DNA And Chromosomes Flashcards
What is a gene?
A short section of DNA that contains a code for making a polypeptide and functional RNA.
What is the code on a gene?
A specific sequence of bases.
What do genes determine?
The proteins of an organism.
What is the locus?
The location of where you find a gene.
What is an allele?
A different version of the same gene.
What might genes differ in that make them alleles?
They might have different base sequences.
What are chromosomes?
Tightly coiled-up DNA.
What are homologous pairs of chromosomes?
Chromosome pairs that have the same exact genes, but may have different alleles.
What is a human karyotype?
A picture of all the 23 homologous pairs of chromosomes in order.
Where is DNA stored in eukaryotic cells?
In the nucleus.
What is DNA like in eukaryotic cells?
In the form of chromosomes, it’s linear.
What is DNA tightly wound around?
Histones.
What are histones?
Proteins that wound around DNA.
Why is DNA wound around histones?
So it fits in the nucleus and doesn’t get tangled.
What is DNA wrapped around a histone protein called?
A nucleosome.
What is DNA like in prokaryotic cells?
It’s much shorter and circular, and free in the cytoplasm (has no nucleus).
What is a benefit of prokaryotic DNA being shorter?
It doesn’t have to get wrapped by histones, it supercoils to fit in the cell.
Where is DNA also found?
In mitochondria and chloroplasts.
Why is DNA found in mitochondria and chloroplasts.
To code for enzymes which are essential for their own reactions (respiration and photosynthesis).
What is DNA in mitochondria and chloroplasts similar to?
DNA in prokaryotic cells.
