Download eukaryotic

Organelle/Macromolec
ule
Main function
Structure
Organisms
carboxysome
carbon fixation
protein-shell
compartment
some bacteria
chlorosome
photosynthesis
light harvesting
complex
green sulfur bacteria
flagellum
movement in external
medium
protein filament
some prokaryotes and
eukaryotes
magnetosome
magnetic orientation
inorganic crystal, lipid
membrane
magnetotactic bacteria
nucleoid
DNA maintenance,
transcription to RNA
DNA-protein
prokaryotes
plasmid
DNA exchange
circular DNA
some bacteria
ribosome
translation of RNA into
proteins
RNA-protein
eukaryotes,
prokaryotes
thylakoid
photosynthesis
photosystem proteins
and pigments
mostly cyanobacteria
Organelle
Main function
chloroplast
(plastid)
photosynthesis
endoplasmic
reticulum
translation and folding of
new proteins (rough
endoplasmic reticulum),
expression of lipids
(smooth E.R.)
Golgi apparatus
sorting and modification
of proteins
Structure
Organisms
double-membrane
compartment
plants, protists
(rare
kleptoplastic
organisms)
single-membrane
compartment
rough E.R. is covered with
ribosomes, has folds that are
all eukaryotes
flat sacs; smooth E.R. has
folds that are tubular
single-membrane
compartment
cis-face (convex) nearest to
rough endoplasmic reticulum;
all eukaryotes
trans-face (concave) farthest
from rough E.R.
mitochondrion
energy production
double-membrane
compartment
most
eukaryotes
vacuole
storage, homeostasis
single-membrane
compartment
eukaryotes
nucleus
DNA maintenance, RNA
transcription
double-membrane
compartment
all eukaryotes
Notes
has some DNA; theorized to
be engulfed by the ancestral
eukaryotic cell
(endosymbiosis)
has bulk of genome
Minor eukaryotic organelles and cell components
Organelle/Macromol
ecule
Main function
Structure
Organisms
acrosome
helps spermatozoa fuse with
ovum
single-membrane compartment
many animals
autophagosome
vesicle which sequesters
cytoplasmic material and
organelles for degradation
double-membrane compartment
all eukaryotic cells
centriole
anchor for cytoskeleton
Microtubule protein
animals
green algae and other
unicellular photosynthetic
organisms such as
euglenids
eyespot apparatus
detects light, allowing phototaxis
to take place
glyoxysome
conversion of fat into sugars
single-membrane compartment
plants
hydrogenosome
energy & hydrogen production
double-membrane compartment
a few unicellular
eukaryotes
lysosome
breakdown of large molecules
(e.g., proteins + polysaccharides)
single-membrane compartment
most eukaryotes
melanosome
pigment storage
single-membrane compartment
animals
muscular contraction
bundled filaments
not characterized
not characterized
breakdown of metabolic hydrogen
single-membrane compartment
peroxide
animals
fungi
myofibril
parenthesome
peroxisome
vesicle
material transport
single-membrane compartment
all eukaryotes
all eukaryotes
State
quiescent/
senescent
Interphase
Cell division
Phase
Abbreviation
Description
G0
A resting phase where the cell
has left the cycle and has
stopped dividing.
Gap 1
G1
Cells increase in size in Gap 1. The G1 checkpoint
control mechanism ensures that everything is ready
for DNA synthesis.
Synthesis
S
DNA replication occurs during this phase.
Gap 0
Gap 2
G2
Mitosis
M
During the gap between DNA synthesis and mitosis,
the cell will continue to grow. The G2 checkpoint
control mechanism ensures that everything is ready to
enter the M (mitosis) phase and divide.
Cell growth stops at this stage and cellular energy is
focused on the orderly division into two daughter
cells. A checkpoint in the middle of mitosis
(Metaphase Checkpoint) ensures that the cell is ready
to complete cell division.
Mitosis (M Phase)
The relatively brief M phase consists of nuclear division (karyokinesis).
