory molecule binds to the enzyme regulatory site to change the shape of the active site to better fit the substrate molecule for induced fit binding.
D. A regulatory molecule binds to the enzyme regulatory site to change the shape of the active site so the substrate cannot have an induced fit bind to the active site, stopping the reaction.
Correct Answer:
A. A competitive inhibitor binds to an active site before the correct substrate can bind to it, stopping the reaction.
The inbibitor and the substrate compete for the active site.
The other choices describe other terms:
B. Enzyme-substrate complex
C. Allosteric Regulation (Non-competitve Inhibition) Activation
D. Allosteric Regulation (Non-competitve Inhibition) Repression
Descirbe the Centrioles and their function, including the three types of filaments found in the cytoskeleton.
Centrioles: Produce the microtubles for the cell and cell division and the basal body (attachment point) of cilia and flagella.
Microfilaments: (Smallest) Help entire or parts of the cell move, determine and stabilize cell shape, composed of actin and show dynamic instability. (less stable)
Intermediate Filament: Anchor cell or the nucleus, maintains rigidity in surface cells, and does not show dynamic instability (more stable)
Microtubles: (Largest) Form internal skeleton, form framework for motor proteins to move other structures, make up centrioles, aid in cell division form skeleton for external projections (cilia, flagella), composed of tublin, and Show dynamic instability (less stable).
What are the structures that make up nuleus, and their functions?
Nucleolus, Chromatin, Nuclear Envelope, and Nuclear Pores.
Nucleuolus: Site where ribosomes are assembled.
Chromatin: Spaghetti-like DNA and protein combined chromosomes.
Nuclear Envelope: Phospholipid Bilayer that separates DNA transcription from translation.
Nuclear Pores: Allows passage of mRNA and other substances through the nucleus.