THE PLANT CELL: Structures & Functions Flashcards
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
Cellular process in which energy of organic molecules is released for biological work
CELLULAR RESPIRATION
Plants form new individuals by asexual or sexual reproduction
Reproduction
The 2 people that invented the first compound microscope.
Hans and Zacharias Janssen
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
Dutch microscopist made his own microscopes (ca. 500) and observed various types of microscopic organisms;
Antonie van Leeuwenhoek
he is known as the “Father Of Microscopy and Microbiology”
Antonie van Leeuwenhoek
german microscopist , found that plants were composed of cells;
Matthias Schleiden
found that animals were composed of cells.
Theodore Schwann
German concluded that cells can only come from preexisting cells
Rudolf Virchow
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.
General Cell Types
Prokaryotic cells - Bacteria and Archaea
Eukaryotic cells - Protists, Fungi, Plants, Animals
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
Evolution of the eukaryotic cell
endosymbiont theory
Heterotrophic bacteria became mitochondria.
Cyanobacteria became chloroplasts.
Host cell was a large prokaryotic cell.
Endosymbiotic hypothesis
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
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
Three structures define a plant cell:
Cellulosic Cell Wall
Plastids
Large Central Vacuole
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
Inner wall
Surrounds cells of secondary tissues
Wood, cork
Composed of
Cellulose
Hemicellulose
Pectin
Lignin/suberin
Secondary Wall
Long chain of ß glucose monomers
Cellulose molecule
all higher plants except grass have how much percentage of pectin in their walls
30-35%
grass plants have how much pectin percentage
10%
*Dissolves and thickens in water
*May make you feel satiated
*May lower cholesterol
*Includes pectins, gums and mucilages
soluble fiber
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
