EBIO 1210 Test 1

Are hydrophilic molecules polar or nonpolar?

Polar

What are the building blocks of a phospholipid?

Phosphate + Glycerol + 2 fatty acid chains

Building blocks of Large Carbohydrates?

Polysaccharides (from the simplest sugars- monosaccharides)

C-H bond has features that are essential for life:

(1) serves as an energy source (2) does not mix with water & serves as a barrier around cells to keep certain substances in or out

In which major human tissue systems do aquaporins play a role?

- Saliva - Gastrointestinal juices during digestion - Kidneys - Lungs - Tears - Sweating

Site of protein synthesis in the cell

Ribosome

Endocytosis vs. Exocytosis

-Endocytosis: substance is being ingested -Exocytosis: substance is being explorted

• Predict when a protein is needed for movement: For small nonpolar, hydrophobic substances? ____ For polar or charged, hydrophilic substances? ____ • Predict when (ATP) energy is needed for movement: When substances move from high to low concentration, i.e., along their concentration gradient? ___ When substances are moved from low to high

-Nonpolar, hydrophobic.... no protein needed - Polar, hydrophilic.... protein needed - High to low... No ATP needed (passive transport) - Low to high... ATP needed (active transport)

The positive charge on the inside causes K+ channels to open "behind" the action potential. Predict what will happen: A) K+ rushes out of the cell and the original electrical gradient starts to reestablish. B) K+ rushes into the cell and the electrical gradient remains reversed.

A) DOWN its concentration gradient

What provides the energy for facilitated downhill diffusion of the hydrophilic sugar fructose? A) the potential energy contained in the concentration gradient of the fructose B) the transport protein C) the potential chemical energy contained in C-H bonds of the sugar

A) No energy is required because it is going "downhill"

Place the components of the endomembrane system into a functional sequence: (example: insulin)

1. DNA for insulin copied into mRNA and exported from nucleus 2. Insulin synthesized by ribosomes on rough ER 3. Insulin protein packaged into transport vesicles and transferred to near side of Golgi apparatus 4. Transport vesicles fuse to form first flat sacks of Golgi apparatus 5. Processed in Golgi apparatus into a mature protein 6. Packaged into transport vesicles at opposite side of Golgi apparatus and transported to plasma membrane 7. Exocytosis: Fusion of vesicle with the plasma (outer cell) membrane 8. Insulin travels through the bloodstream and triggers sugar uptake by a target organ

What are the three classes of lipids?

1. Fats 2. Phospholipids 3. Steroids

The 3 classes of lipids and their functions:

1. Fats- store energy 2. Phospholipids- Form biological membranes 3. Steroids- Act as hormones/ regulate genes

What makes a water molecule stick to other water molecules as well as to other "water-loving" molecules?

1. Hydrogen bond 2. Polarity

What are the 3 types of work that require energy provided by ATP?

1. Mechanical- motor molecules (muscles, vesicles) 2. Transport- Pumps in brain, heart, and muslces 3. Chemical- Synthesizing life's large molecules

Name the four levels of protein structure and their corresponding shapes:

1. Primary = Amino acid sequence 2. Secondary = Curling or pleating 3. Tertiary = Folding (**Becomes 3-D) 4. Quaternary = Two or more subunits

What are two examples of Active Transport?

1. Sodium-Potassium Pump 2. CA2+ pump of muscles cells

Identify the sequence of information flow from DNA to RNA to proteins

1. Synthesis of mRNA in the nucleus 2. Movement of mRNA into cytoplasm via nuclear pore 3. Synthesis of protein

Predict how many molecules of water are needed to completely break down a polymer consisting of 20 monomers:

19 Always one less molecule than there are monomers

Predict which type of fatty acid should be abundant in the membrane phospholipids of plants and microbes from hot environments: A) saturated B) monounsaturated (with one C=C) C) polyunsaturated (with more than one C=C)

A) Saturated

Smooth ER synthesizes: A) Steroid hormones B) Protein hormones

A) Steroid hormones

Predict how many molecules of water are needed to completely break down a fat into its monomers?

3 A fat is a TRIglyceride = 3 fatty acid bonds.... need a water molecule to break EACH bond

What are the building blocks of a steroid?

4 Carbon-Hydrogen rings

Temperate zone: Walnuts, canola oil Mediterranean zone: Olive oil Tropical zone: Palm oil, coconut oil, macadamia nuts Q22. Predict what should be a source of polyunsaturated fat (with more than one C=C) A) Walnuts and canola oil B) Olive oil C) Palm and coconut oil; macadamia nuts

A) Walnuts & canola oil in colder climates will have more polyunsaturated

Predict: Vitamin B5 is A) hydrophilic B) hydrophobic

A- Hydrophilic There is a more balanced ratio of O-H bonds with C-H bonds.... This provides enough "stickiness" for B5 and water to attract

Vitamins A, E, and C?

