Plant cells differ from animal cells in having
A plant cell has rigid wall on the outside. It has plastids and a centrally located large vacuole. All of these are absent in an animal cell.
Read the given statements and select the correct option.
Statement 1: The cisternae in Golgi complex have cis face and trans face.
Statement 2: The cis face is also called forming face and trans face is also called maturing face.
Golgi complex consists of a stack of cisternae which are curved to give definite polarity to the Golgi apparatus. The convex side (forming/cis face) receives vesicles from endoplasmic reticulum. The concave side (maturing /transface) buds off vesicles as secretion.
Polyribosomes are aggregation of
Ribosomes may-occur singly as monosomes or in rosettes and helical groups called polyribosome. The different ribosomes are connected with a 10-20A thick strand of mRNA. They are formed during periods of active protein synthesis when a number of copies of the same polypeotide are required.
Which one is the mis-matched pair?
Golgi apparatus was discovered by Camillo Golgi in nerve cells of barn owl and cat.
Select the wrong statement with respect to the structure of a plant cell.
Cell wall is the outer rigid protective and supportive covering of plant cells,fungi and some protists. Cell membrane is covering of protoplasm which occurs inside the cell wall.
Which of these is not correct regarding ribosomes?
Ribosomes are naked ribonucleoprotein protoplasmic particles (RNP) which function as a site for protein synthesis.
According to unit membrane structure, the thickness of plasma membrane is about
According to Robertson's concept of unit membrane, the cell membrane is trilaminar. It has a thickness of about 75Å with a central lipid layer of 35Å thick and two peripheral protein layers of 20Å each.
Cell recognition and adhesion are facilitated by components of plasma membrane. These components are generally
Proteins have very specific shapes which make them ideal as receptor molecules for chemical signalling between cells. Branching side chain glycolipids on the outer surface of cell membranes are also involved in cell-cell recognition.
The function of intracellular membrane is not to
In tracellular membrane is involved in establishing compartments in the cells and provides organization of enzymes and pigments. It provides a channel for nutrient distribution. Rigidity to the cell is provided by cell wall.
Continuity of cytoplasm from the cell to cell is maintained through cytoplasmic connections in plants called
Plasmodesmata are cytoplasmic bridges between adjacent plant cells which develop in minute pores of their walls. They form a protoplasmic continuum called symplast.
It provides channels for controlled passage of small sized particles between adjacent cells as well as transfer of some specific signals.
A phospholipid molecule is amphipathic and produces two layers coming in contact with H2O. The head of phospholipid molecule is
The lipid molecules are amphipathic, i.e., they possess both polar hydrophilic (water loving) and nonpolar hydrophobic (water repelling) ends. The hydrophilic region is in the form of a head occurring at outer surface while the hydrophobic part contains two tails of fatty acids. Hydrophobic tails usually occur towards the centre of the membrane. It results in the formation of a lipid bilayer. Most common lipid in the bilayer is phospholipid.
Lysosomes are _____ vesicular structures formed by the process of packaging in the _____ .
Lysosomes are single membrane bound vesicles which contain hydrolytic enzymes. They are believed to be formed by the joint activity of ER and Golgi complex. Precursors of hydrolytic enzymes are synthesized at RER and are transferred to the forming face of Golgi complex. These precursors are then changed to enzymes. Enzymes are packed in larger vesicles and are pinched off at maturing face. These vesicles combine with endosomes to produce lusosomes.
Smooth endoplasmic reticulum is well developed in which synthesize
The SER provides surface for the synthesis of including phospholipids, cholesterol, steroid hormones and hormones, adrenal corticoid hormones), ascorbic acid are visual pigments.
In which of the following part of mitochodrie such dehydrogenase enzyme is located?
Succinate dehydrogenase, anenzyme complex involume in TCA cycle, is located in inner mitochondrial membrare.
Mechanical rupport, enzyme circulation/protein synthesis and detoxification of drugs are function of
ER functions as cytoskeleton or skeletal framework by providing mechanical support to colloidal cytoplastic matrix. It conducts information from cell to cell. RER helps in protein synthesis. SER takes part in detoxification of tox chemicals in liver.
