Structure of Cell Flashcards
If we study a cell under a microscope, we would come across three features in almost every cell: what are those?
All activities inside the cell and interactions of the cell with its environment are possible due to these features.
plasma membrane, nucleus and cytoplasm.
–Extremely delicate, thin , elastic, living and semi-permeable membrane
–Made up of two layers of lipid molecules in which protein molecules are floating
–Thickness varies from 75-110 A˚
–Can be observed under an electron microscope only
Plasma Membrane
Function of Plasma Membrane
Functions:
–Maintains shape & size of the cell
–Protects internal contents of the cell
–Regulates entry and exit of substances in and out of the cell
–Maintains homeostasis
–Non-living and outermost covering of a cell (plants & bacteria)
–Can be tough, rigid and sometimes flexible
–Made up of cellulose, hemicellulose and pectin
–May be thin or thick, multilayered structure
–Thickness varies from 50-1000 A˚
Cell wall
Function of Cell wall
Functions:
–Provides definite shape, strength & rigidity
–Prevents drying up(desiccation) of cells
–Helps in controlling cell expansion
–Protects cell from external pathogens
–Dense spherical body located near the centre of the cell
–Diameter varies from 10-25 µm
–Present in all the cells except red blood cells and sieve tube cells
–Well developed in plant and animal cells
–Undeveloped in bacteria and blue-green algae (cyanobacteria)
–Most of the cells are ________(having only one nucleus)
–Few types of cells have more than one nucleus (skeletal muscle cells)
- Nucleus
- uninucleated
Fill in the blank:
In nucleus…
1.) Nucleus has a double layered covering called _________.
2.) Nuclear membrane has pores of diameter about ________.
3.) Colourless dense sap present inside the nucleus known as ___________
4.) Nucleoplasm contains round shaped nucleolus and network of _________
5.) Fibres are composed of deoxyribonucleic acid (DNA) and protein histone
6.) These fibres condense to form chromosomes during ________
nuclear membrane
80-100 nm
nucleoplasm
chromatin fibres
cell division
Chromosomes contain stretches of DNA called ______
It transfer the _________ information from one generation to the next
genes, hereditary
Function of Nucleus
Functions:
1. Control all the cell activities like metabolism, protein synthesis, growth and cell division
2. Nucleolus synthesizes ribonucleic acid (RNA) to constitute ribosomes
3. Store hereditary information in genes
Answer what is being describe then fill in the blanks.
-Jelly-like material formed by _____ of water
-Present between the plasma membrane and the nucleus
-Contains a clear liquid portion called _____ and various particles
-Particles are proteins, carbohydrates, nucleic acids, lipids and inorganic ions
-Also contains many organelles with distinct structure and function
-Some of these organelles are visible only under an electron microscope
Granular and dense in animal cells and thin in plant cells
Cytoplasm:
80 %
cytosol
Network of tubular and vesicular structures which are interconnected with one another
Some parts are connected to the nuclear membrane, while others are connected to the cell membrane
Two types: smooth(lacks ribosomes) and rough(studded with ribosomes)
Endoplasmic Reticulum
Function of Endoplasmic Reticulum
Functions:
Gives internal support to the cytoplasm
RER synthesize secretory proteins and membrane proteins
SER synthesize lipids for cell membrane
In liver cells SER detoxify drugs & poisons
In muscle cells SER store calcium ions
Answer what is being describe then fill in the blanks.
Formed by stacks of 5-8 membranous sacs
Discovered by________
Sacs are usually flattened and are called the _______
Has two ends: ______ face situated near the endoplasmic reticulum and _______face situated near the cell membrane
Golgi body
Camillo Golgi
cisternae
cis, trans
Function of Golgi body
Functions:
Modifies, sorts and packs materials synthesized in the cell
Delivers synthesized materials to various targets inside the cell and outside the cell
Produces vacuoles and secretory vesicles
Forms plasma membrane and lysosomes
-Small, spherical, single membrane sac
-Found throughout the cytoplasm
-Filled with hydrolytic enzymes
-Occur in most animal cells and in few type of plant cells
Lysosomes
Function of Lysosomes
Functions:
Help in digesting of large molecules
Protect cell by destroying foreign invaders like bacteria and viruses
Degradation of worn out organelles
In dead cells perform autolysis
-Single membrane sac filled with liquid or sap (water, sugar and ions)
-In animal cells, vacuoles are temporary, small in size and few in number
-In plant cells, vacuoles are large and more in number
-May be contractile or non-contractile
Vacuoles
Function of Vacuoles
Functions:
Store various substances including waste products
Maintain osmotic pressure of the cell
Store food particles in amoeba cells
Provide turgidity and rigidity to plant cells
-Small, rod shaped organelles bounded by two membranes - inner and outer
-Outer membrane is smooth and encloses the contents of mitochondria
-Inner membrane is folded in the form of shelf like inward projections called cristae
-Inner cavity is filled with matrix which contains many enzymes
-Contain their own DNA which are responsible for many enzymatic actions
Mitochondria
Function of Mitochondria
Functions:
Synthesize energy rich compound ATP
ATP molecules provide energy for the vital activities of living cells
________are double membrane-bound organelles found inside plants and some algae.
They are responsible for activities related to making and storing food.
They often contain different types of pigments that can change the colour of the cell.
Plastids
_____are plastids that produce and store pigments
They are responsible for different colours found in leaves, fruits, flowers and vegetables.
Chromoplasts
Carrot
Pigment:
Carotene
Mango
Pigment:
Xanthophyll
Tomato
Pigment:
Lycopene
Are colourless plastids that store foods.
They are found in storage organs such as fruits, tubers and seeds.
Leucoplasts
Potato tubers
Food:
Starch
Maize grains
Food:
Protein
Castor seeds
Food:
Oil
Double membrane-bound organelles found mainly in plant cells
Usually spherical or discoidal in shape
Shows two distinct regions-grana and stroma
Grana are stacks of thylakoids (membrane-bound, flattened discs)
Thylakoids contain chlorophyll molecules which are responsible for photosynthesis
Stroma is a colourless dense fluid
Chloroplasts
Function of Chloroplasts
Functions:
Convert light energy into chemical energy in the form of food
Provide green colour to leaves, stems and vegetables
Centrosome is the membrane bound organelle present near the nucleus
Consists of two structures called centrioles
Centrioles are hollow, cylindrical structures made of microtubules
Centrioles are arranged at right angles to each other
Centrosome
Function of Centrosome
Functions:
Form spindle fibres which help in the movement of chromosomes during cell division
Help in the formation of cilia and flagella
Formed by microtubules and microfilaments
Microtubules are hollow tubules made up of protein called tubulin
Microfilaments are rod shaped thin filaments made up of protein called actin
Cytoskeleton
Function of Cytoskeleton
Functions:
Determine the shape of the cell
Give structural strength to the cell
Responsible for cellular movements
Nucleus is undeveloped
Only one chromosome is present
Membrane bound organelles are absent
Size ranges from 0.5-5 µm
Examples: Bacteria and blue green algae
Prokaryotic cell
Nucleus is well developed
More than one chromosomes are present
Membrane bound organelles are present
Size ranges from 5-100 µm
Examples: All other organisms
Eukaryotic cell
-Generally small in size
-Cell wall is absent
-Plastids are absent
-Vacuoles are smaller in size and less in number
-Centrioles are present
Animal cell
-Generally large in size
-Cell wall is present
-Plastids are present
-Vacuoles are larger in size and more in number
-Centrioles are absent
Plant cell
