The Second of the Big Four

Nucleic Acids

Nucleic Acids

• These are macromolecules are made up of nucleotides– Polymer - nucleic acid– Monomer - nucleotide

• Contain H, O, C, N and P• Consist of three parts: a five carbon sugar, a

phosphate group and a nitrogen base.• Covalent bonds connect nucleotides together to form

nucleic acid.• Store and transmit hereditary information

Nucleic Acids

• There are two types of nucleic acids– DNA (Deoxyribonucleic acid, deoxyribose is the five

carbon sugar)– RNA (Ribonucleic acid, ribose is the five carbon

sugar)

• There are three kinds of RNA– mRNA (messenger RNA)– tRNA (transfer RNA)– rRNA (ribosomal RNA)

DNA

• James Watson and Francis Crick discovered that DNA had a double helix shape in 1953

• Contains the genetic code for producing proteins.

• Each DNA triplet codes for one amino acid• The “coding” side is complimentary to the

“complimentary” side

DNA

• The nucleotides of DNA are made up of

1.

2. and

DNA

3. Nitrogen Bases- Adenine and Guanine

are purines- Thymine and Cytosine

are pyrimidines- Adenine can only bond

with Thymine- Guanine can only bond

with Cytosine

DNA

• DNA is made of two long chains of nucleotides joined by hydrogen bonds

• The end with the phosphate exposed is the 5’ end.

• The other end is the 3’ end.

• DNA Structure

The Double Helix

DNA

• DNA is almost always wrapped around proteins called histones.

• The histones are the proteins that we cut with the enzyme in our DNA extraction lab.

• chromatin

• This ….

…. not this is what’s found in the cell.

Review of Wednesday

• Nucleic acids are macromolecules that are made up of _______.• Nucleic acids are made up of _______, ______, and ______.• There are two types of nucleic acids, _____ and _____.• The sugar in DNA is called _______.• There are three types of RNA, _____, _____ and _____.• The structure of DNA is called _____.• The structure of DNA was discovered by ______ and ____ in the year ______.• Each _______________ codes for one amino acid.• Adenine and Guanine are _________.• Cytosine and Thymine are _________.• Cytosine only bonds with _________.• Thymine only bonds with _________.• The end of the DNA with the phosphate group exposed is called _______.• _________ are the proteins that DNA is wrapped around in the nucleus.

Review of Wednesday

• Nucleic acids are macromolecules that are made up of nucleotides.• Nucleic acids are made up of a phosphate group, a five carbon sugar, and a

nitrogen base.• There are two types of nucleic acids, DNA and RNA.• The sugar in DNA is called deoxyribose.• There are three types of RNA, mRNA, tRNA and rRNA.• The structure of DNA is called double helix.• The structure of DNA was discovered by Watson and Crick in the year 1953.• Each DNA triplet codes for one amino acid.• Adenine and Guanine are purines.• Cytosine and Thymine are pyrimidines.• Cytosine only bonds with Guanine.• Thymine only bonds with Adenine.• The end of the DNA with the phosphate group exposed is called 5’ prime.• Histones are the proteins that DNA is wrapped around in the nucleus.

Activity

• Draw a DNA triplet with the 5’ end on the top left hand corner and the nitrogen sequence A-C-G on the left side, the complimentary base should be on the right.

Building a DNA Model

• Using the materials provided the people at your table will build a 12 base pair model of DNA. The Mike and Ikes are the nitrogen bases (red compliments with green, yellow compliments with orange), the marshmallows (or gumballs) are the phosphate groups, and the liquorice is the sugar. Remember to show the 5’ ends and the 3’ ends so we can string them all together.

DNA

• Complementary base pairing allows each strand of DNA to serve as a template for DNA replication

• Replication always proceeds from the 5’ to the 3’

• DNA is an illustration of function following form (structure dictates function).

Replication Enzymes

• Helicase – splits the double helix• DNA polymerase – attaches the free-floating

nucleotides to the exposed nitrogen bases of the original DNA

• RNA primase – inserts short, temporary strands of RNA during replication.

• Exonuclease – strips away the RNA strands• Ligase – inserts phosphate groups in any gaps that are

left• Replication • Replication Enzymes

DNA Replication

• There is one old strand and one new strand in each daughter molecule after replication

RNA

• Different from DNA in that:– the five carbon sugar is ribose– it is generally single stranded– Contains Uracil instead of Thymine

RNA

• Messenger RNA (mRNA)– Called messenger RNA

because they serve as “messengers” from DNA to the rest of the cell

– A sequence of three nucleotides in mRNA is called a codon.

Draw a mRNA strand with one codon. Include Uracil as one of the nitrogen bases

RNA

• Transfer RNA (tRNA)– odd shaped molecules with about 75 nucleotides in

it’s structure. – 3 exposed nitrogen bases called anti-codons.– tRNA molecules carry amino acids to the ribosome

during protein synthesis– each tRNA molecule can only carry one amino

acid

RNA

tRNA

RNA

• Ribosomal RNA (rRNA)– The RNA is the main structural component of

ribosomes

A P E

RNA

• A ribosome consists of 2 subunits: 50s sub-unit and a 30s sub-unit compose a 80s ribosome.