DNA, Genes, and chromosomes Flashcards
what type of DNA molecules does eukaryotic cells contain
linear DNA molecules that exist as chromosomes - thread like structures, each one made up of one long molecule of DNA
where are chromosomes found
the nucleus
what must happen to the DNA molecule for it to fit into the nucleus
it must be wound up as it is very long
what is DNA wound around
around proteins called histones which also help support the DNA
what happens after dna is wound around histones
they are then coiled up very tightly to make a compact chromosome
which organelles have their own DNA
mitochondria and chloroplasts which is similar to prokaryotic DNA as its circular and shorts than the DNA in the nucleus and is not not associated with histone proteins
what is DNA like in prokaryotes
prokaryotes dont carry DNA as chromosomes, bu the DNA molecules are shorter and circular. The DNA isnt wound around histones, it condenses to fit in the cell by supercoiling
what is a gene
a gene is a sequence of DNA bases that codes for either a polypeptide or a functional RNA
why is the sequence of amino acids in a polypeptide important
the sequence of amino acids in a polypeptide forms the primary structure of a protein
what do different polypeptides have a different number and order of
amino acids
what determines the order of amino acids in a particular polypeptide
the order of bases in a gene
what is each amino acid coded for by
by a sequence of three bases in a gene called a triplet
what is the first stage of protein synthesis
to make a polypeptide, DNA is first copied into messenger RNA
what do genes that dont code for polypeptides code for instead
functional RNA
what is functional RNA
functional RNA is RNA molecules other than mRNA,which performs special tasks during protein sysnthesis e.g. tRNA and ribosomal RNA
