DNA, genes and chromosomes Flashcards
Compare and contrast the DNA in eukaryotic cells and prokaryotic cells.
Comparisons: Nucleotide structure is identical; Nucleotides joined by phosphodiester bond; DNA in mitochondria and chloroplasts are similar structure to DNA in prokaryotes;
Contrasts: Eukaryotic DNA is longer; Eukaryotic DNA contain introns, prokaryotic DNA does not; Eukaryotic DNA is linear, prokaryotic DNA is circular; Eukaryotic DNA is associated with histones, prokaryotic DNA is not;
Give ways in which the arrangement of prokaryotic DNA is different from the arrangement of the human DNA.
Prokaryotic DNA is Circular as opposed to linear in eukaryotes;
Not associated with histones ; Only one molecule DNA with plasmids;
What is meant by a gene?
A DNA base sequence that codes for a polypeptide or functional RNA (ribosomal RNA and tRNA)
What is a homologous pair of chromosomes?
Two chromosomes that carry the same genes at the same loci, but maybe different alleles
Describe a eukaryotic chromosome found in the nucleus.
A very long, linear molecule of DNA that is coiled and associated with proteins called histones.
Describe the DNA found in prokaryotes, chloroplasts and mitochondria.
DNA is short, circular molecules, not associated with proteins.
The genetic code is degenerate, what does this mean.
One amino acid is coded for by more than one triplet code/codon (3 nucleotide bases).
The genetic code is universal, what does this mean.
In every organism the same triplet code in DNA codes for the same amino acid.
The genetic code is non-overlapping, what does this mean.
Each base belongs to just one triplet. Each base in the sequence is read once, after the first triplet code ends, then next one begins.
What is a triplet code or codon?
3 bases on a DNA/mRNA that code for a specific amino acid.
In Eukaryotes, what is in between genes?
Non-coding multiple repeats of base sequences. This makes up much of nuclear DNA. It does not code for amino acids.
In eukaryotes, what are introns and exons?
Exons are the regions in a gene that code for amino acid sequences. Introns are non-coding regions within a gene that do not code for amino acids. They are removed from mRNA during splicing.
What is a locus/loci?
The fixed position of a gene on a particular DNA molecule.
