Homework #1 is due nowBonus #1 is posted and due 10/24

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…

Fig 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6:500–506

2 hypotheses about how Ca++ signals are transduced:Signatures vs. Switches

Stomata regulate gas exchange: CO2 in, O2 and

water out

H2OH2O

Stomata

closedopen

Fig 5. Sanders et al., The Plant Cell, S401–S417, Supplement 2002

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 1. Allen et al., Nature, Vol 411:1053-1057, 28 June 2001

Stomata aperture in response to Ca++ spikes:More spikes= more closing

Fig 2. 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 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6:500–506

2 hypotheses about how Ca++ signals are transduced:Signatures vs. Switches

Signal transduction

– such as changes in

cellular components

or production of new cellular components

Fig 8.11

How do cells express genes?

a gene

The relationship between DNA and genes

promoter coding region terminator non-geneDNA

Fig 8.3

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

• Overview of transcription

Figure 8-4

Fig 8.4

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.

Fig 7.8

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

The relationship between DNA and RNA

Fig 8.6

Fig 8.4

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

Fig 8.8

How does the RNA polymerase know which strand to transcribe?

5’5’3’

3’5’

Reverse promoter, reverse direction and strand transcribed.

RNA

DNARNA RNA

DNA

UU

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

3’

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

Incoming nucleotide

P

Error

P-P

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

Error

P

P-P-PP

U

3’

5’

Error repair on 5’ end not possible.

Incoming nucleotide

DNARNA RNA

DNA

UU

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

Fig 8.11

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

Protein

Homework #1 is due nowBonus #1 is posted and due 10/24