1. DNA Structure and Function
Basis of Heredity

2. Chemical Basis of Life

3. The Central Dogma cells can make exact copies of DNA
replication
transcription
processing
translation
cells can make exact copies of DNA
DNA encodes all of the information necessary for cellular functions
RNA is made from a DNA template and functions in protein synthesis
proteins are translated from messenger RNA and carry out cellular functions

4. Nucleotides
nucleotides are the building blocks of nucleic acids
ribose + base + 5' phosphate
5 different bases
adenine (A)
guanine (G)
cytosine (C)
thymine (T)
uracil (U)
DNA vs
RNA
2' oxygen
thymine (T)
uracil (U)
double stranded
single stranded
DNA = deoxyribonucleic acid
RNA = ribonucleic acid

5. Nucleic Acid Structure
nucleic acids are polymers of nucleotides
nucleotides linked through phosphate bonds
strand has polarity—5'-PO4 and 3'-OH ends
order of the nucleotides defines a sequence
4 letter alphabet

6. Double Strands specific base pairing A and T G and C hydrogen bonds
anti-parallel (5'-3')
complementary strands
template for synthesis

7. DNA Replication the DNA strands are separated
each strand serves as template
complementary strands are synthesized (5'3')
yields 2 identical DNA molecules
semi-conservative replication
carried out by cellular proteins (= enzymes)
complex process involving many proteins
DNA polymerase

8. DNA Polymerase Activity
'replication fork' moves along DNA
leading strand
lagging strand
numerous replication forks act simultaneously

9. Chromosomes genomic DNA is very long humans, 6 x 109 bp
~1.8 meters total length
total length reduced via associates with proteins
individual DNA molecules condensed into chromosomes
humans have 22 pairs + X/X or X/Y (ie, diploid)

10. Chromosome Replication
unfolding of chromosomes, DNA replication, and refolding
chromosomal duplication
sister chromatids
joined at centromeres

11. Mitosis DNA synthesis chromosomal duplication
separation of sister chromatids
cell division (cytokinesis) results in 2 identical daughter cells
somatic cell reproduction
asexual process
sexual reproduction involves germ line cells
oogenesis (egg formation)
spermatogenesis (sperm formation

12. Meiosis two consecutive rounds of cell division meiosis I
DNA replication (2n4n)
separation of chromosome pairs (4n2n)
meiosis II
no DNA replication
separation of chromatids (2n1n)
fertilization (1n2n)

14. Recombination independent chromosome assortment 2n possible variants
'crossing-over'
recombination between homologous chromosomes
at least once per chromosome pair
positions ~ random

15. Genes and Alleles gene = unit of information (~protein)
locus = physical location on a chromosome
allele = different molecular forms (ie, sequence) of a gene
homozygous = same allele on both chromosomes
heterozygous = different alleles on chromosome pairs
genotype = genetic makeup
(ie, total genes)
phenotype = observable traits

16. Types of Inheritance dominant-recessive
dominant allele 'masks' recessive allele
incomplete dominance
phenotype between dominant and recessive traits
co-dominance
shared expression of traits (eg, AB blood type)
polygenic
several genes influence trait (often continuous variation)
pleiotrophy
single gene affecting several traits