The M phase has been broken down into several distinct phases,
sequentially known as:
prophase,
metaphase,
anaphase,
telophase
cytokinesis
Prophase: The two round
objects above the nucleus
are the centrosomes. The
chromatin has condensed.
Prometaphase: The nuclear membrane has
degraded, and microtubules have invaded the
nuclear space. These microtubules can attach
to kinetochores or they can interact with
opposing microtubules.
Metaphase: The chromosomes have aligned at
the metaphase plate.
Early anaphase:
Kinetochore microtubules
shorten.
Telophase:
The decondensing
chromosomes are surrounded
by nuclear membranes. Note
cytokinesis has already begun,
the pinching is known as the
cleavage furrow.
Cytokinesis “from the greek cyto- (cell) and kinesis (motion, movement)”
Cytokinesis is final part of telophase; however, cytokinesis is a separate process that
begins at the same time as telophase.
Cytokinesis is a separate process, necessary for completing cell division.
In both animal and plant cells, cell division is also driven by vesicles derived from
the Golgi apparatus, which move along microtubules to the middle of the cell.
is the process in which the cytoplasm of a single eukaryotic cell is divided to form
two daughter cells. It usually initiates during the late stages of mitosis, and
sometimes meiosis, splitting a binucleate cell in two, to ensure that chromosome
number is maintained from one generation to the next.
The end of cytokinesis marks the end of the M-phase.
http://www.johnkyrk.com/meiosis.html
Interphase:
Before meiosis begins, genetic material is duplicated.
First division of meiosis
Prophase 1: Duplicated chromatin condenses. Each chromosome consists of two,
closely associated sister chromatids. Crossing-over can occur during the latter part
of this stage.
Metaphase 1: Homologous chromosomes align at the equatorial plate.
Anaphase 1: Homologous pairs separate with sister chromatids remaining together.
Telophase 1: Two daughter cells are formed with each daughter containing only
one chromosome of the homologous pair.
Second division of meiosis: Gamete formation
Prophase 2: DNA does not replicate.
Metaphase 2: Chromosomes align at the equatorial plate.
Anaphase 2: Centromeres divide and sister chromatids migrate separately to each
pole.
Telophase 2: Cell division is complete. Four haploid daughter cells are obtained.
Meiosis I
•Prophase I –
• The chromosomes condense and become visible
•The centrioles form and move toward the poles
•The nuclear membrane begins to dissolve
•The homologs pair up, forming a tetrad .
• Each tetrad is comprised of four chromotids - the two
homologs, each with their sister chromatid
•Homologous chromosomes will swap genetic material
in a process known as crossing over.
•Genetic material from the
homologous chromosomes is
randomly swapped
•This creates four unique
chromatids
•Since each chromatid is
unique, the overall genetic
diversity of the gametes is
greatly increased
•Metaphase I Microtubules grow from the
centrioles and attach to the centromeres
•The tetrads line up along the cell equator
Compare Metaphase I to Metaphase II and to
the Metaphase stage of mitosis.
•Anaphase I The centromeres break and
homologous chromosomes separate (note
that the sister chromatids are still attached)
•Cytokinesis begins
Compare Anaphase I to Anaphase II and to the
Anaphase stage of mitosis.
Telophase I
•The chromosomes may decondense (depends
on species)
•Cytokinesis reaches completion, creating two
haploid daughter cells
Compare Telophase I to Telophase II and to the
Telophase stage of mitosis.
Meiosis II
•Prophase II Centrioles form and
move toward the poles
•The nuclear membrane dissolves
Compare Prophase II to Prophase I
and to the Prophase stage of mitosis.
Metaphase II
•Microtubules grow from the centrioles and
attach to the centromeres
•The sister chromatids line up along the cell
equator
Compare Metaphase II to Metaphase I and
to the Metaphase stage of mitosis.
•Anaphase II The centromeres break
and sister chromatids separate
•Cytokinesis begins
Compare Anaphase
Telophase II
•The chromosomes may decondense
(depends on species)
•Cytokinesis reaches completion,
creating four haploid daughter cells
Compare Telophase II to Telophase I
and to the Telophase stage of mitosis.
A Comparison between Mitosis and Meiosis