structure of DNA and RNA Flashcards
what is DNA?
the hereditary material in human and almost all other organisms
where is DNA located?
most in the cell nucleus but some is found in the mitochondria
how is the information in DNA stored?
in codes
what are the four chemical bases?
-adenine (A)
-guanine (G)
-cytosine (C)
-thymine (T)
what bases pair up with each other?
A and T
C and G
what are the pairs called?
base pairs
each base is also attached to a what and a what?
a sugar molecule and a phosphate molecule
together, a base, sugar and phosphate are called a what?
nucleotide
how are nucleotides arranged?
in two long strands that form a spiral called a double helix, base pairs form horizontal rungs, the sugar and phosphate molecules form the vertical side pieces
what is an important property of DNA?
that it can replicate/make copies of itself
each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases, this is critical when cells divide because…
because each new cell needs to have an exact copy of the DNA present in the old cell
what three components are nucleotides made up of?
-deoxynbase
-phosphate group
-nitogen containing organic base
what is a deoxynbase?
a pentose sugar, has 5 carbon atoms
how are nucleotides formed?
by a condensation reaction between their three component parts (a mono nucleotide)
what is RNA?
contains the sugar ribose (another pentose)
what is DNA made up of?
two polynucleotide strand joined together by hydrogen bonds formed between the bases on each nucleotide
adenine and thymine always join together using what?
two hydrogen bonds
cytosine and guanine alway join together using what?
three hydrogen bonds
what are the two distinct ends of a polypeptide chain?
three prime end (3’)
five prime end (5’)
each base pair is how long apart?
0.34 nm
what is a phosphdiester bon?
a bond between a sugar group and a phosphate group
what is a polypeptide chain?
a string of amino acids connected together by peptide bonds
what are deoxyribose molecules?
a pentose (5 carbon sugar) biological molecule
what is a phosphate group?
a functional group characterised by a phosphorus atom bonded to four oxygen atoms (three single bonds and one double bond)
what is a cistron?
a sequence of bases that is the equivalent to one gene
what is a locus?
on a molecule of DNA each particular gene (cistron) occupies a specific position
what are alleles?
different forms of the same genes
what is RNA?
a similar material to DNA, it is made up of a pentose sugar, a phosphate group and one of four bases. the RNA bases are slightly different from DNA which has uracil instead of thymine
what is uracil?
uracil bonds to adenine in the same way that thymine does in DNA. Unlike DNA, RNA is just single polynucleotide strand
what is messenger RNA (mRNA) responsible for?
transcription
what happens during transcription?
and what happens during the process?
the DNA helix splits and unwinds, the process is catalysed by the enzyme RNA polymerase
what is a polynucleotide?
a combination of nucleotide monomers which are connected to each other through covalent bonds
what are introns?
non coding regions of the gene that do not contain codons needed to make the final protein AND are found between exons
what is splicing?
biological process where a newly synthesised pre-mRNA is transformed into a mature mRNA OR in splicing, some sections of RNA transcript (introns) are removed and the remaining sections (exons) are stuck back together
what are exons?
a sequence of DNA that codes for an amino acid sequence.
what is mRNA?
a type of RNA molecule that carries the genetic information from DNA to the ribosome, where it is used to make proteins
the mature mRNA molecule then exits the nucleus and is transported to a what?
ribosome
the mRNA then combines with the ribosome, here it directs the the next process in what?
polypeptide synthesis translation
