The Nature of Genetic Code Flashcards
1
Q
gene
A
- aka. cistron
- the basic unit of inheritance
- a short section of DNA that codes for a specific polypeptide chain
2
Q
Locus
A
Location of a gene on the DNA strand
3
Q
DNA relationship to proteins
A
- the sequence of DNA causes the sequences of amino acids
- mutations cause the 3D shape of the protein to change because the bonds form in different places, causing it to fold differently
- protein may be unable to complete its function
4
Q
Introns
A
- non-coding séquences
* found within genes; kinetochore
5
Q
Possible number of DNA triplets
A
64
6
Q
Degenerate
A
- multiple triplets code for the same amino acids
* some are coded for by 1, others by 2-6
7
Q
Reading method
A
- always read in particular direction
- start amino acid -> methinine
- non-overlapping -> each base is only read once
8
Q
Number of stop triplets
A
3
9
Q
Universal
A
A DNA triplet will code for the same amino acid
10
Q
Alleles
A
- alternative version of a gene (different base sequence)
- can be the same version of the gene and the gene on the other chromosome (inherited by the other parent), or can be different
- cause different primary, secondary and tertiary structures
11
Q
Chromosomes
A
- contain 100/1000s of genes, specialised parts, RNA
- provide continuity between one generation of cells and the next
- χρώμα, σώμα - coloured bodies; affinity for certain stains in microscopy when broken
- DNA arranged in octamers to form nucleosomes
- DNA wrapped around histones - rich in lycine or arginine
- exist as chromatin during interphase - coils and condenses to form chromosomes in prophase
- appear as two chromatids attached at the centromere
12
Q
Chromatids
A
- thread-like structures
- contain one whole continuous length of DNA
- sister chromatids are copies of one another; DNA replication has occurred
13
Q
Homologous chromosomes
A
• zygotes have 23 paternal and 23 maternal chromosomes - they carry the same genes at the same loci but different alleles (hopefully a lot)
14
Q
Nucleosomes
A
- positively charged groups of the side-chains of the histones form string ionic bonds with negatively charged phosphate groups in the DNA backbone
- 150 base pairs of DNA is wrapped around the octamer
- contain linker regions
- solenoids are further looped and coiled around scaffolding proteins (non-histone)
15
Q
Linker regions
A
- stretch of DNA between nucleosomes
- 14-100 base pairs
- histones is this région fold the thread of DNA and nucleosomes (the nucleosome fibres) into a solenoid
