Human Biology Nonmajors UIOWA Exam 1

Protons: nucleus

Electrons: orbiting nucleus

Neutrons: nucleus

What are the 3 subatomic particles discussed in class and where are they located in an atom?

electrons

Which particle has a negative charge?

protons

Which particle has a positive charge?

No charge (neutral)

what is the charge of a neutron?

isotopes have same number of protons but different number of neutrons. Isotopes have different mass numbers. Ions have gained or lost an electron (lost = + charge, gained = - charge). Isotopes are neutral while ions are charged.

Compare & contrast isotopes and ions

to achieve stability through an electron configuration by sharing electrons.

Why do atoms form covalent bonds?

check the electronegativity values, or the molecular dipole moment

How do you know if a covalent bond between two atoms is polar or nonpolar in a diagram? (hint: there is more than 1 way)

ionic bonds form between atoms with a significant difference in electronegativity. Ionic bonds are formed by the stealing on an electron. Ionic bonds are strong. Hydrogen bonds is when H+ is bonded to a highly electronegative atom (O, N, F). H+ bonds form between molecules and are weak.

Both ionic and hydrogen bonds involve attraction between opposite charges. So, what is the difference between an ionic and hydrogen bond?

False: H+ bonds require both substances to be polar and a significant difference in electronegativity between their atoms. If one substance is non-polar, it does not provide the required partial charges.

True or False. A polar substance and a non-polar substance can form a hydrogen bond? Explain.

Ionic bonds: strongest, significant difference in electronegativity, steal an e-

Polar: strong, 2 atoms of different electronegativity share e- unequally

Non-Polar: weaker than polar, form between atoms with similar or identical electronegativities, e- shared equally between atoms

Hydrogen Bonds: weaker than non-polar, dipole-dipole interaction, H+ bond to highly electronegative atom

Van der Waals: weakest, temporary fluctuations in e- density within molecules causing temporary dipoles

Rank the bond types discussed in class by strength. Write a brief description of the nature of the bond (polar covalent, non-polar covalent, ionic, hydrogen/van der Waals)

Bond type

False: Energy & matter are continually exchanged & redistributed, it is expanding & evolving, includes interactions and exchanges on cosmic scale, energy & matter spreads out & interacts overtime

The universe, as we know it, is an isolated (closed) system - TRUE OR FALSE?; How do you know?

basic elements that make us up were first formed in cores of stars through nucleosynthesis; in stars, nuclear fusion reactions combine lighter elements (like hydrogen and helium) to form heavier elements (like carbon, oxygen, and iron

What does it mean to say we are all "made of star stuff"?

True: atoms are fundamental units of matter (anything that has mass and occupies space), mass of an atom comes from protons & neutrons

True or False. Atoms have mass. Explain. (use the terms matter, proton, neutron)

CO₂ is nonpolar because its linear causes the dipoles in the polar C=O bonds to cancel each other out, resulting in no net dipole moment. electronegativity difference is similar

H₂O is polar because its bent, asymmetrical structure means that the dipoles in the polar O-H bonds do not cancel out, resulting in a net dipole moment. electronegativity is not similar.

Carbon dioxide is nonpolar, whereas water is polar. What explains these differences?

Hydrogen bonds are intermolecular forces that occur between polar molecules. They involve a partially positive hydrogen atom covalently bonded to a highly electronegative atom and a partially negative atom in another molecule. Although they are weak interactions compared to covalent and ionic bonds, hydrogen bonds play a crucial role in determining the properties and structures of many substances. They do not occur between non-polar molecules, which have different types of interactions.

Describe hydrogen bonds using the following terms: Intramolecular, Intermolecular, polar, weak interactions, non-polar, partially positive, electronegative

True

True or False. A molecule is either polar or non-polar but it cannot be both.

True: they are a type of intermolecular force

True or False. Hydrogen bonds occur between molecules

water is essential for life; H+ bonds affect water's ability to absorb & retain heat, convert to vapor, exhibit surface tension, dissolve substances, & form a less dense solid

1. life depends on water

2. water has a high level of surface tension

3. density of water is based on temperature

4. water has a high specific heat (heat capacity)

5. water is the universal solvent

Why do we care about the properties of water? Briefly list the 5 important properties discussed and describe how intermolecular hydrogen bonds facilitate the property (if applicable).