A- hydrophobic E- hydrophobic C- hydrophilic

Which lipid has the highest energy content? All have 18 carbon atoms in each of their fatty acid chains. A) a fat containing only saturated fatty acids B) a phospholipid containing only saturated fatty acids

A... - Saturated fatty acids have 3 chains - Phospholipids only have 2 chains

Now predict whether or not hydrogen bonds will form between the fatty acid tails of a fat. A)Hydrogen bonds will not form. B)Hydrogen bonds will form.

A... They hydrogen bonds will not form because the fatty acid does not have the partial positive & negative charges to attract one another

What energizes these pumps?

ATP via phosphorylation

(= ultrafast electric signal) travels along axon as the basis for nerve function

Action potential

Building blocks of Proteins?

Amino acids

What are the building blocks of a protein?

Amino acids

Membrane spanning protein channels allowing (polar) water to move across (hydrophobic) lipid membranes:

Aquaporins

Predict which type of fatty acid should be abundant in membranes of plants and microbes in cold environments. Fatty acids that are A) solid at cold temperature. B) fluid at cold temperature.

B) Fluid

A stimulus opens Na+ channels. Predict what happens: A) Na+ rushes out of the cell and the original electrical gradient increases (cell becomes more positive on the outside). B) Na+ rushes into the cell and the original electrical gradient is reversed (cell becomes more positive on the inside).

B) Goes DOWN its concentration gradient

Use the polarity of the four molecules below to predict which ones can, or cannot, pass directly through the phospholipid bilayer of a biological membrane. A) O2 or H2O can pass through the bilayer, whereas Na+ or a fatty acid cannot. B) O2 or a fatty acid can pass through the bilayer, whereas Na+ or H2O cannot. C) O2 or Na+ can pass through the bilayer, whereas a fatty acid or H2O cannot. D) H2O or a fatty acid can pass through the bilayer, whereas Na+ or O2 cannot.

B) H2O and Na+ are polar. O2 and fatty acids are nonpolar.

Predict what the amino acids making up the INTERIOR of the sodium-potassium pump must be like: A) hydrophobic B) hydrophilic C) able to interact with the fatty acid tails of the membrane D) able to interact with phospholipid head groups

B) Hydrophilic.... Interior that helps hydrophilic substances needs to BE hydrophilic

Predict the properties of an excellent donor of an energized P group: The donor must A) hang on tightly to the P group. B) be "eager" to get rid of the P group. C) be a molecule to which a P group can be added without the input of energy. D) A and C E) B and C

B) If it's gonna be a good donor, it must be eager to get rid of a phosphate group.... willing to USE ENERGY to get rid of it ****Loading from low to high potential energy requires energy input

Rough ER synthesizes: A) Steroid hormones B) Protein hormones

B) Protein hormones

Predict which hormones can pass directly through the lipid bilayer of membranes: A) Protein hormones B) Steroid hormones

B) Steroid hormones.... They are hydrophobic, nonpolar lipids

Three of the following movements across the cell membrane require a membrane-spanning protein (either a protein facilitating diffusion or an energy-driven protein pump). Which does NOT require a membrane-spanning protein? Movement of A) hydrophilic fructose along its concentration gradient. B) a steroid from high to low concentration. C) H2O from high to low concentration. D) Na+ from low to high concentration

B) Steroid is the only hydrophobic

Predict what changes occur in the membranes of a tree growing in South Africa's inverted southern-hemisphere climate with cold temperatures in July and hot temperatures in January: A) The fatty acid composition of the membranes will not change between seasons. B) The proportion of unsaturated fatty acids will be higher in July than in January. C) The proportion of unsaturated fatty acids will be lower in July than in January.

B) Unsaturated = cold temps Saturated = hot temps

Predict: Vitamin D2 is A) hydrophilic B) hydrophobic

B- Hydrophobic There is only one O-H bond amongst many, many C-H bonds

Predict whether or not hydrogen bonds will form between the fatty acid tails of a fat. To build an argument, first decide which statement below is FALSE? A) The C-H bonds of fatty acids are nonpolar. B) The C-H bonds of fatty acids are polar. C) The C atoms in C-C, C=C, and C-H bonds of fatty acids have no partial electrical charge. D) The H atoms in C-H bonds have no partial electrical charge. E) The shared electrons are loosely held in the C-H bonds of fatty acids.

