DNA and Meiosis Flashcards
1
Q
Explain how a change in sequence of DNA bases could result in a non-functioning enzyme
A
- Change in primary structure
- Change in hydrogen/ionic/disulfide bonds
- Alters tertiary structure/active site (of enzyme)
- No enzyme-substrate complexes form
2
Q
Define “allele”
A
(different) form/type/version of a gene/different base sequence of a gene
3
Q
Explain the ‘X’ shape of a chromosome
A
- Two/sister chromatids
- Due to DNA replication
- Joined by a centromere
4
Q
Give reasons why there are more genes than the minimum amount of genes that code for set amounts of amino acids
A
- Start/stop codons
- Non coding DNA/introns/multiple repeats/junk DNA
- Two chains/a non-coding strand/complementary base pairs
- Addition of bases by mutation
5
Q
Why might homologous chromosomes not be genetically identical despite carrying the same genes
A
They carry different alleles
6
Q
Describe the role of independent segregation in meiosis
A
- To provide genetic variation
- Allows different combinations of maternal and paternal chromosomes/alleles
- To produce haploid cells/half the chromosome number
- Allows homologous chromosomes/pairs to arrange randomly at the equator of the cell
7
Q
How is the structure of DNA related to its function?
A
- sugar-phosphate (backbone)/double stranded/helix provides strength
- Long molecule so can store lots of information
- Helix/coiled so compact
- Base sequence codes for amino acids/proteins
- Double stranded so strands can act as templates for replication
- Complementary base pairing so accurate replication
- (weak) hydrogen bonds for unzipping/strand separation
- many hydrogen bonds so stable/strong