exam 1: cells/growth + tissue types

What are the 2 main organ systems of plants?

Shoot (aboveground)

• vegetative organs

  • leaves + stems

• reproductive organs

  • flowers + fruits

Root System (underground)

• only one organ → roots

Shoot System

aboveground. It has vegetative (leaves + stems) and reproductive (flowers + fruits) organs.

Vegetative Organs

Leaves and stems

• Vegetative organs handle the daily survival, growth, and nourishment of the plant. They do not take part in sexual reproduction, though some can create new plants asexually.

Reproductive Organs

Flowers and fruits

• Reproductive organs produce offspring and pass on genetic traits. handle sexual rep.

Root System

Underground! It's only organ is roots.

Determinate Growth

The type of growth that stops after a time. Max size is genetically determined

• Usually a plant cannot heal/regrow

• It's maximum size rarely achieved in nature
  ex: leaves, flowers and fruits

what parts of a plant have determinate growth?

leaves, flowers, fruits

Indeterminate Growth

plant is able to keep growing through life. No max size genetically!

• Usually a plant can heal/regrow.

• It can be limited by resources and environmental factors

ex: roots and stems

which parts of a plant have indeterminate growth?

roots and stems

Cell Theory

1665 – Robert Hooke sees 'chambers' on cork tissue under microscope – calls them "cells"

• 1838 – Schleidern and Swann stated that:

1. All plants and animals are made of cells

2. Cell is the basic unit of life

• 1858 – Virchow added that:

3. Cells arise by reproduction from previous cells - "Omnis cellula e cellula

what r the 3 principles of cell theory?

1) All plants and animals r made of cells

2) cell is the basic unit of life

3) Cells arise by reproduction from previous cells (Omnis cellula e cellula)

Cell Theory - Virchow

Added that cells arise by reproduction from previous cells - "Omnis cellula e cellula"

What r the 4 components all cells have (eukaryotic + prokaryotic) ?

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.

• Composed of organelles suspended in a gel-like material - the cytosol - and protein threads - the cytoskeleton

Nucleus

In eukaryotic cells, DNA is typically housed in the nucleus.

• directs the synthesis of ribosomes and proteins.

• It stores chromatin (DNA + proteins) and the nucleolus (where ribosomes r made)

• Separated from the rest of the cell by the nuclear envelope

Chromatin

Clumps of DNA and protein that resemble jumbled threads

• during cellular growth and maintenance, proteins atttach to chromosomes

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

Chromosomes

During cellular replication, DNA is visible in the form of chromosomes.

• linear in eukaryotes

chromatin is a loose, uncoiled strand used for daily cell functions, while a chromosome is a tightly packed package used safely during cell division

Ribosomes

Structures responsible for protein synthesis. They can either float free in the cytoplasm or be embedded in the endoplasmic reticulum.

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

• they r NOT ORGANELLES!!

Unique Components of eukaryotic cells

• Endomembrane System

  • Vesicles and peroxisomes

• Endoplasmic reticulum

• Golgi apparatus

• Mitochondria

Endomembrane System

Includes the ER and Golgi!

Modify, package, and transport lipids and proteins

endoplasmic reticulum

• unique to euk. and part of endomembrane system

a series of interconnected sacs and tubules that:

• modifies proteins

• synthesizes lipids

golgi apparatus

• unique to euk. and part of endomembrane system

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

Vesicles and Peroxisomes

Bud off from the endomembrane and serve as transport units for diverse materials

• unique to euk.

Mitochondria

The 'powerhouse' of the cell - it is the site of cellular respiration.

• makes ATP from glucose and other nutrients

• uses oxygen and produces CO2 as a waste product

• Contains its own DNA and ribosomes!

• in euk only

what r components unique to plant cells?

• Cell wall

• central vacuole

• plastids such as chloroplast

Central Vacuole

A large, membrane-bound structure that stores water and can fill much of the plant cell.

• Plays a key role in osmosis → regulating water concn in the cell

• also stores nutrients, ions, and waste products.

• surrounded by tonoplast (membrane)

Osmosis

Releasing water under dry conditions and absorbing water under wet conditions

• done by central vacuole in plant cell

Tonoplast

The membrane that surrounds the Central Vacuole in plant cells

Chloroplast

A type of plastid that stores chlorophyll and other pigments for photosynthesis.

• pigments r stored in thylakoids which r found in stacks called grana

• Contains its own DNA and ribosomes.

Thylakoids

The interconnected sacs that store chloroplast pigments

• found in stacks called grana

Grana

Stacks of Thylakoids in chloroplast

what r some other plastids in a plant cell besides the chloroplast?

