BSCI 170 Exam 1

If two elements combine to form a polar covalent bond, what must be true of those two elements?

They differ in electronegativity That is what creates polarity. Atoms with "noticeable" or "significant" differences in electronegativity will have sufficiently unequal sharing of electrons to give the covalent bond a measurable difference in partial charges at the two ends, called polarity. If the difference in electronegativity is slight these charges are too small to matter and still considered non-polar. We will expect electron stripping to occur with "very large" or "extreme" differences in electronegativity resulting in an ionic bond.

Water molecules are special because? The have a polar covalent bond They make things wet They have two hydrogens They have a special bond angle (bent)

They have a special bond angle (bent)

Give one feature of membrane bound organelles that suggests they were once bacteria living outside the cell.

They have their own ribosomes, which are more similar to bacterial ribosomes than eukaryotic ribosomes

What feature is used to recognize integral membrane proteins?

They insert into the hydrophobic region of the membrane Integral proteins can be transmembrane, passing all the way through, or monotopic, inserting into one side, but what they all have in common is part of the protein inserts the hydrophobic region of the membrane. Note the wording is very specific - you can have peripheral membrane proteins that insert between the phosphocholine heads of the phospholipids, so just saying they "stick into" the membrane is not sufficient.

What is the function of ribosomes in cells?

To make proteins

True or False: "It depends on the receiving cell"

True

True or False: All hydrogen bonds are the same length in water.

True

True or False: Membranes with more saturated fatty acids are less fluid.

True

True or False: pH is the measure of how much H+ is in solution

True

True or false: This molecule contains a hydroxyl group

True

Which of the following is not a protein used with G-protein coupled receptors?

Tyrosine Kinase

Which of the following is NOT found in ALL cells? A. Ribosomes B. Plasma membrane C. Vesicles D. RNA

VESICLES Vesicles are made with internal membranes so would not be found in prokaryotic cells.

Which of the following is true for osmosis? Plants do not experience osmosis Water always moves towards a hypertonic solution Water always moves into a cell Water always moves towards a hypotonic solution

Water always moves towards a hypertonic solution It is really important to recognize when osmosis will occur and that water has a net movement towards an area with relatively more overall solute (hypertonic = "more dissolved stuff").

It has 4 unpaired valence electrons

What makes carbon special?

What are the steps after a ligand binds to a Tyrosine kinase receptor?

(1) Dimerize (2) Autophosphorylation (3) Signal Transduction

A DNA double helix has a constant diameter because it consists of paired nucleotides that always have a single-ringed _________________ hydrogen bonding to a two-ringed ______________.

(1) Pyrimidine (2) Purine

What are the 3 stages of cell signaling in order?

(1) Reception (2) transduction (3) response

When water interacts with water molecules that is called ____________, but when water interacts with other polar molecules than is called ____________. These are both a consequence of ____________________ between molecules.

(1) cohesion, (2) adhesion, (3) hydrogen bonding

How many protons does carbon have?

6 protons

What is an acid?

A molecule that donates H+ ions

If you take a bacteria that normally lives in the ocean and drop it in the freshwater pond in your backward, would you expect the cell to be hypertonic, hypotonic, or isotonic compared to the environment? In terms of osmosis, what would you expect to happen in this situation?

A salt water bacteria will probably be hypertonic compared to fresh water. I would expect water to move into the cell.

A protein requires ATP to move molecules, therefore the protein is doing what?

Active Transport

What's important about phosphate molecules? They hydrogen bond + vander waal bond Add energy to molecules/make them more unstable They act as a base + act as an acid Acts as an electropositive atom + acts as a covalent linker

Add energy to molecules/make them more unstable

Which one of these is NOT a way of manipulating a carbon backbone? Adding or removing a carbon Making rings Adding water Making branches

Adding water

When water forms sticks on a piece of glass what property is being expressed? Cohesion Evaporative cooling Adhesion Heat Capacity

Adhesion

What does it mean when we say a fatty acid molecule is unsaturated? How does that effect the density of those molecules compared to saturated fatty acids?

