brief - dna introduction
TRANSCRIPT
Genetics & DNA
The nucleus of living cells contain chromosomes which are made up of a string of genes.
Different genes control the development of different characteristics by issuing instructions to the cell.
Chromosomes and their genes are made of a molecule called DNA.
DNA molecules carry the code that controls what cells are made of and what they do.
DNA stands for deoxyribonucleic
acid.
Each chromosomeis a very long molecule of tightly coiled DNA.
What is DNA?
The DNA moleculelooks like a
twisted ladder thisspiral shape is
called a DOUBLE HELIX
The double helix ‘ladder’ of a DNA molecule is held together by ‘rungs’ made from pairs of chemicals called bases.
DNA Bases
There are four types of bases, and they are usually identified by their initials.
A
T
C
G
ADENINE
CYTOSINE
THYMINE
GUANINE
Base pairs hold the two strands of the DNA helix together.
It is the sequence of these bases along a DNA molecule that forms the genetic code – it’s that simple!
DNA Bases
A T
C G
C G
A T
Structure of Nucleotides
The chemical structure of nucleotides:Symbolic form
Phosphate: Links
neighboring sugars
Sugar: One of two types
possible: ribose in RNA
and deoxyribose in DNA
Base: Four types are possible
in DNA: adenine, guanine,
cytosine and thymine. RNA
has the same except uracil
replaces thymine.
Sugar
(deoxyribose)
Phosphate
DNA Structure
Hydrogen
bonds
Purine base
(guanine)
Pyrimidine base
(thymine)
Purine base
(adenine)
Pyrimidine
base
(cytosine)
Review
Where are chromosomes found?
A) In the nucleus
B) In the cytoplasm
C) In the cell membrane
Review
A part of DNA that carries the code for a particular characteristic is called a:?
A) ladder
B) base
C) gene
Review
DNA stands for:
A) Deoxyribonucleic acid
B) Deoxyribonucleic alkali
C) Don’t know the answer
