Cell Ncert Flashcards
The Physico-chemical approach to study and understand living organisms, is called
Reductionist Biology
G.N. Ramachandran is known for?
- Discovery of Triple Helix Structure of Collagen (Structural Biology)
- Ramachandran Plot, conformations of proteins
- Influence by Pauling’s models of α-helix and β-sheet structures
(α = Alpha, β = Beta)
Cell is __, __ and __ unit of organisms.
fundamental; structural; functional
Single-celled organisms are called __.
What is its characteristic of it?
Characteristics of Unicellular organisms are :
1. Free-living existence present
2. Perform all essential functions
Anything less than a Complete cell has not __
Living-free existence
Exception for the fact “Cell is the fundamental unit of organisms.”
Virus due to its Acellular structure
Living cell was first described by
Anton Von Leeuwenhoek
The nucleus was discovered by
Robert Brown
The structural details of a cell were well-defined after the discovery of __
Electron Microscope
In __, a German __ who observed that all plants are composed of different kinds of cells which form tissues was__
1838; botanist; Matthias Schleiden
In __ year, the thin outer layer of animal cells, now known as plasma membrane, was first reported by __ (German Botanist / British Zoologist)
1839; Theodore Schwann; British Zoologist
Two conclusions of T. Schwann are :
The presence of a Cell wall is a unique character of plant cells.
The bodies of animals and plants are composed of cells and products of cells.
The scientists who together formulated the cell theory were __ and __.
Schleiden and Schwann;
In __ year, the scientist who first explained that cells form from pre-existing cells (Omnis cellula-e cellula) was ___
1855; Rudolf Virchow
Drawback of Cell Theory (proposed by Schleiden and Schwann)
Who modified the hypothesis of Schleiden and Schwann to give a final shape to Cell Theory (Modern Cell Theory)?
It didn’t explain How new cells formed;
Rudolf Virchow
Cell theory as understood today is:
(i) all living organisms are composed of cells and products of cells (given by both Schleiden and Schwann)
(ii) all cells arise from pre-existing cells (Given by Rudolf Virchow)
The outer boundary of a typical plant cell is
Cell wall
Cell membrane is the __ structure of Cell.
Delimiting structure of cell
Genetic material i.e. DNA-containing chromosomes are located inside a dense structure called
Nucleus
The cells which possess membrane-bound nuclei are called
Eukaryotic
Cells which lack membrane-bound nuclei are called
Prokaryotic
Most of the cell volume is occupied by a semifluid matrix called as
Cytoplasm
The main arena of cellular/metabolic reactions which keep a cell in a living state is performed in __
Cytoplasm
The non-membrane-bound organelle found in both prokaryotic and eukaryotic cells is __
Ribosomes
The organelle which contains ribosomes and is specifically present in plants is __
Chloroplasts
Apart from the cytoplasm, organelle containing ribosomes are __
Chloroplasts (in plants), Mitochondria, and rough ER
The type of ER possessing ribosomes is __
Rough ER
Animal cells contain a non-membrane-bound organelle which helps in cell division, is
Centrosome
__ are the smallest living cells and __ in length.
Mycoplasma; 0.3 μm (in length)
The largest isolated single cell is __
an egg of Ostrich
Cell Size:
Mycoplasma -
PPLO -
Bacteria -
Typical Bacteria -
Virus -
Human RBCs -
Typical Eukaryotic cell -
Mycoplasma - 0.3 μm in length
PPLO - 0.1 μm (in Diameter)
Bacteria - 3-5 μm
Typical Bacteria - 1-2 μm
Virus - 0.02-0.2 μm
Human RBCs - 7 μm (in Diameter)
Typical Eukaryotic cell - 10-20 μm
Cell Shape depends on __
Cell functions/activities
Cell Shape:
RBCs -
WBCs -
Nerve cell -
Columnar Epithelial Cell -
Mesophyll Cell
Tracheids -
RBCs - Round Biconcave cell
WBCs - Amoeboid
Nerve cell (longest cell) - Branched & Long
Columnar Epithelial Cell - Long & Narrow
Mesophyll Cell - Round & Oval
Tracheids - Elongated
The prokaryotic cells are represented by
Bacteria, blue-green algae, mycoplasma
PPLO stands for
Pleuro Pneumonia Like Organisms
__ cells are generally smaller and multiply more rapidly than the __ cells.
prokaryotic cells; eukaryotic cells
Which Bacteria -
Rod-shaped ->
Spherical-shaped ->
Comma-shaped ->
Spiral-shaped ->
Rod-shaped -> Bacillus
Spherical-shaped -> Coccus
Comma-shaped -> Vibrio
Spiral-shaped -> Spirillum
A prokaryote which lacks Cell wall is __
Mycoplasma
The fluid matrix filling a cell is __
Cytoplasm
Naked genetic material without any envelope by nuclear membrane is characteristic of __.
