1. RNA
Transcription

2. DNA stands for deoxyribonucleic acid.
A nucleic acid is a long repeating chain of nucleotides.

3. The nitrogen bases are on the inside of the DNA double helix
The nitrogen bases are on the inside of the DNA double helix. The information in DNA is “written” with nitrogen bases. 3

4. The sequence of nitrogen bases provides the instructions for making ribosomes and proteins. Each region of DNA that is used to make a protein is called a gene.

5. Transcription
The primary purpose of transcription is to make copies of the information found in the DNA. The information in a gene is copied from DNA into a similar molecule called RNA.

6. Transcription
Before DNA can be copied, it must unwind and the two strands must separate between the nitrogen bases.

7. Enzyme = RNA Polymerase
Transcription
Once the strands of DNA are separated, enzymes can use the information in the DNA to make RNA copies of the gene.
Enzyme = RNA Polymerase

8. Transcription
The RNA molecules are sent out into the cytoplasm where they attach to ribosomes. Ribosomes are the cell’s workforce which use the instructions to build the cell’s proteins.

9. Transcription
Transcription happens in ALL cells. However, in eukaryotic cells, transcription occurs in the nucleus where the DNA is located.
Nucleus

10. Endoplasmic Reticulum
Transcription
The RNA then travels out of the nucleus to find ribosomes. Many proteins are made by the ribosomes in the cell’s “protein factory”, the rough endoplasmic reticulum.
Ribosomes in
Endoplasmic Reticulum
Free Ribosome
Nucleus

11. Gene Expression
Gene expression describes the process of using the information in the genes of DNA to make products in the cell. Transcription is the first step of gene expression.

12. Gene Expression
It is important that you understand that gene expression is a regulated process. This means that the cell controls how the DNA is used to make proteins and other products.

13. Gene Expression
The cell turns genes ON and OFF so that only certain genes in the cell are expressed. This means that only specific genes are being transcribed. ON

14. Gene Expression
The cell turns genes ON and OFF so that only certain genes in the cell are expressed. This means that only specific genes are being transcribed.
No Products!
OFF

15. DNA vs. RNA
DNA and RNA are very similar nucleic acids, but there are some important differences you need to know.
DNA
RNA

16. DNA contains the sugar deoxyribose. RNA contains the sugar ribose.
DNA vs. RNA
DNA contains the sugar deoxyribose.
RNA contains the sugar ribose.
DNA
RNA
deoxyribose
ribose 16

17. DNA vs. RNA
DNA is double stranded.
RNA is single stranded.
DNA
RNA 17

18. DNA vs. RNA
DNA contains the nitrogen base thymine. RNA contains the nitrogen base uracil.
DNA
RNA
thymine
uracil 18

19. A U G C The 4 nitrogen bases in RNA: Adenine Uracil Guanine Cytosine19

20. Important Fact: U and T will NEVER appear in the same strand together!
Base Pairing
T A C G
U A C G
Important Fact: U and T will NEVER appear in the same strand together! 20

21. A C T C A G 21

22. Why can you immediately cross out answer choices B and D?
These answer choices haveT and U in the same strand.
Remember: U and T will NEVER appear in the same strand together! 22

23. Correctly label the sequence of the nitrogen bases in the RNA segment that is being transcribed from the DNA below.
C G U A A G C U U C G A G U A U G C 23