Silent mutations
Change in the DNA sequence that results to the change in nucleotide base pairs having no subsequent effect on on the amino acid produced
May have occurrred in introns
Key Terms
Silent mutations
Change in the DNA sequence that results to the change in nucleotide base pairs having no subsequent effect on on the amino acid produced
May ...
Missense mutations
A single nucleotide change leads to a different codon and therefore a different AA
Nonsense mutations
Change in nucleotide sequence that leads to one of codons being converted to a terminator codon so the protein produced is truncated
Class of mutations
Beneficial - depends on environment
Neutral - No effect on chances of survival
Disadvantageous - Causes genetic diseases, lessens chanc...
Histones
Basic proteins that associate w/ DNA in the nucleus and help to condense the DNA into a smaller volume
Little balls in which DNA wraps around...
Chromatin
Complex of DNA and proteins that condense to form chromosomes within the nucleus of eukaryotic cells
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| Term | Definition |
|---|---|
Silent mutations | Change in the DNA sequence that results to the change in nucleotide base pairs having no subsequent effect on on the amino acid produced May have occurrred in introns |
Missense mutations | A single nucleotide change leads to a different codon and therefore a different AA |
Nonsense mutations | Change in nucleotide sequence that leads to one of codons being converted to a terminator codon so the protein produced is truncated |
Class of mutations | Beneficial - depends on environment Neutral - No effect on chances of survival Disadvantageous - Causes genetic diseases, lessens chances of survival |
Histones | Basic proteins that associate w/ DNA in the nucleus and help to condense the DNA into a smaller volume Little balls in which DNA wraps around |
Chromatin | Complex of DNA and proteins that condense to form chromosomes within the nucleus of eukaryotic cells |
Euchromatin | Lightly packaged DNA; RNA polymerase can access the bases to transcribe the genes --> genes can be turned on |
Heterochromatin | Tightly packaged DNA; RNA polymerase cannot access the bases to transcribe the genes so they are turned off |
Promoter regions | Region of DNA that acts as the binding site for RNA polymerase to start transcription Intron Usually upstream |
Operator regions | Short region of DNA that is close to the promoter region | Interacts w/ regulatory proteins that controls the transcription of operons |
Downstream | To the right |
Upstream | To the left |
Operon | Functioning unit of DNA containing a group of structural genes expressed together Controlled by one promoter Only found in prokaryotes |
How is gene expression regulated in operons | Transcription factors bind |
Transcription factors | Coded for by regulatory genes Proteins which affects rate of transcription Activates or inhibits transcription of DNA by binding to promoter region w/ RNA polymerase or blocking the promoter region |
Repressor protein | A protein that binds to DNA/RNA inhibiting transcription by binding to the operator |
Gene expression | Production of proteins from a genome |
Control of gene expression | Whether genes are turned on or off |
Why is the control of gene expression necessary | In specialisation and differentiation of cells Increasing/ decreasing complexity Prevent vital resources being wasted |
Why is gene expression more complex on eukaryotes | Have to respond to changes in the internal and external environments Histones - DNA not exposed, genes expression is harder Prokaryotes don't have histones |