• chromoplast (stores orange/yellow pigments)

• amyloplast (stores starch)

Chromoplast

Plastids that store orange/yellow pigments

Amyloplast

Plastids that store starch

Cell Wall Parts

• Middle lamella

  • thin layer of pectin binding adjacent cells

• primary cell wall

  • on surface of all plant cells

• secondary wall

• plasmodesmata (pores)

Middle Lamella

A thin layer of pectin binding adjacent cells in the cell wall!

Primary Cell Wall

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

• composed of cellulose microfibrils bundled together

• thin + elastic to allow for cell enlargement

• only cell wall present in some cells

What is the primary cell wall composed of?

cellulose microfibrils! A threadlike component of the cell wall

Secondary Cell Wall

Made of layers deposited inner to the primary wall.

• Occurs as cell reach mature size.

• lignin is deposited together w/ cellulose to add rigidity

• thicker than primary wall

  • as it grows, it pushes cell membrane in → can lead to cell death

Makes up 90% of wood tissue!!

Lignin in secondary cell wall

Deposited together with cellulose - adding rigidity

Plasmodesmata

Pores that allow for communication between cells in the cell wall

what does the orientation of cellulose microfibrils determine in the cell wall?

Direction of cell enlargement + strength!

• think of it like a spring, it can expand longitudinally but not laterally! only 1 axis of growth

Plant Growth

All tissues originate from meristematic tissue and later differentiate and specialize

Totipotent

plant tissue is totipotent → can regenerate the entire plant

the genetic ability of a single cell to divide, grow, and differentiate into a complete, fertile adult plant

Meristems

Regions of continuous cell division and growth located in different points of the plant.

• all plant tissues originate from meristemic tissue

• there r 3 types: apical, lateral, intercalary

3 Types of Meristems

• Apical meristems

  • at extreme top and bottom of plant, responsible for height and growth in soil

  • SAM + RAM

• Lateral meristems

  • girth

• Intercalary meristems

  • only in grasses

ultimate sources of all cells in plant: apical + lateral 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:

• protoderm (epidermis)

• ground meristem (everything else)

• procambium (vascular transport tissue)

3 types of Primary Meristematic Tissues

• protoderm (epidermis)

• ground meristem (everything else)

• procambium (vascular transport tissue)

they are primary meristems. They are the embryonic precursors that give rise to the primary tissues.

how does apical meristem give rise to primary tissue?

1) Apical Meristem (The ultimate "stem cell" source at the growing tips)

2) Primary Meristems (Protoderm, Procambium, and Ground Meristem)

3) Primary Tissues (The mature, functional systems: Dermal, Vascular, and Ground tissues)

Protoderm

Gives rise to epidermis

- Dermal tissue

• type of primary meristemic tissue

Ground Meristem

Gives rise to ground tissue (photosynthetic, storage, support)

• type of primary meristemic tissue

• catch all category, everything that’s not in epidermis or vascular tissue

  • pith, cortex, mesophyll, etc.

Procambium

Gives rise to vascular tissue which aids in transport

• xylem + phloem

• type of primary meristemic tissue

Lateral Meristem

Responsible for secondary growth!

• increase of girth.

• Located in 2 regions:

  • vascular cambium

  • cork cambium

Vascular Cambium

Gives rise to vascular tissue (secondary xylem + phloem)

• region of lateral/secondary meristem

• arises from procambium

Cork Cambium

Arises from the pericycle and the cortex

• produces periderm (secondary dermal tissue) → bark

• region of lateral/secondary meristem

periderm

secondary dermal tissue

• produced by cork cambium which is a region of lateral meristem

the protective, woody outer layer that replaces the epidermis in plants that undergo secondary growth (widening) “bark”

meristems in a seed

The 3 types of primary meristematic tissue can be observed in the embryo of a seed

turgor pressure

when plants fill w water it exerts turgor pressure against the cell wall → makes for rigid boxes

what are cells glued together with?

pectin

plant tissue

aggregates of diff types of cells derived from groups of specialized cells called meristems

• the aggregated tissue is strong + flexible

what r the 3 main tissue systems of a plant?

• ground tissue system

  • mesophyll, pith, etc.

• vascular tissue system

  • xylem + phloem

• dermal tissue system

  • epidermis and periderm

simple tissues

composed of one type of cell

• perform essential functions like storage, photsynthesis, support, storage, regulation

3 main types: parenchyma, collenchyma, sclerenchyma

parenchyma cells

• most common, usually spherical or elongated, but can have diff shapes “brick like”

• thin primary cell walls, but may develop lignified secondary walls

• living cells perform metabolic functions like:

  • photosynthesis and respiration

  • storage and secretion

• only type of cell that when mature can be reprogrammed into other cell types for tissue culture and wound healing!

