Plant and cell architecture

Leaf Primordial

very early stages of the leaf. Axillary buds are between the leaf and stem, and have similar structure to primordial, and when they grow they produce branches

Vacuole extra

vesicles from golgi separate and the cells that are still dividing fuse into parenchyma - golgi has lipid membrane called the tonoplast - inside the tonoplast there is a liquid solution that has different molecules - vacuolar sap; -vacuole is large structure mainly containing a watery solution - an advantage of having a large vacuole is that the plant can build a large body with less organic material - vacuole is a membrane bound organelle

Vacuole

the vacuole occupies 80-90% of a mature parenchyma or epidermal cell. the Golgi produces provacuoles, present in meristematic cells, which fuse to form the vacuole. -tonoplast -vacuolar sap:

Cytoskeleton

Components: made of two major components, the microtubules and the microfilaments

Overall, plants tend to ___ the levels of CO2 in the atmosphere?

Decrease - the chloroplasts are responsible for taking the CO2 out of the air. plants are dependent on organic molecules coming from the shoot to go to the roots

Vacuole and vacuolar sap

Water Minerals, organic acids, sugars (it is a solution with high concentration of solutes and provides a driving source for the movement of water inside the cells) -secondary metabolites - i.e. anthocyanins, tannin, nicotine - ecological role = responsible for coloration. The color in plants is due to water soluble anthocyanins. Tannins and nicotine have more of a defense function. Lytic enzymes: ribonucleases, protease, glycosidases. important for recycling of nutrients. There will be a release of enzymes and will break proteins into amino acids and the amino acids will be sent to other parts of the tree to store nutrients. Protein bodies - characteristic of seeds, the vacuole becomes a place of storage proteins

in a bell pepper plant, where would you find these different types of plastids?

in a bell pepper plant - in a ripe fruit - when its green you have a lot of chloroplasts, but when it is mature it has more caratinoids and is responsible for the red color

Why do expansins go to the wall rather than the vacuole?

Because they lack a signal sequence that mediates entry into the vacuole. - in this case if they don't have any other signal they go to the wall, in order to go to the vacuole they have to have another sequence to tell them were to go.

the shape of a plant cell is ultimately determined by the:

Cell wall

cytoskeleton functions extra

- During prophase they form a ring that is called the preprophase band that determines where the cell will divide, which is an important factor in determining the shape. - Then it forms the spindle apparatus that seperates the chromosomes. - Microtubules will form a structure - phragmoplast, and then vesicles from the ER move from the center of the cell to the microtubules - As the vesicle fuses it will become plasma membrane for the two cells and the vesicle will become the early cell wall

Nucleus: nucleolus

(1 or more): it is the site of ribosome assembly (small and large subunits) ---synthesis of ribosomes

Golgi examples

After exiting the ER it can be bound to by coding proteins and can influence where the vesicle goes. The proteins can meke it go to the Golgi. The golgi has different stages of development. At the trans golgi the vesicles can separate and go tot other parts of the cell Another fuction of golgi is that is has many enzymes involved in synthesis of cell wall polysaccharides, but not cellulosic. Proteins can be inside vesicles, it can also be polysaccharides. The vesicles can go to different parts of the cells and it can fuse with plasma membrane and the vesicle becomes part of the plamsa membrane and the inside can contribute to part of cell wall. Vesicle can also be coded by clathrin and will go to vacuole Vesicle can also be coded by COP1 which goes back to the ER or back to the golgi

Tissues:

Each organ consists of dermal, ground, and vascular tissues.

Tissues: dermal types

Epidermis: the epidermis covers all parts of the primary plant body. the epidermal cells are tightly connected to each other. Shoot epidermis: cuticle and stomata, also trichomes Root epidermis:yound portions of the roots: root hairs, lack of stomata, no cuticelor only a thin cuticle Older portions: the epidermis tends to become suberized, which makes oler portions of the root impermeable to water and nutrients

Growth and Development of the plant body: Meristems SAM

Meristems: regions of the plants where the cells are dividing. maintain the capacity of cell division - SAM- leaves, stem, and axillary buds - form very close to meristem

