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12 Cards in this Set
- Front
- Back
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What is a PHENOTYPE determined by? |
The proteins that are produced as a result of GENE EXPRESSION. |
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What do INTRA and EXTRA cellular factors control? |
They control what genes are expressed by controlling transcription and translation |
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What is RNA? |
It's like DNA but... -RNA is single stranded -URACIL replaces THYMINE - Has RIBOSE sugar instead of DEOXYRIBOSE sugar |
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What is mRNA? |
-mRNA is MESSENGER RNA -It carries a copy of the Dna code from the nucleus to the ribosome with each triplet of bases called a codon. |
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What are ribosomes made of? |
rRNA and proteins |
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Describe TRANSCRIPTION |
Transcription is the first part of the process of making a protein. It takes place inside the cell nucleus. Transcription involves copying the DNA and the stages are:
1. The DNA in a gene unzips so that both strands are separate – one strand is used as a template 2. Complementary bases attach to the strand being copied – C joins to G and so on 3. Thymine (Base T) is not present and a different base, U, joins with A in the way that T would have done 4. This forms a strand of messenger RNA (mRNA)Messenger RNA is small enough to move out of the nucleus and so it travels to the ribosomes in the cytoplasm. |
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The removal of INTRONS... |
The coding regions of a gene are called exons and the intervening non-coding regions are called introns.
When these genes are to be expressed by a cell they need to be copied and the non-coding parts edited out before they can be turned into protein. This process is called RNA splicing. |
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What are EXONS? |
Exons are coding regions which are joined together to form a mature transcript by the process of RNA Splicing. |
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TRANSLATION is... |
The formation of a polypeptide from mRNA at a ribosome. |
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tRNA |
- tRNA has a cloverleaf shape.
- It is made from a single strand of RNA which folds due to base pairing to form this unusual shape. - It has a triplet anti-codon site and an attachment site for a specific amino acid. |
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Start and Stop codons |
- Start and Stop Codons. The start codon marks the site at which translation into protein sequence begins
- The stop codon marks the site at which translation ends. |
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How are polypeptides formed? |
AMINO ACIDS are joined by PEPTIDE BONDS to form a POLYPEPTIDE which exits the RIBOSOME |
