topic 1 - DNA and RNA Flashcards
cgp (topic 1B) 16 - 17
what are DNA and RNA both types of
nucleic acid
what does DNA stand for
deoxyribonucleic acid
what is DNA
the molecule within cells that contains genetic information, in the form of a sequence of bases that form a code which makes up a protein
what does RNA stand for
ribonucleic acid
what is RNA
a molecule that transfers genetic information from DNA to the ribosomes
what is RNA’s main function
transfer genetic information from the DNA to the ribosomes
what are ribosomes
ribosomes are the body’s ‘protein factories’ - they are macromolecular machines that read the RNA to make polypeptides in a process called translation
what are ribosomes made up of
RNA and proteins
what is a nucleotide a type of
biological molecule
what are nucleotides made from
a pentose sugar (a sugar with 5 carbon atoms), a nitrogen base, a phosphate group
what is nucleic acid
a complex organic substance present in living cells whose molecules consist of many nucleotides linked in a long chain
what is deoxyribose
pentose sugar with an aldehyde group attached to it found in a DNA nucleotide
what forms the DNA nucleotide
phosphate, deoxyribose, nitrogenous base (which varies)
what are the four possible bases for DNA
adenine, thymine, cytosine, guanine
what forms the RNA nucleotide
phosphate, ribose, base (which varies)
what are the four possible bases for RNA
adenine, uracil, cytosine, guanine
what to nucleotides join together to form
polynucleotides
what is a polynucleotide
a polymer of nucleotides
how do nucleotides join up
by a condensation reaction between the phosphate group of one nucleotide and the sugar of another
what are phosphodiester bonds
what is the chain of sugar and phosphates known as
sugar phosphate backbone
what is DNA made of
two polynucleotide chains in a double helix structure
what is complementary base pairing
when each base can only join with one particular partner
what is another term for complementary base pairing
specific base pairing
what are the complementary base pairs
adenine and thymine, cytosine and guanine
how is DNA formed
two DNA polynucleotide strands join together by hydrogen bonding between the bases - two antiparallel polynucleotide strands twist to form the DNA double helix
how many bonds form between A and T
two
how many bonds form between C and G
three
when was DNA first observed
1800’s
what did lots of scientists doubt about DNA at the time
that is could carry the genetic code because it has a relatively simple chemical composition - some argued that genetic information must be carried by protein which are much more chemically varied
what had experiments shown about DNA by 1952
that DNA was the carrier of the genetic code
what happened in 1953
the double helix structure was determined by Watson and Crick
how many polynucleotide chains is RNA made of
one
what is RNA much shorter than
most DNA polynucleotides
