IVC BIO 81 Exam I

Criteria for being a living organism.

Big Ideas: All living things have certain traits in common: Cellular organization, the ability to reproduce, growth & development, energy use, homeostasis, response to their environment, and the ability to adapt.

What are the four major classes of biological macromolecules and what are their function?

All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates: -Carbohydrates include sugars and the polymers of sugars. -The simplest carbohydrates are monosaccharides, or single sugars. -Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks. Lipids: -Lipids are the one class of large biological molecules that do not form polymers. -The unifying feature of lipids is having little or no affinity for water. -Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds. -The most biologically important lipids are fats, phospholipids, and steroids. -Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds. -Unsaturated fatty acids have one or more double bonds. Proteins: -Proteins account for more than 50% of the dry mass of most cell. -Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances. -Primary structure of a protein is its unique sequence of amino acids. -Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain. -Tertiary structure is determined by interactions among various side chains (R groups). -Quaternary structure results when a protein consists of multiple polypeptide chains. Nucleic acid: -The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene. -Genes are made of DNA, a nucleic acid made of monomers called nucleotides. -There are two types of nucleic acids: -Deoxyribonucleic acid (DNA). -Ribonucleic acid (RNA). -DNA provides directions for its own replication. -DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis. -Protein synthesis occurs on ribosomes.

Describe the endosymbiont theory, discuss the evidence.

An early ancestor of eukaryotic cells engulfed a nonphotosynthetic prokaryotic cell, which formed an endosymbiont relationship with its host. The host cell and endosymbiont merged into a single organism, a eukaryotic cell with a mitochondrion. At least one of these cells may have taken up a photosynthetic prokaryote, becoming the ancestor of cells that contain chloroplasts.

What is positive feedback and negative feedback? Give an example of each.

Positive feedback means that as more of a product accumulates, the process that creates it speeds up and more of the product is produced. -For example: Childbirth. Negative feedback means that as more of a product accumulates, the process that creates it slows and less of the product is produced. -For example: Temperature.

Describe the four levels of structure of a protein (include the bonds at each level).

Primary structure, the sequence of amino acids in a protein, is like the order of letters in a long word. -Primary structure is determined by inherited genetic information. -Held together by peptide bonds. The coils and folds of secondary structure result from hydrogen bonds between repeating constituents of the polypeptide backbone. -Typical secondary structures are a coil called an helix and a folded structure called a pleated sheet. Tertiary structure is determined by interactions between R groups, rather than interactions between backbone constituents. -These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions. -Strong covalent bonds called disulfide bridges may reinforce the protein's structure. Quaternary structure results when two or more polypeptide chains form one macromolecule. -Collagen is a fibrous protein consisting of three polypeptides coiled like a rope. -Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains.

Compare prokaryote an eukaryote cells.

Prokaryotic cells are characterized by having: -No nucleus. -DNA in an unbound region called the nucleoid. -No membrane-bound organelles. -Cytoplasm bound by the plasma membrane. Eukaryotic cells are characterized by having: -DNA in a nucleus that is bounded by a membranous nuclear envelope. -Membrane-bound organelles. -Cytoplasm in the region between the plasma membrane and nucleus. Eukaryotic cells are generally much larger than prokaryotic cells.

Describe the path that food takes going into the body through ingestion to elimination.

The digestion process occurs in the digestive tract or gastrointestinal tract. It starts from the mouth, travels through throat, esophagus, stomach, small intestine, large intestine, rectum, and ends in the anus.

Describe the structural characteristics that allow some particles to go directly through the phospholipid bilayer membrane while other molecules must be moved through a facilitated transport protein.

The plasma membrane exhibits selective permeability: allows some substances to cross it more easily than others. In facilitated diffusion, transport proteins speed the passive movement of molecules across the plasma membrane.

Explain how O2 and OC2 are transported in the blood.

Blood arriving in the lungs has a low partial pressure of O2 and a high partial pressure of CO2 relative to air in the alveoli. In the alveoli, O2 diffuses into the blood and CO2 diffuses into the air. In tissue capillaries, partial pressure gradients favor diffusion of O2 into the interstitial fluids and CO2 into the blood.

Compare plant and animal cells.

Both animal and plant cells have mitochondria, but only plant cells have chloroplasts. Both plant and animal cells have vacuoles. Plant cells have a cell wall, as well as a cell membrane. In plants, the cell wall surrounds the cell membrane.

