DNA, genes and protein synthesis Flashcards
3.4.1.1 3.4.2
Explain why DNA is described as semi-conservative
DNA strands separate
New molecules formed have one original/parent strand and one new strand
Suggest two reasons why conclusions made only on basis of this data may not be reliable
Unknown sample size
Differences in genetic predisposition
Give 3 ways in which the structure of the DNA molecule enables it to carry out its functions
Long molecule= can store lots of information
Coiling = compact shape
Weak hydrogen bonds=strands can split easily for replication
Why is specific base pairing important in DNA replication
Identical copies made
Of original DNA’s base sequence
Why is DNA a stable molecule?
Two strands with specific base pairing
Large no. of hydrogen bonds
Describe and explain how the structure of DNA results in accurate replication?
Two strands = semi-conservative rep can take place
Base pairing = strands held together
Weak hydrogen bonds = allows strands to separate
Template bases = for copying
Explain how a change in the DNA base sequence for a protein may result in a change in its structure
Change in primary structure
Change in hydrogen and ionic/disulfide bonds
Altered tertiary structure
The sequence of bases on one strand of DNA is important for protein synthesis. What is its role?
Determines sequence of AAs
Explain why the percentages of bases from the middle part of the chromosome and the end part are different?
Different base sequences
pre-mRNA transcribed from different DNA
Why is the genetic code described as universal?
Same triplet code = same AA in all organisms
Comparing the base sequence for a gene provides more info than comparing the AA sequence for which the gene codes. Why
Base sequence longer than AA sequence
Degenerate DNA code
Why could a mutation of a gene result in it becoming non-functional?
Change in base Frameshift following deletion/addition Therefore mRNA base sequence changes So incorrect AA / stop codon coded for Leading to protein w/ different tertiary structure