An unsaturated fatty acid molecule does not have hydrogen atoms attached to it and contains a double bond that causes a bend in the molecule, making the molecules farther away from each other. This means that an unsaturated fatty acid molecule is less dense and is liquid at room temperature. The saturated fatty acid has at least 2 hydrogens attached to each of its molecules and only has single bonds, making the molecules stay near each other, making the saturated fatty acid dense. "Unsaturated" means a molecule does not have all of the hydrogens it could have because of the presence of one or more double bonds. Unsaturated molecules have a bent shape and push each other further apart making them less dense (more liquid) than saturated fatty acids (more solid).

The element magnesium is a flammable metal while hydroxide is in corrosive drain cleaner - both are very dangerous. However, when these are put together to make the molecule magnesium hydroxide, we get milk of magnesia which makes your upset tummy feel better. This is an example of the Big Idea Emergent Properties because it shows combining two dangerous things makes a new thing that is medicine, which is unexpected.

Answer 1: Emergent Properties Answer 2: combining two dangerous things makes a new thing that is medicine, which is unexpected This is an example of an Emergent Property. The key feature is we are combining things to make something new, and the original properties of the parts do not allow us to predict the new (emergent) properties of the whole.

Carbohydrates include large polymers called Polysaccharides assembled from individual sugar monomers called monosaccharides

Answer 1: Polysaccharides Answer 2: Monosaccharides You must know the proper names for the monomers and polymers of each type of macromolecule. Carbohydrates have monosaccharides and polysaccharides, as well as a special case of two monomers together called disaccharides.

If a membrane transport protein is being used to move two solutes at a time in the same direction we call it a symport protein , and if both solutes are moving towards an area of low concentration we would call the process Facilitated diffusion .

Answer 1: Symport protein Answer 2: Facilitated diffusion You are expected to recognize the difference between types of co-transport proteins and identify what process is occuring.

Which of the following is a characteristic specific to receptor tyrosine kinase activation?

Auto-phosphorylation All RTKs will dimerize and auto-phosphorylate upon ligand binding, both specific features of this type of receptor.

Exocytosis Phagocytosis Pinocytosis Receptor Mediated Endocytosis

Beta cells release many molecules of insulin all at once into the blood A macrophage in the immune system internalizes a virus for digestion by a lysosome A cell lining the small intestine taking up water to transfer to the blood Cells in the brain specifically take in folic acid

What determines how many covalent bonds an element will make when it is part of a molecule?

Bonds are formed by sharing of unpaired valence electrons.

Which of the following is a distinctive feature specific to GPCR activation? A. Dimerization B. Receptor conformational change C. Exchange of GDP for GTP D. Signal transduction cascade activation

C. Exchange of GDP for GTP This is specifically defined in both the modules and the study guide and is uniques to GPCRs. If you were tempted to answer B or D those also occur with RTKs, so are not specific to GPCRs.

What is this group?

Carbonyl

What functional groups are on testosterone?

Carbonyl Hydroxyl

What is the basic unit of life? Cells Sleep Coffee Atoms

Cells

When I add some cells to a hypotonic solution what happens? Cells burst Cells stay the same Depends on what part of the body the cells are in Cells shrivel up

Cells burst

Which molecule cannot pass through a lipid bilayer? Small nonpolar Small polar Charged molecules Large polar

Charged molecules Large polar molecules

Which of the following organelles was likely acquired by endosymbiosis? Golgi apparatus Chloroplast Endoplasmic reticulum Cytoskeleton

Chloroplast

Receptor tyrosine kinases must?

Dimerize

Which subatomic particle has a negative charge?

Electron

Cells working together to make a beating heart is an example of what big idea?

Emergent Properties

What is a difference between prokaryotes and eukaryotes?

Endomembrane system Cytoskeleton Membrane bound organelles

What Big Idea is best represented by the following example: A new strain of COVID-19 virus was recently discovered in England, resulting from random changes in the viral DNA over time causing a change in one of the viral proteins.

Evolution Yes! The key here is recognizing the example is about an organism changing over time. You can recognize an evolution question because it emphasizes organisms changing over time.

True or False: Dehydration reactions break peptide bonds.

False

True or False: G-proteins activate when GTP is exchanged for GDP

False

True or False: Gated ion channels and nuclear hormone receptors use signal transduction.

