BIOL 145 - week 2 - Simpson college

What is the main structural component of a cell wall

Cellulose

Middle lamella first produced

When new cell walls are formed

Primary Cell Wall are laid down on

Either side of the middle lamella

Primary Cell Wall consists of a fine network of

Cellulose, hemicellulose, pectin, and glycoproteins

Secondary Walls

Secondary walls produced inside primary walls. Derived from primary walls by thickening and inclusion of lignin

Communication Between Cells

Plasmodesmata are cytoplasmic strands that extend between cells through minute openings

Plasma Membrane

The semipermeable outer boundary of the living part of the cell. Regulates movement of substances into and out of cell

Nucleus

Sends coded messages from DNA to be used in other parts of the cell

Nucleoli

Composed primarily of RNA

Endoplasmic reticulum is enclosed

Space consisting of a network of flattened sacs and tubes forming channels throughout the cytoplasm

Rough ER

Ribosomes distributed on outer surface of ER.

Smooth ER

Devoid of ribosomes and associated with lipid secretion

Ribosomes

Consist of two subunits that are composed of RNA and proteins

Stroma

Matrix of enzymes involved in photosynthesis

Mitochondria release

Energy produced from cellular respiration

Vacuoles function

Maintenance of cell pressure and pH, storage of numerous cell metabolites and waste products. Inside the vacuole is a watery fluid called cell sap, which is slightly to moderately acidic.

Cell cycle

Orderly series of events when cells divide

Mitosis refers to the process of

Cellular division

Chromosomes in Prophase

Chromosomes condense by coiling and tightening to become shorter and thicker. Chromosomes made of two identical chromatids held together by centromeres. Kinetochore (protein complex) is located on the outer surface of each centromere. Spindle fibers (microtubules) become attached to the kinetochore and anchored to two poles of the cell. Nuclear envelope dissociates. Nucleolus disintegrates

Metaphase

Chromosomes align between the poles around the circumference of the spindle at the cell’s equator. Spindle fibers collectively referred to as the spindle. At the end of metaphase, centromeres holding each sister chromatid separate

Anaphase

Sister chromatids separate in unison and are pulled to opposite poles, with centromeres leading the way. Spindle fibers gradually shorten as material is continuously removed from the polar ends. Chromatids after separation are called daughter chromosomes.

Telophase

Each group of daughter chromosomes become surrounded by a nuclear envelope. Daughter chromosomes become longer and thinner and eventually, indistinguishable. Nucleoli reappear. Spindle fibers disintegrate.

Three basic tissue patterns in roots and stems

Woody dicots, Herbaceous dicots, Monocots

Meristematic (meristems) Tissues

Permanent regions of growth and active cell division

Apical Meristems

Found at the tips of roots and shoots and increase in length as it produces new cells

Primary Meristems

Produce primary tissues

Primary meristems are called

Protoderm, Ground Meristem, Procambium

Lateral Meristems

Produce secondary tissues that increase the girth of roots and stems (= secondary growth). Include the vascular cambium and the cork cambium.

Vascular Cambium

Produces secondary tissues that function primarily in support and conduction. Tissues produced are responsible for most of the increases in girth as a plant grows.

Cork Cambium

Produces bark

Simple Tissues

Parenchyma

Parenchyma

Composed of parenchyma cells

Complex Tissues

Xylem and phloem, epidermis, and periderm,

Xylem and Phloem

Transport water, ions, and soluble food through plant

Epidermis

A protective layer covering all plant organs. Consists of parenchyma or parenchyma-like cell. Includes specialized cells that regulated the movement of gases in and out of the plant, secretory glands, hairs, crystal isolating cells, and cells that increase the surface area of roots.

Periderm

Comprises the outer bark of woody plants

Xylem

Chief conducting tissue for water and minerals that are absorbed by the roots

Vessels

Long tubes made of vessel elements

Tracheids

Tapered at the ends with pairs of pits that allow water to pass from cell to cell

Phloem

Conducts dissolved food materials produced by photosynthesis throughout plant

Companion cells

Narrow, tapered cells associated with sieve tube members

Sieve Tube Members

Lack secondary cell walls and nuclei

How Roots Develop

Upon germination, embryo’s radicle grows out and develops into first root

Adventitious roots do not develop

From another root, but instead from a stem or leaf

Fibrous roots

Large number of fine roots of similar diameter

Protoderm

Gives rise to epidermis

Ground meristem

Gives rise to cortex and pith

Procambium

Gives rise to primary xylem and primary phloem

Region of Elongation

Cells become several times their original length

Region of Maturation

Cells differentiate into various distinctive cell types

The Cortex

Parenchyma cells between epidermis and vascular cylinder

Vascular cylinder

Core of tissues inside endodermis

Pericycle

Outer boundary of vascular cylinder

Most of cells of vascular cylinder are

Primary xylem or primary phloem.

In most dicots and conifers

Vascular cambium develops from parts of the pericycle and other parenchyma cells between the xylem arms and phloem patches

In woody plants

Cork cambium arises in the pericycle outside of the vascular cambium

Determinate growth

Growth that stops after an organ is fully expanded or after a plant has reached a certain size

Indeterminate growth

New tissues are added indefinitely, season after season

Best agricultural soils

Loams composed of 40% silt, 40% sand and 20% clay

Hygroscopic Water

Physically bound to soil particles and unavailable to plants

Gravitational Water

Drains out of pore spaces after a rain

Capillary Water

Water held against the force of gravity in soil pores

Field capacity

Water remaining in soil after water drains away by gravity

Permanent Wilting Point

Rate of water absorption insufficient for plant needs

Available Water

Soil water between field capacity and the permanent wilting point