Republic of the Philippines
Davao del Sur State College
Exam
EDSCI 308
May 7, 2022
Name: ____MAREN M. PENDON_________
Year and Course: I- MAED ST
Score:____________
Equivalent: ________
1- Fill in the blanks with the correct answer.
______________Cell Wall____ 1. Represents a kind of exoskeleton, that provides
mechanical support as well as serving to balance the intracellular osmotic
pressure with that of the medium.
_____________Leucoplasts
2. Colorless plastids.
_____Lycopene________ ___ 3. The red color of ripe tomatoes is the result of
chromoplasts that contain the red pigment called….
__Chloroplasts_____________
4. The plastids with the greatest biological
importance .
_______Lysosome__________ 5. Flattened vesicles arranged as a membranous
network.
_________Stem ___________ 6. Supports plants in case of the presence of
restraining growth.
__________Photosynthesis_ __7. Involves in the production of leaves.
_____Xylem________________8. Responsible for mineral transport in plant cell.
______Gycolysis____________9. First step in the release of energy.
_____Oxidative Phospolyration___10. Play a central role in mitochondria.
11. Description/Enumeration/Explanation.
1. Describe the physical features of chromatin when isolated biochemically.
(10 pts.)
The isolated chromatin of higher organisms possesses several properties
characteristic of the same chromatin in life. These include the presence of
histone bound to DNA, the state of repression of the genetic material, and
the ability to serve as template for the readout of the derepressed portion
of the genome by RNA polymerase. The important respect in which isolated
chromatin differs from the material in vivo, fragmentation of DNA into
pieces shorter (5 × 106 to 20 × 106 molecular weight) than the original,
does not appear to importantly alter such transcription.
2. Briefly identify the importance of nuclear envelope. (10 pts.)
The main role of the nuclear envelope (NE) is to compartmentalize and
protect the unfolded genomic DNA from the cytoplasm in eukaryote cells.
It is composed of a lipid bilayer reinforced in its inner side with a sheetlike structure of proteins called the nuclear lamina.
3. Give the different components of chloroplasts. (10 pts.)
The chloroplast has an inner and outer membrane with an empty
intermediate space in between. Inside the chloroplast are stacks of
thylakoids, called grana, as well as stroma, the dense fluid inside of the
chloroplast. These thylakoids contain the chlorophyll that is necessary for
the plant to go through photosynthesis. The space the chlorophyll fills is
called the thylakoid space.
A chloroplast thus has the following parts:
1. Envelope (Outer membrane)
It is a semi-porous membrane and is permeable to small molecules and
ions, which diffuses easily. The outer membrane is not permeable to larger
proteins.
2. Intermembrane Space
It is usually a thin inter-membrane space about 10-20 nanometers and it
is present between the outer and the inner membrane of the chloroplast.
3. Inner membrane
The inner membrane of the chloroplast forms a border to the stroma. It
regulates the passage of materials in and out of the chloroplast. In addition
to regulation activity, fatty acids, lipids, and carotenoids are synthesized
in the inner chloroplast membrane.
4. Stroma
Stroma is an alkaline, aqueous fluid that is protein-rich and is present
within the inner membrane of the chloroplast. The space outside the
thylakoid space is called the stroma. The chloroplast DNA chloroplast
ribosomes and the thylakoid system, starch granules and many proteins
are found floating around the stroma.
5. Thylakoid System
The thylakoid system is suspended in the stroma. The thylakoid system is
a collection of membranous sacs called thylakoids. The chlorophyll is
found in the thylakoids and is the sight for the process of light reactions
of photosynthesis to happen. The thylakoids are arranged in stacks known
as grana. Each granum contains around 10-20 thylakoids.
6. Peripheral Reticulum
The chloroplasts of certain plants contain an additional set of
membranous tubules called peripheral reticulum that originates from the
inner membrane of the envelope. Tiny vesicles bud off from the inner
membrane of the chloroplast and assemble to form the tubules of the
peripheral reticulum.
