nucleotides + nucleic acids

Question 1

purine bases

Answer 1

adenine

guanine

Question 2

pyramidine

Answer 2

cytosine
uracil
thymine

Question 3

DNA

Answer 3

deoxyribose
A T C G bases - carbon 3
phosphate group - carbon 5

double stranded - antiparallel strands in a helix wound around histones
1 type of DNA

Question 4

RNA

Answer 4

ribose
A U C G bases - carbon 3
phosphate group - carbon 5

single stranded
3 types - mRNA, tRNA, rRNA

Question 5

sugar phosphate backbone

Answer 5

between phosphate at carbon 5 of pentode sugar and hydroxyl group on carbon 3 of the pentode sugar of adjacent nucleotide. Nucleotides joined by phosphodiester bonds

Question 6

semi conservative DNA replication

Answer 6

1. DNA helicase breaks H bonds between bases - leaving two single strands of DNA with exposed bases
2. Free nucleotides bind to exposed bases by complementary base pairing
3. DNA polymerase catalyses formation of phosphodiester bonds between adjacent nucleotides
4. DNA ligase seals strand

Question 7

why DNA replication

Answer 7

• eliminates/ detects mutations

- conserves genetic information accurately through generations

Question 8

gene

Answer 8

section of DNA which codes for a specific protein

Question 9

features of genetic code

Answer 9

1. triplet
   3 bases = 1 codon, every codon codes for an amino acid
2. degenerate
   amino acids have more than 1 codon
3. universal
   all organisms use same code, codons code for same amino acid
4. non-overlapping
   each base part of only 1 codon (read in 3’s)

Question 10

transcription

Answer 10

1. DNA helicase unzips section of DNA containing gene by breaking H bonds
2. sequence on antisense strand used to produce mRNA molecule
3. free RNA nucleotides join your exposed bases on template strand by complementary base pairing
4. RNA polymerase catalysed the formation of phosphodiester bonds between adjacent nucleotides
5. Completed mRNA molecules leaves nucleus’s via pores

Question 11

translation

Answer 11

1. mRNA molecules binds to subunit on ribosome
2. start codon read, tRNA molecule carrying amino acid with complementary anticodon binds to codon
3. repeats
4. peptidyl transferase catalyses formation of peptide bonds between adjacent amino acids forming a primary protein structure
5. chain folds into secondary and tertiary structure