Slides in this set

Slide 1

Preview of page 1

Biological Molecules
­ DNA and RNA…read more

Slide 2

Preview of page 2

Nucleotides ­ Coding Molecules
· The monomer of all nucleic acids is called a Nucleotide.
· A single nucleotide is made up of...
· A phosphate group ­ Always the same
· A sugar molecule ­ 5-carbon sugar (either dioxyribose or ribose)
· One organic base ­ adenine, thymine, guanine, cytosine and uracil.
· These 3 subunits are joined together by covalent bonds.
· A condensation reaction between the phosphate group of one nucleotide and
the sugar of another joins the two together.
· The nucleotides form a chain with the repeating sugar phosphate `backbone'
and the organic bases projecting out.
· Only nucleotides with the same sugar can join together to make Nucleic
An Example…read more

Slide 3

Preview of page 3

Purines or Pyrimidines
Pyrimidines…read more

Slide 4

Preview of page 4

DNA ­ Base Pairing
· The two DNA strands run
`antiparallel' because the
strands run in the opposite
· A pyrimidine always pairs up
with a purine.
· More specifically in DNA,
adenine always pairs up
with thymine and guanine
pairs up with cytosine. (
A+T, C+G).
· In a complete DNA
molecule, the antiparallel
chains twist which is known
as a double helix.…read more

Slide 5

Preview of page 5

Making Copies
· The DNA replication takes place in the interphase stage of
mitosis and is the process that creates two identical sister
· To make a new copy...
· The double helix is untwisted
· The hydrogen bonds between the bases are broken and
the DNA is `unzipped'
· Free DNA nucleotides hydrogen bond onto the exposed
bases according to the base pair ruling.
· Covalent bonds are formed between the phosphate and
sugar to seal the background.
· This continues all away along the DNA molecule until two new
DNA molecules are formed
· This is called `Semi Conservative Replication' as each new
molecule is made from one conserved strand and a newly built
one.…read more

Slide 6

Preview of page 6

Making Copies - Diagrams
1: 2: 3:…read more

Slide 7

Preview of page 7
Preview of page 7

Slide 8

Preview of page 8
Preview of page 8

Slide 9

Preview of page 9
Preview of page 9

Slide 10

Preview of page 10
Preview of page 10


No comments have yet been made

Similar Biology resources:

See all Biology resources »