Macromolecules
What are the four major biological macromolecules? Give one example of each.
Carbohydrates: starch, lipids: phospholipds, proteins: enzymes, and nucleic acids: DNA/RNA
Other examples: sugar (glucose), fats/oils, hormones(made up of amino acids not a type), m/t/rRNA
What is diffusion?
The movement of molecules from an area of higher concentration to an area of lower concentration.
A cell needs to store and protect its DNA. Which organelle does this?
Nucleus
What is one characteristic shared by all living organisms?
Any of the characteristics of life, such as cellular organization, energy use/metabolism, homeostasis, growth and development, response to stimuli, reproduction, or adaptation/evolution.
What is the main structure that makes up the cell membrane? Why is it called a Fluid Mosaic Mondel?
Phospholipid bilayer
Fluid = changing
Mosaic = made of many different parts
What is the monomer of a protein?
Amino Acid
What happens to a red blood cell when it is placed in a hypertonic solution, and why?
It shrinks because water moves out of the cell.
Please provide the mitochondrial evidence for the endosymbiotic theory.
Mitochondria resemble bacteria by having their own DNA, ribosomes, and being able to divide on their own. Leading to have been evolved from older bacteria, being engulfed by other bacteria but not digested because both benefited from the arrangement.
What are the three parts of the cell theory?
1.All organisms are composed of one or more cells
2.The cell is the basic unit of structure and organization
3.Cells arise from pre-existing cells
A phospholipid has two different regions. Which part interacts with water, which part avoids water, and what terms are used to describe these two properties?
The phosphate head is hydrophilic (polar), and the fatty acid tails are hydrophobic (nonpolar). This makes it amphipathic, both polar and nonpolar.
A student eats a sandwich. Before the large molecules in the food can be used as smaller building blocks, what process breaks them apart?
Hydrolysis. Water is used to break bonds between monomers or subunits.
A hormone travels through the bloodstream and reaches several different types of cells. Only one type of cell responds to the hormone. What determines whether a cell can respond to the hormone?
The cell must have the correct receptor for that hormone.
A pancreatic cell produces and secretes large amounts of digestive enzymes. Which two organelles would you expect this cell to have lots of?
Rough ER and Golgi apparatus
The rough ER makes proteins, and the Golgi modifies, sorts, and packages them.
What is chirality? What is its importance in biological systems?
Chirality is a property of a molecule where it has a mirror-image form. These molecules have the same atoms and connections but differ in their three-dimensional arrangement.
Chirality is important in biological systems because enzymes, receptors, and other biological molecules are also three-dimensional and can distinguish between different molecules. As a result, two molecules can interact differently with the body and may have different biological effects.
A cell normally functions at 37°C, but its environment suddenly drops to 10°C. As the temperature decreases, the phospholipids in the cell membrane move less and the membrane becomes more rigid. What change could the cell make to its phospholipids to help maintain membrane fluidity at the lower temperature? Explain why this change would help.
The cell could increase the amount of unsaturated fatty acid tails in its phospholipids. The bends caused by double bonds prevent the phospholipids from packing tightly together, helping the membrane remain fluid even at lower temperatures.
A protein normally folds into a specific shape that allows it to function. A mutation changes one amino acid from nonpolar to charged. How coudl this affect the protein?
The change could alter interactions within the protein and cause it to fold differently. Since protein shape is important for function, the mutation could change or eliminate its function.
What type of transport do each of these use?
A. Oxygen moves directly through the phospholipid bilayer from an area of high concentration to low concentration.
B. Sodium ions are moved from an area of low concentration to an area of high concentration using cellular energy.
C. Glucose moves across the membrane through a transport protein from high concentration to low concentration without using ATP.
D. Water moves across a selectively permeable membrane toward the area with a higher solute concentration.
A. Simple diffusion
B. Active transport
C. Facilitated diffusion
D. Osmosis
A scientist observes that a cell has a large amount of protein accumulating inside its rough ER, very little protein reaching the cell surface, and an unusually large amount of transport vesicles near the ER. Which part of the secretory pathway might be malfunctioning? Explain how you would use the observations to support your answer.
The problem could be with transport from the ER to the Golgi. Proteins are made in the rough ER and normally packaged into vesicles that carry them to the Golgi. If they cannot progress through this pathway, proteins could accumulate in or near the ER while secretion to the cell surface decreases.
Carbon is found in which major biological macromolecules? What properties of carbon make it so important to living organisms, and how do those properties allow carbon to serve as the basis for such a wide variety of biological molecules?
Carbon has four valence electrons, allowing it to form up to four stable covalent bonds. It can bond with other carbon atoms and with elements such as hydrogen, oxygen, nitrogen, and phosphorus. This allows carbon to form chains, branches, and rings with many different structures, making it the foundation of the diverse molecules needed for life.
A researcher named Alex is studying two types of cells. Cell A has a normal plasma membrane, while Cell B has a mutation that causes many of its membrane proteins to stop working. Both cells still have a phospholipid bilayer. Alex notices that Cell B can no longer receive certain signals from outside the cell and has difficulty moving specific substances across its membrane. Why can the cell still have an intact phospholipid bilayer but be unable to perform these functions? What roles do membrane proteins play?
The phospholipid bilayer provides the basic structure of the membrane, but membrane proteins perform many specific functions. Some act as receptors that receive signals, while others act as channels or transporters that move substances across the membrane. Without functioning membrane proteins, the cell can have an intact membrane but still lose important abilities.
A student eats a meal containing carbohydrates, proteins, and lipids. Their digestive system breaks these large molecules into smaller molecules that can be absorbed and used by cells. Identify what each macromolecule is broken down into:
A. Carbohydrates → ?
B. Proteins → ?
C. Nucleic acids → ?
A. Monosaccharides, such as glucose
B. Amino acids
C. Nucleotides
Emma is studying a cell that normally uses a membrane protein to move potassium ions into the cell. Under normal conditions, potassium is moved from an area of lower concentration to an area of higher concentration. One day, Emma adds a chemical that prevents the cell from producing ATP. She notices that potassium movement quickly decreases, but oxygen can still move across the membrane. Why does blocking ATP production affect potassium movement but not oxygen movement? What does this tell you about the two transport processes?
Potassium is being moved against its concentration gradient, so the cell needs energy from ATP to transport it. When ATP production stops, this active transport decreases. Oxygen can move directly through the phospholipid bilayer down its concentration gradient, so it uses simple diffusion and does not require ATP.
A toxic chemical is introduced into a cell. Over time, the cell becomes less able to break down the chemical and also produces fewer lipids than it normally would. The researcher finds that the cell's ribosomes and mitochondria are still functioning normally. Which organelle is most likely affected? Explain how a defect in this organelle could cause both changes in the cell.
The smooth endoplasmic reticulum (smooth ER) is most likely affected. The smooth ER is involved in lipid synthesis and detoxification of drugs and other harmful substances. If it is not functioning properly, the cell could have decreased lipid production and a reduced ability to detoxify the chemical.
Identify the four levels of protein structure and explain what happens at each level.
A mutation changes several amino acids in the membrane-spanning portion of a membrane protein from nonpolar to charged amino acids. The protein is still produced by the cell, but it no longer remains properly embedded in the plasma membrane. Explain how the chemical properties of both the amino acids and the phospholipid bilayer could cause this protein to malfunction.
The interior of the phospholipid bilayer is hydrophobic, so nonpolar amino acids in the membrane-spanning region can interact favorably with it. Charged amino acids are not compatible with this hydrophobic environment. Replacing the nonpolar amino acids with charged ones can make the protein unstable within the membrane, preventing it from being properly embedded and interfering with its function.