Prokaryotes
A small circular DNA outside genomic DNA in bacteria is __
Plasmid DNA
A unique phenotypic characters to bacteria are provided by DNA other than genomic DNA is __
Plasmid DNA
Example of a unique phenotypic character provided to bacteria by plasmid DNA is __
Resistance to antibiotics
The __ confers certain unique phenotypic characters to bacteria
Plasmid DNA
__ is used to monitor bacterial transformation with foreign DNA
Plasmid DNA
Well organized nucleus with a nuclear membrane is the characteristic feature of __ cells
Eukaryotic
__ is the only organelle found in both prokaryotes and eukaryotes
Ribosomes
A specialized differentiated form of the cell membrane called __ which prokaryotes have unique in the form of inclusions.
Mesosomes
Mesosomes are essential infoldings of __
Cell membrane
Most ___ (prokaryotic/eukaryotic) cells, particularly bacterial cells, have a chemically complex cell envelope.
prokaryotic cells
Tightly bound three-layered structure of bacterial cell envelop consists of __
Outermost -> Glycocalyx
Middle -> cell wall
Inner -> plasma membrane
Each layer of the envelope performs ____ (same/distinct) function, they act together as a _____.
Distinct function; Single protective unit
On the Basis of differences in the cell envelopes and Gram staining, bacteria are classified as
Gram-positive and Gram-negative
Bacteria taking up gram stain are ___, and the others that do not are called ___ bacteria.
Gram-positive; Gram-negative
The layer of cell envelope whose composition and thickness varies to a large extent is __
Glycocalyx
The loose sheath of the glycocalyx in bacteria is called
Slime Layer
The thick & tough sheath of the glycocalyx in bacteria is called
Capsule
What determines the shape of the cell?
Cell Wall
____ provides a strong structural support
to a bacterial cell and prevent the bacterium from _____
Cell wall; bursting or collapsing
The selectively permeable membrane of a cell that interacts with the outside world, is
plasma membrane
The membrane, which is structurally similar to prokaryotes and eukaryotes, is
Plasma membrane
A special membraneous structure which is formed by the extensions of plasma membrane into the cell is __
Mesosome
The extensions of the cell membrane are in the form of __
Vesicles, tubules and lamellae
One major role of mesosomes is __
Helps in
i) Cell wall formation
ii) DNA replication & DNA distribution to daughter cells
iii) Respiration
iv) Secretion processes
v) Increase surface area of plasma membrane and enzymatic content
In some prokaryotes like ____, there are other membranous extensions into the cytoplasm called ____ which contain ____.
Cyanobacteria; Chromatophores; pigments
Bacterial cells may be ____ (motile/non-motile/both).
Both (motile or non-motile)
Motile bacteria have thin filamentous extensions from their cell wall, known as
Flagella
All Bacteria show ____ (same/different) number and arrangement of flagella.
different
The three main parts of the bacterial flagellum are __
Filament, hook and basal body
The longest portion of the bacterial flagellum is ____ and extends from the cell surface to the ____ (inside/outside).
Filament; outside
Besides flagella, the two surface structures of Bacteria which do not play a role in motility (locomotion) are __
Pili and Fimbriae
The elongated tubular structures composed of a special protein in bacteria are _____
Pili
Small bristle-like fibers sprouting out of the bacterial cell are ____
Fimbriae
The structure which is known to attach bacteria to rocks in streams or to hosts tissues is ____
Fimbriae
In prokaryotes, Ribosomes are associated with the __ of cells.
Plasma membrane
The average size of a prokaryotic ribosome is
15 nm by 20 nm
The two sub-units of prokaryotic ribosomes are
50S and 30S
The 50S and 30S subunits of prokaryotic ribosomes together form __
70S
Ribosomes are the site of
Protein synthesis
Several ribosomes may attach to mRNA and form a chain, called
Polyribosomes or polysome
The ribosomes of a polysome translate the ___ into __.
mRNA into proteins
Reserve material in prokaryotic cells is stored in the cytoplasm in the form of
Inclusion bodies
Phosphate granule is an example of
Inclusion body
Gas vacuoles are the type of __ found in blue-green and purple and green photosynthesis bacteria
Inclusion bbodies
Gas vacuoles are found in which bacteria?
