Genetic code (BIOL5) Flashcards
1
Q
Describe DNA
A
-
Polynucleotide - many nucleotides joined
- Nucleotides made up of :
- pentose sugar/deoxyribose
- phosphate group
- nitrogenous base
- Nucleotides join, form polynucleotide strands:
- join up b/w phosphates to sugar of another - creates sugar-phosphate backbone
- 2 DNA polynucleotide strands join by H bonds b/w bases
- Bases only join w/ one particular partner:
- Spec. base pairing
- A-T
- C-G
- Nucleotides made up of :
- Forms a double-helix
2
Q
Describe DNA in protein synthesis
A
- Proteins made from amino acids
- Order of nucleotide bases in gene determines order of amino acids in protein
- Each amino acid coded for by 3 bases (triplet/codon)
3
Q
Describe DNA and RNA in protein synthesis
A
- DNA too big to leave nucleus; section copied into RNA
- RNA made of nucleotides containing 1 of 4 bases
- Differences b/w DNA and RNA:
- sugar in RNA - ribose sugar
- nucleotides form single strand
- uracil (U) replaces T - pairs w/ A
4
Q
What are the 2 types of RNA?
A
mRNA
tRNA
5
Q
Describe mRNA
A
- Single polynucleotide strand
- Groups of 3 adjacent bases (codon/triplet)
- Made in nucleus during transcription
- Carried genetic code from DNA in nucleus to cytoplasm where used to make protein during translation
6
Q
Describe tRNA
A
- Single polynucleotide strand, folded into a clover shape
- H bonds b/w base pairs
- Sequence of 3 bases called anticodon; amino acid binding site on other end
- Found in cytoplasm
- Carries amino acids used to make proteins
7
Q
Genetic code is overlapping…
A
Base triplets don’t share their bases
8
Q
Genetic code is degenerate…
A
There’re more possible combinations of triplets
Some amino acids coded for by more than one triplet
9
Q
What are start/stop codons?
A
Some triplets used to tell cell to start/stop production of protein
10
Q
Genetic code is universal
A
Same specific triplets code for same amino acids in all living things
