DNA and RNA

What is DNA?

• DNA stands for…..

deoxyribonucleic acid

• DNA (heredity material) is found

in the nucleus, on the
chromatin/chromosomes.

•
The DNA molecule consists of two
polynucleotide chains that spiral
around to form a double helix
(spiral). (poly=many)

• 2 individual chromatids (sister chromatids)

come together to make 1 whole
chromosome.

• Chromosomes are held together by the

centromere

Each nucleotide consists of…

1, 5-carbon sugar (deoxyribose)

5-carbon
sugar
(deoxyribose)

1, Phosphate group

Phosphate

group

1, Nitrogen containing base

Nitrogen
containing
base

Hydrogen

bonds

Everything is connected by
hydrogen bonds

The two polynucleotide chains are
connected by the joining of 2 nitrogen
containing bases called complementary
base pairs.

They are:

Adenine
Thymine

Cytosine

Guanine

A always pairs with T
G always pairs with C

Creates a complementary strand of the
DNA molecule

Complementary base pairing makes sure
that an exact duplicate of each DNA
molecule will be passed to its daughter
cells when a cell divides.(mitosis)

DNA Replication

1. Before a cell divides, the DNA strands
unwind and separate. (happens during
interphase of the cell cycle)

2. Each strand makes a new partner by
adding the appropriate nucleotides (A-T,
C-G)

16

3.The result is that there are now 2
double-stranded DNA molecules in the
nucleus.

4. When the cell divides, each nucleus will
contain its own identical copy DNA. This
will happen EVERY time a cell divides.

DNA Replication

Complete the DNA sequencing below:

T

A

Determining the order of the

bases in a DNA chain is the goal

of DNA sequencing .

Check to see if the DNA

sequencing is correct. Explain why

or why not.