Blue-green, purple and green photosynthesis bacteria
In eukaryotic cells, there is extensive compartmentalization of cytoplasm through the presence of __
Membrane bound organelles
The cells possessing complex locomotory and cytoskeletal structures are __
Eukaryotic cells
Eukaryotic cells possess an organized nucleus with __
Nuclear envelope
The genetic material of eukaryotes is organized into __
Chromosomes
The organelles that are present in plant cells but not in animal cells are __
Plastids
The characteristic feature of animal cells is the presence of __
Centrioles
The chemical studies on the cell membrane, especially in ___, enabled the scientists to deduce the possible structure of plasma membrane.
Human red blood cells (RBCs)
Cell membrane is mainly composed of __
Lipids and Proteins
The major lipids in the cell membrane are __
Phospholipids
Phospholipids in Cell membrane are arranged in a
Bilayer
In a lipid bilayer, the part of lipids that lie towards inside is __
Hydrophobic
In addition to phospholipids, membrane also contains __
Cholesterol
Apart from cholesterol and lipids, other biomolecules that make up the cell membrane are __
Proteins and carbohydrates
The % of proteins in membrane of Human erythrocyte is __
52%
The % of lipids in membrane of Human erythrocyte is __
40%
Membrane proteins are classified as
Integral and peripheral proteins
The proteins that lie on the surface of Membrane are called
Peripheral proteins
The proteins that are partially or totally buried in Membrane are called
Integral proteins
The fluid mosaic model was proposed by
Singer and Nicolson
The fluid mosaic model was proposed in the year __
1972
According to the fluid mosaic model, what nature of lipids enables the lateral movement of proteins?
Quasi-fluid nature
The quasi-fluid nature of lipids enables which movement of proteins within the bilayer?
Lateral movement
The ability of the protein to move within the membrane is measured as its __
Fluidity
The fluid nature of the membrane is important for __
Cellular functions
Transport of molecules across itself is the most important function of __
Plasma membrane
The nature of permeability of plasma membrane is __
Selectively permeable
The movement of molecules across the membrane without any requirement of energy is called
Passive transport
Neutral molecules move across the membrane by the process of __
Simple diffusion
Simple diffusion occurs along the __ gradient
Concentration
The movement of water by diffusion is called
Osmosis
The type of molecules which require carrier protein to facilitate their transport across the membrane is __
Polar molecules
The proteins required by polar molecules to facilitate their transport are called
Carrier proteins
During active transport, molecules are transport __ the concentration gradient
against
Active transport occurs with the utilization of __
ATP
The type of transport during which ATP is utilized is __
Active transport
An example of active transport is
Na+/K+ pump
The non-living rigid structure forming the outer covering of plasma membrane in fungi and plants is called __
Cell wall
The cell wall acts as an outer covering for which membrane?
Plasma membrane
___ forms an outer covering for the plasma membrane of fungi and plants.
Cell wall
Cell wall protects the cell from __ and __
Mechanical damage and Infection
The cell wall provides a barrier to ___
Undesirable macromolecules
The Algae cell wall is primarily composed of __
Cellulose, galactans, mannans, and minerals
Name a mineral component of the algal cell wall
Calcium Carbonate
Plant cell wall is composed of
Cellulose, hemicellulose, pectins and proteins
The cell wall of young plants which is capable of growth is __
Primary wall
The layer of Cell which specifically holds different neighboring cells together in plants is __
Middle Lamella
Middle lamella in plants is composed of
Calcium pectate
The cell wall and middle lamellae are traversed by __
Plasmodesmata
Cytoplasm of neighboring cells are connected by __
Plasmodesmata
ER, Golgi complex, lysosomes, and vacuoles are part of __ system
Endomembrane system
The organelles whose functions are coordinated are considered as a part of __ system
Endomembrane system
Name three organelles which are not a part of the endomembrane system
Mitochondria, chloroplast, and peroxisomes
The organelle which divides intracellular space into luminal and extra luminal is __
Endoplasmic reticulum
The reticulum of tiny tubular structures scattered in the cytoplasm is called __
endoplasmic reticulum
The region inside ER is called
luminal
The region outside ER is called
extra luminal
The ER often shows ___ attached to their outer surface.
ribosomes
The endoplasmic reticulum bearing ribosomes on their surface is called __
Rough endoplasmic reticulum (RER)
The ER devoid of ribosomes is called as __
Smooth endoplasmic reticulum (SER)
The ER involved in active protein synthesis is __
RER
RER is __ and continuous with the outer membrane of the ___
extensive; nucleus
The site of lipid synthesis in ER is __
Smooth endoplasmic reticulum
Lipid-like steroidal hormones in animals cells are synthesized by __
SER
Golgi bodies were first observed by __
Camillo Golgi
Flat, disc-shaped sacs near the nucleus are called __
Golgi bodies
The diameter of sacs of Golgi varies from __ to __
0-5 μm; 1 μm
The cisternae of Golgi are arranged in __ form.
