THE PLANT CELL: Structures & Functions Flashcards by Miyaki Jan Lim

Biological process that includes capture of light energy and its transformation into chemical energy of organic molecules that are manufactured from carbon dioxide and water

PHOTOSYNTHESIS

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Cellular process in which energy of organic molecules is released for biological work

CELLULAR RESPIRATION

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Plants form new individuals by asexual or sexual reproduction

Reproduction

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The 2 people that invented the first compound microscope.

Hans and Zacharias Janssen

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Englishman was the first to use the term “cell” based on his observations of the cork sliver under the microscope; these are included in his illustrated book Micrographia.

Robert Hooke

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Dutch microscopist made his own microscopes (ca. 500) and observed various types of microscopic organisms;

Antonie van Leeuwenhoek

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he is known as the “Father Of Microscopy and Microbiology”

Antonie van Leeuwenhoek

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german microscopist , found that plants were composed of cells;

Matthias Schleiden

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found that animals were composed of cells.

Theodore Schwann

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German concluded that cells can only come from preexisting cells

Rudolf Virchow

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The cell theory states:

All organisms are composed of one or more cells.
The cell is the basic unit of structure and function in organisms.
All cells come only from other cells.

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General Cell Types

Prokaryotic cells - Bacteria and Archaea
Eukaryotic cells - Protists, Fungi, Plants, Animals

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Cell structure is diverse but all cells share common characteristics such as (4)

Genetic material – in a nucleoid or nucleus
Cytoplasm – a semifluid matrix
Plasma membrane – a phospholipid bilayer
Ribosome for protein synthesis

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Evolution of the eukaryotic cell

endosymbiont theory

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Heterotrophic bacteria became mitochondria.

Cyanobacteria became chloroplasts.

Host cell was a large prokaryotic cell.

Endosymbiotic hypothesis

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Mitochondria and chloroplasts

Similar to bacteria in both size and structure.

Bounded by a double membrane – the outer membrane may represent the engulfing vesicle, and the inner membrane from the prokaryote.

Each contain a circular DNA and divide by splitting

Have their own ribosomes and do produce some proteins like the prokaryotes

Have RNA base sequence suggesting a prokaryotic origin.

Evidences for the endosymbiotic hypothesis

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With a membrane-bound nucleus

With membrane-bound organelles

Cellular functions compartmentalize within organelles and the endomembrane system

possess a cytoskeleton for support and to maintain cellular structure

Eukaryotic Cells

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Three structures define a plant cell:

Cellulosic Cell Wall
Plastids
Large Central Vacuole

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First wall laid down
Outer wall
Surrounds growing cells, meristematic cells, Cells in succulent tissues
Composed of Cellulose, Hemicellulose: alkali-soluble portion of the cell wall, Pectin: water soluble, Glycoprotein

Primary Wall

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Inner wall
Surrounds cells of secondary tissues
Wood, cork

Composed of
Cellulose
Hemicellulose
Pectin
Lignin/suberin

Secondary Wall

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Long chain of ß glucose monomers

Cellulose molecule

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all higher plants except grass have how much percentage of pectin in their walls

30-35%

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grass plants have how much pectin percentage

10%

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*Dissolves and thickens in water

*May make you feel satiated

*May lower cholesterol

*Includes pectins, gums and mucilages

soluble fiber

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Sources of soluble fiber

legumes (beans & peas), oatmeal, oat bran, barely, citrus

*Woody/structural parts of plants *Speeds passage of foods through digestive track *Reduces risk of colon cancer *Includes cellulose, some forms of hemicellulose, lignin

insoluble fiber

Sources of insoluble fiber

fruits & vegetable skins, wheat bran, whole grain cereals

Living surface membrane of a cell Acts as a selective barrier to passage of materials into and out of the cell