  • can turn into sclerenchyma or collenchyma, but they can’t turn into parenchyma

which type of cell can reprogram into other cell types and has a thin primary cell wall?

parenchyma cells

parenchyma tissue

when parenchyma cells aggregate to form simple tissues. Can be:

• cortex and pith

  • serve as storage and support purposes (ground tissue)

• mesophyll

  • can serve a photosynthetic (palisade) and regulatory (spongy) role in leaves.

cortex

region btwn plants epidermal and vascular tissue in most stems + roots

• outside vascular ring for storage, transport, support

• formed by parenchyma cells/tissue

pith

innermost core for nutrient storage. inside cylinder of vascular tissues

• formed by parenchyma cells/tissue

mesophyll

can serve a photosynthetic (palisade) and regulatory (spongy) role in leaves.

• made up of parenchyma cells/tissue

what type of cell are the cortex, pith, and mesophyll made up of?

parenchyma cells! these r simple parenchyma tissues

collenchyma cells + tissue

columnar/cylindrical structure.

• elongated, often containing chloroplast, and alive at maturity

• cell walls r composed of alternating layers of pectin and cellulose - usually thicken at corners

  • strong and flexible

• provides support to young stems and leaves to allow for growth (usually in newer/growing part of plant)

• outermost cells of cortex might aggregate into rights around the stem

which type of cell has a cell wall composed of alternating layers of pectin and cellulose that thicken at the corners

collenchyma! cell walls r strong and flexible to provide support to young stems + leaves

what is the function of collenchyma cells?

provides support to young stems and leaves to allow for growth

sclerenchyma cells + tissue

thick lignified secondary cell walls. DEAD at maturity

2 types:

• fibers

  • long, narrow cells w thick pitted cell walls tapered at ends that aggregate into continuous cylinder around stems or form strands

• sclerids

  • can have many shapes and can form sheets or be in small clusters

which type of cell is dead at maturity?

Sclerenchyma cells! live to make thick lignified secondary cell walls then die

what r the 2 types of sclerenchyma tissue?

• fibers

• sclerids

fibers

• a type of sclerenchyma tissue

long, narrow cells with thick, pitted cell walls tappered at the ends

• Can aggregate into continuous cylinder around stems or form strands.

sclerids

• a type of sclerenchyma tissue

can have many shapes (from simple stone shapes to highly branched).

• Can form sheets (e.g. seed coat) or be in small clusters

what r some examples of complex tissue?

vascular system, epidermis, periderm

complex tissue: vascular system

interconnected network of cells traversing entire plant

composed of:

• Vessel elements and tracheids (water- conducting cells)

• Fibers (sclerenchyma cells for support)

• Living parenchyma cells (help load minerals in and out of conducting cells)

• Sieve-tube members (food conducting cells)

• Companion cells (specialized parenchyma cell)

complex tissue: epidermis

usually a single layer of cells in outer part of plant - as many as 6 layers in succulents

• covered in cutin

complex tissue composed of:

• epidermal cells

  • somewhat elongated, without chloroplast

• guard cells

  • specialized to open/close stomata

• subsidiary cells

  • support epidermis and in close association w guard cells and functions to open/close stomata

trichomes - outgrowths of one or more cells

• in roots they form root hairs.

• in leaves they form protective strucutures to prevent water loss and increase absorption in root

cutin

waxy waterproof material that covers epidermis

trichomes

• part of epidermis

they r outgrowths of one or more cells

• in roots they form root hairs

• in leaves they form protective structures

what forms root hairs in stems

trichomes

periderm

a protective layer that forms in older stems and roots → replaces epidermis

• a type of complex secondary tissue

• its composed of:

  • phellem (cork) cells

  • phellogen/cork cambium

  • phelloderm

what is periderm composed of?

• phellem (cork) cells

• phellogen/cork cambium

• phelloderm

Phellem (cork) cells

one of the cells making up the periderm

• DEAD at maturity (sclerenchyma) and with waxy suberin embedded in cell walls

• outermost tissue of periderm

Phellogen

also known as cork cambium!

• the middle tissue making up the periderm

• Creates the periderm by dividing to produce new cells on both sides

phelloderm

parenchyma like cells btwn the cor cambium and cortex

• innermost tissue in periderm so live longer than phellem cells