뒤로Study Notes: Carbon Compounds in General Biology
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Carbon Compounds
Organic Molecules
Organic molecules are fundamental to life and are primarily composed of carbon atoms bonded with other elements. They are not exclusively produced by living things, but most biological molecules are organic.
Definition: Organic molecules are compounds that contain carbon atoms bonded to hydrogen, oxygen, nitrogen, or other elements.
Biological Relevance: Most macromolecules in living organisms (proteins, nucleic acids, carbohydrates, lipids) are organic.
Non-biological Production: Some organic molecules can be synthesized abiotically (e.g., in laboratory settings or on other planets).
Example: Glucose (C6H12O6) is an organic molecule produced by plants during photosynthesis.
Properties of Carbon
Carbon is a versatile element that serves as the backbone for a vast array of biological molecules due to its unique chemical properties.
Tetravalence: Carbon has four valence electrons, allowing it to form up to four covalent bonds with other atoms.
Bonding Diversity: Carbon can form single, double, and triple bonds, and can bond with many different elements.
Chain Formation: Carbon atoms can link together to form chains, branched molecules, and rings.
Example: Hydrocarbons are molecules consisting entirely of carbon and hydrogen, such as methane (CH4).
Variation in Carbon Skeletons
Carbon skeletons can vary in several ways, contributing to the diversity of organic molecules.
Length: Carbon chains can be short or long.
Branching: Chains may be unbranched or branched.
Ring Structures: Carbon atoms can form closed rings.
Double Bonds: The presence and position of double bonds can vary.
Example: Butane and isobutane are both C4H10 but differ in branching.
Types of Isomers
Isomers are molecules with the same molecular formula but different structures. There are three main types described in biology:
Structural Isomers: Differ in the covalent arrangement of atoms.
Cis-Trans (Geometric) Isomers: Differ in spatial arrangement around a double bond.
Enantiomers: Mirror-image isomers that differ in spatial arrangement around an asymmetric carbon.
Example: Glucose and fructose are structural isomers (both C6H12O6).
Steroid Hormones: Estradiol and Testosterone
Steroid hormones are lipids with a characteristic four-ring structure. Estradiol and testosterone are similar in structure but have different biological effects.
Structural Similarity: Both have the same carbon skeleton and four fused rings.
Functional Groups: The difference in attached functional groups leads to different functions.
Biological Effects: Estradiol is the primary female sex hormone; testosterone is the primary male sex hormone.
Example: Small changes in functional groups (e.g., hydroxyl vs. methyl) result in different hormone activity.
Functional Groups in Organic Molecules
Functional groups are specific groups of atoms within molecules that confer particular chemical properties.
Common Functional Groups: Hydroxyl (-OH), Carbonyl (>C=O), Carboxyl (-COOH), Amino (-NH2), Sulfhydryl (-SH), Phosphate (-PO4), Methyl (-CH3).
Role: Functional groups determine the reactivity and interactions of organic molecules.
Example: The carboxyl group makes amino acids acidic.
Functional Group | Structure | Properties | Example |
|---|---|---|---|
Hydroxyl | -OH | Polar, forms hydrogen bonds | Alcohols (e.g., ethanol) |
Carbonyl | >C=O | Polar, found in sugars | Aldehydes, ketones |
Carboxyl | -COOH | Acidic, donates H+ | Amino acids, fatty acids |
Amino | -NH2 | Basic, accepts H+ | Amino acids |
Phosphate | -PO4 | Negative charge, energy transfer | ATP, nucleic acids |
Methyl | -CH3 | Nonpolar, affects gene expression | Methylated DNA |
Additional info: Functional groups are critical in determining the chemical behavior of organic molecules and are often used to classify and identify biomolecules in biology.
