Download Revisiting Genetics

Revisiting Genetics
Start with the cell
• The cell is the basic building block of
organisms.
• We have about 100 trillion cells that perform
various tasks (e.g. muscle and nerve cells).
• All our cells have common features.
One of your cells
Inside the nucleus
• Genetic information is in the nucleus and is
organized into chromosomes.
• Each chromosome contains different genes
that carry instructions to make proteins.
Chromosomes
Genes are arranged into precise locations along
the length of 23 pairs of much larger structures
called chromosomes.
A chromosome is coiled DNA and proteins called
histones.
About DNA/RNA
DNA = deoxyribonucleic acid:
The components of DNA are called nucleotides.
They are guanine (G), cytosine, thymine,
adenine)
RNA = ribonucleic acid
similar to DNA except it has a uracil nucleotide
rather than a thymine.
Two strands of DNA form a double helix
structure in which an A base always joins
with a T base, and a G always with C.
More on DNA
• DNA is organized in groups of three
nucleotides called a codon – each codon
encodes for a specific amino acid, the building
blocks of proteins. (review amino acids)
Proteins
DNA carries the genetic
code for making proteins.
Proteins essentially keep
organisms going with their
many important functions.
Proteins make the difference between the hair
on your head, the wool on a sheep, the feathers
on a bird and the scales on a fish.
More on proteins
• Proteins are made of different combinations
of 20 amino acids. We have over 100,000
proteins that carry out vital functions.
• Two proteins can have the same 50 amino
acids but in a different order = different
function.
Before proteins are made….
• DNA replicates itself just prior cell division so
that the genetic code is passed on.
• Part of the original DNA strand remains and a
new strand is made. (called semi-conservative
replication)
Making proteins
The DNA double helix is unwound leaving two
single strands ready for transcription.
Transcription
The transfer of genetic information from DNA to
RNA (the photocopy).
Translation
The genetic information is used to make
proteins . (video)