Gene Expression: Key Area 1.3 Flashcards
What do Human genes have?
Introns( non coding regions) and exons ( coding regions).
What is gene expression controlled by?
The regulation of transcription and translation
What can gene expression be influenced by?
Intercellular and extracellular environmental factors.
What does gene expression result in?
The phenotype of an individual human
What are proteins formed of?
Polypeptides, which are chains of amino acids held together by peptide bonds
Describe RNA
- Single stranded
- it’s nucleotides contain ribose instead of deoxyribose in DNA
- has the base uracil (replaces thymine from DNA)
Why is DNA transcribed?
To produce mRNA, which carries a copy of the genetic code
What happens in transcription?
RNA polymerase moves along the DNA unwinding the double helix and aligning RNA nucleotides by complementary base pairing to form a primary transcript
How is a mature mRNA formed?
Introns are removed from the primary transcript and exons spliced
What does alternative RNA splicing allow?
Different mRNAs to be formed from the same primary transcript depending on which RNA segments are treated as exons and introns
What are codons?
Triplets of bases on mRNA
How is a polypeptide formed?
Translation of mRNA
What do codons code for?
Specific amino acids and start/stop codons
What are ribosomes made of?
rRNA and proteins
How is mRNA translated?
mRNA carries a copy of the DNA code from the nucleus to the ribosomes, where it is translated
