Functional Groups Worksheet displaying examples of thiol, phosphate, and methyl groups with their structures and properties.

Let's solve this Functional Groups Worksheet step by step. The worksheet asks you to:

1. Identify the name of the functional group.
2. Describe the properties imparted to the molecule by that group.
3. Circle the functional group in the given molecule.

We have three rows, each with a different functional group.

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🔹 Row 1: –SH Group

#### ✔ Name of Functional Group:
Thiol (or sulfhydryl group)

> This is the –SH group, where sulfur is bonded to hydrogen.

#### ✔ Properties Imparted to Molecule:
- Polar and can form hydrogen bonds, though weaker than O–H bonds.
- Can form disulfide bridges (–S–S–) when two thiol groups oxidize.
- Important in protein structure (e.g., cysteine residues in proteins).
- Often involved in redox reactions and enzyme activity.

#### ✔ Circle the Functional Group:
In the molecule shown:
```
O
║
C–OH
/
H–C–CH₂–SH
\
N
/ \
H H
```
The –SH group is at the end of the CH₂–SH chain.

👉 Circle the –SH group (i.e., the S–H part at the far right).

---

🔹 Row 2: –O–P(=O)(O⁻)O⁻ Group

This is a phosphate group.

#### ✔ Name of Functional Group:
Phosphate group or phosphoryl group

> The structure shows:
> –O–P(=O)(O⁻)O⁻ — this is a phosphoester group.

#### ✔ Properties Imparted to Molecule:
- Highly polar and charged (negatively charged at physiological pH).
- Increases solubility in water.
- Participates in energy transfer (e.g., ATP).
- Key in nucleic acids (DNA/RNA backbone).
- Can be involved in cell signaling via phosphorylation.

#### ✔ Circle the Functional Group:
In the molecule:
```
H–C–C–C–O–P(=O)(O⁻)O⁻
| | |
H H H
|
OH
|
OH
```
The phosphate group is the –O–P(=O)(O⁻)O⁻ part at the right end.

👉 Circle the entire phosphate group (the P and its four O atoms).

---

🔹 Row 3: –CH₃ Group (Methyl group)

Note: The image shows a carbon bonded to three hydrogens, with one bond extending to another atom. This is a methyl group.

#### ✔ Name of Functional Group:
Methyl group (–CH₃)

#### ✔ Properties Imparted to Molecule:
- Nonpolar and hydrophobic.
- Does not participate in hydrogen bonding.
- Adds bulk and affects molecular shape.
- Common in alkyl chains and organic molecules like lipids and amino acids (e.g., methionine).
- Can influence molecular stability and reactivity.

#### ✔ Circle the Functional Group:
In the molecule shown:
```
NH₂
│
C──C──CH₃
╱ ╲
N C
╱ ╲
O H
```
Wait — let's re-express this more clearly. It’s a six-membered ring (likely a purine derivative), with a CH₃ group attached.

So, the –CH₃ group is on the right side of the ring.

👉 Circle the –CH₃ group (the methyl group attached to the ring).

---

✔ Final Answers Summary:

| Name of Functional Group | Properties Imparted to Molecule | Circle the Functional Group |
|--------------------------|----------------------------------|-------------------------------|
| Thiol (–SH) | Polar; forms disulfide bonds; involved in redox reactions and protein folding | Circle –SH (on CH₂–SH) |
| Phosphate (–O–P(=O)(O⁻)O⁻) | Negatively charged; hydrophilic; involved in energy storage (ATP), nucleic acids | Circle phosphate group |
| Methyl (–CH₃) | Nonpolar, hydrophobic; adds bulk; increases solubility in nonpolar environments | Circle –CH₃ |

---

📝 Additional Notes:

- In real-world applications:
- Thiol groups are crucial in cysteine amino acid.
- Phosphate groups are key in ATP, DNA, and phospholipids.
- Methyl groups are found in methionine, thymine, and many organic compounds.

Let me know if you'd like this as a printable answer sheet!