Ground tissues: 3 kinds

Parenchyma Collenchyma Sclerenchyma

Growth and Development of the plant body: RAM

Root apical meristems: has to break through other tissues before it reaches the outside - the apical meristems are mainly responsible for elongation and branching - primary growth. the apical meristems give oridin to the primary plant body

Ground tissues: Sclerenchyma

support of non-growing parts of the plant, defense. cells with thick cell walls and usually dead at maturity (shel of walnut, or peach pit, defense function to prevent damage to embryo) --when the cell differentiates and is functionally mature the cells are dead - very long bundles of cells

Vascular tissues: types

Xylem phloem

Expansis are proteins present in plant cell walls. what is the correct sequence of events of synthesis and transport of expansis to the cell wall?

Transcription-->processing of mRNA-->exit from the nucleus-->translation and movement through the ER->movement through the Golgi-->delivery within vesicles to the wall.

Vascular tissues: xylem

conducting elements: tracheids and vessels (dead at maturity) Fibers Parenchyma cells - movement of water and nutrients fromt he roots to the shoot. movement occurs through conducting cells of hte xylem and they are called tracheids and vessels. they are surrounded by fibers and parenchyma cells which also have conduction characteristics

Endoplasmic Reticulum

consists of flattened or tubular sacs (cisternae) Functions: sity of phospholipid biosynthesis - synthesis of proteins that are retained int he ER or Golgi, membrane proteins or proteins that will be secreted into the vacuole or outside of the cell. - glycosylation of proteins - proteins will be modified by having the attachment of sugars which can influence final location

Biological Membranes: Structure

- Phospholipid bilayer - glycosyl glyceride bilayer in plastids the lipids in the membrane vary in length and degree of unsaturation (number of double bonds). this is important in determining the temperature at which the membrane transitions from a gel to a liquid. shorter length and more double bonds lower transition temperature (remains liquid at l temperatures) (like in sagebrush)

Cytoskeleton cont...

- The microtubules can grow and shrink - the + end is where it stacks more proteins and will grow and the - end is where they separate. - They are formed by polymerization of actin, the actin molecules form "strings" that twist around each other and forma microfilament. They can grow and shrink by gaining or losing actin subunits - Functions of the cytoskeleton is similar to other eukaryotic cells, however in plants the shape and support is determined by the cell wall.

Chloroplasts continued

- The site of harvesting light, chlorophyll is in the thylakoids and is why they are green Stroma contains the enzymes that will be responsible for taking CO2 from the air and making sugar - Horizontal gene transfer - some genes now move to the nucleus. - An advantage of genes present in the nucleus and some that are in the chloroplast: now can have much better control of the two functions - genes in the nucleus have a higher ability to control the process of photosynthesis - Chloroplasts are at a particular stage of development, in general it is called plastids

Vascular tissues: phloem

- conducting elements: sieve elements (angiosperms) Sieve cells (gymnosperms, ferns) - companion cells, parenchyma cells, fibers - move the carbohydrates in different directions depending on the stage of the plant. can be moved from storage to leaves to grow. --conducting elements: vary depending on group of plants. The sieve elements for the movement of molecules. they are not dead cells, they don't have a nucleus but have metabolism. the cells surrounding are companion cells, parenchyma cells, fibers.

Proteins

- integral (embedded in the lipid bilayer, - ion channels, water channels) - peripheral (they attach by non covalent bonds) ionic or hydrogen bonds to the membrane - participate in signal conduction and this leads to a series of chemical changes inside the cell which can lead to changes in gene expression -anchored: they are anchored by lipid molecules, which are covalently bound to the protein

Nucleus: Chromatin and different forms

- it is composed of DNA and associated proteins --during interphase - the chromatin can be in various stages of condensation. --mitosis - will be condensed in a state to form chromosomes. --Heterochromatin: highly compact and transcriptionally inactive form of chromatin --Euchromatin: dispersed form of chromatin (in different degrees of condensation). some of the euchromatic is transcriptionally active

Functions of membranes

- membranes are semi-permeable barriers that control the movement of substances in and out of the cell and between cell compartments - membranes contain molecules involved in different metabolic processes, (hormone receptors, electron carriers, ATP synthesis) - different membranes carry specific functions: --synthesis of cellulose (plasma membrane) --light absorption (thylakoid membrane of chloroplasts)

cytoskeleton - components defined

- microtubules - hollow cylinders form by polymerization of tubulin - microfilaments: are formed by polymerization of actin - microtubules assemble and disassemble. there is an equilibrium between polymerized and non polymerized forms.

