transcription and genetic code

Question 1

where does transcription occur

Answer 1

nucleus

Question 2

what are the difference between rna and dna

Answer 2

RNA-
ribose not deoxyribose
uracil replaces pyrimidine thymine
usually single stranded
shorter

Question 3

what are the 3 forms of rna

Answer 3

trna (transfer)
rrna (ribosomal)
mrna (messenger)

Question 4

genes contain codes, what are these codes used for

Answer 4

genes contain codes which determine the sequence of amino acids in a protein

Question 5

where are proteins made

Answer 5

at the ribosome

Question 6

what is the definition of transcription

Answer 6

making mrna from dna template

Question 7

why is the genetic code called universal

Answer 7

because most organisms all use the same triplet base codes for the same amino acids

Question 8

what does it mean when a genetic code is degenerate

Answer 8

most amino acids have more than one codon which can code for the amino acid

Question 9

why can a degenerate genetic code reduce mutations

Answer 9

because if a base is placed by mistake/ incorrectly.
it may still be able to code for the correct amino acid

Question 10

what does it mean if the genetic code is non overlapping

Answer 10

the bases are only read once.
meaning one base cant take part in forming another codon

Question 11

what is a triplet code

Answer 11

three letter code
aka- three base code.
a triplet of bases codes for one amino acid

Question 12

what is the first step of transcription

Answer 12

Part of a DNA molecule unwinds and unzips (the hydrogen bonds between the complementary base pairs break) by dna helicase

Question 13

transcription

after the dna is unwinded in the nucleus what happens

Answer 13

The exposed gene can then be transcribed

rna polymerase catalyses formation of hydrogen bonds between rna nucleotide bases and dna exposed nucleotide bases

it will also join the nucleotides together through phosphodiester bond and create a sugar phosphate backbone for the rna

Question 14

what is the difference between rna bases and dna bases

Answer 14

dna contains thymine
rna contains uracil instead of thymine

Question 15

when the dna is unwinded, how do u tell which is the antisense strand/ template strand

Answer 15

the dna is split into the two strands
1- 5’-3’
2- 3’-5’

strand 2 would be the template strand and the rna will have to join up in the 5’-3’ direction

Question 16

once the mrna is created what happens

Answer 16

the antisense strand joins back up to the other strand

whilst the mrna has left through the nuclear pore and join a ribosome for translation