different organelle assembel to form
Answers
Answer:
1. Plasma Membrane
differentially permeable barrier
controls what can and cannot exit or enter the cell
receives chemical signals
directs assembly of the cell wall
2. Cell Walls
up to 60% cellulose
remainder: hemicelluloses, pectins, lignins, proteins
primary cell wall
<25% cellulose. Remainder: hemicelluoses, pectins, glycoproteins
generally thin and flexible
secondary cell wall
not produced by all cells
develops between the primary wall and the plasma membrane (to the inside of the primary wall)
more rigid than primary wall
up to 25% lignin (adds hardness and resists decay)
no glycoproteins
might have wax, e.g. suberin in cork cells
generally, cells with secondary walls are dead at maturity
3. Middle Lamella
calcium pectate
4. Plasmodesmata
lined with plasma membrane
occur in clusters where the primary wall is thin
adjacent cells can maintain individuality; apparently don’t exchange all materials freely
originate from ER caught during formation of the cell plate during cytokinesis
5. Nucleus
contains about 98% of the cell’s DNA (remainder in plastids and mitochondria)
surrounded by a double membrane: the nuclear envelope
nuclear envelope
outer membrane is apparently continuous with the ER
20-40 nm space between the two membranes, except where they fuse to form 30-100 nm diameter pores, bordered with proteins. Things made in the nucleus, like mRNAs, tRNAs, and ribosomal subunits, can exit through the pores. Ribosomal proteins can enter.
Nucleolus: RNA synthesis ==> ribosomal subunits
6. Ribosomes
not membrane-bound organelles, but generally included because of their size and importance to cell function
composition: ½ RNA + ½ protein
perform protein synthesis
two subunits (large and small), which are made in the nucleus; assemble to form a ribosome when they attach to mRNA
free ribosomes: make proteins destined for the cytosol, plastids, mitochondria, peroxisomes
membrane-bound ribosomes (RER): make proteins destined for some membranes, internal secretion (vacuole), and external secretion
7. Endoplasmic Reticulum (ER)
a system of flattened tubes and sacs
continuous with the plasma membrane and nuclear envelope
ER can also be seen threading through plasmodesmata
RER (rough ER) - major protein synthesis center due to the presence of ribosomes
SER (smooth ER) - synthesis of phospholipids and new membranes
Both types of ER form vesicles that can break away and move to other membrane systems, fuse with them to either secrete contents or enlarge an organelle
8. Golgi Body (Dictyosome)
sacs with vesicles
between ER and PM
Part of the packaging system for secretion (e.g. cell wall components)
Modification, especially of molecules that contain sugar like glycoproteins, cell wall polysaccharides
cell plate formation via Golgi-derived vesicles
9. Vacuole
Forms from fusion of Golgi-derived vesicles or ER
Up to 90% of the volume of a mature parenchyma cell ==> allows plant cells to be large without a lot of cytoplasm: cell volume cubed vs. cell surface area squared
pH is usually around 5-5.5
Contains:
Enzymes - especially hydrolytic enzymes
Proteins, sugars, etc.
Pigments - anthocyanins, betacyanins
Alkaloids, other secondary metabolites
Ions - oxalic acid, Cl-, NO3-
Protein bodies are protein storage vacuoles found mostly in seeds. The pH of these storage vacuoles is around neutrality during storage.
Tonoplast
the membrane around the vacuole
Two types of H+ pumps are present: ATP-H+ and PPi-H+
The tonoplasts of lytic vacuoles and protein storage vacuoles have different aquaporins.
10. Microbodies
peroxisomes - photorespiration, generates H2O2
glyoxysomes, in oil seeds - glyoxylic acid cycle: gluconeogenesis, fat —> sucrose
11. Energy Conversion Organelles
own DNA
double membrane
interior membrane system that is critical to their functions
11a. Plastids
chloroplasts - photosynthesis, sulfate assimilation
stroma, thylakoids, lumen
other plastids: chromoplast, amyloplast, leucoplast
All plastids: starch synthesis, amino acid synthesis, fatty acid synthesis
plastids can change from one type to another
11b. Mitochondria
matrix, cristae, intermembrane space
aerobic respiration - ATP production for cellular activities (work)
Answer:
Different organelle assemble to form cell
Explanation:
- An organized structure with a unique morphology and function is called an organelle. includes the cytoskeleton, ribosomes, mitochondria, plastids, vacuoles, and vesicles.
- A group of parts can be assembled, arranged, and joined to form an organelle.
Cell:
- The fundamental building blocks of all life are cells. A human body has many billions of cells.
- They provide the body with structure, take in food's nutrients, convert them into energy, and carry out certain functions.
- Every cell contains cytoplasm, a liquid that is encircled by a membrane.
- Numerous substances like proteins, nucleic acids, and lipids are also found in the cytoplasm. Organelles of the cell are also suspended in its cytoplasm.
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