Exam II - bio 1150

What four molecules are cells constructed of?

Carbohydrates, lipids, proteins, and nucleic acids.

What are the two main uses of nutrients once taken up by cells?

As building blocks to assemble new molecules and for energy harvesting.

What is the human digestive system also known as?

The gastrointestinal tract or alimentary canal.

List the order of organs in the digestive system.

Mouth, pharynx, esophagus, stomach, small intestines, large intestines, anus.

What is ingestion in the context of the digestive system?

The intake of food.

What is the difference between mechanical and chemical digestion?

Mechanical digestion involves physical processes like chewing, while chemical digestion uses digestive enzymes to break down food.

What is absorption in the digestive process?

The uptake of nutrients that have been broken down, which are then transported to blood vessels.

What is the role of accessory organs in digestion?

They secrete digestive enzymes into the gastrointestinal tract to aid digestion.

Name the accessory organs involved in digestion.

Salivary glands, liver, gallbladder, and pancreas.

What is the primary function of the mouth in digestion?

Ingestion, mechanical digestion, and chemical digestion.

What is the function of the pharynx in the digestive system?

It connects the mouth to the esophagus and the nasal cavity to the trachea.

What is peristalsis?

The smooth muscle contractions that propel food through the esophagus.

What occurs in the stomach during digestion?

Food is stored and chemically digested using gastric juices.

What is the role of bile in digestion?

Bile emulsifies fats, making them more accessible to lipases in the small intestine.

What is the primary function of the small intestine?

Chemical digestion and absorption of nutrients.

What happens to carbohydrates during digestion?

Salivary amylase breaks down starch into maltose; in the small intestine, amylase and maltase convert it to glucose.

How are fats digested in the body?

Salivary lipase begins fat breakdown; bile emulsifies fats, and pancreatic lipase breaks them down into glycerol and fatty acids.

What is the role of the large intestine in digestion?

Absorption of water and conversion of undigested wastes into solid feces.

What are organic molecules?

Molecules that contain carbon, essential for building blocks of cells.

What characteristic of carbon allows it to form biological molecules?

Carbon can form four covalent bonds due to having four electrons in its outer shell.

What are functional groups in organic molecules?

Specific groups attached to hydrocarbon chains that give molecules distinct characteristics.

What are macromolecules?

Very large biological molecules that can be consumed for energy or broken down for building blocks.

What is the function of the rectum in the digestive system?

It stores feces until they can be eliminated from the body.

What is the role of the anus in the digestive system?

It is the opening at the end of the rectum through which feces exit the body.

What process causes the formation of polymers?

Dehydration synthesis.

What reaction breaks down polymers into monomers?

Hydrolysis reaction.

What are the four types of molecules that make up cells?

Carbohydrates, lipids, proteins, and nucleic acids.

What are carbohydrates primarily used for?

Energy (as in sugars) or storage (as in starch and glycogen).

What are monosaccharides?

Monomers of carbohydrates or simple sugars; the most common example is glucose.

What are disaccharides?

Double sugars formed by joining two monosaccharide monomers together.

What are polysaccharides?

Complex carbohydrates consisting of many monosaccharide monomers linked together, such as starch and glycogen.

What are lipids commonly referred to as?

Fats.

What are triglycerides?

A type of lipid consisting of a glycerol molecule attached to three fatty acid chains.

What is the structure of phospholipids?

Two fatty acids and a phosphate group; they form the bilayer of the plasma membrane.

What are proteins responsible for in a cell?

Almost all of a cell's functions.

What are amino acids?

Monomers of proteins that link together to form protein polymers.

What is the primary structure of a protein?

The linear sequence of amino acids.

What are nucleic acids?

Macromolecules that store genetic information and provide directions for building proteins.

What are the two types of nucleic acids?

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

What is the structure of DNA?

A double-stranded molecule made of nucleotides, which include deoxyribose sugar, a phosphate group, and nitrogenous bases.

What is the role of the plasma membrane?

It separates the internal environment of the cell from the external environment and regulates molecule passage.

What is the fluid-mosaic model?

A model describing the structure of the plasma membrane as a pattern of phospholipids, steroids, and proteins.

What are channel proteins?

Membrane proteins involved in the passage of solutes through the membrane.

What do receptor proteins do?

They bind specific molecules and change shape to initiate a cellular response.

What is selective permeability?

The ability of the plasma membrane to regulate the passage of molecules into and out of the cell.

What factors determine whether a molecule can freely cross the cell membrane?

The size and nature of the molecule, including polarity and charge.

Which small uncharged molecules can freely cross the cell membrane?

CO2, O2, glycerol, and alcohol.

How do small uncharged molecules cross the membrane?

They slip between hydrophilic heads and pass through hydrophobic tails, driven by concentration gradient.

What are aquaporins?

Special channels that allow water to cross the cell membrane.

What types of molecules cannot freely cross the cell membrane?

Large molecules, ions, and charged molecules.

How do large molecules and ions cross the cell membrane?

Through channel proteins or carrier proteins specific for the substance being transported.

