1. Chemical Ideas: Chapter 5.4 (p 102 to 108)
Learning Outcomes:
Describe how DNA and RNA encode for the amino acid sequence in a polypeptide chain.
Describe the structure of DNA and RNA in terms of a sugar–phosphate backbone and attached bases.
Storyline EP2 (p 144 to 149) Activities EP2.7 and EP2.8.
Explain the role of hydrogen bonding in the pairing of bases in DNA, and the replication of genetic information by RNA.
Illustrate and explain the role of hydrogen bonds as intermolecular forces, which help determine the sequence of amino acids in a polypeptide chain.
Chemical Ideas: Chapter 5.4 (p 102 to 108)

2. Cell structure cytoplasm Rough endoplasmic reticulum Nucleus Ribosomes
~ gel of molecules
Rough endoplasmic reticulum
~ protein synthesis
Nucleus
DNA ~ genetic material
Ribosomes
~ protein synthesis

3. DNA ~ genetic information and the blue print for protein synthesis
Bases in DNA:
Thymine T
Cytosine C
Adenine A
Guanine G
Hydrogen bonds between base pairs

4. Part of a DNA strand- a gene – unzips and transcription of the base pairs produces a strand of mRNA.

5. RNA ~ Ribonucleric acid in a cell
1 gene 1 polypeptide chain
Transcription DNA used as a blue print to make mRNA
Nucleus (DNA)
mRNA carries the code for protein synthesis and goes to ribosomes.
tRNA
collect amino acids in the cell’s cytoplasm and carry them to the ribosomes where they will be built into a polypeptide chain ~ translation

6. Bases carried on the DNA strands code for an amino acid sequence that will form a protein.
Bases in DNA:
Thymine T
Cytosine C
Adenine A
Guanine G
Bases in RNA:
Uracil U
Cytosine C
Adenine A
Guanine G
How bases pair to form mRNA:
Adenine A Uracil U
Cytosine C Guanine G
Thymine T Adenine A
Guanine G Cytosine C

7. Three bases ~ tripet base codes, or codons, are used for each amino acid.
in this example it would bind to GCC, the codon for alanine
Anti-codon for binding to a codon on mRNA:
mRNA from the nucleus

8. sugar phosphate molecule
base
Bases that make up the triplet base codons are attached to sugar phosphate molecules, which together are called RNA

9. Chemical composition of Ribonucleric Acid
Ribose sugar molecules ~ C5H10O5
Phosphate groups H2PO4
One of 4 bases: A,U,G or C

10. H O
BASE
phosphate
H2O OH
A unit of RNA

11. Representations of the structure of RNA

12. - C - H2N COOH CH3 H - C - H2N C = O CH3 H + H2O one tRNA
How an ester bond is formed between the tRNA and an alanine molecule:
an ester link
- C -
H2N
COOH
CH3 H
- C -
H2N
C = O
CH3 H
alanine molecule
+ H2O
one tRNA

13. When a tRNA collects an amino acid it takes it to the mRNA strand that has become attached to a ribosome.

14. Protein synthesis: ribosome read codons on mRNA.
Ribosome moles along the mRNA chain

15. Amino acids bond into the polypeptide chain
tRNA molecules bring amino acids to the mRNA in the ribosome
H2N
COOH
tRNA leave the ribosome when it has delivered its amino acid

16. The bases in RNA are planar and the bases fit together so that groups are in just the right positions for hydrogen bonds to form ~ molecular recognition.
2 hydrogen bonds between uracil and adenine

17. 3 hydrogen bonds between cytocine and guanine

18. EP2 Protein building pages 140 to 149
Read in Chemical Storylines:
EP2 Protein building pages 140 to 149
Make your own
summary notes/annotated diagrams about how amino acids are converted into polypeptide chains inside cells