4371717
Description
| Question | Answer |
| DNA acts as a ____ for a sequence of amino acids that make up a proteins. | Code |
| Where in a cell is DNA largely confined to? | Nucleus |
| Where in the cell does protein synthesis take place? | Cytoplasm |
| How is the DNA in the nucleus transferred to the cytoplasm where it is translated into proteins? | Sections of the DNA code are transcribed onto a single stranded molecule - RNA |
| What are the types of RNA we study? | mRNA tRNA |
| Which type of RNA transfers the DNA code from the nucleus to the cytoplasm and acts as a messenger? | mRNA |
| mRNA is small enough to leave the nucleus through _______ _____ | Nuclear pores |
| Each amino acid is coded for by a sequence of _ nucleotide bases | 3 |
| What name is given to this sequence? | A codon |
| What is meant when it is said that the code is 'degenerate'? | Most amino acids have more than one codon. |
| How many 'stop codons' are there? | 3 |
| What do stop codons mark? | The end of the peptide chain |
| Give an example of what is meant when the code is said to be 'non-overlapping'? | A base sequence 123456 is read as 123 456 rather than 123 234 345 456 etc |
| It is a _________ code - it is the same codon codes for the same amino acids in all organisms | Universal |
| RNA is made of a ______ nucleotide chain | Single |
| Ribonucleic acid is a _______ made up of repeating mononucleotide sub-units | Polymer |
| It forms a single strand in which each nucleotide is made up of: | - A pentose sugar ribose - One of the organic bases (AUGC) - A phosphate group |
| Messenger RNA (mRNA) is a long strand arranged in a single helix. It is made when DNA makes a mirror ____ of part of one of its two strands | Copy |
| mRNA enters the __________ through nuclear pores | Cytoplasm |
| There it acts as a template upon which _______ are built | Proteins |
| tRNA is relatively small and is made up of around how many nucleotides? | 80 |
| It is single stranded and folded into what shape? | Clover leaf |
| One end of the structure extends. What is this the point of? | Amino acid attachment |
| What is there at the opposite end of the tRNA molecule? | An anticodon |
| What is the anticodon? | A sequence of three organic bases which is complementary to the organic bases on an mRNA molecule |
| What are the complementary base pairings? | AU GC |
| DNA provides the instructions for protein synthesis in the form of a long sequence of ___________ and the bases they possess | Nucleotides |
| A complementary section of part of this sequence is made in the form of a molecule called pre-mRN during a process called.... | Transcription |
| The pre-mRNA is _______ to form mRNA | Spliced |
| The mRNA is used as a ______ to which complentary tRNA molecules attach and the amino acids they carry are linked to form a oolypeptide | Template |
| What enzymes are involved in transcription? | DNA helicase RNA polymerase |
| What does DNA helicase do? | It breaks the H-bonds between the bases on a specific region of the DNA, causing the two strands to separate |
| What does RNA polymerase do to one of these strands of DNA? | It moves along one of them (the template strand) causing the nucleotides on the strand to join with individual complementary nucleotides |
| When does RNA polymerase detach from the DNA? | When it reaches the sequence of bases that act as the stop code |
| What has been successfully produced after RNA polymerase detaches? | Pre-mRNA |
| What has to happen to the pre-mRNA before it leaves the nucleus? | It needs to be spliced |
| Why is this? | It contains introns which do not code for proteins - they need to be removed |
| Which name is given to the sections that do code for proteins? | Exons |
| Once the introns have been removed, the exons can ______ in a variety of combinations | Rejoin |
| This means that a single section of DNA (____) can code for up to a dozen different proteins | Gene |
| What are certain conditions such as Alzheimer's a result of? | Mutations that affect splicing - leading to non-functional polypeptides being made |
| Towards which organelle is the mRNA attracted to when it leaves the nucleus? | Ribosomes |
| What part of tRNA varies? | The sequence of bases on the anticodon loop |
| At the other end of the tRNA molecule there is a point of attachment for an ______ ____ | Amino acid |
| During __________, a ribosome becomes attach to the starting codon at one end of an mRNA molecule | translation |
| A tRNA molecule with a _________ ______ _______ moves to the ribosome are pairs up with the mRNa | Complementary anticodon sequence |
| What does this tRNA molecule carry? | An amino acid |
| A tRNA molecule with a complementary anticodon to the next codon attaches, also carrying an amino acid. How are these amino acids joined? | Peptide bond Enzymes ATP |
| When a third tRNA comes to join onto a codon, the first tRNA is ______ | Released |
| What is this tRNA molecule free to do? | Collect another amino acid from the amino acid pool in the cell |
| This process continues until what is made? | A polypeptide |
| How can many (up to 50) polypeptide chains be made simultaneously? | Up to 50 ribosomes can follow behind the first |
| At what point is the polypeptide chain complete? | When the ribosome reaches a stop codon |
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