Bio 212 : Test 5 - Angiosperms

Front 1

Intro to the Anthophyta

Back 1

1) Most diverse and wide spread group of plants with 300,000 species known (and there are many more yet to be discovered)

2) almost all agricultural plts are
angiosperms and they supply
most of the plt derived medicinal
chemicals that are known

3) highly diverse in number, size
and form

Front 2

4 basic types of angiosperms

Back 2

1) monocot
2) eudicot
3) basal angiosperms (also called "Archaic Angiosperms")
4) Magnoliids

Front 3

MONOCOT characteristics

Back 3

(1) one cotyledon

(2) leaf veins parallel

(3) vascular bundles scattered in stem

(4) fibrous root system

(5) flower parts in 3's

(6) e.g. Grasses (e.g. wheat), palm, lily

Front 4

EUDICOT characteristics

Back 4

(1) 2 cots

(2) veins net-like in leaves

(3) vasc. bundles have ring arrangement in stem

(4) tap root

(5) flower parts in 4 or 5's

(6) e.g. roses, avocados, peas, oaks

Front 5

Advantages and Disadvantages of Flowers

Back 5

a) Monoecious flowers have the male androecium and the female gynoecium in the same flower in addition to the sterile parts of the flower (calyx and corolla)

(1) androecium: stamens (filament + anther)
(2) gynoecium: carpels (megasporophylls = ovary + style + stigma)

b) therefore fertilization is virtually assured

c) but self-fertilization is not always desirable, so…........monoecious plts are often self -incompatable, meaning they can not self.

d) on other hand, plts can be dioecious (the staminate flower (male) and carpellate flower (female) are on different plts, i.e. male plt and female plts). This assures out-crossing.

Front 6

More advantages and disadvantages of flowers

Back 6

e) perfection in flowers
(1) Perfect flower is staminate and carpellate

(2) Imperfect flower is staminate or carpellate

f) Animal pollination gives delivery of male gamete to female gamete (vs. wind for gymnosperms).
(1) This direct delivery system extremely efficient and is a huge advantage over wind pollination.

(2) Animal pollination is so important that there are many flowers that have co-evolved with their animal pollinators to such an extent that only a single animal can pollinate that particular flower.

Front 7

Fruits have TWO mature ovaries.

2 types of mature ovaries:

Back 7

a) DRY FRUITS can be
(1) protective (peas in a pod or a pomegranate)
(2) help in seed dispersal (maple seed=wings, cocklebur=hooks)

b) FLESHY FRUITS have fleshy pericarp
(1) pericarp develops from ovary walls

(2) form a "bait" that animals will eat and carry away and help in seed dispersal (apple, tomato, banana)

Front 8

THREE types of fruit

Back 8

SIMPLE FRUIT: develop from 1 carpel or a few fused carpels that make a single fruit (e.g. grape, apple)

AGGREGATE FRUIT: many individual carpels of a single flower, (sometimes fused, often not) aggregate to form a fruit (e.g. strawberry, raspberry)

MULTIPLE FRUIT: many separately fertilized gynoecia fuse to form the fruit (e.g. pineapple)

Front 9

Simple fruit types

Back 9

BERRY: one to many carpels, each with many seeds, carpel wall is fleshy (e.g. grape, tomato)

DRUPE: one to many carpels, each with 1 seed, inner carpel wall is stony and adheres to the fleshy portion of the enlarged carpel wall (e.g. cherry, peach)

POME: (all are from the rose family) compound inferior ovary, where the perianth enlarges and become fleshy,

Front 10

Accessory fruits

Back 10

a fruit that contains parts other than just the enlarged pericarp

Examples:
(a) Strawberry fruit is an enlarged receptacle with the seeds on the outside. It is an aggregate fruit (individual fruits are fused) and an accessory fruit

(b) Pineapple fruit is many separately fertilized gynoecia fused to form the fruit with other flower parts squeezed between. A pineapple is a multiple and accessory fruit.

Front 11

The Coconut...

Back 11

One of the oddest fruits of all is the coconut

(a) drupe: one to several carpels, each with 1 seed, inner carpel wall (endocarp) is stony and normally adheres to the outer fleshy portion of the enlarged carpel wall.

