Plants and their cell components Flashcards
Evolution
Is a change in the heritable characteristics of a population over generations, or the process of diversification by which new species or populations develop from pre-existing forms
Darwin
“descent with modification”
* Species are descended from a common ancestor
* Species change over time
Population Genetics
A change in population allele frequencies over time
* “modification” is the result of genetic changes
Phylogeny
A hypothesis of ancestor-descendent relationships
Nodes
Represent common ancestors
Tips
Represent the descendants of that ancestor
Roots
As we move from root to tip we are moving forward in time
Anchor the plant and collect water
Vascular Tissues
They transport water and nutrients upward from the soil to leaves, where photosynthesis takes place
Vascular plants
Plants with plumbing
Synapomorphy
- Shared derived trait
A characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants
Synapomorphy in plants
Tracheids
Vascular tissue
Xylem
Phloem
Tracheids
Elongated cells that transport water and mineral salts through the Xylem of vascular plants
Xylem
Transports water through the plant
Phloem
- Living vascular tissue that carries sugar and organic substances throughout a plant
- Organic compounds (made from photosynthesis)
When were xylem first present in fossil records
mid-silurian
The first seed trees
- Mature trees with good genetic characteristics and high seed production
- Evolved for the first time at the end of the Devonian period.
- The earliest member of the lignophyte clade
Progymnosperms
- Extinct seedless vascular plants that may be ancestral to seed plants
Lignophytes
Woody plants
Ethnobiology
The study of how traditional cultures classify objects and organisms in the natural world
Cereal grain
Fruits of grasses (monocots) that can be gathered or cultivated as a food for humans
Human civilization was founded on cereal grains
What are plants?
Plants produce oxygen while packaging the sun’s energy into compounds needed for life. They make up more than 80% of the total biomass on earth
Bacterial cell walls
Composed of peptidoglycan, a complex of protein and sugar
Archaeal cell walls
Composed of polysaccharides (sugars)
Eukaryotic cell walls
Found in plants are composed of cellulose, and the cell walls of fungi are composed of chitin
Archaeplastida super-groups
Consists of three major groups:
- Viridiplantae (green algae and plants)
- Red algae (Rhodophyta)
- Glaucocystophytes (glaucophyta)
Species scape
Each organism’s size is proportional to the number of species in that group
Cavitation
When an air bubble enters the xylem
The Great Oxidation Event
The time in Earth’s history, about 2.4 Ga, when the concentration of oxygen in the atmosphere increased dramatically.
Cyanobacteria
Were responsible for the Great Oxidation Event (or the “rusting” of the Earth)
They introduced oxygen into the atmosphere
Are oxygenic phototrophs
Endosymbiotic theory
The idea that mitochondria and chloroplasts, and possibly other organelles in eukaryotic cells, were once free-living prokaryotes that became part of the cell through a symbiotic relationship (eating each other)
Phagocytosis
A form of endocytosis where cells surround food particles and package them in vesicles that bud off from the cell membrane
Mitochondria
- The energy factories of the cell
- Has a double membrane
Mitochondrial DNA (mtDNA)
Genetic material in the mitochondria of the cytoplasm of a cell; only inherited from the mother. It is haploid and matrilineal
Cristi
- The inner membrane of mitochondria
- Is where membrane bound reactions take place
Chloroplasts (green)
- Capture energy from sunlight and use it to produce food for the cell.
- They are sites of photosynthesis
- They store chlorophyll
- Double membraned.
- Can be different shapes.
- 5x larger than mitochondria.
Endosymbiotic transfer
The process through which chloroplasts and mitochondria relinquish the majority of their genes to the nucleus while not having surrendered the majority of proteins integral to the eubacterial nature of their metabolism
Basic requirements for a plant to live
Light, water, carbon dioxide, oxygen, minerals
What is the product of photosynthesis
Glucose
What adaptations do plants require to survive on land?
Land plants evolved traits that made it possible to colonize land and survive out of water. Adaptations to life on land include vascular tissues, roots, leaves, waxy cuticles, and a tough outer layer that protects the spores.
