Pages in this set

Page 1

Preview of page 1
Lecture 8: plant biology

Plants are ancestors of animals

Three version of the plantae kingdom

Embroyphytes ( plants with embryos- land
plants ), which included BRYOPHYTES,

Streptophyta ­ green
algae plants

Viridiplantae ­ chlorophytes ( noncharophycean)
Growth ­ `irreversible' increase in size.

Development ­ increase in…

Page 2

Preview of page 2
Leaves ­ consist of flattened blade and a stalk, the peptiode, which joins the leaf to a node of the
stem . monocots ­ parallel major veins , run length of the leaf blade. Dicot leaves ­ multibrancehed
network of major veins

Tissues systems include- dermal, vascular, ground

Plant growth…

Page 3

Preview of page 3
When does pattern formation occur? During embryogenesis

Embryos are polar structures

Between primary walls of adjacent cells is the middle lamellae- thin
layer rich in sticky polysaccharides called pectin

Middle lamellae glues the cells together. When cell matures and stops
growing, it strengthens its wall.

Page 4

Preview of page 4
The shape of the plant embryo is determined by:




Plant cell expansion

Extension occurs when water enters the central vacuole by osmosis ­ this accounts for 90%
of cell expansion
Most of the water is packaged…

Page 5

Preview of page 5
Very fast life cycle
Smallest known genome
Complete DNA sequence
27,000 genes
International cooperation


Embryogenesis in Arabidopsis

A. Asymmetric first division:
B-D. Cells have different FATES

Suspensor > transverse divisions

Embryo > precise cell divisions

Page 6

Preview of page 6

suspensor & embryo lineages

E-F GLOBULAR: protoderm forms

> future epidermis;

G. HEART: cotyledons initiated

& root meristem formed


axis extension > future hypocotyl


cotyledon greening, vascular tissues

Asymmetric first division is linked to cell polarity & cell fate

· The plane of division is…

Page 7

Preview of page 7
Evidence for the role of positional information in specifying cell fate

· Cells within differentiated tissues, such as leaf tissue can be induced to REDIFFERENTIATE into
a completely new embryo or plant, containing the FULL RANGE OF CELL TYPES- totipotency

· Involves a change in the relative position (local contacts)…

Page 8

Preview of page 8
Lecture 9: Meristems & Organogenesis

Growth in organisms is irreversible as the organism
increases in size

There are two components in plant growth

Cell proliferation
Cell growth


-plant known as annuals complete their life
cycle from germination through flowering
and seed production to death in a single year


Page 9

Preview of page 9
- Roots

- stems

- Leaves

- Flowers

Apical meristems

Tips of roots and buds of shoots
Primary growth ­ elongation enables
roots to ramify throughout the soil and
shoot to increase their exposure to light
and co2
Restricted to the youngest parts of the
plant ­ tips of the…

Page 10

Preview of page 10
zone of cell division blends into the ZONE OF ELONGATION
cell elongate ­ ten times their of their original length.
Even before they finish elongation the cells of the root begin to specialize in structure and
function, where this zones goes to the ZONE OF MATURATION (differentiation)

· SAM and…


No comments have yet been made

Similar Dance resources:

See all Dance resources »