exams 1-3 review

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Questions and Answers

What is a fundamental aspect of cell structure that allows eukaryotic cells to perform multiple biochemical processes simultaneously?

The compartmentalization of membranous structures (correct)

The existence of a cell membrane

The presence of DNA as genetic material

The presence of ribosomes

What is the primary difference between prokaryotic and eukaryotic cells in terms of their structural complexity?

The size of the cell

The presence of a cell membrane

The level of structural complexity (correct)

The number of ribosomes

What is the primary function of chloroplasts and mitochondria in eukaryotic cells?

To synthesize proteins

To provide structural support to the cell

To store genetic material

To store and utilize chemical energy (correct)

Which of the following is NOT a characteristic shared by all cells?

The presence of an endomembrane system Signup and view all the answers

What is the term for the concept that cells have evolved over billions of years to develop specific structures and functions?

Evolution Signup and view all the answers

What is the primary difference between eukaryotic and prokaryotic cells in terms of their structural components?

Eukaryotic cells have membrane-bound organelles, whereas prokaryotic cells do not. Signup and view all the answers

Which of the following is NOT a emergent property of water due to its polarity?

Viscosity Signup and view all the answers

What is the primary reason for the formation of ionic bonds between two elements?

The difference in electronegativity between the two elements is significant. Signup and view all the answers

What is the term for the ability of an element to attract and hold onto electrons?

Electronegativity Signup and view all the answers

Which of the following molecules would be classified as hydrophilic?

A molecule with a polar covalent bond Signup and view all the answers

What is the primary function of phosphate groups in organic molecules?

To add energy to the molecule, making it less stable and more chemically reactive Signup and view all the answers

What is the term for the process by which cells change the length of a carbon backbone?

Adding or removing carbons Signup and view all the answers

What type of molecule is formed when a carboxyl group is added to a carbon backbone?

Organic acid Signup and view all the answers

What is the primary structure of a protein?

The sequence of amino acids Signup and view all the answers

What is the term for the process by which biological macromolecules are assembled?

Dehydration synthesis Signup and view all the answers

What is the direction of water movement during osmosis?

From the side with lower total solute concentration to the side with higher total solute concentration Signup and view all the answers

What type of transport proteins moves a single solute across the membrane?

Uniport proteins Signup and view all the answers

What is the term for the process of bringing assemblages of molecules into a cell using the membrane itself?

Endocytosis Signup and view all the answers

What type of receptors bind hydrophobic ligands that can freely pass through the membrane?

Cytoplasmic receptors Signup and view all the answers

What is the advantage of signal transduction cascades in cell signaling?

They can amplify signals, create diversity of responses, and allow plasticity Signup and view all the answers

What primarily determines the secondary structure of a protein?

Hydrogen bonding between the carboxyl and amino groups Signup and view all the answers

What is the main function of transport proteins in cell membranes?

To allow for the facilitated diffusion of polar molecules and ions Signup and view all the answers

What is the effect of a high proportion of saturated fatty acids on membrane fluidity?

It makes the membrane more viscous Signup and view all the answers

What type of membrane protein is characterized by being partially hydrophobic and inserting into the hydrophobic region of the bilayer?

Integral membrane protein Signup and view all the answers

What is the main difference between channel proteins and carrier proteins?

Channel proteins create aqueous pathways for the diffusion of ions, while carrier proteins move molecules across the membrane by changing shape Signup and view all the answers

What is the primary function of the electron transport chain in the light reactions?

To pump hydrogen ions across the thylakoid membrane Signup and view all the answers

What is the product of the carbon fixation phase of the Calvin Cycle?

Two 3C organic molecules Signup and view all the answers

What is the primary function of photolysis in the light reactions?

To split water into oxygen and hydrogen ions Signup and view all the answers

What is the primary function of the citric acid cycle in cellular respiration?

To oxidize acetyl-CoA to CO2 Signup and view all the answers

What is the primary function of ATP synthase in the light reactions?

To convert the proton gradient into ATP Signup and view all the answers

What is the primary function of the enzyme complex ATP synthase in the mitochondria?

To generate ATP through the process of chemiosmosis Signup and view all the answers

What is the primary consequence of the electron transport chain being unable to function in the mitochondria?