Parallel
The Golgi cisternae around the nucleus are arranged __
Concentrically
The forming face of the Golgi body is called __
Convex cis
Concave trans is the __ face of Golgi body
Maturing
The primary function of Golgi apparatus is __
Packaging of materials
Materials to be packaged in the form of vesicles from ER fuse with which face of Golgi?
Cis
Proteins synthesized by ribosomes are modified by
Golgi apparatus
Modified proteins from cisternae are released through __ of Golgi apparatus
trans face
Golgi apparatus is an important site for the formation of _ and _
glycoproteins and glycolipids
Membrane-bound vesicular structures formed by the process of packaging in the Golgi apparatus are called
Lysosomes
Which organelle forms lysosomes?
Golgi apparatus
Lysosomal vesicles are rich in __
Hydrolytic enzymes
The hydrolases present in lysosomes are -
Lipases, proteases, carbohydrases
Enzymes of lysosomal vesicles get active at __ pH
Acidic
Carbohydrates, proteins, lipids, and nucleic acids in lysosomes are digested by an enzyme
Hydrolases enzyme
The membrane-bound space found in cytoplasm is
Vacuole
Water, sap, and excretory waste are stored in
Vacuoles
The vacuole is bound by a single membrane called
Tonoplast
Vacuoles can occupy up to how much volume of a plant cell?
90%
The transport of a number of ions and other materials against concentration gradients into the vacuole is facilitated by __
Tonoplast
The vacuole responsible for osmoregulation and excretion in Amoeba is __
contractile vacuole
Food vacuoles are formed by engulfing food particles in __
Protists
The number of mitochondria in a cell depends on __ of the cell.
physiological activity
The diameter of mitochondria varies from _ to _
0.2 to1 μm
The length of mitochondria varies from _ to _
1 to 4.1 μm
Each mitochondrion is a ___ structure.
double membrane-bound
The inner compartment of mitochondria is filled with a dense homogeneous substance called __
Matrix
The membrane of mitochondria forming the continuous limiting boundary of the organelle is __
Outer mitochondrial membrane
The inner mitochondrial membrane forms a number of infoldings called __
Cristae
The infoldings increasing the surface area of mitochondria are __
Cristae
Mitochondria is the site of which respiration?
Aerobic respiration
Energy is released by mitochondria in the form of __
ATP
Mitochondria are also called _
Powerhouse of Cell
The ribosomal subunits present in a mitochondrial matrix are __
70S
Mitochondria divide by __
Fission
The pigment imparting organelles present in plants and some euglenoids is __
Plastid
Plastids are classified into Chloroplast, leucoplast, and chromoplast on the basis of __
Pigments
Chlorophyll containing plastids are called __
Chloroplasts
Along with chlorophyll, chloroplast contains __
Carotenoid pigments
Light energy trapped by pigments of chloroplast is required for __
Photosynthesis
Name two carotenoid pigments of Chloroplast.
Carotene and xanthophyll
The three colors provided to plants by chloroplasts are __
yellow, orange or red colour
The colorless plastids are called __
Leucoplasts
The function of leucoplast is to __
store nutrients
Carbohydrate-storing leucoplasts are called __
Amyloplasts
Leucoplast storing oils and fats is called __
Elaioplasts
Protein-storing leucoplast is known as __
Aleuroplasts
The majority of chloroplast of green plants is found in which cells?
Mesophyll cells
The number of chloroplasts in Chlamydomonas is __ per cell.
one
Number of chloroplasts in a mesophyll cell is __ per cell.
