Transcript Genetics - Liberty Public Schools

Nucleic Acids and
Genetics
Chapter 5
A. P. Biology
Mr. Knowles
Liberty Senior High School
Is Genetics Important to Me?
Genetics
• Basic unit of heredity- Gene- a linear
sequence of nucleotides of DNA.
• Genotype- genetic make-up of
organism; its potential characteristics.
• Phenotype- the observable physical
traits of an organism.
• The Phenotype is the organism’s
physical expression of its Genotype.
Eukaryotes are Diploid
• Locus - is a gene’s location on the
chromosome.
• Allele- an alternative form of a gene
at a specific locus.
• Eukaryotes have pairs of identical
chromosomes- diploid. May have
two alleles of a gene.
• Prokaryotes are not diploid.
When good DNA goes Bad!
• A permanent change in the
sequence of nucleotides mutation. Mutations change
the information of that gene.
• DNA- function is to store and
transfer information.
Mistakes in DNA -->Mutations
How is DNA Accurately
Transferred?
• DNA serves as a template
for its own replication; an
exact pattern.
• How, you ask?
• By base pairing.
What is a Nucleotide?
• Subunits of DNA/RNA are
Nucleotides = nitrogenous base
+ deoxy- or ribose sugar (5
carbons) + PO4
• Purines: Adenine and Guanine
• Pyrimidines: Cytosine,
Thymine, Uracil
Monosaccharides of Nucleic
Acids
Adenosine Monophosphate
• Base = adenine
• In DNA, sugar =
deoxyribose (In RNA, sugar
= ribose)
• A phosphate group, PO4
• The Nucleotide = AMP
Adenosine Monophosphate
Adenosine Triphosphate
(ATP)
Guanosine Monophosphate
Thymine Monophosphate
Cytosine Monophosphate
Uracil Monophosphate (in
RNA)
Base Pairing Rules
• In DNA,
A=T
C G
• In RNA,
A=U
C G
H-Bonding Between Bases
QuickTime™ and a
Animation decompressor
are needed to see this picture.
Characteristics of DNA
• Chains of nucleotides linked together by
phosphodiester bonds.
• Carbon 5 of deoxyribose is attached to
PO4.
• Carbon 3 of deoxyribose is a OH- free
to attach to the next nucleotide.
• Double helix is held together by Hbonding.
Double Helix
• DNA is antiparallel:
5’PO4 -------------------------3’OH
3’OH -------------------------5’PO4
The 3-D Structure of DNA
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are needed to see this picture.
DNA Replication
• Begins at a specific location on the
circular bacterial chromosome-origin
(OriC).
• Occurs in two directions at the same
time-two moving replication forkspoints where the two strands separate
to allow replication of DNA.
Bring on
DNA
Replication!
Replication,
must I see!
Replication Fork
Show me
the
Replication!
DNA Replication
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Cinepak decompressor
are needed to see this picture.
DNA Replication
Prokaryotes
Eukaryotes
• single, circular
• multiple, linear
chromosome.
chromosomes.
• one single origin • several origins on
on the
each chromosome.
chromosome.
• rate of about 50• rate of over 1,000 100 nt/second
nt/second.