nucleic acids + DNA Flashcards
1
Q
structure of a nucleotide
A
- pentose monosaccharide
- phosphate group (PO42-)
- nitrogenous base
2
Q
polynucleotide
A
- NT linked in condensation reactions
- Phosphate on C5 forms covalent bond with OH group on C3
- phosphodiester bonds
- forms long strong sugar phosphate backbone
3
Q
sugar in DNA structure
A
- deoxyribose
- one fewer O2 than ribose
4
Q
pyrimidines
A
- smaller bases
- single carbon ring
- thymine + cytosine
5
Q
purines
A
- larger bases
- double carbon ring
- adenine + guanine
6
Q
DNA structure
A
- coiled in a double helix
- held by H-bonds between bases
- two antiparallel strands
- polymer so contains a lot of info
- double strand = stable + accurate replciation
7
Q
RNA nucleotides
A
- pentose sugar is ribose
- uracil base instead of T
8
Q
semi conservative replication
A
- DNA unwinds + separates : DNA helicase
- DNA unzips
- 2 separate strands = templates
- free NT activated + align
- complementary base pair
- purine to pyrimidine
- bases joined by DNA polymerase
- H-bonds reform
- sugar phosphate backbone reforms
- using phosphodiester bonds
- two identical mol of DNA formed
- each with one old strand and one new strand
9
Q
continuous replication
discontinuous replication
A
- DNA polymerase binds to end of strand
- free DNA NT added without any breaks
- DNA polymerase can’t bind to end of strand
- Free DNA NT added in sections then joined.
10
Q
triplet code
A
- sequence of 3 bases = codon
- codons code for amino acids
11
Q
degenerate code
A
- many amino acids can be coded for by more than one codon.
12
Q
Transcription
A
- RNA polymerase attaches to DNA double helix
- section of DNA with gene needed unwinds + unzips
- DNA helicase breaks H-bonds
- antisense strand (3’ to 5’) = template
- mRNA carries same base sequence as sense strand
- RNA polymerase lines up free RNA NT alongside template strand
- free RNA NT complementary base pair on antisense strand
- Uracil replace thymine
- RNAP catalyses formation of phosphodiester bonds between RNA NT
- stop codon reached
- mRNA detaches from DNA
- mRNA leaves nucleus through nuclear pore
- mRNA travels to ribosome.
- double helix reforms
- hydrogen bonds reform
- DNA rewinds
13
Q
translation
A
- rRNA catalyses translation
- mRNA binds to start codon (AUG)
- tRNA with complementary anticodon binds to start mRNA codon
- tRNA anticodon bind to complementary mRNA codon
- amino acids arranged in correct sequence
- forms primary structure of protein
- amino acids bound by peptide bonds : catalysed by peptidyl transferase
- amino acids added one at a time
- stop codon stops translation
- polypeptide released
- folding into secondary/tertiary
- further modifying at golgi
14
Q
structure of ATP
A
- ribose pentose sugar
- joined to base (adenine)
- and 3 phosphates
15
Q
how does ATP release energy
A
ATP + H2O = ADP + Pi + energy
- hydrolysis reaction
