botany chapters 1-5

Robert Hooke, 1665

Who discovered cells and when were they discovered?

Cell theory

All living organisms are composed of cells and cells form a unifying structural basis of organization

Matthias Schleiden and Theodor Schwann, 1838

Who developed the cell theory and when?

Robert Brown, 1831

Who discovered the nucleus and when?

Rudolf Virchow, 1858

Who argued there is no spontaneous generation of cells and when was it argued?

Louis Pasteur, 1862

Who experimentally disproved spontaneous generation and when was it disproved?

Light microscopes

Increase magnification as light passes through a series of transparent lenses made of glass or calcium fluoride crystals

Compound microscope

• Light passes through thinly sliced material

• In general can distinguish organelles 2 micrometers or larger in diameter

• Can magnify up to 1500x

Dissecting microscope

• Allow three-dimensional viewing of opaque objects

• Can magnify up to 30x

Electron microscopes

Use a beam of electrons produced when high-voltage electricity is passed through a wire

Transmission electron microscope

Up to 200,000x magnification, but material must be sliced extremely thin

Scanning electron microscope

• Up to 10,000x magnification

• Surface detail can be observed on thick objects.

Scanning tunneling microscope

• Uses a probe that tunnels electrons upon a sample

• Produces a map of sample surface

• Even atoms can become discernible

• First picture of DNA segment showing helical structure

Prokaryotic cells

Lack a nucleus - bacteria

Eukaryotic cells

Contain a nucleus - plants and animals

Cell walls

Rigid boundary of cells

Organelles

Membrane-bound bodies found within eukaryotic cells that have various shapes and sizes with specialized functions

Protoplasm

What does the cell wall surround?

Protoplasm

Consists of all living cell components, including the cytoplasm and the nucleus itself

Plasma membrane

The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition

Cytoplasm

Consists of all cellular components between the plasma membrane and the nucleus

Cytosol

Fluid within cytoplasm containing organelles

Why do smaller cells grow faster?

Smaller cells have relatively large surface to volume ratios enabling faster and more efficient cellular communication

What is the main structural component of cell walls?

Cellulose (long chains of glucose monomers)

Hemicellulose

Holds cellulose fibrils together inside the cell wall

Pectin

Gives stiffness (like in fruit jellies) inside of cell wall

Glycoproteins

Proteins with associated sugars found inside cell wall

Middle lamella

Sheets that hold cells together, first produced when new cell walls are formed (shared by two adjacent cells)

Primary walls

Laid down on either side of middle lamella

Secondary walls

Produced inside primary walls

Lignin

A complex organic polymer that gives structure to plants, especially wood and bark

Plasmodesmata

Are cytoplasmic strands that extend between cells through minute openings

Fluid mosaic model

Plasma membrane is dynamic structure (always changing)

Nucleus

Control center of the cell and contains DNA

Nuclear envelope

Layer of two membranes that surrounds the nucleus of a cell

Nucleoli

Composed primarily of RNA

Chromatin strands

Composed of DNA and proteins; coil and become chromosomes

Endoplasmic reticulum

An 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 and associated with protein synthesis and storage

Smooth ER

Devoid of ribosomes and associated with lipid secretion

Ribosomes

Consist of two subunits that are composed of RNA and proteins

Dictyosomes

Stacks of flattened discs or vesicles

What are the functions of dictyosomes?

•To modify carbohydrates attached to proteins that are synthesized and packaged in the ER.

•To assemble polysaccharides (sugars) and collect them in small vesicles.

Plastids

organelles found in plant and algae cells that perform photosynthesis and other functions

They are membrane-bound and contain their own DNA and ribosomes

Grana

Stacks of thylakoids

Thylakoid

First steps of photosynthesis occur in ______ membranes (contain chlorophyll)

Stroma

Matrix of enzymes involved in photosynthesis

Chromoplasts

Synthesize and accumulate carotenoids (yellow, orange, red)

Leucoplasts

Colorless, may synthesize starches (amyloplasts) or oils (elaioplasts)

Mitochondria

Releases energy produced from cellular respiration

Microbodies

Small, spherical bodies distributed throughout the cytoplasm that contain specialized enzymes

Central vacuole

A membranous sac that takes up 90% of volume in a plant cell

Cytoskeleton

Involved in movement within cell and in cell's architecture

Microtubules

Control addition of cellulose to cell wall

Are thin, hollow, tubelike and composed of tubulins (proteins)

Microfilaments

Long, thin fibers that function in the movement and support of the cell

Traits of plant cells

•Cell walls

•Cell plate and plasmodesmata

•Plastids and vacuoles

Traits of animal cells

•Internal or external skeletons; no cell walls

•Plasma membrane called cell membrane.