(b) Coconut has 3 carpels. The fused outer carpel walls are a fibrous husk. The flesh is solid endosperm of the seed and the coconut milk is a liquid endosperm. The embryos float in the liquid endosperm

Front 12

Life Cycle of Anthophyta

Back 12

1) most efficient life cycle in the plant kingdom

2) Angiosperms are the ultimate in heterospory
a) microgametophyte is a 3 celled pollen grain
b) megagametophyte is a 7 or 8 celled embryo sac
(Note that Angiosperm gametophyte plts are even more reduced in the Angiosperm life cycle than in the Gymnosperm life cycle.)

Front 13

Microsporogenesis

Back 13

1) cells in the anther develop into diploid microsporocytes (microspore mother cells)

2) microspore mother cell undergoes meiosis to form 4 haploid pollen cells

3) each pollen cell undergoes mitosis twice to form 4 haploid cells of which 2 or 3 survive and develop into a mature pollen grain or microgametophyte

4) usually 2 of the 3 cells of the microgametophyte are sperm cells

Front 14

Megasporogenesis

Back 14

1) in the early ovule there is the nucellus (the megasporangium) and a single diploid megasporocyte (megaspore mother cell)

2) megaspore mother cell undergoes meiosis to form 4 haploid megaspores

3) 3 of the 4 megaspores disintegrate and the remaining cell forms the megagametophyte

4) the nucleus of the megagametophyte undergoes mitosis 3 times to form 8 haploid nuclei.

5) The 8 nuclei undergoes development into 7 different cells, one of which has 2 nuclei (the central cell). But only limited cell division occurs. This structure is the embryo
sac and is the mature megagametophyte.

6) Important cells of the embryo sac: egg cell & polar nuclei of the central cell.

Front 15

Fertilization

Back 15

1) Pollen lands on the stigma and a tube germinates from the pollen grain (pollination)

2) Pollen tube contains the tube nucleus and 2 sperm cells. Tube grows down the stigma to the ovule and enters through the micropyle.

3) Upon entering the embryo sac, the pollen tube disgorges the tube nucleus and 2 sperm cells.

4) One sperm fuses with the egg cell to make the zygote & the other fuses with the 2 polar nuclei of the central cell= double fertilization.

result: diploid embryo and triploid endosperm

Front 16

Development of seed

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1) In the embryo sac, the triploid central cell expands to form the endosperm

2) integuments become the seed coat

3) zygote develops into an embryo

--->Seed germination and growth of the new sporophyte

Front 17

Why is the angiosperm life cycle so effective?

Back 17

1) gametophyte generation is much reduced, sporophyte dominates

2) vulnerable gametophytes held and protected in the robust sporophyte

3) direct, efficient delivery of gametophytes to each other, usually aided by animals

4) resulting embryo well protected & provided with food by seed and sporophyte

5) several mechanisms to ensure out-crossing including (some of these seen in gymnosperms too)

(a) some flowers contain only one of two sets of sex organs (dioecious) and so there are staminate and carpellate plants

(b) different times for ripening of male and female flowers

(c) self-incompatability.

Front 18

Intro to angiosperm evolution

Back 18

1) What Darwin was asking was this: How can it be that angiosperms appear late in the fossil record, but then very rapidly become the dominant and most diverse plt group? Answer unknown.

2) Recent morphologial and molecular analysis point to the Bennettitales (extinct gymnosperm) or one of the extinct Gnetophytes (gymnosperm clade) as the most likely candidates for Angiosperm ancestors.

Front 19

characteristics unique to angiosperms

Back 19

•flowers (a few basal angio’s don’t have)

•closed carpels (few basal angio’s have open)
•double fertilization with triploid endosperm
•3 nuclei in microgametophytes

•8 nuclei in megagametophytes
•stamens with 2 pairs of pollen sacs

•phloem with sieve tube member and
companion cells
•triapperturate pollen (single being the ancestral state, triapperturate is derived, found in eudicots)

Front 20

basic evolutionary trends in flowers

Back 20

(a) ancestral flowers: many parts, indefinite in #
modern flowers: few parts, definite # of parts

(b) ancestral flowers: flower parts in spirals or 4 separate whorls of floral parts
modern flowers: whorls fused/reduced to 1, 2 or 3

(c) ancestral flowers: ovary superior
modern flowers: ovary inferior

(d) ancestral flowers: radial symmetry
modern flowers: bilateral symmetry

Front 21

origin of flower petals

Back 21

most extant flower petals evolved from sterilized stamens, not leaves.
evidence:

(a) petal vascular pattern matches that of stamens and not leaves

(b) archaic stamens are often of various shapes, colors, may even be scented, or broad and fleshy

(c) molecular evidence confirms this view

Front 22

Co-evolution of flowers and animal pollinators

Back 22

1) The driving force in evolution is making sure that the genetic material is passed to the next generation.

