DNA, genes and chromosomes Flashcards
(27 cards)
What is DNA like in prokaryotic cells?
Short, circular and not associated with proteins
Do prokaryotes form chromosomes?
No
What is DNA like in the nucleus of eukaryotic cells?
Long, linear and associated with proteins called histones
Which other organelles contain DNA?
Mitochondria and chloroplasts
What is the DNA like in mitochondria and chloroplasts?
Short, circular and not associated with proteins
What does this DNA not contain?
Introns
What is organised into chromosomes during cell division?
DNA and histones
What do diploid chromosomes come in?
Pairs
Where do each chromosome come from?
Parents
What are homologous chromosomes?
Pair of chromosomes that carry the same genes in the same loci but not the same alleles
What is a locus on a chromosome?
A gene that is on a fixed position on DNA
What is an allele?
Different versions of the same gene
What do homologous chromosomes consist of?
A maternal and paternal chromosome
What is a sequence of three nucleotide bases called?
Base triplet
What does a base triplet code for?
Specific amino acid
What are the different types of base triplet?
DNA base triplet, mRNA base triplet
What is the name for mRNA base triplets?
Codon
How many different DNA triplets are there?
64
How many amino acids are there?
20
What is degeneracy?
Different triplets or codons coding for the same amino acid
What is a stop code?
Doesn’t code for an amino acid but indicates the end of a code for a polypeptide
What is the start triplet for all polypeptides?
ATG
Why is the code non-overlapping?
Each base is only read once as part of the triplet
Why is the code universal?
Same triplets code for the same amino acids in all organisms