Plasma Membrane

Not uniformly distributed Some are organized as part of lipid rafts or microdomains Movement/occurrence under certain conditions or restrictions Heterogenous

proteins in cell membranes

all materials to pass through the cell membrane, breaks in the cell walls to connect plasma membrane

plasmodesmata

have raft and non-raft portions in the cell membrane

Lipids

portions with lipid and proteins

non-raft

clustering of specific lipids and proteins “ordered” clustering or domains microdomains move along the surface

lipid rafts

organized into sets in the cell membrane immune adhesion, viral, synaptic, chemotaxis, protein clusters, but there are _____ which are also not part of lipid rafts

proteins

are a dynamic assembly of proteins and specialised membrane microdomains that are free-floating in the fluid-mosaic lipid bilayer

Lipid Rafts

are composed of the lipid bilayer, cholesterols and sphingolipids. These three components self-assemble and forms microdomains that are highly ordered. The lipid components of these structures are rich in long hydrocarbon chain with hydroxylated ceramide backbones (Simons & Sampaio

Lipid Rafts

an anchor to link cell membranes and protein. These proteins function as enzymes, adhesion molecules, complement regulators, or co-receptors in signal transduction pathways

Glycosylphosphatidylinositol (GPI)

the cell membrane is heterogenous and patchy due to nature of proteins which diffuse or remain attached to its neighbors

Fluid mosaic model

is full of organelles external to the endomembrane system

Cytoplasm

the solution where all this stuff are suspended in. composed of: water, enzymes, precursors, intermediate by –products.

cytosol

are full of membrane-enclosed compartments

Eukaryotic cells

separate incompatible chemical and physical conditions proteins can be both synthesized and hydrolyzed within a single cell Organelles

membranous organelles

pivotal subcellular organelles that have evolved to perform specialized functions in plant cells, including photosynthesis and the production and storage of metabolites.

plastids

synthesis of fats and lipids Plastid

Leucoplasts

specialized for dividing to form new plastid, usually found in meristematic cells Plastid

proplast

chloroplast that develops in the absence of light. Plastid

etioplast

plant cells that have had their cell walls removed by treatment with cellulytic enzymes

Protoplasts

contains large amounts of starch, but no chlorophyll, specialized for storage Plastid

amyloplast

contains red, orange, or yellow carotenoid pigments that are water insoluble, impart color to fruits, etc.; pigments as droplets/plastoglobuli Plastid

Chromoplast

contains oil droplets, usually found in fruits or seeds Plastid

Elaioplast

are typically 5-10 microns in diameter Have their own DNA, RNA, proteins, ATP They normally occur around the perimeter of photosynthetic cells and adjacent to the intercellular air spaces to maximize CO2 uptake.

Chloroplasts

Pigments present in chloroplast include (2)

chlorophylls and carotenoids.

Commonly found in flowers and fruits Contain a diversity of carotenoid pigments [yellow, orange or red] Responsible for flower, fruit and even root coloration in many species, e.g. carrots and sweet potato tuber Plastid

Chromoplasts

Serve as attractants for fruit dispersal signaling that fruit is ripe High nutritional value to animals; many birds eat _______-rich fruits to supply their feathers with colour.

Chromoplasts

Non-pigmented plastids Found in organs that are associated with long-term storage such as roots and seeds

Leucoplasts

Types of Leucoplasts

Amyloplasts, Proteinoplasts, Elaioplasts

leucoplast for synthesis and storage of starch

Amyloplasts

Type of plastids that may be present in statocytes/statolith in the root and be involved in gravity detection

Amyloplasts

Plastids that are capable of re-differentiating into other plastid types, e.g. in the re-greening of potato tubers where cell layers deep within the tuber undergo chloroplast formation

Amyloplasts

leucoplast for protein synthesis and storage

Proteinoplasts

leucoplast for lipid synthesis and storage

Elaioplasts

Largest, fluid-filled organelle with single-membrane [tonoplast]

Vacuole

Meristematic cells contain numerous small provacuoles which eventually fuse, forming a large acidic __________

central vacuole

Contents of a vaculole

water starch salts protein bodies crystals granules/fibrous materials

participate in growth through regulation of turgor Turgid ____ makes up 50-90% of cell volume maintain homeostasis function as storage organelle (of proteins in seeds, malic acid in CAM pathway, anthocyanin pigment) sequester (isolate) toxic materials (secondary metabolites, crystals) contain both anti-fungal enzymes and anti-herbivory compounds degrade old organelles (autophagy) participate in programmed cell death via autolysis.

