BIO421 - PLANT CELL STRUCTURES

What is the function of the plasma membrane?

It regulates the traffic of molecules between the cell and their surroundings

What is the function of the nucleus?

The control center of the cell enclosed in membrane containing genes

What is the cytoplasm?

Entire region between the plasma membrane and nucleus made up of cytosol and organelles

What is the cytosol?

Mostly water, enzymes, and byproducts. Contain free ribosomes and microtubules & microfilaments.

Differentiate animal and plant cell

Plant cells have chloroplasts, animal cells don't., Plant cells have walls exterior to their plasma membrane (cell wall), animal cells don't

Why is the plasma membrane referred to as the edge of life?

It is the boundary that separates the living cells from non-living surroundings

What is glycocalyx and its function?

Covalently sugar coated extracellular surface of a plasma membrane, formed by covalently bonded glycoproteins and glycolipids that are interacting with the extracellular matrix and facilitate intercellular communication

What is the glycolipid and its function?

It is a lipid with a carbohydrate attached responsible for cell recognition (recognize surface markers) and structural stability.

What is glycoprotein and its function?

It is a protein with a carbohydrate attached responsible for acting as receptors and provide support for cell to cell adhesion.

What is the phospholipid bilayer and its function?

Composes the plasma membrane and other membranes of the cell. Made up of phospholipids, cholesterol, and proteins.

What are phospholipids and its functions?

Has hydrophilic head and hydrophobic tail (amphipathic) so it arranges itself into a bilayer in an aqueous solution.

What are integral/intrinsic proteins?

Nestled into phospholipid bilayer and stick out on either end, helpful for transporting larger molecules across cell membranes.

What are peripheral/extrinsic proteins?

Proteins that do not extend across the membrane and help with transport or communication

Describe selective permeability.

A membrane allows some substances to cross more easily than others and blocks the passage of some substances altogether.

Describe transport proteins.

Proteins that regulate traffic of materials.

Give the roles of membrane proteins.

(IETCAS) Intercellular joinings, Enzymatic activity, Transport , Cell to cell recognition, anchorage/attachment, Signal transduction

What is meant by the term fluid mosaic model?

Fluid mosaic model is a term used to describe the behavior of the plasma membrane. Mosaic because there is a pattern of different types of molecules put together (proteins, cholesterol, and phospholipids). Fluid because it exists in two dimensions, its molecules are able to drift like icebergs.

What is the nucleus?

It is the control center of the cell containing the genes. It is also the site of ribosome synthesis.

Describe genes.

Genes are a specific stretch of DNA that contains the code for the structure of a specific protein. It contains information necessary for the manufacture of proteins.

What is a nuclear envelope?

It borders the nuclear membrane.

What is the function of nuclear pores?

These allow the passage of materials between the nucleus and cytoplasm. The nuclear pore complex controls it.

What is the nucleoplasm?

A gel like substance where chromatin is stored.

What is the nucleolus?

The site in which new ribosomes are assembled.

How do you make ribosomes?

Some chromosomes have DNA that encode ribosomal RNA, which combines with proteins to make the subunits of the ribosome. These are then transported out through the nuclear pores to the cytoplasm.

What are chromatins?

The complex formed by DNA and its supporting structural proteins. (DNA + histones)

What are ribosomes?

Dot-Like structures embedded on the rough endoplasmic reticulum or cytoplasm, produced by the nucleolus, site for protein synthesis

How does the DNA control the cell?

The central dogma of molecular biology, wherein DNA contains the information, this information is coded into mRNA, ribosomes read that RNA and creates proteins.

What is the endomembrane system?

It manufactures and distributes cellular products. Everything except mitochondira, chloroplasts, plastids.

Describe the endoplasmic reticulum or ER.

Consists of a network of membranous tubules and flattened sacs responsible for modification of proteins and synthesis of lipids

What is lumen?

The space inside the hollow discs and tubules of the ER

What is the rough ER and its function?

ER with ribosomes attached to it wherein proteins fold and undergo modifications. It is also the site of phospholipid synthesis. Has membranous and secretory.

What happens to modified proteins not meant to stay in the ER?

Packaged into vesicles that are used for transport and shipped to golgi apparatus.

What is the smooth ER and its functions?

Responsible for: Synthesis of carbohydrates, lipids, and steroid hormones, Detoxification of medications and poisons, Storage of calcium ions

What is the golgi apparatus/golgi body?

An organelle made up of flattened membrane discs responsible for sorting, tagging, packaging, and distribution of transport vesicles containing lipid and proteins.

Who discovered the golgi apparatus?

Camilo Golgi

Describe the process that occurs in the golgi apparatus.

Vesicles enter the cis side, and empty their contents into the lumen of the golgi body. They undergo modifications then these are packaged into vesicles that exit from the trans side.

What are vacuoles?

Organelle which stores waters and wastes, isolates hazardous materials and breaks down components similar to a lysosome. It is a membranous sac that bud from ER, golgi or plasma membrane.

What are chloroplasts?

Organelles that perform photosynthesis. It has 3 major components: Space between two membranes, Stroma, thylakoid/grana

What are thylakoids?

Membrane discs arranged in interconnected stacks called grana, containing light harvesting chlorophyll

What is a mitochondria

Organelle that harvests energy from sugars and other foods and converts it into another form of chemical energy named adenosine triphosphate. It is the site of cellular respiration.

What is a stroma?

The fluid surrounding the thylakoids.

What are cristae?

Inward protrusions/sheets in an organelle increasing surface area of mitochondria

Differentiate intermembrane space and mitochondrial matrix.

Intermembrane space is the space between membranes. Mitochondrial matrix contains DNA and ribosomes.

What is the cytoskeleton?