(a) Therefore any change that aids in passing the genetic material to next generation is very likely to be retained through natural selection.

(b) Since animal pollination is a very efficient method of passing pollen to the gynoecium, structures that aid in that process are strongly selected for.

(c) The same applies to animal pollinators, as the flowers are animal’s food source.

Front 23

Examples of flowers/animal pollinators

Back 23

1) hummingbirds and monkey flowers
2) bees and many flowers (ex: rosemary)

Front 24

Family Asteraceae: examples of a highly derived flowers

Back 24

1) radial Disk flowers + bilateral ray flowers: composite

2) Disk flowers (many flowers on a head)
(a) 5 fused stamens

(b) 5 fused petals, also fused to ovary

(c) inferior ovary (epigynous)

(d) sepals often absent

3) bilateral ray flowers (sometimes sterile)

Front 25

Intro to Bioinformatics/Genomics

Back 25

A. no need to cover this until 2000 when human genome project was completed

B. Goal was to sequence the whole genome of man

C. the race to sequence the human genome was started in 1990 by DOE & originally slated to finish about 2005

1) chromosome sections were assigned to many labs around the world: USA, Great Britain, China, France, Germany, Russia, etc.

2) used technologies that gave very accurate sequences but was laborious and slow

3) used genomes of several anonymous donors

D. race was joined by Celera Genomics in 1995, using robotic DNA sequencers

1) they fragmented the genome & sequenced the pieces.
2) then used computers to overlap the pieces to generate a map
3) much quicker, but possibly less accurate
4) genome used was the president of the company: Craig Venter
5) the pieces were patented, even though Celera didn’t know the functions (if any) of the individual pieces.

E. Celera won the race by publishing the draft sequence in 2000 (official announcement was that it was a tie)

F. final publication of a highly accurate human genome by Celera was in Spr. 2003

Front 26

How people used to find a gene

Back 26

1) making a DNA library of the organism of choice

2) screen library with a DNA probe

a) probe: short sequence of DNA that is “unique” to that gene or other DNA segment.

b) sometimes you have a good probe or not so good (very specific or not)

c) done by Southern analysis of the clones in a DNA library.

3) could take up to 2yrs of full-time work if unlucky

Front 27

The power of having genomic info in a rapidly searchable database is enormous and it has changed mol. bio. profoundly and forever.

Back 27

1) It will change the world as profoundly as mol. bio. did in the 1980's

2) With the power of computers and databases, what once took yrs, now can take only minutes.

3) It will help in finding therapies to genetically based diseases more rapidly (e.g. Huntington or Tay-Saks)

4) It will help in finding cures for diseases that have a genetically determined host susceptibility profile (e.g. most cancers or Alzheimer's disease)

5) potential for abuse is enormous (more later)

Front 28

Genbank

Back 28

one of hundreds of other db of genomic information) with a search engine

Researchers now use a computer to do a search of a huge db of genome info

a searchable database of
•genomes
•chromosomes
•cloned pieces of DNA (commonly referred to as “clones” for short)
•viruses
•plasmids
•tRNA's, rRNA's , mRNA’s, etc.
•cDNA’s (DNA copies of mRNA’s)
•EST’s (expressed sequence tags)
•proteins

Front 29

Comparative genomics

Back 29

compares the genomes of many different organisms, looking for the similarities and differences to find information on evolution.

1) requires the sequencing of the human genome and genomes of many other organisms (191 genomes done as of 3/2006, most recent is pig as of 10/09)

2) mostly confirms what we know about living things

Front 30

Information from the HGP can be classified in 3 basic categories.

Back 30

1) comparative genomics
2)
3) pharmacogenomics