topic 2- proteins

Question 1

transcription

Answer 1

DNA transcribed and an mRNA molecule produced.

Question 2

gene

Answer 2

sequence of nucleotide bases in DNA molecule that codes for the production of a specific sequence of amino acids
make up polypeptide

Question 3

translation

Answer 3

mRNA translated and an amino acid sequence is produced

Question 4

mRNA

Answer 4

single stranded molecule of many RNA nucleotides joined together
carries the genetic code for a protein / copy of part of the template DNA strand

Question 5

transcription process

Answer 5

occurs in nucleus
H bonds between bases break as part of DNA molecule unwinds
exposes gene to be transcribed
complimentary copy of code made by building mRNA
- catalysed by RNA polymerase
free RNA nucleotides pair up with comp bases on exposed strand of ‘unzipped’ dna
after transcription dna mol reforms
mrna leaves nucleus via pore in nuclear envelope

Question 6

translation process

Answer 6

occurs in cytoplasm
mRNA attaches to ribosome after leaving nucleus
free mols of tRNA in cyto
tRNA bind with their specific amino acids
bring them to mRNA on ribosome
anticodon on tRNA pairs with complementary triplet on mRNA molecule- codon
two tRNA molecules fit into ribosome at any time
peptide bond then formed between amino acids

Question 7

tRNA

Answer 7

single stranded molecule
folds into clover like structure
triplet of unpaired bases at one end- anticodon
region at other end where specific amino acid can attach

Question 8

triplet code

Answer 8

sequence of DNA nucleotide bases determined by this
some code for start/stop signals
allow cell to read dna correctly and produce correct sequence of amino acids

Question 9

non overlapping

Answer 9

each base read only once
adjacent codons do not overlap
no single base can take part in formation of multiple codons

Question 10

degenerate

Answer 10

multiple codons can code for the same amino acids
limits effect of mutations
64 dff codons, 20 AA

Question 11

features of genetic code

Answer 11

universal degenerate
non overlapping

Question 12

universal

Answer 12

same triplet code codes for same AA in all living things

Question 13

amino acids structure

Answer 13

monomers of polypeptides
central carbon bonded to:
- amine group- NH2
- COOH
- hydrogen atom
- R group

Question 14

peptide bond

Answer 14

form between AA
covalent bonds
OH lost from COOH of amino acids
H atom lost from amine group of another AA
C atom bonds to nitrogen of other AA
condensation reaction
broken down by hydrolysis

Question 15

tRNA function

Answer 15

each trna bring specific AA to ribosome
trna with complementary codon binds with mrna codon
trna bonds to ribosome

Question 16

dna replication summary

Answer 16

involves formation of phosphodiester bonds
involve dna helicase
uses dna nucleotides + dna polymerase
produces double stranded dna

Question 17

types of mutations

Answer 17

insertion
deletion
inversion
substitution

Question 18

nonsense mutation

Answer 18

substitution
creates premature stop codon
polypeptide chain produced is incomplete

Question 19

duplication

Answer 19

production of one or more copies of a gene/ region of chromosome
two copies of gene/ section appear on same chromosome

Question 20

dna replication

Answer 20

copying dna before parent cell divides
doubling dna ensures both daughter cells have full copies of parental dna/ full number of chromosomes

Question 21

dna replication process

Answer 21

semi conservative
during s phase
helicase unwinds dna double helix
H bonds broken between base pairs
two single polynucleotide dna strands formed
act as template for formation of new strand from free nucleotides - base pairing
new nucleotides joined together by dna polymerase