Question

1. how many amino acids are involved in the reaction to make a dipeptide?
2. in model 1 the original amino acids are combined through a condensation reaction to make the dipeptide.

a. what does r₁ represent in the dipeptide?
b. what does r₂ represent in the dipeptide?

1. put a box around the atoms in the amino acids that become the h₂o molecule produced by the reaction in model 1.
2. a peptide bond is a covalent bond linking two amino acids together in a peptide.

a. circle the peptide bond in model 1.
b. between which two atoms in the dipeptide is the peptide bond located?
c. between what two functional groups is the peptide bond located?

1. there are 22 different amino acids found in nature. two were shown in model 1. additional examples are shown below. with your group, write one or two grammatically correct sentences to describe how these amino acids are similar and how they are different. use the terms r - group, amine group, and carboxyl group in your description.

h₂n - c - cooh
h₂n - c - cooh
h₂n - c - cooh
h₂n - c - cooh
h
h
h
h
h₂c - sh
h₂c - c - nh₂
h₂c - c - cooh
h₂c - c - cooh
h
h
h
h
glycine (gly)
cysteine (cys)
asparagine (asn)
phenylalanine (phe)

Explanation:

Step1: Answer question 4

A dipeptide is formed by the combination of two amino - acids.

Step2: Answer question 5a

In a dipeptide, $R_1$ represents the side - chain of the first amino acid.

Step3: Answer question 5b

In a dipeptide, $R_2$ represents the side - chain of the second amino acid.

Step4: Answer question 6

In a condensation reaction to form a dipeptide, the hydrogen from the amino group ($-NH_2$) of one amino acid and the $-OH$ from the carboxyl group ($-COOH$) of the other amino acid combine to form $H_2O$. So, box the $H$ of the amino group and the $OH$ of the carboxyl group.

Step5: Answer question 7a

The peptide bond in a dipeptide is the $-CO - NH-$ bond. Circle this bond in Model 1.

Step6: Answer question 7b

The peptide bond is located between the carbon (C) of the carboxyl group of one amino acid and the nitrogen (N) of the amino group of the other amino acid.

Step7: Answer question 7c

The peptide bond is located between the carboxyl functional group ($-COOH$) and the amino functional group ($-NH_2$).

Step8: Answer question 8

All amino acids have a common structure with an amino group ($-NH_2$), a carboxyl group ($-COOH$), and a hydrogen atom attached to the central carbon. They differ in their R - groups. For example, glycine has a simple $H$ as its R - group, while phenylalanine has a complex aromatic R - group.

Answer:

1. Two amino acids
2. a. The side - chain of the first amino acid

b. The side - chain of the second amino acid

1. Box the $H$ of the amino group and the $OH$ of the carboxyl group
2. a. Circle the $-CO - NH-$ bond

b. Between carbon (C) and nitrogen (N)
c. Between carboxyl group ($-COOH$) and amino group ($-NH_2$)

1. All amino acids have an amino group, a carboxyl group and a hydrogen attached to the central carbon. They differ in their R - groups. For example, glycine has a simple $H$ as R - group and phenylalanine has an aromatic R - group.