文档介绍：Arrangement of DNA in Prokaryotes
DNA Supercoiling
To package the DNA into the cell requires that the DNA be supercoiled.
There are over 50 supercoiled domains in the E. coli chromosome, they are stabilized by association with the structural proteins.
The Nucleus
The nucleus is both a storehouse and a processing factory for ic information.
The process of protein synthesis occurs in the cytoplasm
Chromosomes and DNA
Histones are spaced
along the DNA double
helix at regular intervals,
the DNA itself being
wound around each
histone molecule. The
packing forms a discrete structure called a nucleosome. Nucleosomes aggregate and form a fibrous material called chromatin. Chromatin itself can pacted by folding and looping to eventually form an intact chromosome
Mitosis (有丝分裂)
During cell division, the nucleus divides following a doubling of the chromosome number, a process called mitosis, yielding two cells, each with a plement of chromosome.
Metaphase: chromosomes are paired in the center of the cell.
Anaphase: chromosomes are separating.
Organelles: Mitochondria and Chloroplasts
Eukaryotic cells have a number of important functions localized in discrete bodies anelles:
Mitochondria: in which energy metabolism is carried out,
Chloroplasts:in which the process of photosynthesis is carried out in plants and algae.
Structure of the mitochondrion
A bilayer of phospho-
lipid with embedded
proteins.
Cristae(脊): sites of
enzymes involved in
respiration and ATP
production and of
specific transport
proteins that regulate
the passage of
metabolites into and
out of the matrix of the
mitochondrion.
Matrix(基质):contains a number of enzymes involved in the oxidation pounds (TCA cycle).
Structure of the chloroplasts
Thylakoids(类囊体):the thylakoid membrane is highly impermeable to ions and other metabolites because its function is to establish the proton motive force necessary for ATP synthesis.
Detailed structure of the chloroplasts
Stroma contains large amoun