ATP can only be produced through glycolysis and fermentation Signup and view all the answers

What is the role of deamination in the process of fermentation?

To recycle NADH back to NAD+ Signup and view all the answers

What is the primary role of beta-oxidation in the process of cellular respiration?

To break down fatty acids into acetyl-CoA, NADH, and FADH2 Signup and view all the answers

What is the primary difference between the investment and payoff phases of glycolysis?

The investment phase consumes ATP, while the payoff phase produces ATP Signup and view all the answers

What is the primary difference between anabolic and catabolic reactions in terms of free energy change?

Anabolic reactions have a negative ΔG, while catabolic reactions have a positive ΔG Signup and view all the answers

What is the role of ATP in reaction coupling?

To provide energy for endergonic reactions Signup and view all the answers

What is the function of NADH in metabolic pathways?

To transfer energy through redox reactions Signup and view all the answers

What is the purpose of allosteric effectors in enzyme regulation?

To inhibit or activate enzyme function Signup and view all the answers

What is the relationship between enthalpy, entropy, and free energy in reactions?

ΔG = ΔH - TΔS Signup and view all the answers

Study Notes

Big Ideas in Biology

Structure-Function relationships: understanding that structure determines function in biology
Emergent Properties: complex systems exhibit properties not found in individual components
Energy transformation: energy is converted from one form to another
Regulation: biological processes are controlled and regulated
Evolution: changes in populations over time
Cell Theory: all living organisms are composed of cells, cells are the basic units of life, and cells arise from pre-existing cells

Cell Structure and Function

All cells have a cell membrane (plasma membrane), cytoplasm (cytosol), ribosomes, DNA (chromosomes), and RNA
Two types of cells: prokaryotes (small, structurally simple) and eukaryotes (larger, structurally complex)
Eukaryotic cells have an endomembrane system, including the nuclear envelope, rough and smooth endoplasmic reticulum, Golgi apparatus, and vesicles
Prokaryotes lack internal membranes, limiting compartmentalization
Eukaryotic cells have membrane-bound organelles (chloroplasts and mitochondria) for photosynthesis and energy storage, obtained through endosymbiosis
Plant cells have cell walls, a large central vacuole, and chloroplasts, distinguishing them from animal cells

Chemistry of Life in Water

Elements: atoms with a specific number of protons and electrons
Electron configuration: electrons occupy shells and orbitals around the nucleus
Chemical bonds: formed by sharing unpaired electrons between atoms
Electronegativity: the ability of an atom to attract electrons in a covalent bond
Polar and non-polar covalent bonds: differences in electronegativity determine bond type
Ionic bonds: extreme differences in electronegativity result in ion formation
Water: a highly polar molecule with emergent properties (cohesion, adhesion, surface tension, high heat capacity)
Hydrogen bonds: weak intermolecular forces between polar molecules
Acids and bases: ionic molecules that donate or accept H+ or OH- ions, affecting pH

Carbon Backbones and Functional Side Groups

Organic molecules: composed of carbon backbones with functional side groups
Cells can manipulate carbon backbones to create diverse molecules
Functional side groups: add polarity, shape, or reactivity to molecules
Examples of functional side groups: hydroxyl (OH), carbonyl (=O), carboxyl (COOH), amino (NH3), sulfhydryl (SH), phosphate (PO4), and methyl (CH3) groups

Biological Macromolecules

Lipids: hydrophobic molecules, including triglycerides, phospholipids, and steroids
Triglycerides: composed of three fatty acids attached to a glycerol molecule
Phospholipids: amphipathic molecules with hydrophobic tails and hydrophilic heads
Steroids: hydrophobic molecules, including cholesterol
Proteins: polymers of amino acids connected by peptide bonds
Primary structure: sequence of amino acids
Secondary structure: hydrogen bonding between carboxyl and amino groups
Tertiary structure: interactions between R-groups, folding the polypeptide
Quaternary structure: interactions between R-groups on different polypeptides