Epidermis
Outer layer of above-ground cells surrounded by a waxy cuticle to prevent water loss
Synanthropic pioneer
A plant that lives near and benefits from humans and the artificial landscapes they create
Plant cell key features
- Cell wall
- Plasma membrane
- Vacuole
- Cytosol/Cytoplasm
- Nucleus
- Chloroplast
- Mitochondria
- Endoplasmic reticulum
- Golgi bodies
Totipotency
The ability for single cell to change from one cell type to another and even develop into a whole plant
Cell wall components
Cellulose (main component)
Hemicellulose
Pectin
Cellulose
A substance (made of sugars) that is common in the cell walls of many organisms. They make up for 30% of the dry weight
Hemicellulose
A matrix containing a gluelike substance that holds cellulose fibrils together
Pectin
As cells form, the middle lamella (a layer of pectin) is produced first. It is normally shared between two adjacent cells
Primary cell wall
consisting of a fine network of cellulose, hemicellulose, pectin and glycoproteins in laid down on either side of the middle lamella
Secondary cell wall
When more layers of cellulose are built, it gives more rigidity
Lignin
Wood
Plasmodesmata
Small channels that directly connect the cytoplasm of neighboring plant cells to each other, establishing living bridges between cell
Plasma membrane components
- Lipid bi-layer with hydrophilic ‘heads’ and hydrophobic ‘tails’.
- Proteins and protein complexes.
Plasma membrane functions
- Detection, transduction and transport of molecules to and from the cell.
- Synthesis of cellulose.
- Formation of intercellular connections
Vacuole structure
- Can take up to 90% or more of the volume of a cell.
- Surrounded by a membrane (tonoplast)
Vacuole function
- Maintenance of cell pressure and pH.
- Movement of water in and out of the vacuole is involved in controlling turgor pressure of the cell
- Store a variety of things such as water, nutrients, or waste products. Larger in plant cells
Turgor pressure
Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall, no water makes the plant less rigid
Nucleus structure
- Has 2 membranes (each has a lipid bylayer) which constitute the nuclear envelope
- The outer envelope is connected with the endoplasmic reticulum, especially the rough ER.
Nucleus function
- Contains DNA
- Control centre of the cell
Endomembrane system (Endoplasmic Reticulum)
- Storage
- Cell signalling
- Lipid biosynthesis
- Movement of molecules and proteins
Endomembrane System (Golgi Apparatus)
- “Post office” packages are dropped of and destinations are assigned
- Proteins sorted
- Glycosylated
- Transfer of proteins
Endomembrane system
- A group of membranes and organelles in eukaryotic cells that works together to modify, package, and transport lipids and proteins
- It contains the nucleus, endoplasmic reticulum, golgi apparatus, vesicles, and the plasma membrane.
Ribosomes
- Site of protein synthesis. It is made up of two sub-units (60S and 40S)
- Ribosomes genes are some of the slowest evolving genes
Plastids
Plant organelles that make/store food or pigments
- Chloroplasts (green)
- Leucoplasts (white)
- Chromoplasts (other than green)
Leucoplats (white)
Store starch and oil
Chromoplats (other than green)
Stores pigments that are responsible for the bright colors in fruit and flowers (other than green)
Etioplast
Plastids that do not contain chlorophyll because they have been kept out of the light for a period of time.
Primary producer (Autotroph)
An organism that can synthesize its own food from inorganic sources
Gross primary productivity (GPP)
Total amount of chemical energy produced in a given area and time period
Three main components of plant cell structure
- Microtubules
- Intermediate Filaments
- Microfilaments
Cytoskeleton
Determine cell shape, cell division, organelle anchoring and movement
* Network of thread-like proteins found throughout the cytoplasm
Three main components:
* Microtubules
* Intermediate filaments (not well studied in plants)
* Microfilaments
Microtubules
- They organize the position of organelle
- Are part of appendages (flagella and cilia) involved in cell motility
- Made up of α and β tubulin proteins
- Stacked in 13 rows to form an alpha helix
- Form a thin, hollow, tube-like structure 15-25
Intermediate Filaments
Thinner than microtubules (12 nm in diameter)
Hold the nucleus in position and control nuclear shape
Microfilaments
- Formed from actin protein
- Organized into helical chains twisted around each other (8 nm in diameter)
- Controls cell shape
- Move cell contents around the central vacuole
- Driven by motor proteins
Motor proteins
- Proteins associated with microtubules and microfilaments
- Attach to the cargo to be moved (i.e. transport vesicles going from ER to Golgi)
- These proteins move, release, reattach and move again using ATP
- Motor proteins are a eukaryotic invention allowing for larger cell size and differentiation