NaCl are held together by ionic bonds, negative charge of H2O is attracted to positive Na ions & positive charge of H2O are attracted to negative Cl ions; partial negative ends of water molecules face the sodium ions, and the partial positive ends face the chloride ions.n ionic bonds are broken and ions are separated and become surrounded by H2O

Describe how the polarity of water and polarity of salt facilitates salt dissolving in water - what is occurring on a molecular level?

Diffusion: molecules move from an area of high concentration to an area of low concentrations until they reach equilibrium, does not require energy;

Osmosis: movement of water molecules, water always moves to an area of high water concentration to an area of low water concentration to balance solute concentrations

Describe diffusion in your own words. What is different about osmosis?

Carbon: carbon can create a wide variety of organic molecules like carbs, proteins, lipids, & nucleic acids; creates strong and stable bonds

What uniquely behaving element comprises 18% of the human body? And why do you think it was integral to creating life on our planet?

monomer: amino acids

structure: primary (order of amino acids), secondary (3D folding, H+ bonds between amino acids), tertiary (2nd 3D folding, H+ bonds & disulfide bridges between R groups), quaternary (subunits bond together, final protein form)

function: structural support, enzymes, transports molecules/ions across cell membranes or through blood, immune defense (antibodies), regulates DNA & RNA

Protein

monomer: none

structure: long chains of H+ and C, nonpolar, phospholipid (amphipathic - hydrophobic & hydrophilic regions)

functions: stores energy (triglycerides stored in adipose tissue), steroids (hormone synthesis), regulate cell membrane fluidity, carotenoids (pigments/vitamens)

Lipid

monomer: sugar

structure: multiple ringed sugars, linear or branched, monosaccharides (one), disaccharides (2)

functions: source of energy (glucose), energy storage (glycogen), starch, cellulose, chitin (structure for plants & animals)

carbohydrate

monomer: nucleotide

structure: phosphate + nitrogenous base + sugar backbone, polymer (nucleic acid - DNA, RNA), chains of nucleotides

functions: information storage, ATP, form structures, cell signaling, make proteins, transports substances

Nucleic Acids

Prokaryote: lacks most organelles, do not have nucleus, smaller, found in bacteria & archaea, contain DNA, has cell membrane

Eukaryotes: has a nucleus, various organelles, larger, humans/plants/animals have these, has DNA, has cell membrane

Which cell type has which feature? Prokaryote, Eukaryote, or both

▪ Has a nucleus

▪ Lacks most organelles

▪ Is larger on average

▪ Humans have this type

▪ Contains DNA

▪ Has a cell membrane made of a phospholipid bilayer

plant cells have a cell wall made of cellulose, chloroplasts to convert sunlight into glucose, central vacuole to store water and nutrients

What features do plant cells have that animal cells lack?

lipids: Form the structural foundation of the membrane (phospholipids), stabilize fluidity (cholesterol), and contribute to cell recognition (glycolipids).

proteins: Facilitate transport, signaling, and structural support (integral and peripheral proteins).

carbohydrates: Play roles in cell recognition, communication, and forming the glycocalyx (glycoproteins and glycolipids).

List the 3 biomolecules that make up a cell membrane and their function in the membrane:

Hydrophilic Heads: Found on the outer and inner surfaces of the bilayer, interacting with aqueous environments (both extracellular fluid and cytoplasm).

Hydrophobic Tails: Located in the interior of the bilayer, away from water, forming a hydrophobic core.

Draw or describe a phospholipid bilayer - where do you find hydrophilic and hydrophobic parts of a phospholipid?

diffusion: high to low concentration directly through phospholipid bilayer, does not require proteins, small nonpolar molecules

facilitated diffusion: high to low concentration through a carrier protein, cannot pass directly through lipid billayer, large polar molecules

Compare and contrast Diffusion and Facilitated Diffusion

Active Transport: Moves substances against their concentration gradient (low to high), requires energy, and often uses a pump protein.

