DNA

Miss Sofía Paz

10th grade

DNA structure

1. DNA nucleotide structure

2. The four bases in DNA

3. How DNA nucleotides are linked together by covalent bonds into a single strand

NUCLEOTIDE

Base

Deoxyribose

Phosphate

DNA is a kind of nucleic acid

Sugar

DNA

Polynucleotide: made by a lot of nucleotides…. Nucleotide: organic molecule.

Building block of nucleic acids

Ribose

Aldopentose

The simplest form of sugar

Monosaccharide with 5 carbon atoms and an aldehyde functional group at position 1.

Monosaccharide

R = Side chain

• Electrons on the alcohol oxygen are used to bond carbon #1

• The hydrogen (green) is transferred to the carbonyl oxygen (green) to make a new alcohol group (green)

Deoxyribose

Nitrogen containing BASES

RNA

Cyclic nitrogen containing molecule with properties of a base.

Organic compounds.

NUCLEOSIDES

BASE + SUGAR = NUCLEOSIDE

Nitrogenous base Ribonucleoside Deoxyribonucleoside

Adenine Adenosine A

Deoxyadenosine dA

Guanine Guanosine G

Deoxyguanosine dG

Thymine Thymidine

dT

Uracil Uridine U

Cytosine Cytidine C

Deoxycytidine dC

NUCLEOTIDES

BASE + SUGAR + PHOSPHATE = NUCLEOTIDE

•Ester bond:Carboxyl group

combines with the hydroxyl from the phosphate group.Very strong covalent bond.

•Glycosidic bond:Bond between a

carbohydrate and another group. Also a covalent bond.

• Covalent bonds connect the sugar of one nucleotide to the phosphate group of the next.

Sugar-Phosphate “Backbone”

A covalent bond is a chemical link between two atoms in which electrons are shared between them.

Deoxyribonucleic acid.

Contains Thymine

Contains the genetic information

Double stranded

DNA

DNA

• 1950’s Rosalind Franklin & Maurice Wilkins

X-ray crystallography

• Watson & Crick (1953 described their model)

Saw the photos of R.Franklin and created a model.

Sugar-phosphate backbone on the outside and bases inside of the double helix. Nitrogen bases aligned formed hydrogen bonds.

Complementary base pairs, due to size of bases and ability to form hydrogen bonds with each other.

RNA

RNA

Usually single stranded

Contains Uracile

Contains ribose

Viruses contain their genetic Info

in RNA genome.

More prone to hydrolisis

than DNA

Protein synthesis, catalyze

reactions.

Chemical structure of nucleic acids

• https://www.youtube.com/watch?v=2d1R7M5y8Tk