Transcript here

LB145
Sec 001-004
Today’s Outline
- Announcements:
Homework #3 is due on Thursday.
Flexible Grade Weightings due TODAY!
Honors option meeting: 8:15-8:45am on
Monday (see website)
- Calvin Cycle (a human experiment)
- Mendel’s Peas
Fig. 10-17
STROMA
(low H+ concentration)
Cytochrome
complex
Photosystem II
4 H+
Light
Photosystem I
Light
Fd
NADP+
reductase
H2O
THYLAKOID SPACE
(high H+ concentration)
1
e–
Pc
2
1/
2
NADP+ + H+
NADPH
Pq
e–
3
O2
+2 H+
4 H+
To
Calvin
Cycle
Thylakoid
membrane
STROMA
(low H+ concentration)
ATP
synthase
ADP
+
Pi
ATP
H+
Fig. 10-5-4
CO2
H2O
Light
NADP+
ADP
+ P
i
Light
Reactions
Calvin
Cycle
ATP
NADPH
Chloroplast
O2
[CH2O]
(sugar)
The Calvin Cycle
3.0
Photosynthesis and Mendel
3.1
Mendel’s Experiments
• Gregor Mendel – the
father of modern
genetics.
• Inheritance of traits in
pea plants (P. sativum).
• Flower color, seed shape,
pod shape, pod color,
flower position, stem
length, embryo color.
2.1
The Evolution of Wrinkled Peas
Wrinkled peas aren’t just wrinkled…
Round
Wrinkled
2.2
The Evolution of Wrinkled Peas
They taste good too!
Round
Wrinkled
1.1
Fact Sheet: Pisum sativum
• Common names: Field peas.
• Native to: Near East  Iraq,
Turkey, Israel, Palestine, etc.
• A key crop of the Neolithic
Agricultural Revolution, oldest
recorded samples date to
10,000 BCE.
3.3
Inheritance of Pea Plant Traits
• In pea plants, traits are
often controlled by one set
of alleles. These alleles can
combine in a homozygous
(dominant or recessive) or
heterozygous fashion
depending on parental
alleles.
• Examples:
– The Round vs. Wrinkled pea
trait is controlled by the alleles
R and r
– The Yellow vs. Green pea trait is
controlled by the alleles Y and
y.
3.5
From Traits to Genes
• Amazingly, Mendel had no
knowledge of DNA, genes or
chromosomes.
• The traits (alleles) that
Mendel described
correspond to specific genes
within the pea plant
genome.
Molecular Biology: Central Dogma
The “R” allele of the
sbe1 gene codes for
the SBE1 protein.
The SBE1 protein is an
enzyme that converts
simple starch (amylose)
to complex starch
(amylopectin).
How does it all work?
2.4
Inside the Pea Cell: Sugar and Starch
Fig. 10-17
STROMA
(low H+ concentration)
Cytochrome
complex
Photosystem II
4 H+
Light
Photosystem I
Light
Fd
NADP+
reductase
H2O
THYLAKOID SPACE
(high H+ concentration)
1
e–
Pc
2
1/
2
NADP+ + H+
NADPH
Pq
e–
3
O2
+2 H+
4 H+
To
Calvin
Cycle
Thylakoid
membrane
STROMA
(low H+ concentration)
ATP
synthase
ADP
+
Pi
ATP
H+
Fig. 10-5-4
CO2
H2O
Light
NADP+
ADP
+ P
i
Light
Reactions
Calvin
Cycle
ATP
NADPH
Chloroplast
O2
[CH2O]
(sugar)
The Calvin Cycle
2.4b
Inside the Pea Cell: Sugar and Starch
Calvin
Cycle
Glyceraldehyde 3-phosphate
2.4c
Hexose-phosphate
isomerase
Fructose biphosphase
Glucose 1phosphate
Fructose 6phosphate
Phosphoglucomutase
ADP-Glucose
Fructose 1,6biphosphate
ADP-glucose
phosphorylase
G3P
Fructose biphosphate
aldolase
Inside the Pea Cell: Sugar and Starch
Glucose 6phosphate
2.4d
Inside the Pea Cell: Sugar and Starch
Starch synthetase
ADP-Glucose
Starch branching enzyme
Amylose
Amylopectin
Starch-branching
enzyme
Sucrose
2.1
The Evolution of Wrinkled Peas
Wrinkled peas aren’t just wrinkled…
they taste good too!
Round
Wrinkled
(R allele of sbe1 gene)
(r allele of sbe1 gene)
G3P

(Intermediates)

Amylose
functioning starch branching enzyme 
Amylopectin
G3P  Sucrose

(Intermediates)

Amylose
non-functioning starch branching enzyme
2.9
Question: What do seed shape and
seed taste have in common?
- Wrinkled peas are wrinkled because they have a
higher water content than round peas. When they
dry, round peas retain their shape while wrinkled
peas do not due to water loss.
Think and Write Down an Answer:
- Why would wrinkled (sweet) peas have a higher
water content than round (starchy) peas?
Discuss your answer with your neighbor (2 mins)
- Name cards will be used to find out what your team thought.
4.0
In Detail: The Genetics of
Round and Wrinkled Peas
5.0
The Artificial Selection of
Round and Wrinkled Peas
5.1
Artificial Selection of Sweet Peas
• Wrinkled peas are sweeter and in ancient
times farmers tended to select them for
breeding.
5.2
Artificial Selection:
• Consider two fields with pea plants.
• Some plants produce wrinkled peas, others produce
round peas (50% wrinkled peas, 50% round peas).
5.3
Artificial Selection:
• Question: assuming you were a farmer and could weed
out wrinkled peas or round peas, would it be easier to
create a permanent monoculture of round peas or a
permanent monoculture of wrinkled peas?
5.4
Artificial Selection:
• From a mixed field, what is easier to facilitate
through artificial selection?
(a) Monoculture of
(dominant) round peas.
(b) Monoculture of
(recessive) wrinkled
peas.
(c) Both scenarios have
equal difficulty.
5.5
Darwin and Selection
• Darwin used the example
of artificial crop selection
as an example to support
his theory of natural
selection.
For THURSDAY:
1. Homework #3 – the Photo Problem
2. StudyNotes 4 is due on Tuesday Feb 12th.