mr. malinkovich
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Mr. Malinkovich. OFFICE: Room 321 -before school -by appointment. Honors Biology 2/7/14. Objective : SBBAT : Describe the structure and function of DNA Agenda : Go over last week’s quiz Notebook self-check Take quiz over: Meiosis, genetic variation, genetic complexity - PowerPoint PPT PresentationTRANSCRIPT
Mr. Malinkovich
OFFICE: Room 321-before school
-by appointment
Honors Biology 2/7/14• Objective: – SBBAT: Describe the structure and function of DNA
- Agenda:- Go over last week’s quiz- Notebook self-check- Take quiz over:
- Meiosis, genetic variation, genetic complexity- Discuss yesterday’s activity- Take notes
- BR: Update TOC: DNA class notes- HW: NONE
Genetic Variation
• Genetic variation among individuals is caused by differences in genes or other DNA segments
• Natural selection can only act on variation with a genetic component (does not act on acquired traits)
• Sources of Variation– Mutations
• Random changes that alters the expression of a trait– Chromosomal rearrangements
• Combinations of chromosomes during gamete formation – Rapid Reproduction
• Quick reproductive cycles = increased chance for mutations– Sexual reproduction
• Mixing of genes from individuals
Genetic Variation
• Mutations can result in favorable traits – Altered continuous or discrete traits
• Increase chance of survival/ reproduction• Increase diversity
• Mutations can result in disease– Decrease chance of survival/ reproduction
• Recombination can– Increase diversity by creating new combinations of existing
alleles– Lead to disease if there are errors in meiosis
• Nondisjunction:
Genetic Complexity
• Sometimes knowing individual’s genotype is not enough to predict phenotype– Complex Traits
• Behavior• Intelligence• Personality
– There is direct evidence that complex traits are affected by genotype and environmental factors• Maze-bright vs maze-dull• Hippocampus development and maternal touch
– involved in memory and spatial navigation
Genetic Complexity
• Sometimes the genotype for a trait involves several genes that are all expressed– Skin color– Incomplete dominance
• Partial expression of dominant allele– Blending of dominant and recessive phenotypes– Sickle cell trait vs disease
– Codominance• Expression of multiple dominant alleles
– Blood types» A, B, AB, O
AA
A
A
TC
G
CG
TG
C
T
Macromolecules: Nucleic Acids• Examples:– RNA (ribonucleic acid)• single helix
– DNA (deoxyribonucleic acid)• double helix
• Structure:– monomers = nucleotides
RNA
DNA
Nucleotides• 3 parts – nitrogen base (C-N ring)– pentose sugar (5C)• ribose in RNA• deoxyribose in DNA
– phosphate (PO4) group
Are nucleic acidscharged molecules?
Nitrogen baseI’m the A,T,C,G or Upart!
Types of nucleotides• 2 types of nucleotides– different nitrogen bases – purines• double ring N base • adenine (A)• guanine (G)
– pyrimidines• single ring N base • cytosine (C)• thymine (T)• uracil (U)
Purine = AGPure silver!
Nucleic polymer• Backbone– sugar to PO4 bond– phosphodiester bond• new base added to sugar of previous
base• polymer grows in one direction
– N bases hang off the sugar-phosphate backbone
Dangling bases?Why is this important?
Pairing of nucleotides• Nucleotides bond between
DNA strands– H bonds– purine :: pyrimidine– A :: T• 2 H bonds
– G :: C• 3 H bonds
Matching bases?Why is this important?
DNA molecule• Double helix– H bonds between bases join
the 2 strands• A :: T• C :: G
H bonds?Why is this important?