Flashcards
Genes and Protein Synthesis
Cards in this deck (12)
- 1What is a gene?A small part of a DNA strand which determines the sequence of amino acids in a polypeptide (the primary structure of a protein)
- 2How many amino acids and codes are there?20 different amino acids
64 different codes - 3What are the properties of a genetic code?Degenerative (most amino acids have more than one triplet code - codons)
Non-overlapping
Universal - 4What are codons?Base triplets
- 5What are the 3 types of RNA?Messenger (mRNA)
Transfer (tRNA)
Ribosomal (rRNA) - 6What is the structure and function of mRNA?STRUCTURE:
A single polynucleotide strand
Made in the nucleus during trascription
FUNCTION:
Carries the genetic code from the DNA to the ribosomes in the cytoplasm where protein is made - 7What is the structure and function of tRNA?STRUCTURE:
A single polynucleotide strand folded into a clover shape
Small molecules, about 80 nucleotides long
Hydrogen bonds between specific base pairs hold the molecule in this shape
Has a specific sequence of three bases at one end called an anticodon
Has an amino acid binding site at the other end
FUNCTION:
Carries amino acids to the ribosomes so that the protein can be assembled - 8What is the structure and function of rRNA?STRUCTURE:
Forms the two sub-units in a ribosome, along with proteins
FUNCTION:
Ribosome moves along the mRNA strand during protein synthesis
rRNA in a ribosome helps to catalyse the formation of peptide bonds between the amino acids - 9What are the two stages of protein synthesis?Transcription
Translation - 10Outline the process of transcription1. DNA unwinds (hydrogen bonds are broken between base pairs by DNA helicase)
2. One of the DNA strands acts as a template against which a matching mRNA strand can be formed (template strand). The DNA strand which is copied is called the sense/coding strand
3. The exposed bases on the template strand of DNA attract RNA nucleotides with a complimentary base
4. RNA polymerase moves along the DNA, forming bonds that add nucleotides one at a time to the RNA
5. Behind the RNA polymerase, the DNA strands join up to reform the double helix
6. When the RNA polymerase reaches a particular sequence of bases on DNA, it recognises it as a 'stop' codon and detaches - 11Outline the process of translation1. Translation starts with the start codon (methionine)
2. Inside the ribosome, the anticodon of the rRNA binds to the complementary codon on the mRNA
3. The tRNA molecule carrying a methionine attaches itself at the ribosome according to complementary base pairing. As ribosomes fit 2 tRNA molecules, a second one also attaches to the ribosome at the bigger sub-unit
4. A peptide bond forms between the two amino acids and the first tRNA moves out of the ribosome. The ribosome moves along the mRNA so that a third tRNA can be attached to the ribosome
5. A third tRNA comes into the ribosome and the process repeats
6. The ribosome moves along the mRNA strand, building a polypeptide chain until a stop codon occurs in the mRNA (these do NOT code for any amino acids)
7. The mRNA separates from the ribosome and the completed polypeptide chain is released to the cytoplasm - 12TRUE OR FALSE: The ribosome and mRNA can be used againTRUE
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- User has deleted their subject information Flashcards on Genes and Protein Synthesis, created by Deleted user on 05/03/2018.
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- Deleted user · Mar 2018
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- Mar 5, 2018
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- Created by Yinka F · Jan 25, 2018
- Copied by Yinka F · Mar 5, 2018
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