Chapter 8
Self-Quiz
Unit 2: Cell: The Basic Units of Life
Photosynthesis and Respiration
Review
Photosynthesis
is the metabolic process in plants and algae that captures
energy and uses it to turn CO
2
and H
2
O into sugars
(glucose).
The process is
compartmentalized
in the
and produces
as a by-product.
Respiration
is the series of reactions that uses the O
2
and glucose made during photosynthesis to
manufacture
for cellular work, with
and
produced as by-products of the process. The breakdown of food molecules in this process is called aerobic
. Many of the reactions of respiration are compartmentalized in
.
The temporary storage and transfer of energy in both photosynthesis and respiration require the use of reduced electron
carriers
such as
and
.
Photosynthesis
occurs in the chloroplast in two stages.
The
reactions occur on the
membranes
which separate the
from the
.
Pigments
such as
and
, and
(ETCs) are used to capture
solar
energy, excite electrons, and manufacture
NADPH
and
.
The "excited" electrons are
captured
by the
complex and are transferred from the chlorophyll to the ETC in Photosystem
.
Photosystem
receives the excess electrons and forms NADPH. A channel protein pumps protons into the
space, and are moved into the
by ATP synthase, producing
.
The
reactions
of photosynthesis occur in the
of the
chloroplast.
Products of the light reactions are used to energize CO
2
and make the sugar
monomer
in a process known as carbon
.
is the source of
energy,
while
is the source of high-energy
electrons.
Other products of the dark reaction include the sugar
polymers
and
.
Respiration
occurs in three stages.
First,
glycolysis
takes place in the
and begins the breakdown of
to produce
and small amounts of
and
. In the absence of O
2
, the pyruvate made during glycolysis enters the anaerobic respiration of
fermentation,
which produces
and either
or
acid.
Next,
if O
2
is present, aerobic respiration takes place. Pyruvate is directed to the inner matrix of the
, where it enters the citric acid
cycle.
is released as the
pyruvate
is degraded, yielding a few additional ATP and numerous molecules of
NADH.
Finally,
the electrons in NADH and O
2
are used during oxidative
phosphorylation
(which occurs on the mitochondrial inner membrane) to manufacture more than 30 molecules of ATP, again through the
and using
. In this process
is required and
is released.
Chapter 10
Self-Quiz
Unit 2: Cell: The Basic Units of Life
Cell Division
Review
Eukaryotic
cells multiply by
dividing
to form
cells in a
process
called the
division
cycle.
An undifferentiated cell that can divide to produce one or more
cell types is called a
cell.
In the
nucleus,
DNA
is packed with protein in strands called
. During cell division,
chromatin
is condensed into visible bodies called
. Each species has a
unique
of specific number and shape of chromosomes. Humans have 46 chromosomes consisting of 22
pairs and 2
chromosomes.
In
cells,
the actively dividing state is
, while the period between mitotic division is
. Each daughter cell receives the full complement of DNA of the parent cell and is genetically identical to the parent; this is called DNA
and requires DNA
.
Interphase
prepares the cell for division and is composed of 4 sub phases.
In the
phase, the cell prepares for the DNA synthesis by producing necessary
and
and growing in size.
In the
phase DNA synthesis occurs to prepare for DNA
. Each strand of DNA is
duplicated
to form the two arms of
of the
chromosomes,
held together by
, each of which has two
.
In the
phase, the cell prepares for mitosis by producing another set of proteins.
The
phase is a resting alternative to the G1 stage where cells do not prepare for mitosis. Most somatic cells are in this phase when they reach maturity.
Mitosis is composed of 5 sub phases.
In
, chromatins condense into
,
move toward
, and microtubules form the mitotic
.
In
, the nuclear
breaks
down,
and the spindle microtubules connect kinetochores to opposing
.
In
, chromosomes line up in the middle of the cell called the metaphase
, or equatorial plate.
In
, DNA
occurs when sister
separate at the kinetochore and the daughter
move toward the centrosomes at the
poles.
In
, spindle microtubules break down, nuclear
form around the new chromosomes, and the chromosomes unfold to their interphase state. In plants,
vesicles
fuse to form a new cell
. In
, actin
filaments
divide the cell in
two.
In plants, new cell
formation is completed.
Germline
cells
in
undergo
; each diploid parent cell yields four haploid
. The union of a male gamete called a
and a female gamete called an
results in a diploid
. This process of sexual
reproduction
is called
. The gender of a human zygote is determined by the
.
Meiosis
consists of two nuclear divisions, meiosis I and meiosis II.
In
meiosis I,
homologous chromosomes form pairs of
. Microtubules from only one pole attach to each chromosome of a homologous pair, and each daughter cell receives only one of the pair. This
division produces two haploid cells, each with two chromatids on each chromosome.
In
meiosis II,
the two
in each daughter cell separate. The
result
is four haploid
gametes.
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