Facilitated Diffusion: Moves substances with their concentration gradient (high to low), does not require energy, and uses channel or carrier proteins to assist the movement.

Compare and contrast Active Transport to Facilitated Diffusion:

Diffusion and Facilitated Diffusion are passive processes that move substances along their concentration gradient without requiring energy.

Active Transport, Endocytosis, and Exocytosis are active processes that require energy. Active Transport uses transport proteins to move substances against their gradient, while Endocytosis and Exocytosis involve vesicles to transport larger amounts of materials into or out of the cell.

How is endo- and exocytosis different from diffusion, facilitated diffusion, & active transport?

cell signaling is essential for maintaining physiological balance and coordinating complex biological processes. The ability of a cell to respond to signals depends on the presence and function of specific receptors, the availability of signaling pathways, and the cell's specific type and state. Cells that lack the appropriate receptors or signaling machinery will not respond to certain signals

Why is it important for cells to receive signals? Why can some respond to signals while others cannot?

cell membrane is essential for maintaining the cell's internal environment, facilitating communication and transport, and supporting cell structure and protection. It achieves these functions through its unique composition of lipids, proteins, and carbohydrates, and by employing various transport and signaling mechanisms.

What are the main functions of the cell membrane, how does a cell accomplish these tasks, and what components/processes are involved?

lysosomes & peroxisomes

analogous cellular component

Lysosomes

cell organelle filled with enzymes needed to break down certain materials in the cell

Peroxisomes

involved in fatty acid oxidation & detoxification

membrane composed of lipid bilayer similar to those found in prokaryote cell membranes

mitochondria has a outer & inner membrane, contain their own DNA similar to DNA found in prokaryote, have their own ribosomes

What features of the endomembrane system and mitochondria suggest they evolved in or from a prokaryotic cell?

spherical and enclosed by a lipid bilayer, move molecules between different compartments within the cell (ex: ER to golgi apparatus), brings extracellular material into the cell

proteins move vesicles along, endocytosis = carry external material into cell, exocytosis = release contents outside of cell

What is a vesicle? How do they move about the cell?

- protein encoded in the DNA within nucleus

- transcribed into mRNA through transcription & travels to ribosomes in ER

- translate into a chain of amino acids (synthesis)

- ER is surrounded by lipid bilayer and helps form vesicles that transport proteins

- vesicles transport protein to golgi apparatus & undergoes modifications

- vesicles leave golgi & transported to final destination within cell or towards plasma membrane

- exocytosis or endocytosis occurs

Describe the flow of a protein through the endomembrane system using the following terminology: nucleus, ER, Golgi apparatus, vesicles, ribosomes, lipid bilayer, blueprint/instructions, protein, exocytosis, endocytosis, synthesis.

cellular damage, activation of apoptosis, inflammation, oxidative stress, and disruption of cellular functions

What would happen if a lysosomal enzyme escaped the lysosome and was free in the cytoplasm?

enclosed by a double membrane system: outer membrane is smooth & contains proteins; inner membrane has increases surface area and impermeable to most ions & small molecules

What is a unique about mitochondria in terms of the phospholipid bilayer?

maintaining cell shape, enabling intracellular transport, supporting cell division, facilitating cell motility, providing mechanical strength, participating in signaling, enabling cell adhesion, and establishing cellular polarity

what are the roles of the cytoskeleton?

carbs = primary source of energy (broken down into glucose & used by cells to produce ATP through glycolysis and oxidative phosphorylation)

can get from proteins and fats as well

Where do humans get energy?

required to produce ATP which powers other activities, maintain of cellular homeostasis, required for metabolic processes, muscle contraction & movement, body temp maintenance, etc.

Why do we need an input of energy?

catalyze chemical reactions, lower activation energy, central to catabolic and anabolic pathways, have active site where substrate molecules bind

What do enzymes do?

adenosine triphosphate, when broken down (hydrolyzed) releases energy, powers endergonic reactions, drives anabolic & catabolic reactions, synthesizes macromolecules, maintains cellular function

What is ATP and what is it used for in our cells?

