DNA

Question 1

DNA in eukaryotic cells

Answer 1

linear DNA molecules that exist as chromosomes

long so has to be wound up to fit into nucleus

DNA molecules wound around proteins called histones
histones support the DNA
the DNA is then coiled up very tightly to make a compact chromosome
the mitochondria and chloroplasts have their own DNA

Question 2

DNA in prokaryotes

Answer 2

carry DNA as chromosomes but are shorter and circular

DNA isn’t wound around histones, it condenses to fit in the cell by supercoiling

Question 3

what is a gene

Answer 3

a gene is a sequence of DNA bases that codes for either a polypeptide or a function RNA

Question 4

what does the sequence of amino acids form

Answer 4

in a polypeptide, forms the primary structure of the protein

Question 5

what does the order of the bases determine

Answer 5

the order of amino acids in a particular polypeptide

Question 6

how are polypeptides made

Answer 6

DNA is first copied into messenger RNA - first step of protein synethesis

Question 7

what do genes that don’t code for a polypeptide code form

Answer 7

functional RNA - which are RNA molecules other than mRNA which perform special tasks during protein synthesis eg tRnA and rRNA

Question 8

genes in eukaryotic cells

Answer 8

genes that do code for polypeptides contain introns, which are removed during protein synthesis so they don’t affect the amino acid order

genes that do code for amino acids are called exons

Question 9

what are non-coding repeats

Answer 9

regions of multiple repeats outside of the genes

these are DNA sequences that repeat over and over

these don’t code for amino acids

Question 10

genes in the form of alleles

Answer 10

a gene can exist in more than one form - alleles

the order of bases - slightly different - code for slightly different versions of the same polypeptide