2.2 the plant cell structure

Anton van Leeuwenhoek

perfected the art of grinding lenses (pieces of glass with curved surfaces) and used them in microscopes of his own design to produce clear, magnified images. (1600s)

Robert hooke

an English physicist and microscopist of the 1600s, made significant discoveries with thecompound microscope (a microscope with two lenses, the eyepiece and the objective).

organelles

tiny structures within cells (little organs)

Robert brown

a Scottish botanist, first identified and named the cell’s **nucleus** 

nucleus

an organelle that serves as cell’s control center

**Matthias Schleiden** & **Theodor Schwann**,

German botanist and zoologist, published separate papers in 1838 and 1839, respectively, that clearly stated that cells are the structural units of life. 

cell theory

theory that the cell is the basic unit of life, of which all living things are composed, and that all cells are derived from preexisting cells.

Rudolf virchow

German scientist who extended the cell theory in 1855 by stating that all **cells come from preexisting cells.** That is, **cells divide to give rise to new cells.**

august Weismann

pointed out that since cells come from preexisting cells, **all cells in existence today trace their origins back to ancient cells.**

Germ plasm theory

states that an organism cells are divided into somatic cells, the cells that make up the body and the germ cells, the cells that produce the gametes.

prokaryotic cells

small, unicellular, no true nucleus, single haploid chromosome

prokaryotic cells

lack membrane bound organelles; cell division by binary fission

ex; bacteria and archaea cells

eukaryotic cells

large and complex, can be uni or multicellular ; has nucleus

eukaryotic cells

paired diploid chromosome; has membrane bound organelles; cell division by mitosis

ex; plant and animal cells

mitochondria

power plant of the cell

ribosome

factories that make products in the cell

Golgi Apparatus

packaging and transport system of the cell

cell wall

communication system of the cell

lysosome

waste removal system of the cell

plasma membrane

the outer boundary of the cell; surrounds a plant cell

• a physical boundary that confines the contents of the

cell to an internal compartment

plasma membrane

regulates the flow of materials into and out of the cell• a selective barrier that allows the interior of the cell to

have a chemical composition quite different from that of the outside environment

nucleus

has selective double membrane, the nuclear

envelope, which contains pores lined with protein

molecules.

nucleoplasm

interior of the nucleus, contains the

DNA, which is associated with certain protein

molecules to form chromatin, a threadlike material

nucleoli

involved in making and assembling the subunits of ribosomes

nuclear pores

made up of proteins, form channels between the interior of the nucleus and the cytoplasm.

nuclear envelope

contains pores lined with protein

molecules.;

barrier that separates the nucleus from the cytoplasm in eukaryotic cells

Chloroplasts

convert light energy to chemical energy• 

plastids that have a photosynthetic function and occur in certain leaf and stem cells

Chloroplasts

* contain the enzymes necessary for photosynthesis

plus the green pigment chlorophyll

chlorophyll

a molecule with

the vital role of absorbing light energy

thylakoids

flat, disclike sacs; membranous stacks of thin, flat, circular plates

grana

thylakoids when arranged in stacks are called

stroma

contains enzymes that catalyze the chemical reactions of photosynthesis that convert carbon dioxide to carbohydrate.

free-living ancestors

The presence of DNA and ribosomes in chloroplasts is significant because it indicates that they had 

Leucoplasts

colorless plastids that form and store starch, oils, or proteins• common in seeds and in roots and stems modified for food storage

Chromoplast

* contains pigments that provide yellow, orange, and red colors to certain flowers, such as marigolds, and to ripe fruit, such as tomatoes and red peppers

Chromoplast

* often form from chloroplasts when chlorophyll breaks down; for example, when green tomatoes ripen and turn red

Mitochondria

* convert the chemical energy in food molecules to ATP
* tiny organelles bounded by double membranes

Mitochondria

* where cellular respiration occurs
* vary in shape but often appear as tiny rods
* has complex internal structure
* also contains a small amount of DNA and a few

ribosomes

cristae

folds in the inner membrane of mitochondria

matrix

the fluid inside the inner mitochondrial membrane; where other respiratory enzymes are found

ribosomes

* sites of protein synthesis
* small organelles that are protein-manufacturing centers of the cell
* use instructions from DNA in the nucleus to assemble proteins by

joining amino acids in precise sequences

ribosomes

0. are most numerous in the cytoplasm, where they are found free—not associated with a particular organelle—or bound to the endoplasmic reticulum.

Endoplasmic Reticulum

* extensive network of parallel membranes that extends throughout the cell’s interior

Endoplasmic Reticulum

* probably continuous with both the plasma membrane and the nuclear envelope surrounding the nucleus
* one of the major manufacturing centers of the cell

rough ER

ER that has ribosomes attached; site of protein synthesis

smooth ER

ER without ribosomes and is associated with lipid synthesis.