•Divide by pinching in two; no cell plate nor plasmodesmata

•Centrioles present during cell division.

•No plastids nor vacuoles

Dictyosomes function

To modify carbohydrates attached to proteins that

are synthesized and packaged in the ER.

• To assemble polysaccharides and collect them in small vesicles.

• Vesicles pinched off from margins of dictyosomes.

• Vesicles migrate to plasma membrane, fuse with it, and secrete contents

to the outside of cell.

• Contents may include cell wall polysaccharides, floral nectars, and

essential oils in herbs.

Radicle

root-like part of a developing plant embryo

Root cap

Thimble-shaped covering of parenchyma cells that protects a growing root tip from abrasion

Region of cell division

Area adjacent to the root cap where cell division occurs

Protoderm

primary meristem that gives rise to epidermis

Ground meristem

primary meristem that gives rise to pith and cortex

(i.e., inner tissues of the stems and roots)

Procambium

primary meristem that gives rise to vascular Cambium

Region of elongation

Area where cells grow longer

• Located just behind the region of cell division

Secondary tissues

Layers of tissues added after primary tissues

Region of differentiation

Area where cells differentiate into distinct types that form various tissues

Root hair

Thread-like extensions along the root that increase surface area for better absorption

Cortex

• A thick area of parenchyma cells between the epidermis and inner tissues used to store food

Endodermis

A one-cell layer boundary between the cortex and inner tissues

Casparian strip

Bands of cell wall material in endodermis that are made of suberin, which is water-resistant

• Force materials entering or exiting the inner tissues to pass thru plasma membranes or plasmodesmata of the endodermis

Passage cells

Thin-walled cells in the endodermis that lack suberin and which allow fluids to pass w/o going thru plasma membrane

Pericycle

A one-cell layer just inside the endodermis from which lateral roots arise

Vascular cylinder

The collective core of tissues inside the endodermis that are involved in transport of fluids

• i.e., the xylem and phloem

Food storage roots

Roots specially adapted to store large amounts of food

Water storage roots

Roots specially adapted to store large amounts of

water

• Found especially in arid regions

Propagative roots

Roots specially adapted to grow into individual new plants

Adventitious buds

Buds located in places other than the stem

Easier to propagate

Pneumatophore

Specialized roots that extend above ground and above water to aid in gas exchange

Aerial roots

Roots extending above ground

Contractile roots

Roots that pull the plant deeper into the soil for thermal stability

Buttress roots

Above-ground roots that add to stability

Parasitic roots

Roots on plants that lack chlorophyll and which depend on photosynthesizing plants for nutrients (needs host)

Ex. Beech drops, squaw root

Haustoria

Projections that connect parasitic roots to their host plant

Saprophyte

Organisms that lack chlorophyll and obtain nutrients from decaying organic matter

Fungi!

Epiphyte

Plants that grow on other plants. Have aerial roots

Ex. Orchids

Epiparasite

A parasite of a parasite

Mycorrhizae

Fungi associated with/ plant roots that aid the plant in uptake of nutrients

Root nodule

Swellings in roots that contain a large # of nitrogen-fixing bacteria

Node

The area of a stem where a leaf attaches

Internode

The region between nodes

Blade

The broad, flat part of a leaf (recognizable)

Petiole

The stalk that attaches the leaf blade to the plant steM (leaves the leaf scar on twigs)

Axil

The angle between the petiole and the stem

that contains a bud

Deciduous

Trees that lose their leaves in autumn, regrow in spring

Leaf scar

A mark left on a twig from where a leaf grew

USUALLY HEART-SHAPED

Bundle scar

Tiny holes within a leaf scar caused by the

xylem and phloem that was within the leaf that

previously grew there

Protoderm

Becomes epidermis

Procambium

Becomes vascular cambium

Leaf primordial

Become leaves

Horn shaped under microscope