Cell wall composition

- middle lamella: it glues plant cells together - primary wall: present in all plant cells - it forms while the plant is growing - secondary wall: present in some plant cells, --Tracheids, vessels, fibers. this wall forms after cessation of cell growth --primary wall: as the cells are separating there is a middle lamella that forms int he middle of the two "cells" then more substances enter in between the lamella called the primary wall

Cell wall Functions

- prevents bursting of the plasma membrane in a hypotonic solution - the cell wall determines the size and shape of a plant - the cell wall contributes tot he support of the plant. - plant defense - plants cell wall is a structure that is hard to penetrate, particularly by microorganisms

Chloroplasts (plastids)

- site of photosynthesis - chloroplast envelope: two membranes - the thylakoid membranes contain photosynthetic pigments (chlorophyll, carotenoids) and electrons transport carrier - site for the light reactions of photosynthsis in which light energy is converted into chemical energy. -stroma: site of fixation and reduction of CO2 into sugars - the chloroplasts contain circular DNA, tRNA, ribosomes. - mitochondria nad chloroplasts are semiautonomous organelles, most of their proteins are coded by nuclear genes.

Functions of the nucleus

- storage and replication of genetic information - assembly of ribosomal subunits - transcription of DNA into RNA and processing of RNA (transcription is converting DNA into RNA, then the RNA that has been processed will move into cytoplasm which is where translation occurs). (nuclear envelope is connected to another system of membranes - the ER)

cytoskeleton functions

- the microtubules form the preprophase band that marks the future plane of cell division. - microtubules form the spindle apparatus that separates chromosomes during meiosis. - during cytokinesis, the microtubules form the phragmoplast - the phragmoplast directs the deposition of ER vesicles to the growing plate.

Overview of plant structure

- vegetative plant body part not involved in sexual reproduction Organs: --Roots: anchorage, absorption of water and minerals, transport, storage --stem: support of leaves, transport, photosynthesis --Leaves: photosynthesis

General Characteristics of green plants

1. Transform solar energy into chemical energy. photosynthetic pigments: chlorophyll a, b and caratinoids 2. cell walls rich in cellulose

General characteristics of Land plants:

1. land plants are multicellular photosynthetic eukaryotes 2. land plants have an embryo that is retained and protected for some time by the parent 3. non motile - they grow towards their food source (light, water, minerals). indeterminate growth - as long as plant is alive they have capacity to continue growing when conditions are favorable. 4. most land plants have supporting tissues 5. most land plants have structures to move water from roots to aerial parts of the plant (xylem), and structures to move their products of photosynthesis and non-photosynthetic organs. 6. most land plants have structures to conserve water (cuticle - waxy layer that reduces water loss, and stomata)

Nucleus: nuclear envelope

2 lipid bilayers, the perinuclear space, and nuclear pores.

Nucleus: Parts

Nuclear Envelope Nucleolus Chromatin

ER continued

Transport of some proteins mRNA binds to something that is free in cytosol and then translated into sequence of amino acids and then the polypeptides free in cytoplasm Also translation could start, but polypeptide has sequence of amino acids that is recognized by SRP (signal recognition particle) and then the molecule will interact with a receptor on the membrane of the ER. The receptor opens and then the polypeptide is guided to the inside of the ER and the process of translation continues, then the signal will be cleaved and then the polypeptide is in the lumen of the ER, and can have additional information to determine where it will go, it can be on membrane, or in the lumen, or exported from the ER Vesicles that carry protein are cargo, the vesicles can separate and can continue through the golgi apparatus

Golgi Apparatus (golgi complex)

a dynamic structure consisting of flat sacs and cisternae Functions: --modification of proteins and lipids via the addition of oligosaccharide side chains (sugars) --synthesis of non-cellulosic cell wall polysaccharides --vesicles separate fromt he golgi and deliver their content to the plasma membrane or the vacuole --the fate of the vesicles is determined by the proteins that bind to them

When do plants respire?

all the time - plants release CO2 to the air through respiration and take CO2 from the air via photosynthesis

Why do expansis go to the wall rather than the chloroplasts?

because they have a signal sequence that mediates binding tot he ER - signal sequence determines where the expansins go.