False

True or False: Hydrogens bond to other hydrogens during hydrogen bonding

False

True or False: If a chemical reaction uses 24 molecules of testudamine to make 1 molecule of polytestudone you would expect that reaction to use dehydration synthesis.

False If you are combining several small molecules into a bigger molecule that is making a polymer so you would use dehydration synthesis.

What is NOT one of the 4 major classes of macromolecules? Proteins Nucleic Acids Fats Lipids

Fats

What is signal amplification?

From one signal to many

What does water form around charged ions?

Hydration shell

Water has a lot of useful properties such as cohesion and high heat capacity, which pretty much all result from what?

Hydrogen bonds This is almost always the answer to a property of water question. Most of the very interesting properties of water are emergent properties of many water molecules interacting through hydrogen bonds.

A student submitted this drawing showing hydrogen bonding between water molecules. There are three bonds labeled A, B, and C. Two of these bonds are not quite correct. Pick those two and explain what's wrong with each one.

Hydrogen bonds must be between a positive charge and a negative charge (O and H in water molecules), and must always be the same length. bond B!

What do we call reactions that use water to break covalent bonds between amino acids when digesting protein?

Hydrolysis reactions Hydrolysis reactions break down polymers into monomers, using water to add H and OH groups to the molecules where the covalent bond is broken. Hydro-lysis means to break with water.

ALL lipids have one property in common, which is they are _________________.

Hydrophobic The lipids is a category of molecules that includes anything organic that does not dissolve in water which means they are all hydrophobic. The lipids includes molecules that are structurally very different from each other, such as triglycerides and steroids.

Icefish living in the waters under the antarctic ice sheets need to make their membranes more fluid compared to warm water fish, or their cells would solidify and not work correctly in the cold. What is one way icefish could change the composition of their membranes to make them more fluid?

Icefish could change the composition of their membranes to make them more fluid by adding more double bonds to the phospholipids to create unsaturated fatty acids. This allows for fluidity. The icefish could also manipulate the levels of cholesterol in their fatty acids Membranes can be made more fluid by: • Adding more phospholipids with unsaturated fatty acids • Adding cholesterol to make the membrane less viscous • Making the membrane with phospholipids with shorter fatty acids tails

What do we mean when say having internal membranes allows greater "compartmentalization" in eukaryotic cells? Why is this advantageous?

Internal membranes allows eukaryotic cells to create spaces inside membrane structures (lumens) that are new compartments separate from the cytoplasm. More compartments allows cells to perform more reactions at the same time without them interfering with each other.

What type of bond is being shown? (No sharing of electrons, large electronegativity difference)?

Ionic Bond

Which one of the following properties would most reliably indicate something is a living organism?

It is made of cells Bingo! The Cell Theory states that ALL living organisms are made of one or more cells. Non-living things are not made of cells, so this is a reliable indicator of life. You will learn a lot about cells in this course! Many properties we associate with life are also found among non-living things, such as movement, growth, or burning molecules using oxygen. Two properties we reliably associate with all life on Earth are: (1) all living things are made of cells, and (2) all living things evolve over time.

How is RME different from other types of endocytosis? It can bring in bigger molecules It uses receptors It's just different Can bring in more harmful molecules

It uses receptors

What is the proper term for a molecule that binds to and activates a receptor protein?

Ligand

What does not happen during transduction?

Ligand comes inside the cell

Which of these are a property of life? Living things evolve Living things stagnate Living things decay Living things are made of atoms

Living Things Evolve

What organelle is not part of the endomembrane system?

MITOCHONDRIA AND CHLOROPLAST

If I add cholesterol to a membrane what happens? Membrane becomes more fluid Membrane becomes more solid Membrane inverts Membrane breaks apart

Membrane becomes more fluid & Membrane becomes more solid

Which one of the following will have the lowest rate of diffusion across a phospholipid bilayer (assuming no proteins are present)?

Na+ (sodium ion) Ions have the most difficulty crossing the bilayer, with large polar molecules coming in a close second. Small molecules, including non-polar gasses and even polar molecules like water, are able to pass the membrane by moving in between the phospholipid molecules.