4. This structure has a vital and major task in carrying information in a
coded form from cell to cell and from organism to organism . Within the
cells , DNA is not free but is complexed with proteins. (10 pys.)
The nucleus (plural, nuclei) houses the cell’s genetic material, or DNA, and is
also the site of synthesis for ribosomes, the cellular machines that assemble
proteins. Inside the nucleus, chromatin (DNA wrapped around proteins,
described further below) is stored in a gel-like substance called nucleoplasm.
Enclosing the nucleoplasm is the nuclear envelope, which is made up of two
layers of membrane: an outer membrane and an inner membrane. Each of these
membranes contains two layers of phospholipids, arranged with their tails
pointing inward (forming a phospholipid bilayer). There’s a thin space between
the two layers of the nuclear envelope, and this space is directly connected to
the interior of another membranous organelle, the endoplasmic reticulum.
Nuclear pores, small channels that span the nuclear envelope, let substances
enter and exit the nucleus. Each pore is lined by a set of proteins, called the
nuclear pore complex, that control what molecules can go in or out.
Most of an organism’s DNA is organized into one or more chromosomes, each of
which is a very long string or loop of DNA. A single chromosome can carry many
different genes.
In prokaryotes, DNA is typically organized into a single circular chromosome (a
loop). In eukaryotes, on the other hand, chromosomes are linear structures
(strings). Every eukaryotic species has a specific number of chromosomes in the
nuclei of its body’s cells. For example, a typical human body cell would
have 464646 chromosomes, while a comparable fruit fly cell would have 888.
Chromosomes are only visible as distinct structures when the cell is getting
ready to divide. When the cell is in the growth and maintenance phases of its life
cycle, the chromosomes instead resemble an unwound, jumbled bunch of
threads. In this form, the DNA is accessible to the enzymes that transcribe it into
RNA, allowing the genetic information to be put to use (expressed).
In both their loose and compact forms, the DNA strands of chromosomes are
bound to structural proteins, including a family of proteins called histones (see
picture below). These DNA-associated proteins organize the DNA and help it fit
into the nucleus, and they also play a role in determining which genes are active
or inactive. The complex formed by DNA and its supporting structural proteins
is known as chromatin. You can learn more about DNA, chromatin, and
chromosomes in the DNA and chromosomes article.
5. Compare and contrast in its molecular level, the significant and major
events occuring between photosynthesis and cellular respiration . (20 pts)
Photosynthesis and cellular respiration are complementary processes by which
living things obtain needed substances. They both consume and create the same
substances (water, glucose, oxygen, and carbon dioxide) but in different ways.
Through these processes, plants obtain the carbon dioxide they need and living
organisms obtain the oxygen they need. They are also necessary to the energy
exchange that living things need to survive.
Photosynthesis is the process by which green plants create their own food by
turning light energy into chemical energy. Chlorophyll in the leaves transform
carbon dioxide, water, and minerals into oxygen and glucose. Photosynthesis
takes place in the chloroplasts of cells. This process is what gives energy to all
living organisms either directly or indirectly. Without it, life on Earth would cease
to exist.
Cellular respiration, on the other hand, is the process by which living things
convert oxygen and glucose to carbon dioxide and water, thereby yielding energy.
It does not require the presence of sunlight and is always occurring in living
organisms. Cellular respiration takes place in the mitochondria of cells.
While photosynthesis requires energy and produces food, cellular respiration
breaks down food and releases energy. Plants perform both photosynthesis and
respiration, while animals can only perform respiration.
Answer the following questions concisely.
1. Identify and describe the different techniques commonly used to study cell
biology.
2. Identify the major regions of mitochondria and give its function.
3. Describe the basic steps of phagocytosis.
4. Trace the path of cell secretion of which Golgi Apparatus in involved.
5. In table form, compare and contrast RER and SER in terms of functions.
6. What do you think is the major importance of photosynthesis?