Step 1 Glycolysis

starting molecule: glucose

ending molecules: 2 pryuvate, 2 ATP, 2 NADH

general process: split glucose into 2 3-Carbon compound, anaerobic (no use of O2 needed)

how many steps?: 10 enzyme catalyzed steps

energy used or created?: 2 molecules of ATP are consumed initially, 4 molecules of ATP are produced = net gain of 2 ATP molecules per molecule of glucose

where does it occur?: cytoplasm of cell

step 2a prep step

- pyruvate is shuttled from cytosol to mitochondrial matrix

- pyruvate is transformed into Acetyl CoA

- first molecules of CO2 formed

step 2b Krebs Cycle

- pathway is circular

- FAD/FADH & NAD/NADH are electron carriers because they can bind to and release H+ atoms easily (coenzymes)

- primary point is to produce NADH & FADH that are used in ETC to generate ATP through oxidation phosphorylation

- oxidation in krebs cycle: break down acetylene coA to release energy in form of electrons

Step 3: Electron Transport Chain

location: inner mitochondrial membrane

main process: generation of ATP through oxidative phosphorylation, involving electron transfer and proton pumping

biomolecules from TCA cycle: NADH and FADH2

energy source: high energy electrons from NADH & FADH2

hydrogen ions source: from NADH & FADH2

highest proton concentration: intermembrane space

oxygen's role: acts as the final electron acceptor, forming water

ATP synthase

- substrates: ADP & inorganic phosphate

- products: ATP & water

- source of energy: proton gradient (proton motive force) across the inner mitochondrial membrane

- location: inner mitochondrial membrane

energy transfer, maintaining cellular homeostasis, biosynthesis, & adaptation; survival and proper function

Why is it important for cells to be able to make their own ATP?

electron transport chain (ETC) in the inner mitochondrial membrane: responsible for transferring electrons & using their energy to pump protons

proton pump: integral parts of the ETC complexes that actively transport protons

setup: electrons move through the ETC which use the energy from electron transfer to pump protons into the intermembrane space which creates a proton gradient which is essential for ATP synthesis & synthase

What 2 things are needed in order to set up the H+ gradient in the intermembrane space, where do these two things

come from? How is this gradient set up?

carbon atoms: come from metabolism of carbs, fats, & proteins, specifically from breakdown of these molecules during cellular respiration (Glycolysis/TCA Cycle)

oxygen atoms: come from O2 inhaled from atmosphere which is used in process of cellular respiration & combines with Carbon to form CO2 (ETC: final e- acceptor, forms H2O)

Where do the carbon and oxygen molecules come from that make up the CO2 gas that we exhale?

oxygen is the final electron acceptor and forms water; without oxygen, ETC stops and ATP synthesis is inhibited potentially leading to cellular dysfunction and death

What is the role of oxygen in oxidative phosphorylation (what is it turned into)? What happens if oxygen is not available?

aerobic: requires oxygen, occurs in mitochondria, involves glycolysis, the TCA cycle, and the electron transport chain, produces up to 32 ATP per glucose, and results in water and carbon dioxide as byproducts

anaerobic: Does not require oxygen, occurs in the cytoplasm, involves glycolysis followed by fermentation, produces only 2 ATP per glucose, and results in byproducts like lactic acid or ethanol and carbon dioxide

How does anaerobic respiration and aerobic respiration of glucose differ?

- alcoholic beverages: ethanol & CO2

- bread: CO2 & ethanol (mostly evaporated)

- fermented dairy products: lactic acid

- fermented vegetables: lactic acid

- fermented soy products: lactic acid & other compounds

- alcoholic vinegar: acetic acid (from ethanol)

What do humans consume that are the products of anaerobic respiration of other species?

- beta-oxidation: fatty acids from stored fats (triglycerides) in adipose tissue are broken down in mitochondria into acetyl-CoA which then enters TCA cycle

- Ketogenesis: Produces ketone bodies from fatty acids, which can be used for ATP production.

Protein Catabolism: Breaks down proteins into amino acids, which are converted to TCA cycle intermediates.

Lactate Utilization: Converts lactate back to pyruvate for ATP production.

Alternative Substrates: Uses other molecules like glycerol for energy.

How is ATP made when there is no glucose available?