Golgi Apparatus

* collects and processes materials that are

to be exported from the cell
* produces and transports some of the

polysaccharides that make up the cell wall

Golgi Apparatus

also collects materials that are stored inside large, membrane-bounded sacs called vacuoles

Golgi body, or dictyosome

a factory for processing and packaging proteins and polysaccharides• 

consists of several flattened sacs, each of which is surrounded by a membrane

vesicles

sacs that contain cellular products.•

 transport materials to the plasma membrane, to the outside of the cell, or to other organelles within the cell

Vacuole

* may occupy as much as 90 percent of the volume of the cell

• surrounded by the vacuolar membrane (tonoplast); same as plasma membrane

Vacuole

* a large membrane-bounded sac filled with a liquid containing water, dissolved salts, ions, pigments, and waste products
* present in many types of cells; plant cells and the cells of certain protists

Vacuole

* temporary storage area
* helps the cell maintain its shape by making it turgid (from the Latin turg, “swollen”).
* provide strength for nonwoody plants. These plants are erect because the vacuoles pressing against the cell walls give them rigidity. 

turgid cell

* one that is swollen or firm due to water uptake.

Cytoskeleton

also important in cell movement•

includes two types of fibers, microtubules and microfilaments

Cytoskeleton

composed of protein fibers• 

a network of fibers that extends throughout the cytoplasm and provides structure to a eukaryotic cell

Microtubules

involved in the addition of cellulose to the cell wall• 

also make up the spindle

a part of flagella and cilia

spindle

special structure that moves chromosomes during cell division

flagella and cilia

hairlike extensions of certain

cells that aid in locomotion;

Microfilaments

much thinner than microtubules• 

can contract and responsible for cytoplasmic streaming

Cytoplasmic streaming

he movement of cytoplasm within the cell• the movement of cytoplasm in leaf cells helps orient the chloroplasts for optimal exposure to light, which strikes the leaf cells at different angles during the day as the sun crosses the sky

Cell wall

* surrounds plant cells
* a coating secreted by the cell
* supports and protects each plant cell while providing

routes for water and dissolved materials to pass to and

from the cell

Cell wall

* composed of cellulose
* provide strength to the entire plant; a massive tree stands

tall and does not collapse on itself because of the

combined strength of its ____

* cellulose

a long-stranded polysaccharide that consists of as many as several thousand linked glucose molecules.

lamella

a layer of pectic compounds, cements the primary cell walls of adjacent cells together. After growth ceases, multiple layers of a secondary cell wall with a different chemical composition may form between the primary cell wall and the plasma membrane.

lignin

In addition to cellulose, secondary cell walls usually contain ___

\-a hard substance in which the cellulose fibers become embedded.

cell signaling

Cells in a multicellular plant need to communicate among themselves, a process that is known as ___

plasmodesmata

tiny channels through adjacent cell walls that connect the cytoplasm of neighboring cell; generally allow molecules and ions but not organelles to pass from cell to cell.

nucleolus

Inner part of the nucleus that begins the assembly of ribosomes.

chloroplast

Captures energy from light for photosynthesis. Solar panels of the cell.

Golgi body/apparatus

Modify, sort, and ship proteins and lipids. Post office of the cell.

Smooth Endoplasmic Reticulum

Creates lipids for the cellular membrane.

Rough Endoplasmic Reticulum

Proteins are assembled and transported into/out of the cell.

lysosome

Uses enzymes to break down old organelles and macromolecules. Garbage disposal of the cell.

vacuole

Stores water, salts, and carbohydrates. Kitchen of the cell.

cytoskeleton

Helps the cell maintain its shape; also involved in movement.

cytoplasm

Material inside the cell membrane but outside of the nucleus.

centriole

Help organize cell division.

cell wall

Gives plant cells extra stability and structure.

cell membrane

Controls what comes in and goes out of the cell.

plant cell

have plastids, have cell wall, have large central vacuole and plasmodesmata

plant cell

no centrioles, no cholesterol in cell membrane; store excess glucose as starch; have fixed regular shape

animal cell

no plastids; no cell wall; has small, temporary vacuoles; no plasmodesmata

animal cells

have paired centrioles; have cholesterol in cell membrane; stores excess glucose as glycogen; have an amorphous shape

phospholipid

composed of a glycerol molecule to which are attached two fatty acids and a molecule containing a phosphate group.

hydrophilic

The polar “head” has affinity for water

hydrophobic

The nonpolar “tail” has aversion to water

membranes

regulate the passage of materials because they are selectively permeable; that is, they prevent the entrance or exit of certain materials while permitting—and even helping—the entrance or exit of other materials.

membranes—particularly the plasma membrane

receive information from their surroundings, including other cells (cell signaling).

Diffusion

the movement of a substance from a region of higher concentration to a region of lower concentration

Osmosis

the movement of water through a selectively permeable membrane from a solution with a higher concentration of water to a solution with a lower concentration of water

Osmosis

the diffusion of water across a selectively permeable membrane

isotonic

solution with a solute concentration equal to that inside the cell; flaccid

hypertonic

a solution with a solute concentration higher than that within the cell; plasmolyzed

hypotonic

a solution with a solute concentration lower than that within the cell; turgid

turgor pressure

internal pressure of water against the cell wall 

active transport

cells expend energy to move specific substances against their concentration gradients (low to high);

Working against the concentration gradient requires a direct expenditure of energy, usually supplied by**ATP**, the cell’s energy-carrying molecule.

Facilitated diffusion

materials diffuse from a region, higher concentration to a region of lower concentration through special passageways in the membrane.

carrier proteins

channels in the membrane that function as conveyor belts; membrane proteins

active transport

the assisted movement of a substance from a lower concentration to a higher concentration of that substance.