It is a network of filaments that serves as both skeleton and muscles for the cell, functioning in both support and movement.

What are microfilaments?

Actin filaments that help maintain cell shape and are important in cell movement

What are microtubules?

Made of globular proteins called tubulins that form a hollow, straw-like tube which helps cell resist compression forces. During cell division, these form spindle which pull chromosomes apart.

What are centrioles?

These are tubelike structures (specialized microtubules) that aid in cell division, guiding the movement of chromosomes when cell divides

What are flagella/flagelum?

Long, hair-like structures that extend from the cell surface and are used to move an entire cell in an undulating wavelike motion.

What are cilia?

Generally shorter and more numerous than flagella and promote movement by coordinate back and forth motion

Name the function of cilia and flagella in nonmoving cells

Move fluid over the surface of the tissue

What is the function of cell walls?

It protects the cell by maintaining its shape and restraining the cell from absorbing too much water. It is also the site for cell metabolism.

What are plasmodesmata?

These are specialized channels between plant cells. It creates open channels through cell boundaries.Plasma membrane passes through it.

What are primary pit fields?

These are regions of plasmodesmata clustered together.

What is the cell wall made up of?

Cellulose, hemicellulose, pectins

Describe the composition within a cell wall.

Cellulose molecules form microfibrils that are bounded together by hemicellulose.

Describe the middle lamella.

Middle lamella glues together the wall of one cell to an adjacent cell, it is made up of pectins.

Differentiate symplast and apoplast

Symplast pathway is created by the connection of the protoplast through the plasmodesmata (within cytoplasm) while the apoplast pathway is the intracellular space between cells within cell walls which permit rapid diffusion of gases.

What are dictyosomes?

Individual, disc shaped stacks of membrane bound cavities (cisternae) that make up golgi body (cisternae -> dictyosomes -> golgi body)

What is the role of dictyosomes in cell metabolism?

This is where vesicle processing takes place. Modification of vesicle membrane or modification of its contents may take place.

Describe how a material is brought to a dictyosome, what happens inside, and how is it released.

ER vesicles form cisterna, which then attaches to dictyosome, creating the forming face. The materials are processed based on use, then it exits through the maturing face.

What are some of the things that might happen to material after it is released by dictyosome?

Materials are transported to either plasma membrane, cell wall or vacuole.

What are plastids?

Group of dynamic organelles able to perform many functions.

Function of peroxisomes

These detoxify byproducts of photosynthesis

Function of glyoxysomes

These are involved in conversion of fats to sugar

What are amyloplasts?

involved in the storage of starch (a type of leucoplast)

What are chromoplasts?

Contain abundantly colored lipids that manifest in flowers and fruits

What are etioplasts?

Develop from proplastids that have not been exposed to light and develop into chloroplasts when exposed to light

What are leucoplasts?

Colorless plastids involved in the synthesis of fats and lipids

Name the task of cells of shoot/root tips

Cell division and production of new protoplasm

Name the task of epidermis

Water retention and has cutin & wax which are barriers against fungi and insects

Name the task of epidermal gland cells

Protection, by producing poisons that inhibit animals from harming plants

Name the task of green leaf cells

Collecting solar energy by photosynthesis

Name the task of root epidermal cells

Collecting water and minerals

Name the task of vascular cells

Transporting water, minerals, and organic molecules

Name the task of petals cells

Pigments that attract pollinators

Name the task of scent cells

Fragrances that attract pollinators

Name the task of nectary cells

Sugars that attract pollinators

Name the task of stamen cells

Indirectly involved in producing sperm cells

Name the task of carpel cells

Indirectly involved in producing egg cells

Name the task of fruit cells

Produce sugars, aromas, flavorful compounds that attract fruit-eating/seed-dispersing animals

What is the negative consequence of having multicellularity and division of labor?

As each cell becomes more specialized, it depends more on the others. Damage to one part of the organism may result in the death of all cells.

Differentiate a monolayer and bilayer.

Monolayer occurs when phospholipids form a single layer with the hydrophilic ends forming hydrogen bonds with water molecules and the hydrophilic ends projecting out of the water. With agitation, phospholipids form a bilayer, allowing the greatest number of hydrogen bonds to form while minimizing disruption caused by fatty acids.

What is exocytosis?

A form of material movement that is a means to excrete by fusing a vesicle to a cell membrane then releasing its contents to the cell exterior.

What is endocytosis?

A form of material movement wherein a small invagination forms in the other membrane then pinches shut, creating a new vesicle that contains extracellular material.

Define impermeable membrane.

Impermeable membrane allows nothing to pass through. Note that no biological membrane is impermeable to everything.

Define freely permeable membrane

It stops nothing from passing through (virtually anything).

Describe the principle of compartmentalization.

IT is the formation of many compartments, each specialized for a particular process. Cells are filled with many compartments (organelles) which have selectively permeable membranes

What is facilitated diffusion?

The presence of large intrinsic/integral membrane proteins allow hydrophilic, charged molecules to diffuse through the membrane.

What is active transport?

Large intrinsic/integral membrane proteins bind a molecule and force it through the membrane, consuming energy in the process.

What is the tonoplast?

The vacuole membrane

Differentiate proplastids and chloroplasts.

Proplastids: plastids of young, rapidly dividing cells, undiffirentiated. They turn into chloroplasts when exposed to light.

What are plastoglobuli?

These are microscopic, lipid proteins found inside chloroplasts and chromoplasts.

What is phytoferritin?

Plant version of iron, this iron-storage protein is found in plastids

What is a polysome?

Cluster of multiple ribosomes translating messenger RNA

What are alpha and beta tubulin?

Proteins with globular tertiary structure that associate as dimers called tubulin. Building blocks of microtubules when aggregated