Bio 1700 Exam 2

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

oxidative phosphorylation

The formation of ATP by directly transferring a phosphate group to ADP from an intermediate substrate in catabolism.

substrate-level phosphorylation

the addition of a phosphate group to a molecule

Phosphorylation

Proteins that speed up chemical reactions

enzymes

When the temperature drops, the plasma membrane becomes less fluid. In order to keep its mobility high (or normal), the cell changes the composition of phospholipids of the plasma membrane. Propose two possibilities.

The cell makes phospholipids with more unsaturated fatty acids The cell makes phospholipids with shorter fatty acids.

In the photo-bleaching experiment, what would be a conclusion if the bleached area stayed black (no green fluorescence)?

Proteins in the plasma membrane do not move. In other words, the plasma membrane is not fluid.

Which of the following molecules do not require a transport protein to cross the plasma membrane?

steroid hormones, oxygen, CO2

do nonpolar molecules require a transport protein to cross the plasma membrane?

no

do large polar molecules require a transport protein to cross the plasma membrane?

yes

do small molecules require a transport protein to cross the plasma membrane?

no

do huge charged molecules require a transport protein to cross the plasma membrane?

yes

do steroid hormones require a transport protein to cross the plasma membrane?

no

does glucose require a transport protein to cross the plasma membrane?

yes

does oxygen require a transport protein to cross the plasma membrane?

no

does CO2 require a transport protein to cross the plasma membrane?

no

does mRNA transcript require a transport protein to cross the plasma membrane?

yes

Some people will sprinkle table salt on slugs to kill them. Explain why it is an effective way of killing slugs.

Sprinkling salt on the body of slug means an increase of solute (Na+ & Cl-) concentration; that is, creation of hypertonic environment. Therefore, water in the cells of slug goes out, leading to the death of slug

Cells that produce a lot of digestive enzymes, those found in the stomach, the small intestine, and the pancreas, are enriched in rough endoplasmic reticulum and Golgi apparatus. What is a possible reason for this observation?

These organelles are essential to secrete secreted proteins like digestive enzymes.

Cells isolated from the stomach of the mouse secrete pepsin to help break down food in the stomach. Under the guidance of Dr. T (a great professor here at OU), the students in BIOS 1700 irradiated them with X-rays to create mutations. With a great deal of dedication and patience, they finally created a cell line that fails to secret pepsin. Interestingly, these cells have a high level of pepsin in the cytoplasm. What gene (or portion) is likely to be mutated?

The pepsin gene itself is likely mutated in the signal sequence.

When reactants have more energy than products in a chemical reaction what is ΔG (positive or negative)

ΔG\=Products-Reactants Products\>Reactants: ΔG

A proton gradient created as shown in Fig. 5.13 has (potential/kinetic) energy. (Choose one)

potential

Chemical reactions always have an unstable state called the (A) state even in exergonic (or spontaneous) reactions. This state has an amount of energy called (B), so we have to provide additional energy to push the reaction forward to get products from reactants. In the cell, (C) help reduce (B) so that chemical reactions go faster. Since (C) themselves do not change, (C) are also called (D).

A: transition B: activation energy C: enzymes D: catalysts

Enzymes are remarkable biological molecules that catalyze chemical reactions. The site for chemical reactions in an enzyme is called an (A) site and consists of several amino acids. In many cases, these amino acids are not next to each other in its (B) structure but assemble in one functional unit in its (C) structure. Therefore, folding enzymes into the right configuration is essential.

A: an active or a catalytic B: primary C: tertiary

Threonine dehydratase is the first enzyme in the process of making isoleucine from threonine. The activity of this enzyme is regulated positively and negatively. This is a typical example of regulatory loops, which helps us understand how the cell (or the body) controls biological chemical reactions. The enzyme has two (A) sites, one for threonine, and the other for isoleucine. To make a balance of threonine and isoleucine, the enzyme becomes more active when the cell has excess of threonine because binding of threonine to one of the (A) sites stimulates the catalytic activity of threonine dehydratase. On the other hand, when isoleucine accumulates in the cell, the enzyme becomes less active because binding of isoleucine to the other (A) sites inhibits the catalytic activity of this enzyme. Threonine and isoleucine are called (B) regulators. The effect of isoleucine on threonine dehydratase is also called (C).

A: allosteric B: non-competitive C: negative feedback

In cellular respiration, glucose is broken down to CO2 , and O2 becomes H2O. Its chemical reaction can be written as follows:

C6H12O6 + 6O2 -\> 6CO2+6H2O

When you describe the redox reaction of glucose consumption with the gain or loss of electrons, carbon atoms in glucose are oxidized in CO2 because carbon atoms in C6H12O6 ( \______ ) electrons. On the other hand, oxygen atoms in the O2 gas are reduced because oxygen atoms in H2O ( \______ ) electrons.

loses, gains

Production of energy by breaking down glucose to CO2 in cellular respiration is analogous to (catabolism/anabolism). Circle One

Catabolism

Electrons fed by electron carriers into the electron transport chain are used to run ( \__________ ) pumps. They are ( \__________ ), ( \____________ ), and ( \____________ ). Electrons leave the electron transport cha

Proton, Complex I, Complex III, Complex IV, Reducing, Water

In β-oxidation, fatty acids are broken down into ( \___________ ), during this process ( \__________________ ) are created.

Acetyl-CoA, FADH2 and NADH

This is a hypothetical situation: There is a mouse with a mutation that makes the F0 subunit of ATP synthase less effective. In other words, the F0 subunit lets protons go through without efficiently turning its "fan." This means the conversion of potential energy in the proton gradient across the inner membrane to kinetic energy is less efficient. How does this mutant mouse look in comparison to the normal healthy mouse? Why?