B. The C-H bonds of fatty acids are NONPOLAR. Fatty acids are not water soluble, so they cannot be polar.

What information do genes pass on?

Blueprints for making the all-important proteins

These make proteins like insulin for export from the cell

Bound ribosomes

Where are proteins for export synthesized?

Bound ribosomes on the rough ER

Key Function of Membranes:

Bring in food & building blocks; eliminate waste; keep out unwanted materials

Predict what changes occur in membranes of a plant in Colorado that grows throughout the hot summer season and overwinters during the cold winter: A) The fatty acid composition will not change between seasons. B) The proportion of unsaturated fatty acids will be higher in the summer and then decrease in the winter. C) The proportion of saturated fatty acids will be higher in the summer and then decrease in the winter.

C

What energizes ATP? A) The phosphate groups add many bonds with tightly held electrons. B) Each phosphate group adds more negative charges that attract each other. C) Each phosphate group adds more negative charges that repel each other.

C) - Can't be A because bonds with tight electrons are very stable... not reactive or energy rich - When charges are the same, they repel each other (like a magnet).... pops off a phosphate group and gives it to a different molecule

The sugar glucose is hydrophilic. What is needed to move glucose from the gut into intestinal cells after a sugar-rich meal? A) a membrane protein and ATP B) no membrane protein and no ATP C) a membrane protein, but no ATP D) no membrane protein, but ATP

C) It's hydrophilic so it needs a membrane. However, it is going from high to low concentration so no ATP is needed.

Predict which type of fatty acid should offer the greatest benefit for membranes of plants and microbes in the coldest places on Earth: A) saturated B) monounsaturated (with one C=C) C) polyunsaturated (with more than one C=C)

C) Polyunsaturated

Four of the following statements accurately describe how various living organisms keep their membranes at an appropriate fluidity to function. Which statement is FALSE? A) Mammals invest energy to regulate body temperature. B) Humans must acquire fatty acids essential for optimal membrane protein function with the diet. C) All organisms are capable of synthesizing all fatty acids they require for optimal membrane protein function. D) Cholesterol optimizes membrane fluidity of mammals. E) Plants alter the fatty acid composition of membrane phospholipids.

C... Humans need fatty acids from diet! We cannot synthesize them all.

Which lipid has the lowest number of C-H bonds? All have 18 carbon atoms in each of their fatty acid chains. A) a fat containing only monounsaturated fatty acids B) a fat containing only saturated fatty acids C) a phospholipid containing only monounsaturated fatty acids D) a phospholipid containing only saturated fatty acids

C... Only 2 chains

At ____ temperature, membrane can become too fluid (= leaky); at ____ temperature, membrane can lose fluidity and become too rigid. A) cold; hot B) cold; even colder C) hot; cold D) hot; even hotter

C... hot = too fluid and cold = too rigid Organisms either invest energy to maintain a constant body temperature (mammals) or invest energy to increase or decrease fluidity as needed (microbes, plants, non-regulating animals)

Predict: How can the cell increase the fluidity of its membranes? A) replace phospholipids with fats B) increase the length of fatty acids in the phospholipids C) increase the number of unsaturated fatty acids D) increase the number of saturated fatty acids

C.... More unsaturated = More fluidity

Picture the beginning synthesis of a polymer made of the following kind of monomers. Each monomer contains 2 carbon (C) atoms, 6 hydrogen (H) atoms, and 1 oxygen (O) atom; each monomer has the formula C2H6O. What is the formula of the molecule formed after connecting three of these monomers?

C6H14O

Where is DNA copied into mRNA during protein synthesis

Cell nucleus

Are molecules with ionic bonds hydrophobic or hydrophilic?

Charge = Hydrophilic

This is the precursor for steroid hormones, stabilizes biological membranes in animals, and has a role in heart disease

Cholesterol

What class of lipids are the sex hormones estrogen and testosterone?

Cholesterol

What is the Precursor in synthesis of steroid hormones: Sex hormones & steroid stress hormones?

