Bio 100

Exam 2

What is energy?

Energy is the ability to do work against an opposing force.

What is kinetic energy?

Energy of movement. Example: a moving car.

What is potential energy?

Stored energy. Example: a book on a shelf.

What is the first law of thermodynamics?

Energy cannot be created or destroyed; it only changes form.

What is the second law of thermodynamics?

Energy conversions are inefficient; some energy is always lost as heat.

What is entropy?

Entropy measures disorder in a system; high entropy = more disorder, low entropy = more order.

What is ATP?

ATP is the cell’s energy currency, coupling energy-releasing reactions with energy-requiring reactions.

What does organic mean in biology?

Organic molecules contain carbon and hydrogen atoms.

What are the four organic macronutrients?

Carbohydrates, Proteins, Nucleic Acids, Fats

What is a monomer?

A small molecule that can chemically bond to form a polymer.

What is a polymer?

A large molecule made of repeating monomers. Examples: proteins, DNA, plastics.

Monomers of the four macronutrients

Carbs = monosaccharides; Proteins = amino acids; Nucleic acids = nucleotides; Fats = glycerol + fatty acids

What is dehydration synthesis?

Monomers join to form polymers; water is removed.

What is hydrolysis?

Polymers are broken into monomers; water is added.

What are energy nutrients?

Nutrients storing potential energy in bonds: carbs, fats, proteins.

Functions of carbohydrates

• Hydrophilic (dissolve in water); - Easily accessible energy source; - Can form long polymers broken down by enzymes

What are monosaccharides?

Single sugar units. Examples: glucose, fructose, galactose.

What are disaccharides?

Two monosaccharides joined. Examples: sucrose, lactose, maltose.

Which monosaccharides make up disaccharides?

Two monosaccharides, usually including glucose.

Functions of starch, glycogen, and fiber

Starch is a polysaccharide used for long-term energy storage in plants

Glycogen is a polysaccharide used for short-term energy storage in animals

Fiber is a polysaccharide used for the structural components of leaves, stems, and roots within plants

Three types of lipids

Triglycerides- used for energy storage. 

Cholesterol- Cell membrane function and hormone production 

Phospholipids- Structure of the cell membrane 

Functions of fats

Triglycerides used for energy storage. 

Cholesterol- Cell membrane function and hormone production 

Phospholipids- Structure of the cell membrane 

Functions of sterols (cholesterol)

Maintain membrane integrity, regulate cholesterol, precursor for hormones, vitamin D, bile acids

LIPIDS

Functions of phospholipids

Form the bilayer of cell membranes

Saturated vs. unsaturated fats

Saturated- Carbons are bound by two carbons and two hydrogens, are hydrophobic, form long straight chains

Unsaturated- Carbons are bound by only two hydrogens, are less hydrophobic, form bent chains.

What are proteins?

Chains of amino acids linked by peptide bonds.

What is an amino acid?

Basic unit of protein; Amino acids consist of a central carbon linked to an amino group, a carboxyl group, and a variable r group. 

What are peptide bonds?

Strong bonds linking amino acids into polypeptides

Protein structure levels – primary

Linear sequence of amino acids

Protein structure levels – secondary

Folding patterns (α-helix, β-sheet) due to interactions between amino acids

Protein structure levels – tertiary

3D shape of a single polypeptide; protein becomes functional

Protein structure levels – quaternary

Multiple polypeptides interacting to form complex protein

Mechanical vs. chemical digestion

Mechanical = physically breaking down food (chewing, stomach churning); Chemical = enzymes break nutrients into smaller molecules

Functions of mouth and esophagus

Mouth = mechanical + chemical digestion; Esophagus = food transport to stomach

Functions of stomach

Mixes food mechanically; pepsin breaks down proteins

Functions of small intestine

Main site of digestion & absorption of nutrients

Functions of large intestine

Absorbs water, produces vitamins, breaks down soluble fiber

Functions of liver

Produces bile, processes and stores nutrients

Functions of gallbladder

Stores and releases bile

Functions of pancreas

Produces digestive enzymes; regulates blood sugar

Functions of salivary glands

Lubricate food; release digestive enzymes

Small intestine and villi

Villi increase surface area for absorption; contain capillaries (blood) & lacteals (fat)

What is an enzyme?

Protein that speeds up chemical reactions by lowering activation energy

What is the active site of an enzyme?

The pocket where the substrate binds

What is a substrate?

Molecule that binds to an enzyme and is acted upon

What is a product in enzyme reactions?

The molecule produced after the enzyme converts the substrate

Explain E + S → ES → E + P

E + S = enzyme + substrate bind; ES = enzyme-substrate complex; E + P = product formed, enzyme ready to reuse

Digestion & absorption of fats

Fats → fatty acids + glycerol → absorbed via lacteals into lymphatic system

Digestion & absorption of proteins

Proteins → amino acids → absorbed into blood via capillaries

Digestion & absorption of carbohydrates

Carbs → monosaccharides → absorbed into blood via capillaries

Mitochondrion function

Produces ATP; powerhouse of the cell

Endosymbiotic theory

Mitochondria were once free-living bacteria absorbed by a larger cell

Components of plasma membrane

Phospholipids, proteins, cholesterol, carbohydrates; selectively permeable

How substances move through plasma membrane

Passive transport, active transport, bulk transport (endocytosis/exocytosis)

Passive transport types

Simple diffusion, osmosis, facilitated diffusion

Hypertonic solution effect on animal cell

Water leaves → cell shrinks

Hypotonic solution effect on animal cell

Water enters → cell swells

Isotonic solution effect on animal cell

No net water movement → cell stable

Active transport example

Sodium-potassium pump moves ions against gradient using ATP

Endocytosis vs. exocytosis

Endocytosis = cell takes in material; Exocytosis = cell expels material

Four stages of aerobic cellular respiration

Glycolysis (cytoplasm), Pyruvate conversion (mitochondria), Krebs cycle (mitochondria), Electron Transport Chain (mitochondria)

Products of glycolysis

2 ATP + 2 NADH

Products of pyruvate conversion

2 NADH + 2 Acetyl-CoA

Products of Krebs cycle

2 ATP + 6 NADH + 2 FADH2

Products of Electron Transport Chain

~34 ATP

Functions of vitamins

Support enzymes, cell function, immune system, vision, bone health, blood clotting

Digestive system flow (diagram)

Mouth → esophagus → stomach → small intestine → large intestine; accessory organs: liver, gallbladder, pancreas, salivary glands