20-40
__ chloroplast membrane is less permeable
Inner
The space limited by inner membrane of the chloroplast is called __
Stroma
Thylakoids are present in __
Stroma
A number of organized flattened membranous sacs present in the stroma are called __
Thylakoids
Thylakoids are arranged in piles called __
Grana
The flat membranous tubule joining thylakoids of different grana are called __
stroma lamellae
The stroma of the chloroplast contains enzymes required for the synthesis of _ and _
carbohydrates and proteins
The pigments present in thylakoids are called __
Chlorophyll pigments
The ribosomal subunit present in chloroplasts is __
70S
Ribosomes were first observed under an electron microscope by __
George Palade
Ribosomes are composed of _ and _
RNA and proteins
The membrane-less, protein-synthesizing organelles are called __
Ribosomes
The eukaryotic ribosome is __S.
80S
The prokaryotic ribosome is __S.
70S
The two subunits of 80S ribosome are __
60S and 40S
The two subunits of 70S ribosome are __
50S and 30S
S (Svedberg’s Unit) in ribosomal subunit stands for __
Sedimentation coefficient
Sedimentation coefficient is the measure of _ and _
density and size
An elaborate network of filamentous proteinaceous structures consisting of microtubules, microfilaments, and intermediate filaments present in the cytoplasm is collectively referred to as __
Cytoskeleton
Cytoskeleton is composed of proteinaceous structures like __
microtubules, microfilaments, and intermediate filaments
Two hair-like outgrowths of the cell membrane are __
Cilia and flagella
The small structures causing movement of either cell or surrounding fluid are called __
Cilium
An extension longer than cilia which is responsible for cellular movement, is __
Flagella
Cilium and flagellum are covered by __
Plasma membrane
The core of flagellum or cilium is called __
axoneme
Axoneme consists of a number of __ running in parallel to long axis.
microtubules
Axoneme has __ of radially arranged peripheral microtubules
nine doublets
The arrangement of axonemal microtubules is called
9+2 array
Central sheath is connected to one of the tubules of each peripheral doublet by
radial spoke
The number of radial spokes in 9+2 arrangement is
Nine
Peripheral doublets are interconnected by
linkers
The cilium and flagellum emerge from Centriole like structure called
basal bodies
An organelle usually containing two cylindrical structures called centrioles is called
Centrosome
Centrosomes are surrounded by
amorphous pericentriolar material
Centrioles in centrosome lie __ to each other
perpendicular
Centriole are made up of __ evenly spaced peripheral fibrils of tubulin protein.
nine
The protein forming peripheral fibrils in centriole is
Tubulin protein
Each of the __ in centriole is a triplet
peripheral fibril
The proteinaceous, central part of Proximal region of Centriole is called
hub
Hub is connected with tubules of peripheral triplets by
radial spokes
Radial spokes are composed of
Protein
The basal body of cilia or flagella is formed by
Centrioles
The basal body of spindle fibers is formed of
Centriole
The nucleus was first described by
Robert Brown
The material of the nucleus stained by the basic dyes was
given the name chromatin by
Flemming
The nucleolus, chromatin, and nuclear matrix are characteristics of which nucleus?
Interphase nucleus
The space between two parallel membranes of Nuclear envelope is called
perinuclear space
The outer membrane of Nucleus remains continuous with
endoplasmic reticulum
The outer membrane of Nucleus remains continuous with ER and bears.
ribosomes
Movement of RNA and protein between Nucleus and cytoplasm takes place through
nuclear pores
Some mature cells in mammals lacking Nuclue are
Erythrocytes
The plant cells devoid of a Nucleus are
Sieve tube cells
The nuclear matrix or the Nucleoplasm contains __ and __.
nucleolus and chromatin
The spherical structures present in nucleoplasm are called
nucleoli
The site of active ribosomal RNA synthesis in Nucleus is
Nucleolus
Chromatin primarily contains
DNA
Basic proteins present in chromatin are
histones
Human beings have __ pairs of chromosomes.
23
The primary constriction on chromosomes is called
Centromere
Kinetochores are present on the sides of
Centromere
The disc-shaped structures present on the sides of the centromere are called
Kinetochores
A chromosome having a middle centromere forming two equal arms of the chromosome is called
Metacentric chromosome
A chromosome whose centromere is slightly away from the middle of chromosome resulting in one shorter and one longer arm is called
sub-metacentric chromosome
The centromere is situated close to its end forming one extremely short and one very long arm in __ chromosome.
acrocentric chromosome
Chromosomes having terminal centromere are called
chromosome
Secondary constriction in chromosomes gives appearance of __
satellite
Minute enzyme-containing vesicles in both plants and animals, are called
Microbodies
Each mitochondrion is a double membrane-bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into ___ compartments.
two aqueous compartments,