Cholesterol

Phosphorylation of the sodium/potassium pump (Na+/K+ pump) energizes uphill transport of what? A) 1 Na+ and 1 K+ are pumped uphill B) only Na+ is pumped uphill C) only K+ is pumped uphill D) 3 Na+ and 2 K+ are pumped uphill E) 3 Na+ and 3 K+ are pumped uphill

D)

Predict: To allow passage of H2O molecules, the amino acids in the aquaporin's outer middle regions in contact with the membrane's fatty acid tails have to be __________ and the amino acids lining the protein's inner channel and its top and bottom portions have to be __________. A) hydrophilic, hydrophilic B) hydrophobic, hydrophobic C) hydrophilic, hydrophobic D) hydrophobic, hydrophilic

D) Outside is touching the hydrophobic tails, so it must be hydrophobic. Where the water moves through must be hydrophilic

A hydrophilic amino acid R (rest) group in a water-soluble protein hormone (like insulin in the blood stream) has the potential to interact with A) only the water molecules surrounding the protein. B) only other hydrophilic R groups of the protein. C) only hydrophobic R groups of the protein. D) A and B E) A, B, and C

D) Hydrophilic can only interact with other hydrophilic

Predict: The inside of the barrel-shaped protein that carries water-insoluble vitamins through the water-based blood fluid consists of _______ amino acids, while its outside portions in contact with the blood fluid consist of ______ amino acids. A) hydrophilic, hydrophilic B) hydrophobic, hydrophobic C) hydrophilic, hydrophobic D) hydrophobic, hydrophilic

D) INside must be hydrophobic to offer a frienly non-water environment.... and the outside is hydrophilic so it can travel throgh the water-based blood

In what type of cells do you expect to find a particularly high level of rough ER? A) pancreas cells (produce insulin) B) testes (produce testosterone) C) fat cells (produce the protein hormone leptin) D) A and C E) A, B, and C

D) Insulin is a protein and fat cells produce a protein.... Thus rough ER

Which statement is most accurate? A) Unsaturated fatty acids are good and saturated fatty acids are bad. B) Unsaturated and omega-3 fatty acids are good, while saturated and omega-6 fatty acids are bad. C) The human body adjusts its fatty acid composition by synthesizing those fatty acids that are in low supply. D) All fatty acids (saturated and unsaturated, omega-3 and omega-6) have essential roles in humans. E) Fish oil is the only source of omega-3 fatty acids.

D) They all have essential roles.... We just need BALANCE

Which fat has the SECOND greatest number of C-H bonds? Each fatty acid chain has 18 carbon atoms. A) a fat containing only monounsaturated fatty acids B) a fat containing 1 saturated fatty acid and 2 monounsaturated fatty acids C) a fat containing only saturated fatty acids D) a fat containing 2 saturated fatty acids and 1 monounsaturated fatty acid

D) saturated C-H bonds are more abundant than the 1 C=C bond in the monounsaturated

Four of the five features below are characteristics of C-H bonds. Which is not? a) Nonpolar b) High chemical potential energy c) Low stability d) Low chemical potential energy e) Can be burned to carbon dioxide and water

D- Low chemical potential energy

Building blocks of Nucleic acids?

DNA & RNA (built from nucleotides)

How are large molecules formed?

Dehydration Synthesis- Large molecules are formed from monomers by removing water: -H from one end & -OH from the other

Predict at which structural level(s) one can alter the function of a protein: A) only primary B) only secondary C) only tertiary D) only quaternary E) primary, secondary, tertiary, and quaternary

E) All of them

Which of the following statement(s) regarding ATP is/are correct? A) ATP serves as a main energy carrier inside cells. B) In the cell, ATP drives reactions that require energy by the transfer of a phosphate group to specific reactants. C) The regeneration of ATP from ADP and phosphate is a reaction that requires energy. D) A and B only E) A, B, and C

E) All of them

Which of the following accurately complete(s) the sentence: Protein hormones ____________________________? A) deliver their message to a receptor in the outer cell membrane of the target cell B) pass easily through the outer cell membrane of the target cell C) bind to a gene regulatory protein in the nucleus of the target cell D) use a signal transduction system to deliver their message to the nucleus of the target cell E) A and D

E) Protein hormones are water soluble and can not pass directly through to the nucleus.

What happens during muscle relaxation? A) Ca2+ moves back into the SR by passive transport. B) Ca2+ moves back into the SR by active transport. C) An ATP-fueled Ca2+ pump is involved. D) A and C E) B and C

E) Re-establishing an uneven distribution requires energy. Calcium is pumped against its concentration gradient using ATP

What initiates muscle contraction? A) Ca2+ is rapidly released via passive transport B) Ca2+ moves from cytosol to the SR C) Ca2+ moves from SR to the cytosol D) A and B E) A and C

E) The sarcoplasmic reticulum (SR) holds a high volume of calcium which is suddenly released... it's basically a storage..... The calcium then moves to the cytosol

Ribosomes are bound to this to make proteins for export from the cell

Endoplasmic Reticulum (ER)

This is the fusion of transport vesicle with the plasma membrane

Exocytosis

True or False? Altering the primary structure of a protein always changes its function. A) True B) False

False.... Sometimes alterations don't change the shape and function

What are the building blocks of lipids?