How can you tell the difference between noncompetitive and competitive inhibition?

Competitive inhibitors bind to the active site of an enzyme, competing with the substrate. Noncompetitive inhibitors bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective.

Explain the small intestine create the huge surface area to facilitate the digestion.

The small intestine has a huge surface area, due to villi and microvilli that are exposed to the intestinal lumen. The enormous microvillar surface creates a brush border that greatly increases the rate of nutrient absorption. Transport across the epithelial cells can be passive or active depending on the nutrient.

Describe the three main types of blood vessels and their functions.

The three main types of blood vessels are arteries, veins, and capillaries. -Arteries: branch into arterioles which carry blood away from the heart to capillaries. -Venules: converge into veins that return blood from capillaries to the heart. -Capillaries: carry blood away from the heart to the capillaries.

What structural differences between plant and animal cells cause the different effects of a hypotonic and hypertonic solution. (also explain what the effects of each of the conditions in the cells are and what the ideal condition is called).

Animal cells: -Isotonic solution: Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane. -Hypertonic solution: Solute concentration is greater than that inside the cell; cell loses water. -Hypotonic solution: Solute concentration is less than that inside the cell; cell gains water. Plant cell: -A plant cell in a hypotonic solution swells until the wall opposes uptake; the cell is now turgid (firm). -If a plant cell and its surroundings are isotonic, there is no net movement of water into the cell; the cell becomes flaccid (limp), and the plant may wilt. -In a hypertonic environment, plant cells lose water; eventually, the membrane pulls away from the wall, a usually lethal effect called plasmolysis.

What would be the effect on the water molecule if oxygen and hydrogen had equal electronegativity?

Atoms in a molecule attract electrons to varying degrees. Electronegativity is an atom's attraction for the electrons in a covalent bond. The more electronegative an atom, the more strongly it pulls shared electrons toward itself. Polar covalent bond, one atom is more electronegative, and the atoms do not share the electron equally.

Why does O2 move into the tissues at the arteriole end of a capillary bed, what forces are at work? Describe how gas exchange is regulated in a respiratory system in terms of the partial pressures of oxygen and carbon dioxide.

CO2 produced during cellular respiration lowers blood pH and decreases the affinity of hemoglobin for O2; this is called the Bohr shift. Some CO2 from respiring cells diffuses into the blood and is transported in blood plasma, bound to hemoglobin. The remainder diffuses into erythrocytes and reacts with water to form H2CO3, which dissociates into H+ and bicarbonate ions (HCO3−). In the lungs the relative partial pressures of CO2 favor the net diffusion of CO2 out of the blood.

What are the four emergent properties of water that contribute to Earth's suitability and explain why those properties do so?

Cohesive behavior. -Collectively, hydrogen bonds hold water molecules together, a phenomenon called cohesion. -Cohesion helps the transport of water against gravity in plants. -Surface tension is a measure of how hard it is to break the surface of a liquid. -Adhesion is an attraction between different substances, for example, between water and plant cell walls. Ability to moderate temperature. -Water absorbs heat from warmer air and releases stored heat to cooler air. -Water can absorb or release a large amount of heat with only a slight change in its own temperature. -Kinetic energy is the energy of motion. -Heat is a measure of the total amount of kinetic energy due to molecular motion. -Temperature measures the intensity of heat due to the average kinetic energy of molecules. Expansion upon freezing. -Ice floats in liquid water because hydrogen bonds in ice are more "ordered," making ice less dense. -Water reaches its greatest density at 4°C. -If ice sank, all bodies of water would eventually freeze solid, making life impossible on Earth. Versatility as a solvent. -A solution is a liquid that is a homogeneous mixture of substances. -A solvent is the dissolving agent of a solution. -The solute is the substance that is dissolved. -An aqueous solution is one in which water is the solvent.

Describe the 4 different types of bonds, and give examples of each.

Covalent bonds: -A covalent bond is the sharing of a pair of valence electrons by two atoms. -In a covalent bond, the shared electrons count as part of each atom's valence shell. Ionic bonds: -Atoms sometimes strip electrons from their bonding partners. -An example is the transfer of an electron from sodium to chlorine. Hydrogen bonds: -A hydrogen bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom. -In living cells, the electronegative partners are usually oxygen or nitrogen atoms. Van Der Waals interactions: -Van der Waals interactions are attractions between molecules that are close together as a result of these charges.

Why is it found that animals have varying alimentary canals and how can an animals alimentary canal indicate diet?

