nucleic acids and genetics chapter 5 a. p. biology mr. knowles liberty senior high school
TRANSCRIPT
Nucleic Acids and Genetics
Chapter 5
A. P. BiologyMr. 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
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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 H-bonding.
Double Helix• DNA is antiparallel:
5’PO4 -------------------------3’OH
3’OH -------------------------5’PO4
The 3-D Structure of DNA
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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 forks- points where the two strands separate to allow replication of DNA.
Bring on DNA
Replication!
Replication, must I see!
Replication Fork
DNA Replication
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DNA ReplicationProkaryotes
• single, circular chromosome.
• one single origin on the chromosome.
• rate of over 1,000 nt/second.
Eukaryotes
• multiple, linear chromosomes.
• several origins on each chromosome.
• rate of about 50-100 nt/second