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
