B2.2 Organelles and compartmentalization

adaptations of the mitochondria

• double membrane

• compartment of enzymes and substrates of the Krebs cycle in the matrix

• cristae of inner membrane

double membrane

creates small volume of intermembrane space

cristae of inner membrane of mitochondria

large surface area to volume ratio, contain ATP synthase enzymes

adaptations of the chloroplast

• double membrane

• stroma in chloroplast

• thylakoid exterior

• thylakoid interior

stroma in chloroplast

compartmentalized, contains enzymes and substrates of the Calvin cycle

thylakoid membrane

large surface area, provides more photosystems

thylakoid volume

small volume to allow proton accumulation, creating a high concentration in the intra-membrane space

major functions of the nucleus

1. stores cell’s genetic material

2. via gene expression, nucleus coordinates cell’s activities, including growth, metabolism, protein synthesis, and division

nucleoplasm

semifluid matrix inside the nucleus

chromatin

DNA within the nucleus in its less condensed form of cell DNA, organizes to form chromosomes during prophase of mitosis or meiosis

nucleoli

organelles that synthesize ribosomes, one or more within the nucleus

nuclear double membrane

• allows pores in nuclear membrane

• breaks into several vesicles during mitosis and meiosis

nuclear envelope

two concentric membranes which surround the nucleus: inner nuclear membrane and outer nuclear membrane

• outer nuclear membrane continuous with the endoplasmic reticulum

• semi-permeable phospholipid bilayers

nuclear pore complex

relatively large structure creating selective passageway through which molecules are able to travel between the nucleus and the cytoplasm, much larger than channel proteins

substances imported into the nucleus via nuclear pores

histones, helicase, DNA polymerases, RNA polymerases, transcription factors, splicing factors, many others

• proteins responsible for all aspects of genome structure and function are synthesized at ribosomes in cytoplasm

substances exported out of the nucleus via nuclear pores

mRNA, tRNA, ribosomes

nuclear membrane disassembly and reassembly during cell division

• nuclear membrane continuous with RER

• during mitosis nuclear pore complexes detach from sections of nuclear membrane

• during prophase, nuclear membrane separates into vesicles still connected to the RER, vesicles moved to edge of the cell

• separation of vesicles of membrane give space for metaphase spindle

• after anaphase, vesicles attach to chromosomes at each pore of the cell

• during telophase, vesicles moved around new sets of daughter chromosomes, nuclear membrane and endoplasmic reticulum reformed

• nuclear pores reform completing the construction of the new nuclear membranes

• chromosomes separate from cytoplasm into two nuclei