Lecture 3 Flashcards
What is produced by photosynthesis
Glucose (fixed carbon)
What do plants use glucose for
Structural integrity of plants, energy for basic cell processes
What did terrestrial plants evolve from
Primordial algae and scum
What helped terrestrial plants evolve
Firm cell wall
How did the cell wall help with evolution of terrestrial plants
Strength for upward and downward growth
Water retention
Barrier against bacteria and other creatures
How many layers of the modern cell wall
Two
Layers of the modern cell wall
Primary and secondary
When is the primary wall deposited
Early in the cells life
When is the secondary wall deposited
Late in the cells life
Is growth from outside to inside or inside to outside
Outside to inside (secondary forms inside the primary wall)
What does the thickness of the wall depend on
Species and type of cell
Example of cells with thick cell wall (secondary)
Xylem cell in trees (wood)
Which wall has subtypes of layers
Secondary
Main components to plant cell walls
Cellulose
Hemicellulose
Lignin
Parts of the cell wall that act as rebar
Cellulose and hemicellulose
Parts of the cell wall that act as concrete
Lignin
How does lignin act as concrete
Sticky substance surrounds the structural filaments of cellulose and hemicellulose
Most abundant bio polymer and organic compound on earth
Cellulose
What percent of a tree is cellulose
40-50%
What is cellulose made entirely of
Beta glucose
What is starch made entirely of
Alpha glucose
How do alpha and beta glucose differ
Orientation of OH group on the first carbon
Alpha and beta glucose are —— of each other
Anomers
Carbon that gives rise to different anomers
Anomeric carbon
What are glucose molecules joined by in cellulose and what bond is formed
1 carbon of one molecule and the #4 carbon of the other
Beta 1,4 glycosidic bond is formed
Name of the simplest cellulose unit
Cellobiose
Length of cellulose is referred to as
Degree of polymerization
What can the degree of polymerization of cellulose be up to
10,000 (10,000 glucose molecules or more)
How are stands of cellulose arranged
In parallel
Microfibrils make a
Macrofibril
Macrofibrils make a
Cellulose fiber
Cellulose chain are secreted from the cell by
Cellulose synthase complexes
Cellulose synthase complexes are arranged
In rosettes of six subunits
How many microfibrils are produced by the subunits at a time
Six
Each fibril emerging from the cell wall is composed of how many glucose chains
36
What percent of the plant genome is dedicated to construction, architecture, sensing functions, and metabolism of the plant cell wall
10%, 2,500 genes
Most genes involved in cell wall polysaccharide synthesis are grouped into gene families for
Substrate generation, glycosyl transfer, targeting and trafficking, cell wall rearrangement, and modification by hydolysases, esterases, and lyases
