Nucleic acids Flashcards
1
Q
Genetic Code
A
-linear
-triplet
-non overlapping
degenerate
-unambiguous
-universal
code for production of polypeptides
2
Q
triplet code
A
- polynucleotide strand has 3 times the number of bases than amino acid chain
- 3 bases removed polypeptide would have fewer amino acids
- if polypeptide has 3 more bases polypeptide has more amino acid
3
Q
Characteristics
A
- triplet code= 3 bases code for each amino acid
- 64 codes (only 20 amino acids founds in proteins)
- punctuated= 3 non coding codes (stop codon)
- universal= all organisms have same triplet code for amino acid
- non overlapping= each base occurs only occurs in 1 triplet
- degenerate= more than one codon for each amino acid
4
Q
Protein synthesis
A
sequence of bases represents information carried in DNA and determines sequence of amino acids in proteins
5
Q
Transcription
-definition
A
- one strand of DNA acts as template for production of mRNA (complementary)
- occurs in nucleus
6
Q
Translation
-definition
A
- mRNA acts as template to where complementary tRNA molecules
- amino acids link to form polypeptide
- occurs on ribosomes in cytoplasm
7
Q
Transcription
-process
A
- DNA helices breaks H bond
- two strands separate and unwind (bases exposed)
- RNA polymerase binds to template strand of DNA
- RNA nucleotides align
- RNA polymerase moves along DNA to form bonds adding RNA nucleotides
- synthesis of molecule of mRNA
- RNA polymerase separates from template strand when reach stop codon
- new RNA detaches from DNA
8
Q
Translation
-process
A
- mRNA small so leaves through nuclear pore
- goes to ribosomes containing rRNA
- reads code and polypeptide assembled
- tRNA collects amino acid and takes to ribosomes
- built to make polypeptide
9
Q
Ribosomal RNA
A
site of translation of genetic code into protein
10
Q
Transfer RNA
A
- single stranded
- folds to clover leaf shape
- one end is amino acid attachment site
- one end sequence of 3 bases (anti codon)
11
Q
remaining combinations
A
- some start stop
- several triplets code for amino acids
12
Q
DNA function in cells
A
-forms code for protein synthesis
13
Q
Mutation
A
- base sequence codes for different MRNA sequence
- wrong amino acid
- wrong protein
- wrong function
14
Q
ensure correct amino acid added
A
- each tRNA has specific linkage with one amino acid type
- tRNA joins to mRNA
- codon joins base pairs with anti codon of tRNA
15
Q
after translation
A
- B moves to space and adds amino acid to chain
- A released to combine with other identical amino acid
- B moves to A’s position