Questions: 5'-GAATCC-3' 3'-CTTAGG-5' 5'-CCTTCC-3' 3'-GCAAGG-5' 5'-AGGTCC-3' 3'-TCCAGG-5' 5'-GGATCE-3' 3'-CCTAGG: 5'

The question appears to involve sequences of nucleotides, which are the building blocks of DNA. DNA sequences are typically written from the 5' end to the 3' end. Let's analyze the sequences provided:

1. $5^{\prime}$-GAATCC-3'
2. $3^{\prime}$-CTTAGG-5'
3. $5^{\prime}$-CCTTCC-3'
4. 3'-GCAAGG-5'
5. $5^{\prime}$-AGGTCC-3'
6. 3'-TCCAGG-5!
7. $5^{\prime}$-GGATCE-3'
8. $3^{\prime}$-CCTAGG: $5^{\prime}$

Let's break down each sequence:

1. $5^{\prime}$-GAATCC-3': This is a standard DNA sequence.
2. $3^{\prime}$-CTTAGG-5': This is the complementary strand to the first sequence, written in the 3' to 5' direction.
3. $5^{\prime}$-CCTTCC-3': This is another standard DNA sequence.
4. 3'-GCAAGG-5': This is a standard DNA sequence written in the 3' to 5' direction.
5. $5^{\prime}$-AGGTCC-3': This is another standard DNA sequence.
6. 3'-TCCAGG-5!: This sequence has an exclamation mark at the end, which is unusual and likely a typo.
7. $5^{\prime}$-GGATCE-3': This sequence has an 'E' at the end, which is not a valid nucleotide (A, T, C, G are the valid nucleotides).
8. $3^{\prime}$-CCTAGG: $5^{\prime}$: This sequence is written in the 3' to 5' direction, but the notation is unusual with the colon.

To summarize:

• Sequences 1, 2, 3, 4, and 5 are valid DNA sequences.
• Sequence 6 has a typo with an exclamation mark.
• Sequence 7 has an invalid nucleotide 'E'.
• Sequence 8 has an unusual notation but is otherwise a valid sequence.

The correct sequences are:

1. $5^{\prime}$-GAATCC-3'
2. $3^{\prime}$-CTTAGG-5'
3. $5^{\prime}$-CCTTCC-3'
4. 3'-GCAAGG-5'
5. $5^{\prime}$-AGGTCC-3'

The sequences with issues are: 6. 3'-TCCAGG-5! (typo) 7. $5^{\prime}$-GGATCE-3' (invalid nucleotide) 8. $3^{\prime}$-CCTAGG: $5^{\prime}$ (unusual notation)