Polynucleotides: DNA and RNA Structure and function
http://vega.org.uk/video/programme/80 Slide 2 State that DNA is a
polynucleotide, usually double-stranded, made up of nucleotides
containing the bases adenine, thymine, cytosine and guanine. State
that RNA is a polynucleotide, usually single-stranded, made up of
nucleotides containing the bases adenine, uracil, cytosine and
guanine. Slide 3 Slide 4 Structure diagrams of phosphate, ribose
and deoxyribose sugars attached to nitrogenous bases Slide 5
Structure of DNA and RNA Basic Unit = NUCLEOTIDE A nucleotide
consists of:- PENTOSE sugar molecule In DNA this is DEOXYRIBOSE In
RNA the pentose sugar is RIBOSE PHOSPHATE Nitrogen-containing BASE:
a purine or pyrimidine Slide 6 There are FOUR different bases in
DNA Making four different types of NUCLEOTIDE : Slide 7 Purine and
pyrimidine molecules Slide 8 Within a DNA or RNA Molecule
Nucleotides join together, to form polymers, called POLYNUCLEOTIDES
Sugar- phosphate backbone Bases sticking out to one side Slide 9
Slide 10 Nitrogenous bases in DNA and RNA PurinesPyrimidines Number
of rings Names of bases Found in DNA? Found in RNA? Slide 11 State
that DNA is a double-stranded polynucleotide. Describe how a DNA
molecule is formed by hydrogen bonding between complementary base
pairs on two antiparallel DNA strands. Explain how twisting of the
DNA molecule produces the double helix shape. Slide 12 Slide 13
Slide 14 Each DNA Molecule actually contains TWO Polynucleotide
strands NOTE : Base-pairing rule Hydrogen bonds Strands are
anti-parallel A - TG - C Slide 15 Slide 16 Slide 17 So, a section
of a DNA molecule Slide 18 Furthermore, The two strands are wound
into a HELIX The famous DOUBLE HELIX Slide 19 Outline how DNA
replicates semi-conservatively, with reference to the role of DNA
polymerase. Slide 20 DNA REPLICATION Step 1Double helix unwinds
Step 2 Hydrogen bonds break and strands separate Under control of
the enzyme : DNA-HELICASE Slide 21 Step 3 Nucleotides in the cell
are activated, by combining with TWO PHOSPHATES : Slide 22 Step 4
Activated nucleotides attach to spare bases on each strand of DNA -
according to the base-pairing rule. Result : TWO DNA molecules
identical to each other and the original. Under the control of the
enzyme : DNA-POLYMERASE Slide 23 This type of replication is
described as : SEMI-CONSERVATIVE What does this mean? Slide 24 If
replication was CONSERVATIVE The original molecule Would act as a
template to make a complete copy Slide 25 However,
SEMI-CONSERVATIVE Means only HALF the original molecule appears in
each of the new molecules
>>>>>>>>>>> Slide 26 State that a
gene is a sequence of DNA nucleotides that codes for a polypeptide.
Outline the roles of DNA and RNA in the cells of living organisms.
Slide 27 Slide 28 Slide 29 Slide 30