What would you expect in a bond that is formed between two elements with extreme differences in electronegativity? A. Equal sharing of electrons B. Unequal sharing of electrons C. No sharing, electron stripping D. They would not form a bond

No sharing, electron stripping Watch the wording for these questions, because differences in electronegativity are relative. "Similar" means they will make a non-polar covalent bond, "moderate," or "noticeable" indicate they are different enough to form a polar covalent bond, and "very large" or "extreme" differences would give an ionic bond, characterized by one element striping an electron from another and never giving it back (no sharing).

You just ate a meal full of cellulose, will you be able to digest it?

No, because Eukaryotes can't digest beta linkages

What type of bond is this? (Sharing Electrons, no electronegativity difference)?

Nonpolar covalent

Which of the following is definitely part of the endomembrane system? Mitochondria Plasma membrane Ribosomes Nuclear envelope

Nuclear envelope

Nucleic acids such as DNA and RNA are made by polymerization of what monomers?

Nucleotides

Which of the following structures would NOT be common to all cells?

Nucleus

Serine is a polar amino acid. Where would you expect to find it in a protein?

On the surface

Using information from the periodic table, predict how many magnesium atoms and how many chlorine atoms would be expected to combine in a stable magnesium chloride molecule. Briefly explain how you know.

One Mg and two Cl atoms, because Mg has two unpaired valence electrons and Cl have just one unpaired valence electron.

What will happen in this cell? Active transport Facilitated diffusion Osmosis Diffusion

Osmosis

What is this? Triglyceride Fat Phospholipid Lipid

Phospholipid

All biological membranes are based on what structure?

Phospholipid bilayer The phospholipid bilayer is the basis for all cell membranes, including the cell membranes of both prokaryotes and eukaryotes and the internal membranes of the endomembrane system and the membrane bound organelles.

All living things belong to one of two major groups based on what kind of cells they have. The first cells to evolve were relatively simple and are called .... what?

Prokaryotic

Hemoglobin is a protein composed of four polypeptide chains bound to an iron atom. What level of protein structure does this represent?

Quaternary

What is response plasticity?

Same cells have different responses to the same signal

What are these examples of?

Secondary Structure

Atoms are composed of a nucleus made from protons and neutrons surrounded by clouds of electrons. Those electrons are organized into layers called what?

Shells Electrons are distributed in shells.

What is a ligand?

Specific molecule from a sending cell that binds to a specific receptor

What Big Idea is best represented by the following example: Tuna fish have sleek, torpedo shaped bodies for reduced friction and greater swimming speed. Dolphins also have sleek, torpedo shaped bodies and can swim fast.

Structure-Function Relationships We have two creatures that are not closely related but have similar features (torpedo shaped body) associated with similar abilities (swimming fast). This suggests a structure-function relationship. You can recognize structure-function questions because we observe a key feature associated with the same function in different contexts.

A list of the Top 10 Fastest aquatic animals will always include porpoises, tuna fish, and mako sharks. These animals all share a streamlined torpedo shape that allows them to move quickly through water. What Big Ideas is this an example of?

Structure-Function Relationships. Note: It would not be Evolution, because these are not closely related and there is nothing about changes over time. It would not be emergent properties, either, because we expect torpedo shaped objects to be streamlined and there is nothing new or surprising here.

Singal cascades cause everything EXCEPT for? Transfusion Plasticity Diversity Amplification

TRANSFUSION

How many rings does a purine have?

TWO (2)

Which of the following statements would you expect to be true if you know that two atoms are joined by a non-polar covalent bond?

The electrons are shared equally. Relative differences in the electronegativities of two elements determines if a bond will be non-polar, polar, or ionic.

Consider the following models of an oxygen atom: These are both valid models, but in the context of this class which model do we prefer and why?

The model on the right, because it shows paired and unpaired electrons We are interested in atoms combining to form molecules, and paired vs unpaired valence electrons is the single most important piece of information we need!

In addition to "uses energy," what is another way to tell if the movement of a solute through a membrane protein has to be active transport?

