M3: Cell Structure Flashcards
Plant cells consist of a box-like cell wall surrounding a mass of _
protoplasm
The protoplasm contains organelles, such as
Nuclei
Mitochondria
Chloroplasts
The physical framework within which a plant’s metabolism occurs.
Cells
They regulate the passage of molecules into and out of cells and organelles.
They divide the cell into numerous compartments, each with its own specialized function.
They act as surfaces that hold enzymes.
Membranes
Biological membranes are composed of_ and a _ bilayer.
proteins
phospholipid bilayer
_ proteins are at least partially immersed in the lipid bilayer.
Intrinsic
_ proteins are located outside the membrane.
Extrinsic
• In the fluid _ _, some proteins diffuse laterally and others are bound to adjacent proteins.
• Oligosaccharides can be bound to intrinsic proteins, converting them into _.
mosaic membrane
glycoproteins
• _ —additional membrane molecules can be incorporated into existing membranes
Growth
Transport of material
• _—membrane “bubbles” that can carry materials with the cytoplasm
_ and _
Vesicles
Exocytosis and endocytosis
• _ -all biological membranes are selectively permeable.
Allows for compartmentalization
Permeability
• _ -constantly changing in response to age and environment
Dynamic
● _ are more permeable to hydrophobic substances than anything carrying an electric charge.
Membranes
● Movement of charged substances is assisted by large intrinsic proteins that span the membrane.
Facilitated diffusion
● Molecular pumps bind to a molecule on one side of the membrane, change shape, and release the molecule on the other side—requires energy.
Active transport
Structurally more simple than eukaryotic cells.
They are found in domains Bacteria and Archaea.
Prokaryotic
Contain a membrane bound nucleus and organelles.
They are found in plants, animals, fungi, and protists.
Eukaryotic
A mass of proteins, lipids, nucleic acids, and water within a cell Includes organelles but not the cell wall
Protoplasm
The selectively permeable membrane that covers the protoplasm
Located inside of the cell wall
Plasma membrane
The _ stores the organism’s genetic information.
Is surrounded by the nuclear envelope.
nucleus
Nucleus
○ Composed of two membranes:
○ Contains small holes called _ _
outer and inner membranes.
nuclear pores.
The nucleus holds _ ,
consisting of DNA, enzymes, histone proteins, RNAs, and water.
○ Contains , where ribosomes are made and partially assembled.
○ Occupies up to% of the cell volume.
nucleoplasm
nucleoli
50
The _ _ has a single membrane, the tonoplast.
central vacuole
○ Stores water, salts, crystals, starch, protein bodies, and other granules.
○ Critical for cell enlargement.
○ Recycles _ by taking in
old, impaired organelles and using digestive enzymes to break them down.
central vacuole
monomers
the site of cellular respiration.
mitochondria
Also Have an outer and inner membrane.
○ Inner membrane folds forming cristae increasing surface area.
○ Have their own circular DNA resembling that of prokaryotes.
○ Can divide or enlarge as needed.
mitochondria
_ have an inner and outer membrane and an inner fluid called the _.
Plastids
stroma
○ Includes chloroplasts.
○ Diverse metabolisms take place in
other plastid classes.
○ Contain their own circular DNA
resembling that of prokaryotes.
Plastids
● _ are responsible for photosynthesis and contain _.
Chloroplasts
chlorophyll
○ Membrane sheets called _ project into the stroma.
○ They can form stacks of vesicles called _.
thylakoids
grana
● Starch-storing plastids.
● Occur in nonphotosynth etic areas of the plant.
Amyloplasts
3 other plastids
chromoplasts
leucoplasts
phytoferritin
- _- store bright lipid
pigments found in some fruits and
flowers. - _- large, unpigmented plastids
involved in fat and lipid synthesis.
3.- a plant protein attached to
stored iron that is almost exclusively stored in plastids.
Chromoplasts
Leucoplasts
Phytoferritin
● _ are the site of protein synthesis.
○ Occur in the cytoplasm.
○ Are aggregates of 3 molecules of
ribosomal RNA and ~50 types of
protein.
○ Bound together by the messenger
RNA, forming a cluster called a _.
Ribosomes
polysome
● _ _ is a system of narrow tubes and sheets of membrane within the cytoplasm.
● Important in both manufacture and transport of molecules.
● Two forms:
○ _ (covered with ribosomes)
○ _ (involved in lipid
synthesis and membrane assembly)
Endoplasmic reticulum (ER)
Rough
Smooth
_ are stacks of thin vesicles held together in an array that processes materials to be secreted.
○ Have a forming face where ER vesicles accumulate.
○ And a maturing face where vesicles are released after the contents are processed.
Dictyosomes
_ consists of all the cell membranes except for the inner membranes of and _
Endomembrane system
mitochondria and plastids
● _ is the clear substance of the cytoplasm and is composed of water, enzymes, and other chemicals
Cytosol
_ are small, spherical bodies that isolate reactions that produce or use hydrogen peroxide (H2O2).
Microbodies
○ _ detoxify by-products of photosynthesis.
○ _ are involved in
converting stored fats into sugars.
Peroxisomes
Glyoxysomes
Microtubules are structural elements of the cell that act as a “_.”
cytoskeleton
○ The means of motility for organelles and whole cells.
○ Composed of two types of protein with a globular tertiary structure: _ and_.
○ Separate chromatids during cell division.
● _ are another component of the cytoskeleton.
● Assemblies of a globular protein called.
○ Involved in structure and movement
alphatubulin and beta-tubulin
Microfilaments
actin
○ _ is sometimes converted
into lipids and stored as large oil
droplets.
○ Crystals of calcium oxalate or
calcium carbonate.
○ Silica, tannins, or phenols.
○ Since there is no excretory
mechanism, some of these products are simply stored waste.
Starch
● Majority of plant cells have cell walls (except some sperm cells).
● Not only provides strength and protection but is also a site of considerable metabolism.
cell wall
cell walls are primarily composed of
○ Cellulose
○ Hemicellulose
○ Pectins
● Parallel cellulose molecules crystallize into , which cover the plasma membrane.
○ Cellulose microfibrils are bound together by other polysaccharides called .
○ The wall of one cell is glued to the
walls of adjacent cells by the middle lamella composed of _.
microfibrils
hemicelluloses
pectins
● Plant cells have a thin _ _ _ .
● Cells requiring more strength may form a
secondary, lignified cell wall between the primary wall and the plasma membrane.
primary cell wall
● Cells of multicellular organisms interact and must communicate.
○ Interacting cells sense that they are part of a larger organism and identify how they should differentiate.
○ This requires extensive intercellular communication.
association of cells
● Cells can secrete messenger compounds.
● Plant cells cannot communicate via direct
physical contact.
○ In plants the cell wall and middle
lamella are a barrier.
○ Plasmodesmata allows direct
communication.
Association of cells
_ are small channels that connect adjacent cells.
○ The plasma membrane passes
through them and creates a contiguous membrane from cell to cell.
○ A small stream of the cystol and a section of the ER also pass through the plasmodesmata.
○ These occur singly or in clusters called primary pit fields.
Plasmodesmata
● Plasmodesmata connect protoplasts to create the_.
symplast
● Many cells do not abut each other tightly, so there is intercellular space between.
○ All intercellular space and cell walls together are called the _.
apoplast
The _ and _ together make up the entire plant.
symplast and apoplast