Cell organelle extracted from edosperm of germinating castor beans are
Glyoxysomes are microbodies which contain enzyres for β-oxidation of fatty acids and glyoxylate pathway. They are considered to be special peroxisomes. They occurs abundantly in germinating endosperm cells of oil seeds.
As they release hydrolase that digest old andd damaged cells, the term suicide bags is aptly used by cell biologists for
The lysosomes may be called "suicide bags’ of the cell in view of their autolytic role, or "disposal units’ of the cell because they digest the incoming food materials and remove the foreign bodies, toxic molecules, and debris, or "recyling centres" as they break down worn out cells cell organelles to component molecules for building organelles and cells.
Ribosomes are synthesized in
Nucleolus is a dense, rounded, dark-staining, granular structure without a limiting membrane. It consists largely of RNAs and proteins. Nucleolus syntesizes and stores RNA. It also receives ribosomal proteins from the cytoplasm for storage. It forms ribosomal subunits by wrapping the RNAs with nitosomal proteins. The ribosomal subunits later have the nucleus through the nuclear pores.
_____ is the single membrane bound organelle.
Sphaerosome, lysosome and glyoxysome are bounded by single membrane.
Non-membrane bound cell organelle is
A covering membrane is absent around ribosomes, centrioles and nucleolus.
Extranuclear inheritance is due to the presence of geries in
Chloroplasts and mitochondria are semi-autonomous cell-organelles possessing their own DNA and proteins. In animals an individual gets mitochondria and mitochondrial. genes from its mother because the middle piece of a sperm that contains mltochondria does not enter the egg during fetilization. This inheritance pattern of mitochondrial genes is called uniparental inheritance or extra nuclear inheritance or maternal inheritance.
The cell organelle involved in the glycosylation of proteins is
In many cells proteins released from the endoplasmic reticulum are combined with carbohydrate to produce complexes like glycoproteins. This occurs in both Golgi complex and rough endoplasmic reticulum as they contain enzymes called glycosyl-transferases.
Cell organelle responsible for autolysis is
Autolysis, caused by the lysosomal enzymes, plays a role in the disappearance of tail during the metam orphosis of frog's tadpole, and in softening of gum tissue to allow eruption of teeth in vertebrates. For autolysis, enzymes of primaryly so somes are released from the cell. Autolysis occur in ageing, dead and diseased cells.
Cells which are secretory in function have abundant
Dictyosome is a cup-shaped structure of flattened membranous vesicles found in plant cell. They modify proteins from the ER, and may also polymerise sugars to polysaccharides. They then package these materials for delivery to destinations within the cell, for secretion, or for storage.
______ aregranular structures first observed under electric microscope as denseparticles by ________ (1955).
Ribosomes are granular structures which were discovered by Robinson and Brown (1953) in plant cell and by Palade (1955) in animal cell. Palade (1955) also coined the term ribosomes hence, they are also called Palade particles. Ribosomes occur in both prokaryotic and eukaryotic cells.
Arrangement of microtubules in a flagellum and a centriole is respectively
Acentriole possesses a whorl of nine peripheral fibrils. Fibrils are absent in the centre. The arrangement is, therefore, called 9 + 0. Flagella contains an axoneme of a peripheral doublet fibrils and 2 central singlet fibrils. This arrangement is called 9 + 2 or 11 stranded.
Ribosomes are composed of
Chemically, ribosomes consist of two parts, proteins and rRNA. Proteins are both structural and enzymatic.
Read the given statements and select the correct option.
Statement 1: Peroxisomes are involved in photorespiration of the plant cells and help in the lipid metabolism of animal cells.
Statement 2: They are the cells' garbage disposal system.
Peroxisomes are found in photosynthetic cells and perform photorespiration. They also take part in lipid metabolism. Lysosomes are the cells' garbage disposal system.
These are the densely stained reticular structures present near the nucleus, consisting of many flat, disc shaped cisternae of 0.5 - 1.0μm diameter. These are
Camillo Golgi discovered the Golgi apparatus as reticular structure. Typically it is 0.5 - 1.0 pm in diameter but its shape and size depend upon the physiological state of the cell.
The best material for the study of structure of cell membrane is
RBCs lack nucleus and may other cell organelles thus they are best suited to study cell membrane without any complication.