dna structure
polymer (nucleic acid) monomer (nucleotides) 1. sugar 2. phosphate group 3. Nitrogenous bases (adenine thmine guanine cytosine)
two differences b/t dna and rna
- dna contains the sugar deoxyribose, whereas rna contains the sugar ribose
- dna uses the nitrogenous base Thymine, whereas rrna uses uracil instead of thymine (both use AG, and C)
3.
deoxy
means dna has onle less oxygen tatm on its sugar than rna
thymine and cytosine
have one ring
adenine and guanine
have two rings (very important for douoble helix structure
who binds with who?
Adenine and thymine
cytosine and guanine
“Georgle Clooney at the Oscars”
why AT and GC bond
- three rings across the helix (rule one)
2. the number of hydrogen bonds b/t the nitrogenous bases on opopsite sides of the helix
gene expression
dna controls all the activities in the cell
it does this by making proteins that exert their effects on the organsims
genes are units of dna that code for a particular protein
transcription
DNA –> mRNA
- dna opens at a gene and an enzyme transcribes the code from the dna to mrna
- transferring the information from dna to mrna
- occurs in the nucleus
mRNA
messenger
translation
mRNA –> Protein
- the code on the mrna tells the ribosome which amino acids to add to the protein
- occurs in the rough ER or cytoplasm
genetic information flow
DNA –>mRNA –> Protein
mutations
changes in dna sequences; a change in the dna will result in a change the mrna codons and the wrong amino acid could be added
- nucleotide substitutions (one nucleotide is changed) ex:sickle cell
- nucleotide deletions (when one nucleotide is deleted it throws off the “reading frame” by shifting all the nucleotides over one place and everything that follows is incorrect