What is diffusion?

The movement of molecules from an area of higher concentration to lower concentration until equilibrium is reached.

What is osmosis?

The diffusion of water across a differentially permeable membrane.

What is osmotic pressure?

The pressure that develops in a system due to osmosis.

What happens to an animal cell in an isotonic solution?

There is no net gain or loss of water.

What occurs to an animal cell in a hypotonic solution?

The cell gains water, potentially leading to cytolysis or hemolysis.

What happens to an animal cell in a hypertonic solution?

The cell loses water, leading to shriveling.

What are carrier proteins?

Proteins that combine with molecules or ions to transport them across the membrane and change shape in the process.

What is facilitated transport?

The process where molecules like glucose or amino acids are transported from high to low concentration without energy.

What is active transport?

The movement of molecules against their concentration gradient, requiring energy.

What is an example of active transport?

The sodium-potassium pump.

What is bulk transport?

The transport of macromolecules into or out of cells via vesicle formation.

What is exocytosis?

The process where a vesicle fuses with the plasma membrane to exit the cell.

What is endocytosis?

The process of bringing substances into the cell.

What is phagocytosis?

The process of 'eating' where cells engulf large particles.

What is pinocytosis?

The process of 'drinking' where cells take in liquid.

What is receptor-mediated endocytosis?

A process that uses pits with receptors to draw in specific molecules.

What is energy?

The capacity to do work.

What are the forms of energy?

Solar energy, chemical energy, mechanical energy, potential energy, and kinetic energy.

What does the First Law of Thermodynamics state?

Energy cannot be created or destroyed, only converted between forms.

What does the Second Law of Thermodynamics state?

Energy conversion results in loss of energy as heat.

What role do chloroplasts play in energy flow?

They produce carbohydrates like glucose in photosynthetic organisms.

What role do mitochondria play in energy flow?

They break down glucose to generate ATP.

What is adenosine triphosphate (ATP)?

The molecule directly used by cells for work, consisting of adenosine and three phosphate groups.

How do enzymes function in metabolism?

They facilitate specific cellular reactions required for metabolism and are continually reused.

What is activation energy?

The energy required for a chemical reaction to occur, which enzymes lower to allow reactions to proceed more readily.

What factors influence enzyme activity?

Temperature, salt concentration, pH, and concentration of enzyme or substrate.

What are cofactors and coenzymes?

Inorganic ions or nonprotein organic molecules that assist enzymes in reactions.

What are cofactors in biochemical reactions?

Inorganic ions such as copper, zinc, and iron that assist enzymes.

What are coenzymes?

Organic nonprotein cofactors that assist enzymes in biochemical reactions.

How do vitamins function in the body?

As coenzymes, hormones, and antioxidants, and they direct organ functions.

What are the two categories of vitamins based on solubility?

Water-soluble vitamins (e.g., B and C) and fat-soluble vitamins (e.g., A, D, E, K).

What is the primary function of mitochondria?

To break down food molecules to produce ATP, the energy currency of the cell.

What claims are made about energy drinks?

They claim to increase energy, mental awareness, and reduce muscle fatigue.

What is caffeine and its primary effects?

A natural psychoactive chemical that increases metabolic rate and reduces drowsiness.

What are enzyme inhibitors?

Substances that prevent reactions by blocking an enzyme's active site.

What is the difference between competitive and noncompetitive enzyme inhibitors?

Competitive inhibitors directly block the active site, while noncompetitive inhibitors bind to an allosteric site, indirectly affecting the active site.

What is the role of B vitamins in energy drinks?

They interact with energy pathways and can supplement deficiencies.

What is the equation for cellular respiration?

Glucose + 6 oxygen → 6 carbon dioxide + 6 water + energy (ATP).

What are redox reactions?

Reactions that involve the transfer of electrons, where reduction is the gain and oxidation is the loss of electrons.

What are the three main stages of cellular respiration?

Glycolysis, the preparation reaction, and the citric acid cycle.

Where does glycolysis occur and what does it produce?

In the cytosol, producing 2 ATP and 2 pyruvate molecules.

What happens during the preparation reaction in cellular respiration?

Pyruvate is oxidized to form acetyl-CoA, producing NADH and releasing CO2.

What is produced during the citric acid cycle?

Two molecules of ATP and additional NADH, while breaking down pyruvic acid into carbon dioxide.

What is the function of the electron transport chain?

To use electrons from NADH to pump hydrogen ions, producing ATP through ATP synthase.

How many ATP molecules can one glucose molecule yield?

A total of 38 ATP molecules.

What is fermentation?

The anaerobic conversion of food's chemical energy into ATP energy without oxygen.

What occurs during lactic acid fermentation?

In the absence of oxygen, NADH reduces pyruvate to lactic acid, allowing ATP production to continue.

What type of fermentation do yeasts undergo?

Alcoholic fermentation, producing ethyl alcohol and carbon dioxide from pyruvate.

What is the role of taurine in energy drinks?

An amino acid that acts as an antioxidant and may enhance athletic performance.