Fatty acids

Building Blocks of a Fat

Glycerol + 3 fatty acid chains

Where are proteins processed for maturity?

Golgi apparatus

What potential energy to Nonpolar Covalent Bonds have?

High chemical potential energy- reactive!

What kind of energy state do substances with loosely held electrons have?

High potential energy state = unstable, reactive

A saturated fatty acid is saturated with the maximal number of:

Hydrogen atoms and C-H bonds

This type of bond forms water molecules, based on the electrical attraction between opposite partial electrical charges

Hydrogen bonds

How are large molecules broken down?

Hydrolysis- Large molecules are broken down by adding water.

Phospholipids have a _______ head and a ________ tail:

Hydrophilic head Hydrophobic tail

Which molecules can pass directly through the phospholipid bilayer with no help?

Hydrophobic/ Nonpolar

How is hemoglobin altered to become sickle cell?

It is altered in its primary structure. One single amino acid is substituted..... Creates an exposed nonpolar hydrophobic side chain

The steroid cholesterol is transported in bloodstream via...

LDL (low density lipoprotein)

Familial hypercholesterolemia is caused by insufficient numbers of what?

LDL receptors.... Cholesterol then cannot be removed from the bloodstream

These hormones move into nucleus & bind directly to gene regulatory protein.

Lipid soluble steroid hormones

What potential energy to Polar covalent bonds have?

Low chemical potential energy- stable!

What kind of energy state do substances with tightly held electrons have?

Low potential energy state = stable, not reactive

The passage of hydrophilic (polar or charged) molecules through the phospholipid bilayer requires what?

Membrane spanning transport proteins

Proteins for secretion need to be wrapped in _______

Membrane vesicles

Will nonpolar molecules dissolve in water?

No.... Nonpolar = Hydrophobic

Are hydrophobic molecules polar or nonpolar?

Nonpolar

Facilitated diffusion of water through membranes via aquaporin proteins

Osmosis

Where would you expect to find a particularly high level of smooth ER?

Ovaries and testes (produce estrogen and testosterone, both steroid (sex hormones)

Diffusion and Facilitated Diffusion are examples of what?

Passive transport

Cholesterol is removed from arteries when LDL binds to a receptor in membrane & is removed from the bloodstream via....

Receptor mediated endocytosis

Free ribosomes, floating in cytoplasm, make proteins for use in same or different cell.

Same

Which releases more energy... Burning a saturated or unsaturated fatty acid

Saturated.... only needs a nudge The C=C bond is stronger and costs more energy to break than C-H

Role of cholesterol in animal membranes:

Temperature buffer

The solubility of a substance in water is determined by what?

The RATIO of its POLAR groups (i.e. O-H and C=O bonds) to NONPOLAR groups (C-H bonds)

Predict the result(s) of removing hydrogen atoms from the fatty acid tails of a saturated fat:

The number of carbon-carbon (C=C) double bonds in the fat molecule increases. The fat becomes more fluid

What forms the basic membrane structure?

The phospholipid bilayer.... its hydrophobic core is impenetrable to most molecules (to all polar/charged molecules)

This pump is ESSENTIAL for nerve impulses... Proper functioning of which pump is thus critical for mental health and learning ?

The sodium-potassium pump

What do all of the energy-rich substances (methane, hydrocarbon, hydrogen gas ) have in common?

They all contain electrons loosely held between two partner atoms *** C-H bonds provide energy... but hydrogen has no carbon, so this cannot be the answer

What do all biologically important large molecules have in common?

They are based on Carbon (C bonds with up to four partners, facilitating the formation of large molecules) They are constructed from small building blocks

What do the two low-energy products CO2 and H2O have in common?

They both contain electrons tightly held by one of the partner atoms. They both contain oxygen

What are genes?

They contain hereditary information

How are transport vesicles moved without going astray?

They go along "tracks" of cytoskeleton.... A motor protein powered by ATP moves along a microtubule track of cytoskeleton

What is an ionic bond?

Transfer of electrons (between atoms with the largest differences in electronegativity) (atoms have full charge)

True or False..... Pump function requires presence of specific polyunsaturated fatty acids as components of membrane phospholipids

True

These hormones relay message via signal transduction pathway to a gene regulatory protein.

Water soluble (Polar) protein hormones

How does cholesterol act as a temperature buffer?

• Prevents hydrophobic chains from packing too closely together: increases fluidity at low temperatures • Limits lateral phospholipid movement & stabilizes membranes at high temperatures