Lecture 2

What does Meiosis produce?

SPORES

What does mitosis produce?

GAMETES

What is a spore?

• Single cell that can divide to produce a multicellular organism (often with a protective coat)

What is a gamete?

Single cell that can unite with another gamete to produce a diploid zygote.

How many divisions of phyla for land plants?

10

Land Plants: What are the 4 major divisions?

1. Mosses

2. Ferns

3. Conifers

4. Angiosperms

What is Bryophyta?

(The mosses)

• Low growing (to the ground)

• Confined to damp areas

  • Swimming sperm (reason why they like damp areas)

  • No true vascular tissue (rudimentary vascular system)

• No true leaves

  • True leaves require vascucular tissue

• Gametophyte dominant

• Homosporous (1 spore size)

What is the division Pterophyta?

Ferns, Horsetails, etc.

What are Pterophyta?

• Al lot of tropical

• Appeared around 400 mya

• Vascular tissue

  • Xylem 7 phloem

  • Support & supply

• Swimming sperm therefor reproduction needs water

• Sporophyte dominant

• Homosporous or heterosporous

What does it mean to be sporophyte dominant?

The plant you see is a sporophyte

For what special fern makes how many types of leaves at what time and for what purpose?

Cinnamon Fern:

In SPRING they make 2 types of special leaves:

1. For photosynthesis

2. To create sporangia

What is sporangia?

The place in which spores are formed.

How many sizes of spores?

What are the sizes?

Two sizes:

1. Homospory

2. Heterospory

What is homospory?

1 size of spore from meiosis

What is heterospory?

2 sizes from meiosis

What is a homosporous spore production look like?

1. Sporangium on sporophyll

2. Single type of spore

3. Typically a bisexual gametophyte (cosexual)

4. Broken into either egg or sperm

What is a heterosporous spore production look like?

2 options:

1. Megasporangium on megasporophyll

2. (by meiosis) Megaspore

3. Female gametophyte

4. Eggs

OR

1. Microspongium on microsporophyll

2. (Through meiois) Microspore

3. Male gametetophyte

4. Sperm

Who has homosporous spore production?

Most ferns

Mosses

Who has heterosporous production?

Some ferns

All seed plants

What are the divisions of seed plants we need to know

Coniferophyta

Anthophyta

What do seed plants both have?

Seeds + Pollen

What are some characteristics of a seed?

It is an embryo + nutrition + seed coat

• Develops from ovule

  • Novel structure appearing in seed plants

  • Site of female meiosis (fertilization)

  • Thus contains female gametophytes, female sex organs,, egg & embryo

What is an ovule?

Immature seed

What does the ovule (conifer) at the early stage (just BEFORE meiosis in megasporangium)

Has a:

• Micropyle

• Integument

• megasporangium

What is a micropyle?

Where the pollen will come into

What is an integument?

What will become the seed coat.

What is the megasporangium?

(female) = nucleus (2n)

What does the ovule (conifer) at the early stage (just AFTER meiosis in megasporangium)

Has:

• micropyle

• integument

• megasporangium

• single functional (creates 4 only 1 survives) megaspore (1n); will become a megagametophyte ( by dividing and dividing(1n)

What is the division of coniferophyta?

Conifers

What are conifers?

• around 550 species (not that much)

• reproductive organs in cones

• sporophyte dominant

• heterosporous

• microgametophyte = pollen

• megagametophyte

  • within ovule

  • makes egg and then nourishes embryo

Conifers are either trees or shrubs

What is the nutrition in conifers?

megagametophyte

• makes eggs in archegonium

What is pollen?

• Mature male gametophyte (makes sperm)

• Few cells in size

what are gymnosperms?

naked seeds

how fast is the production?

VERY SLOW

What does reproduction look like for male cones?

• development started a year ago

• This year they will pollinate female cones started 1 year ago

What does reproduction look like for female cones?

• Initiated 2 years ago

• Pollinated 1 year ago (female meiosis after pollination)

• will mature into woody cone THIS YEAR with mature seeds.