Homework #1 is due now Bonus #1 is posted and due 10/24

DNA contains the information to make RNA and/or proteins. Fig 8.11 DNA contains the information to make RNA and/or proteins. Protein

General model of Ca++ signaling

Ca++ is involved in signal transduction for responses of: in Plants Development Cold Guard cell closing Osmotic shock Light Fungal infection Touch Pollen tube growth Wounding… in Animals Neurons Muscle movement Wounding Development Fertilization Hormones … How can there be specificity?

Everything has its place…

2 hypotheses about how Ca++ signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6:500–506

Stomata regulate gas exchange: CO2 in, O2 and water out H2O H2O

Stomata open closed

Ca++ fluxes in guard cells in response to hormone or stress that cause stomatal closing. Wildtype vs. det3 and gca2: mutants that fail to close stomata following treatment Fig 5. Sanders et al., The Plant Cell, S401–S417, Supplement 2002

Stomata aperture in response to Ca++ spikes: More spikes= more closing Fig 1. Allen et al., Nature, Vol 411:1053-1057, 28 June 2001

Spike timing is critical for response Fig 2. Allen et al., Nature, Vol 411:1053-1057, 28 June 2001

Duration of spikes for stomata closing Fig 2. Allen et al., Nature, Vol 411:1053-1057, 28 June 2001

2 hypotheses about how Ca++ signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6:500–506

Signal transduction – such as changes in cellular components or production of new cellular components

How do cells express genes? Fig 8.11 How do cells express genes?

The relationship between DNA and genes Fig 8.3 The relationship between DNA and genes a gene promoter coding region terminator non-gene DNA

Combinations of 3 nucleotides code for each 1 amino acid in a protein.

Fig 8.4 Overview of transcription Figure 8-4

Each nucleotide carbon is numbered Fig 7.5 +8.2 Each nucleotide carbon is numbered

Fig 7.8 Each nucleotide is connected from the 5’ carbon through the phosphate to the next 3’ carbon.

Each nucleotide is connected from the 5’ carbon through the phosphate to the next 3’ carbon. Fig 7.8

The relationship between DNA and RNA Fig 8.6

What is so magic about adding nucleotides to the 3’ end? Fig 8.4 What is so magic about adding nucleotides to the 3’ end?

How does the RNA polymerase know which strand to transcribe? Fig 8.8

Reverse promoter, reverse direction and strand transcribed. RNA 5’ 3’ 5’ 3’ 5’

Why do polymerases only add nucleotides to the 3’ end? RNA RNA DNA DNA U U

Hypothetically, nucleotides could be added at the 5’ end. Incoming nucleotide 3’ 5’ Hypothetically, nucleotides could be added at the 5’ end.

Error P P-P

The 5’ tri-P’s can supply energy for repair Error P The 5’ tri-P’s can supply energy for repair U P-P-P P

Error repair on 5’ end not possible. Incoming nucleotide Error repair on 5’ end not possible. 5’ 3’

Need for error repair limits nucleotide additions to 3’ end. RNA RNA DNA DNA U U

DNA contains the information to make RNA and/or proteins. Fig 8.11 DNA contains the information to make RNA and/or proteins. Protein

Homework #1 is due now Bonus #1 is posted and due 10/24