functions of vacuole

contains anthocyanin pigment

Vacuole

Crystals in cells

Raphides, prismatic, druse, rosette, sand cystolith

Raphides, prismatic, druse, rosette, sand are made out of the compound

Calcium oxalate

cystolith

Calcium carbonate

a double-membraned organelle containing nuclear genes aligned on chromosomes acts as an organizer of cytoplasmic and nuclear activities during the cell cycle helps in shuttling of regulatory factors & gene products via nuclear pores aids production of mRNAs and ribosomes organizes the uncoiling of DNA to replicate key genes

Nucleus

It thus coordinates innumerable metabolic pathways to achieve growth, division and differentiation of the cell, and stores the genetic material of the cell in the form of multiple, linear chromosomes

Nucleus

regulates protein traffic and performs metabolic functions in the cell

endomembrane system

endomembrane system organelle (8)

Nuclear Membrane Endoplasmic reticulum (ER) Golgi bodies Peroxisomes Vacuoles Endosomes Autophagosomes Outer Nuclear Envelope

Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates) Distributes transport vesicles, secretory proteins surrounded by membranes Is a membrane factory for the cell

Rough ER

Synthesizes lipids Metabolizes carbohydrates Detoxifies drugs and poisons Stores calcium ions

Smooth ER

consists of flattened membranous sacs Modifies products of the ER Manufactures certain macromolecules Sorts and packages materials into transport vesicles

Golgi Apparatus

flattened membranous sacs of golgi apparatus

cisternae

faces of the golgi apparatus

cis - packaging trans - shipping

the site of protein synthesis in the cell composed of ribosomal RNA and proteins found within the cytosol of the cytoplasm or attached to the endoplasmic reticulum

Ribosomes

found in all eukaryotic cells. bounded by a double membrane surrounding fluid-filled matrix. inner membranes (cristae) house protein complexes that produce ATP. matrix contains enzymes that break down carbohydrates

Mitochondria

single-membrane vesicles containing enzymes

Microbodies

two Microbodies in plant cells

Peroxisomes Glyoxysomes

with enzymes for converting fats to carbohydrates found in germinating oil-bearing seeds and seedlings rarely found in animals cells

Glyoxysomes

contain oxidase that catalyzes H2O2 production produce catalase that breaks down H2O2 found in leaves

Peroxisomes

not found in plant cells is a membranous sac of hydrolytic enzymes that can digest macromolecules work best in the acidic environment inside the lysosome are made by rough ER and then transferred to the Golgi apparatus for further processing

lysosome

forms a food vacuole types of cell can engulf another cell

phagocytosis

fuses with the food vacuole and digests the molecules use enzymes to recycle the cell’s own organelles and macromolecules,

lysosome

process that use enzymes to recycle the cell’s own organelles and macromolecules,

autophagy

also enhance exchange of materials among organelles, between membranes and organelles and even between cells.

Cytoskeleton

(=circular streaming movement of organelles and other particles around central vacuole) is guided by actin filaments and microtubules of the cytoskeleton

Cyclosis

thickest Two intertwined strands of actin Maintenance of cell shape (compression-resisting "girders"); cell motility (as in cilia or flagella); chromosome movements in cell division; organelle movements

Microtubules

thinnest Hollow tubes Maintenance of cell shape (tension- bearing elements); changes in cell shape; muscle contraction; cytoplasmic streaming in plant cells; cell motility (as in amoeboid movement); division of animal cells

Microfilaments

medium sized filaments Fibrous proteins coiled into cables Maintenance of cell shape (tension- bearing elements); anchorage of nucleus and certain other organ- elles; formation of nuclear lamina

Intermediate Filaments

with a 9 + 2 pattern of microtubules and are involved in cell movement. occur only in the sperm cells of lower vascular and non-vascular plants.

Flagella

Meristematic cells do not have secondary cell walls

True