The movement of solute through a membrane protein has to be done through active transport if the solute is being moved in the opposite direction of its concentration gradient from a lower concentration to a higher concentration. It also has to be active transport if ATP is required to transport the solute through a transport protein such as a Sodium Potassium Pump. Sometimes it is difficult to recognize if energy is being used for transport - but you can always recognize active transport because at least one solute is moving "up its gradient" towards high concentration.

Why are amino groups important?

They act as biological bases

The mitochondria imports malate from the cytoplasm into the mitochondrial matrix using an antiport protein for the co-transport of malate and citrate. The facilitated diffusion citrate provides the energy to actively transport malate into the mitochondria. (1) In which direction is citrate being transported? What information from the question did you use to answer this? (2) What has to be true about the concentration of citrate inside the mitochondria? What information from the question did you use to answer this?

1) Citrate is being transported into the cytoplasm, outside of the mitochondria to create a difference in the gradient of citrate inside vs outside of the mitochondria. The difference in gradient is the energy source provided so malate will be actively transported into the mitochondria with citrate, which is following its gradient from high to low concentration. 2) The concentration of citrate inside the mitochondria must always be lower inside the mitochondria than in the cytoplasm so that the difference in concentration of the citrate always causes the malate to be pushed into the mitochondria with the citrate. While malate goes into the mitochondria, the antiport protein is constantly moving citrate into the cytoplasm, unless a specific pump is being used to move citrate out. (1) You should know an antiport move solutes in opposite directions, so citrate is leaving the mitochondria as malate is coming in. (2) Citrate has to be at higher concentration inside the mitochondria in order for it be transported by facilitated diffusion.

What are the three main benefits of using signal transduction cascades between receptor activation and cellular responses?

1) Signal Amplification 2) Response Diversity 3) Response Plasticity

1. What level of structure does this protein represent? 2. What do we call the secondary structures represented by the "corkscrew" shapes in this model?

1. Tertiary Structure 2. Alpha Helix The model shows a protein folded into a complex 3 dimensional structure. The information given specifically says this is a single polypeptide, so it would be a tertiary structure not a quaternary structure. The model shows the secondary structures formed along the length of the polypeptide consisting of alpha helices ("corkscrews") and beta sheets (arrows).

How many bonds is oxygen able to form? (Atomic number 8)

2

How many unpaired valence electrons does oxygen have? (Atomic number 8)

2

The figure below shows the starting conditions of an experiment with an artificial cell placed in solution. The membrane of the artificial cell has pores that will allow ions to pass through freely, but not larger molecules like sugars. Apply the two step process you learned in class, explaining briefly what you did for each step, to answer the question: "Will osmosis occur in this experiment, and if so in which direction will water move? How do you know?"

Your Answer: 1. Calcium ions can diffuse through the artificial cell pores, so naturally Calcium will diffuse 1.3M into the cell with its concentration gradient to get to equilibrium. Lactose will not diffuse because it is too large. This leaves 3.7M (Calcium and Lactose together) total inside the cell and 1.8M total outside the cell. 2. The inside of the cell will be hypertonic because there is a higher concentration of solutes inside the cell. Due to this, Osmosis will occur and water will move toward the hypertonic concentration inside the cell. Step 1 would be to "do diffusion" by determining which solutes can diffuse and determining their equilibrium concentration. Here, there are pores that allow ions to pass so Ca+ will diffuse, but the larger sugar lactose will not diffuse. After diffusion occurs, the Ca+ concentration will be the same on both sides - to find that, get the total amount of calcium and divide by two: 3.0 M + 0.4 M = 3.4 M; 3.4 M/2 = 1.7 M Ca+ on each side. Step 2 is to determine if there is a difference in total concentration of all solutes, and if so which area is hypertonic. Once Ca+ reaches equilibrium there will be 1.8 M total solutes outside and 3.7 M solutes inside, therefore inside the artificial cell is hypertonic and water will move into the cell.

The carboxyl functional group makes an organic molecule into an acid. Why?

because the molecule will drop a hydrogen ion A carboxyl group will ionize in water because the H from the OH part will "fall off" and become an H+. More H+s make water more acidic, so that makes molecules with carboxyl groups acids.

What are RTKs usually called?

growth factor receptors