Hey guys! Welcome back to Biology with Gracie!
Today the topic focus is: PROTEIN SYNTHESIS
Protein Synthesis GCSE & A Level Specification Content
I have gone through all the GCSE and A Level specifications for AQA, Edexcel and OCR* and picked out the points related to protein synthesis, so you aware of what you need to know for your exams. The Word document and PowerPoint presentation attached below include this information in organised tables. Summary tables also include a scale which indicates the detail your specification requires you to know about protein synthesis.
Scale summary
Scale: 1 - 3
(1) Key details of protein synthesis not required to be learnt
(2) Some details of protein synthesis required to be learnt
(3) Most details of protein synthesis required to be learnt
The scale is explained in further detail in the attachments. Please be sure to like this post and comment below if you have used these documents and whether you have found them useful.
Word Document:
PowerPoint Presentation:
*I am aware there are other key exam boards in the UK, such as WJEC and CCEA. If you are on these exam boards (or any others) please let me know and if you would like me to I’ll include the relevant specification information in my next posts and videos. Generally, the content that I cover in these posts and videos should cover most exam board requirements for these exams, however if there are any significant points or processes that I do not mention please message me and I'll be sure to add them in.
GCSE Content
Key points from all GCSE foundation tiers / combined sciences
For GCSE biology foundation tiers and GCSE combined sciences the key details of the process of protein synthesis are not required to be known (1). Here is a summary of the general key points foundation / combined sciences students need to learn*:
Nitrate ions absorbed from the soil & glucose produced during photosynthesis are required to form amino acids for protein synthesis.
Three DNA bases (triplet code) code for an amino acid. Each gene contains the code (base order) which controls order of amino acid assembly to produce a protein.
Enzymes and amino acids (monomers of proteins) are important in protein (polymers of amino acids) synthesis & breakdown.
*Individual GCSE biology foundation tier & combined science specifications do not include all these points. This is just a summary of all specification points as stated beforehand. Please refer to the Word document & PowerPoint presentation attached above to see which points you need to know for your specific specification.
Key points from all GCSE higher tiers
For GCSE biology higher tiers some detail of protein synthesis is required (2) although for the Edexcel higher tier similar detail to A Level specifications is required (3). Some specifications require key words such as mRNA, transcription & translation to be used whilst others do not. Here is a summary of the general key points higher students need to learn*:
DNA base order/triplet code determines amino acid order in protein, affecting protein made in protein synthesis.
Transcription: Unzipping of DNA around gene (RNA polymerase binds to non-coding DNA). (RNA polymerase) Produces a copy of (/complementary) mRNA in nucleus (from coding DNA).
Translation: mRNA travels to ribosome in cytoplasm and attaches. Carrier molecules (/tRNAs) transfer specific amino acids to ribosome in order determined by mRNA to add to growing protein (/polypeptide) chain (translation).
*The key terms in brackets are only required for Edexcel GCSE biology higher tier specification. This is just a summary of all specification points as stated beforehand. Please refer to the documents above to see which points you need to know for your specific specification.
A Level Content
Key points from all A Level specifications
For A Level biology the key details of the process of protein synthesis are required to be known (3). Check out my revision resources below on transcription to help you. Here is a summary of the general key points A Level students need to learn*:
The base sequence of each gene / nucleic acids carry the coded genetic information that determines the sequence of amino acids (monomers) linked by peptide bonds (formed in condensation reactions) during protein synthesis. The triplet code (sequence of 3 bases) codes for specific amino acids as well as start codons (AUG - methionine) and stop codons (UAG, UGA & UAA).
Transcription: - RNA polymerase binds to DNA double helix at start codon. Hydrogen (H+) bonds between DNA's sense (coding) strand & antisense (template) strand break. DNA unwinds. - RNA polymerase lines up free RNA mononucleotides alongside DNA's template strand. Complementary base pairing between DNA and RNA bases occurs forming H+ bonds (2 H+ bonds between A & U bases and 3 H+ bonds between G & C bases). - RNA polymerase separates DNA template strand mRNA strand, assembling mRNA strand by joining the mRNA nucleotides. H+ bonds reform between DNA strands (2 H+ bonds between A & T bases and 3 H+ bonds between G & C bases). DNA winds back up into a double helix.
Translation: - mRNA leaves the nucleus through a nuclear pore & enters the cytoplasm, where it attaches to a ribosome. - tRNA molecule carrying a corresponding amino acid (e.g. AUG = methionine) complementary base pairs to start codon (AUG) on mRNA strand with its anticodon (UAC). A second tRNA molecule with an anticodon complementary to the next codon, complementary base pairs carrying the corresponding amino acid. As this continues an enzyme catalyses the formation of peptide bonds between amino acids using ATP. - This continues until tRNA reaches a stop codon (which do not code for any amino acids) and the polypeptide chain of amino acids detaches from the ribosome to go on to further stages of protein development.
mRNA structure: Sugar-phosphate backbone forms the nucleic acid structure composed of nucleotides. This backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule. Hydrogen bonds form between DNA bases and mRNA bases during transcription as described above.
tRNA structure: Folded with three hairpin loops that form the shape of a three-leafed clover. One of the loops contains the anticodon (e.g. UAC) which complementary base pairs to the corresponding mRNA codon (e.g. AUG). On the opposing side, the tRNA has an amino acid binding site where the corresponding amino acid binds (e.g. AUG = Methionine).
rRNA role: Ribosomal RNA in the ribosome catalyses the formation of a peptide bond between the two amino acids attached to the tRNA molecules.
*Individual A Level biology specifications do not include all these points. This is just a summary of all specification points as stated beforehand. Please refer to the Word document & PowerPoint presentation attached above to see which points you need to know for your specific specification.
Revision Resources
Question Bank
These resources includes lots of key questions on protein synthesis, separated into A Level biology & GCSE biology and combined sciences for AQA, OCR and EDEXCEL. This is great practice of information recall and exam technique.
GCSE Question Pack - Protein Synthesis
A Level Question Pack - Protein Synthesis
Transcription Mind Map
This mind map I have produced includes the key points about transcription that most A Level specifications expect you to know. Use this as a visual resource to aid your learning and revision. I have attached two hand-created versions and a computer-created version to select which you prefer. Comment down below which design you like best!
Transcription FAB 5
This resource includes the 5 key parts of transcription for rapid revision!
Transcription Storyboard Process
Here I have created a storyboard of the transcription process. Comment down below or DM me on Instagram any other revision resources you'd like to see.
I hope you guys have found this post useful. Visit my YouTube channel Biology with Gracie to see a full video on this post about protein synthesis and make sure to like this post and my Instagram post. Although creating all these revision resources and specification summaries takes time, knowing that I'm helping you guys out really makes it worth it! Make sure to comment below any requests for posts or videos as well as in answer to the questions in the post.
Thank you for being here, thank you SO much!
See you soon,
Grace