DNA, genes and chromosomes KRQ 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.