Tissues: epidermis extras and function

function of epidermis depends on if it is a shoot or root epidermis - shoot epidermis: control gas exchange. they need a certain gas for photosynthesis (CO2). the stem and leaves controlt he CO2 that gets in and can regulate the amount of water vapor that is lost from the plant --root epidermis: varies on portions of root-->young portions root hairs would be permeable to the movement of water into the plant and the oler portions of roots as it gets away from the teip the epidermis becomes impermeable -->most of water is absorbed in the younger portions of the roots.

unsaturated lipids increase the fluidity of membranes. where would you expect to find membranes with a higher concentration of unsaturated lipids?

in plants growing in cold climates

Cytoskelection functions continued: microfilaments

microfilaments: cytoplasmic streaming - particles and organelles move along microfilaments using ATP. - tip growth of plant cells (pollen tubes, root hairs) the movement of vesicles to the growing tips is directed by microfilaments. - Imagine have pollen tube, some are small and some are long, the base is not growing, but it is the tip and the movement of vesicles is determined by microfilaments

Ground tissues: Parenchyma:

photosynthesis, storage, basic metabolic processes. - commonly the most abundant type of tissue cell in a plant. the cells where the photosynthesis is occuring. if you cut a carrot there will be a lot of paranchyma cells in it.

Growth and Development Cont: vascular cambium

vascular cambium and cork cambium: it causes growth in diameter: secondary growth - under certain developmental and/or environmental conditions the SAM becomes a floral meristem

Plastids cont.

plastids originate from protoplastids present in meristematic cells - chromoplasts leucoplasts or amyloplast -within the cell have structures called proplastids, and then depending on where cell goes within the plant, proplastid will differentiate in different ways -The proplastid will express different genes in order to be in different parts of cell - If proplastid is destined to be on the shoot apical meristem it will eventually become chloroplast - When the floral meristem becomes the flower, the proplastids can become (they came from meristematic cells) and will become chromoplasts - instead of incorporating more chlorophyll they will include more caratonids

The plant cell:

protoplast: is everything but the cell wall - include plasma membrane and everything inside Cell wall

Mitochondria

site of respiration - the matrix contains most of the enzymes of the Krebs cycle - the inner membrane contains the molecules involved in electron transport - intermembrane space accumulates H+ that are used to produce ATP - the mitochondria contain circular DNA, t-RNAs, ribosomes ----initially the electron carriers andwill be donating to oxygen to form water, and at the same time have the formation of proton gradient, which will be used to form ATP ----endosymbiosis is the evolutionary origin of the mitochondria ----mitochondria has its own DNA as well as machinery for translation

Ground tissues: collenchyma

support of growing portions of the plants - supports parts of plants that are growing. an example is celery - beneath dermis there is a bundle where the cells are thicker and are plastic enough so the cell can grow.

Biological membrane: extras

the bulk of a membrane is the phospholipid bilayer - the tow layers of phopholipids there is a hydrophobic and hydropylic end on outside. the tails are formed by hydrocarbon chains. - glycosyl glyceride bilayer in plastids - instead of having phosphate they have galactose or another saccharide/sugar, but it is still polar - in order for the membrane to be functional it has to be a liquid consistency, because proteins have to be able to move through the lipid bilayer.

Plasmodesmata

they allow intercellular transport of certain substances - molecules move through the cytoplasmic sleeve. there is a regulation of the cytoplasmic sleeve, most proteins are too large to go through the sleeve. but things like viruses can go through the sleeve

Carbohydrates

they attach to proteins and lipids (structural role) - there are variations in the structure of membranes due to differences in lipids and proteins - lipid presence and protein presence. On the outside of the membrane in plant cells there can be a lot of carbohydrates Carbohydrates: attach to proteins and lipids (structural role, cushioning - to protect membrane because in a functional plant cell - outside the membrane is the cell wall, and inside is very high hydrostatic pressure. The carbohydrates are like a lotion which aborbs some pressure and allows movement of membrane even when pressed hard against the wall.