BOT3015 - Plant Cells, and Growth

What are the 2 main organ systems of plants

Shoot and Root System

Shoot System

This system is usually aboveground. It has vegetative and reproductive organs.

Vegetative Organs

Leaves and stems

Reproductive Organs

Flowers and fruits

Root System

This system is usually underground; It's only organ is roots.

Determinate Growth

The type of growth that stops after a time. Usually a plant cannot heal/regrow. It's maximum size rarely achieved in

nature (Usually applies to leaves, flowers and fruits)

Indeterminate Growth

The type of growth where a plant is able to keep growing through life. Usually a plant can heal/regrow. It can be limited by resources and environmental factors

(Usually applies to roots and stems)

Cell Theory

Created in 1838 by Schleidern and Swann. States that all plants and animals are made of cells and cells are the basic units of life.

Cell Theory - Virchow

Added that cells arise by reproduction from

previous cells - "Omnis cellula e cellula"

Cell - Parts

1. Plasma Membrane

2. Cytoplasm

3. DNA

4. Ribosomes

Plasma Membrane

A phospholipid bilayer with embedded proteins. It serves as a barrier between the cell and the environment. It controls the passage of organic molecules, ions, water, oxygen, and

cellular waste

Cytoplasm

The entire region of the cell between the plasma

membrane and the nuclear envelope. It is comprised of organelles suspended in a gel-like material - the cytosol - and protein threads - the cytoskeleton

DNA - The Nucleus

In eukaryotic cells, DNA is typically

housed in the nucleus. It directs the synthesis of ribosomes and proteins. It stores chromatin and the nucleolus

Chromatin

Clumps of DNA and protein that resemble jumbled threads

Nucleolus

The part of the nucleus where ribosomes are

made

Nuclear Envelope

A double membrane that separates the nucleus from the rest of the cell

DNA - Chromatin and Chromosomes

During cellular replication, DNA is visible in the form of chromosomes. During cellular growth and maintenance, proteins attach to chromosomes, making them resemble

jumbled threads.

Ribosomes

These structures are responsible for protein

synthesis. They can either float free in the cytoplasm or be

embedded in the endoplasmic reticulum. They receive instructions from nucleus in the form of mRNA on the specific order of amino acids to build a given protein.

Eukaryotic Cells - Unique Components

Endomembrane System, Vesicles and peroxisomes, Endoplasmic reticulum, Golgi apparatus, and Mitochondria

Endomembrane System

Modify, package, and transport lipids and proteins

Vesicles and Peroxisomes

Bud off from the endomembrane and serve

as transport units for diverse materials

Endoplasmic Reticulum

A series of interconnected sacs and tubules that modify proteins & synthesize lipids

Golgi Apparatus

A series of flattened membranes that receives proteins and lipids from the ER, which it then sorts, tags, packages, and distributes.

Mitochondria

The 'powerhouse' of the cell - it is the

site of cellular respiration.

Mitochondria Functions

Makes ATP (the cell's main energy-carrying molecule) from glucose and other nutrients. Uses oxygen and produces carbon dioxide as waste product. Contains its own DNA and ribosomes

Plant Cells

Contains unique components such as: Cell wall, central vacuole and plastids such as chloroplast

Central Vacuole

A large, membrane-bound structure which

stores water and can fill much of the cell. Plays a key role in osmosis. Stores also nutrients, ions, and waste

products.

Osmosis

Releasing water under dry conditions and absorbing water under wet conditions

Tonoplast

The membrane that surrounds the Central Vacuole

Chloroplast

A type of plastid that stores chlorophyll and other

pigments for photosynthesis. Contains its own DNA and ribosomes.

Tylakoids

The interconnected sacs that store chloroplast pigments.

Grana

Stacks of Tylakoids

Chromoplast

Plastids that store orange/yellow pigments

Amyloplast

Plastids that store starch

Cell Wall Parts

Middle lamella, primary cell wall, secondary wall, plasmodesmata

Middle Lamella

A thin layer of pectin

binding adjacent cells

Primary Cell Wall

Occurs on the surface of all plant cells - initially deposited on the surface of middle lamella

Microfibrils

A threadlike component of the cell wall, composed of cellulose molecules.

Secondary Cell Wall

Made of layers deposited inner to the primary wall. Occurs as cell reach mature size.

Lignin

Deposited together with cellulose - adding rigidity

Plasmodesmata

Pores which allow for communication between

cells

Plant Growth

All tissues originate from meristematic tissue and later

differentiate and specialize

Totipotent

Stem cells with the potential to differentiate into any type of cell.

Meristems

Regions of continuous cell division and growth

located in different points of the plant.

3 Types of Meristems

Apical meristems, Lateral meristems, & Intercalary meristems

Apical Meristem

Located at very end of stems (shoot apical

meristems) and roots (root apical meristems). They produce 3 types of primary meristematic tissues

3 types of Primary Meristematic Tissues

Protoderm, Ground Meristem, & Procambium

Protoderm

Gives rise to epidermis

- Dermal tissue

Ground Meristem

Gives rise to ground

tissue (photosynthetic, storage, support)

Procambium

Gives rise to vascular tissue

(transport)

Lateral Meristem

Responsible for secondary growth

- increase of girth. Located in 2 regions

Vascular Cambium

Gives rise to vascular tissue

Cork Cambium

Arises from the pericycle and the cortex - produces periderm (secondary dermal

tissue)