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DNA and RNA
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DNA forms
B form (right-handed double helix).
A form (right-handed helix).
Z form (left-handed helix).
RNA forms
Single stranded.
Double stranded.
Types of RNA
Ribosomal RNA (rRNA), 85%.
Transfer RNA (tRNA), 10%.
Messenger RNA (mRNA), less than 5%.
Gene (‫)المورث‬
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Gene is the basic unit of genetic
information.
Gene: genetic information transcribed
into a single RNA, translated into a single
protein.
locus
alleles
Gene organization
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Besides codons (three bases of mRNA =
amino acid).
Regulatory sequences.
The promoter: region where RNA
polymerase binds (starts transcription).
A stop site.
Upstream and downstream control
sequences.