Since this defective F0 subunit of ATP synthase cannot give energy to the F1 subunit of ATP synthase efficiently, this mouse produces fewer ATP molecules than normal (healthy) mice. In order to keep a certain level of ATP for normal life, this mutant mouse continues to consume glucose or fatty acids (and other biological organic molecules). So, this mouse probably looks very thin and small, and less energetic.

This is a hypothetical situation: You have a pet mouse named "Stick" that is extremely skinny. You find that Stick has a mutant phosphofructokinase 1 (an enzyme that works in the third step of glycolysis). This mutant enzyme does not bind to ATP or citrate. Propose a possible reason why Stick is skinny and doesn't put on weight, even when over fed.

This mutant phosphofructokinase 1 does not bind to ATP or citrate, which normally works a negative feedback effector. This means that this mutant enzyme cannot sense whether or not cells produced enough ATP (or running the citric acid cycle). Therefore, cellular respiration continues to run regardless of how much ATP is produced. Stick keeps consuming glucose as he eats. So, he does not have any chance to store energy from food in fat or glycogen.

What does the cell theory state?

1. All living things are made up of cells 2.
2. Cells are the basic units of structure and function in living things
3. New cells are produced from existing cells

Function of the Plasma Membrane

homeostasis and compartmentalization

amphipathic

having both a hydrophilic region and a hydrophobic region

Phospholipids are

amphipathic

Phospholipid heads are

hydrophilic, polar

Phospholipid tails are

hydrophobic, nonpolar

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

factors that increase membrane fluidity

lower temps, shorter fatty acid chains, more unsaturated fatty acids, more cholesterol

The plasma membrane is

selectively permeable

passive transport movement

high to low concentration

active transport movement

low to high concentration

simple diffusion

passive transport through the plasma membrane

facilitated diffusion

passive transport using transmembrane proteins

integral membrane proteins

span the entire membrane, presence of a hydrophopic signal-anchor sequence within the protein

peripheral membrane proteins

proteins associated with but not embedded within the plasma membrane

Osmosis

Diffusion of water through a selectively permeable membrane until water concentration is equal on both sides of the membrane

primary active transport

using energy directly to move a substance against a concentration gradient

is a transport protein needed for active transport?

yes

symporter

transporter that carries two different ions or small molecules, both in the same direction

antiporter

A carrier protein that transports two molecules across the plasma membrane in opposite directions.

secondary active transport

movement of material that is due to the electrochemical gradient established by primary active transport

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

Exocytosis

Process by which a cell releases large amounts of material

Hypertonic

Having a higher concentration of solute outside the cell causing water to leave

hypotonic

having a lower concentration of solute outside the cell causing water to enter the cell

Isotonic

concentration inside and outside of the cell is the same

process of secondary active transport

1. primary active transport- energy is used to move a molecule agianst its gradient 2. an electrochemical gradient is created such that the molecule would naturally flow back across the membrane through simple diffusion 3. a co-transporter moves a different molecule against it's concentration gradient as the first molecule moves with it's concentration gradient

difference between prokaryotes and eukaryotes

eukaryotes have a nucleus and prokaryotes do not

Rough ER function

Makes proteins

smooth ER function

Makes lipids

what happens in the nucleus

replication and transcription

does transcription require proteins?

yes

Where does translation occur?

ribosomes in the cytoplasm

lumen

inside space of an organelle

structure of ER

interconnected flattened sacs

Where does protein synthesis occur?

on rough ER or free ribosomes in cytosol

endomembrane system organelles

all organelles except chloroplast and mitochondria

Chloroplast function

have double membrane, contain their own DNA, plants only, site of photosynthesis

Mitochondria function

have double membrane, contain their own DNA, site of cellular respiration

Golgi apparatus function

sorts proteins to final destination, carbohydrate synthesis, modifies proteins and lipids

secretory vesicles function

carry proteins and lipids to plasma membrane for secretion; require cellular signals for migration

Lysosomes function

digestion of macromolecules

the capacity to do work

energy

organisms who get energy from sunlight

phototrophs

organisms who get energy from chemical compounds

chemotrophs

organisms who get carbon from CO2

autotrophs

organisms who get carbon from organic compounds

heterotrophs

entire set of chemical reactions that maintain life

metabolism

Catabolism

breaks down molecules

Anabolism

builds larger molecules

energy of motion

kinetic energy

stored energy

potential energy

what type of energy is sunlight?

kinetic energy

What type of energy is chemical energy?

potential energy

what type of energy is electricity?

kinetic energy

what type of energy is heat?

kinetic energy

A ball at the top of a hill has what type of energy?

high potential energy

a ball rolling down a hill has what type of energy?

kinetic energy

covalent bonds have what type of energy?

potential energy

first law of thermodynamics

Energy cannot be created or destroyed

second law of thermodynamics

energy transfer or transformation increases the entropy of the universe

Entropy

A measure of disorder or randomness.

reaction that absorbs free energy (non-spontaneous)

endergonic reaction

energy available to do work

Gibbs free energy

chemical reaction that releases energy (spontaneous)

exergonic reaction

a reaction that will proceed without any outside energy

spontaneous reaction

A reaction that will not occur naturally, unless an outside force is added or energy is added to the system

non-spontaneous reaction

A beaker contains two solutions of salt dissolved in water. The two solutions have different concentrations of salt (measured by molarity, M) and are separated by a membrane that is permeable to both salt and water. The salt and water will move through the membrane by diffusion. Side A has a lower concentration of salt than side B.

There will be a net movement of salt from side B to side A and net movement of water from side A to side B.

Of the following options, which will most easily/quickly make it's way through a phospholipid bilayer?

a large hydrophobic molecule

a large hydrophilic molecule

a small hydrophobic molecule

a small charged molecule

a small hydrophobic molecule