Membrane Structure and Transport

Phospholipid bilayer: semipermeable barrier to diffusion between two aqueous compartments
Membrane proteins: transport proteins, receptors, junction proteins, and cell recognition proteins
Fluid mosaic model: phospholipids and proteins can move within the membrane
Membrane fluidity: influenced by lipid composition and cholesterol content
Passive transport: facilitated diffusion of polar molecules and ions across the membrane
Active transport: energy-dependent transport of molecules against their concentration gradient### Photosynthesis
In eukaryotes, photosynthesis occurs in chloroplasts, using components in the stroma, thylakoid membranes, and the thylakoid lumen.
The light reactions use two photosystems to capture light and generate high-energy electrons.
Photosystem II donates high-energy electrons to an electron transport chain (ETC), which starts with the high-energy electron carrier PQ.
The ETC generates a H+ gradient across the thylakoid membrane, powering the enzyme complex ATP synthase to form ATP in the stroma (photophosphorylation).
Electrons leave the light reactions in NADPH, and new electrons are obtained by the splitting of water through photolysis by PSII.
The Calvin Cycle fixes inorganic carbon from CO2 into organic carbon chains, storing energy in chemical bonds.
CO2 is covalently bonded to the 5C molecule RuBP by the enzyme Rubisco, generating two 3C organic molecules in the carbon fixation phase.
The product of the reduction phase is glyceraldehyde-3-phosphate (G3P), which is used to make other organic molecules including fatty acids, amino acids, and nucleic acids.

Cellular Respiration

Cellular respiration is the process of breaking down glucose to make ATP using substrate level and oxidative phosphorylation.
The first process in cellular respiration is glycolysis, which uses glucose as its preferred substrate to make 2 ATP (via substrate level phosphorylation), 2 NADH, and 2 pyruvate.
The two pyruvates from glycolysis are imported into the mitochondria via pyruvate oxidation, getting converted into 2 acetyl-CoA at the same time, and making 2 NADH and 2 CO2.
The 2 acetyl-CoA enter the citric acid cycle, where they are oxidized to CO2, making 2 ATP (via substrate level phosphorylation), 6 NADH, and 2 FADH2.
In the mitochondrial matrix, the NADH and FADH2 from glycolysis, pyruvate oxidation, and the citric acid cycle donate high-energy electrons to the mitochondrial ETC, which uses their energy to pump H+ into the intermembrane space, generating proton motive force (PMF) across the inner membrane.
The flow of hydrogen ions back across the inner membrane powers the production of ATP by the enzyme complex ATP synthase through chemiosmosis.
When the electron transport chain cannot work, such as when oxygen is limited, ATP can only be produced by glycolysis supported by fermentation.
Fermentation recycles NADH back to NAD+ which is necessary to keep glycolysis going.

Metabolism, Energy, Enzymes, and Redox

Metabolism is the sum of all anabolic and catabolic reactions in a cell, connected in a network of reaction pathways.
Anabolic reactions synthesize or "build" molecules with more bonds, making higher free energy products; they also use or store energy (endergonic), reduce entropy, and are non-spontaneous.
Catabolic reactions degrade or "break" molecules to make lower free energy products with fewer bonds; they also increase entropy and release energy (exergonic), and are spontaneous.
The First and Second Laws of Thermodynamics state that energy is transformed in many ways, but always at a cost of energy lost through entropy that is not available to do work.
Free energy (G) is chemical energy available to do work and is expressed as the difference between enthalpy (total energy) and entropy.
Enzymes are proteins that reduce the activation energy of a reaction, and their specificity and function are the result of the structure (shape) of the protein.
Substrates interact with enzymes at the active site, forming an enzyme-substrate complex with a close interaction through induced fit.
Enzymes can be regulated by allosteric effectors that bind somewhere other than the active site (called the allosteric site) and alter the shape of the protein to either inhibit or activate enzyme function.
Positive ∆G reactions are accomplished by reaction coupling which combines a positive ∆G reaction with a negative ∆G reaction to give a new net negative ∆G for the combined reactions.
Redox reactions transfer electrons between molecules, with oxidation being the loss of electrons and reduction being the gain of electrons by molecules.

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Test your understanding of the fundamental concepts in biology, including structure-function relationships, emergent properties, and cell structure. Recognize examples of these big ideas and learn about cell membranes, cytoplasm, and ribosomes.