Digestive systems of vertebrates are variations on a common plan: -Adaptations, often related to diet. -Many carnivores have large, expandable stomachs. -Herbivores and omnivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation.

Describe the regulation of digestion (as described in the PowerPoint) and explain how this is an example of negative and positive feedback.

Each step in the digestive system is activated as needed. The enteric division of the nervous system helps to regulate the digestive process. The endocrine system also regulates digestion through the release and transport of hormones.

Assume that a mutation causes the epiglottis flap in the throat to not function properly. Explain what would happen to the body if water and food were consumed. Where would they go instead?

Epiglottis goes to lungs.

Evolution by natural selection: explain the steps, give an example.

Evolution: change in the genetics of a population over time. Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species. Steps: -Population have heritable variation. -Over reproduce. -Competition for resources. -Differential reproductive success and differential morality. -Overtime, individuals with the variation that is advantageous will be more successful reproducing. So overtime, we will see more of that variant in the population.

Summarize the first and second laws of thermodynamics. In your explanation, include the terms: entropy, enthalpy, heat/disorder, and how they contribute to the overall net energy of the universe.

First law of thermodynamics. -According to the first law of thermodynamics, the energy of the universe is constant. -Energy can be transferred and transformed, but it cannot be created or destroyed. -The first law is also called the principle of conservation of energy. Second law of thermodynamics. -During every energy transfer or transformation, some energy is unusable, and is often lost as heat. -According to the second law of thermodynamics. -Every energy transfer or transformation increases the entropy (disorder) of the universe.

Compare and contrast a hypothesis vs a theory and give an example of each, explain the Scientific Method.

Hypothesis: -Observations can lead us to ask questions and propose hypothetical explanations called hypotheses. -A hypothesis is a tentative answer to a well framed question. -Leads to predictions that can be tested by observation or experimentation. -A hypothesis must be testable and falsifiable. -Failure to falsify a hypothesis does not prove that hypothesis. -For example: flashlight bulb. Theory: -Broader in scope than a hypothesis. -General, and can lead to new testable hypotheses. -Supported by a large body of evidence in comparison to a hypothesis. -FALSIFIABLE!

What are the differences between structural isomers, Cis-trans isomers, and Enantiomers?

Isomers are compounds with the same molecular formula but different structures and properties. Structural isomers have different covalent arrangements of their atoms. Cis-trans isomers have the same covalent bonds but differ in spatial arrangements. Enantiomers are isomers that are mirror images of each other.

Describe the relationship that cellular membranes have with lipids and proteins and the role of phospholipids.

Phospholipids are the most abundant lipid in the plasma membrane. Amphipathic molecules containing hydrophobic and hydrophilic regions. The fluid mosaic model states that a membrane is a fluid structure with a "mosaic" of various proteins embedded in it.

A (hypothetical) predator of Paramecium kills its prey with chemical X (also hypothetical), which kills Paramecium by disabling the paramecium's contractile vacuole (mechanism theoretical). Why is this chemical effective in its purpose?

Remove water from itself. The environment is hypotonic.

How are saturated fats solid at room temperature while unsaturated fats are liquid?

Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds. -Fats made from saturated fatty acids are called saturated fats, and are solid at room temperature. -Most animal fats are saturated. Unsaturated fatty acids have one or more double bonds. -Fats made from unsaturated fatty acids are called unsaturated fats or oils, and are liquid at room temperature. -Plant fats and fish fats are usually unsaturated.

What part of the chemical reaction is changed with the addition of an enzyme? Draw a graph of a reaction with and without an enzyme.

See image.

What was the Stanley Miller's experiment and what is its significance in understanding the origins of life?

Stanley Miller's classic experiment demonstrated the abiotic synthesis of organic compounds. Experiments support the idea that abiotic synthesis of organic compounds, perhaps near volcanoes, could have been a stage in the origin of life.

Explain the process by which triglycerides enter the epithelial cells.

Triglycerides are broken down to fatty acids and monoglycerides by lipase. Monoglycerides and fatty acids diffuse into epithelial cells and are reformed into triglycerides. Triglycerides are incorporated into chylomicrons. Chylomicrons enter lacteals and are carried away by lymph.

Explain the process when a red blood cell is placed into a hypertonic solution. Does the water move in or out? Osmosis or diffusion? Why?

Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration until the solute concentration is equal on both sides. Osmosis is the diffusion of water across a selectively permeable membrane.