Biology:cells

CELL STRUCTURE

Cell Wall

• Bacterial cell wall is made up of peptidoglycans.
• The archean cell wall is made up glycoproteins and polysaccharides. The plant cell wall is mainly composed of cellulose hemi-cellulose
• glycoproteins, pectins and lignin. Animal cell lacks cell wall.

Plant Cell Wall

• Plant cell walls are primarily made up of cellulose which is the most abundant micro molecule on the earth.
• Plant cell wall consists of three layers, the primary cell wall, secondary cell wall wall and middle lamella

Cell Membrane/Plasma Membrane

• Plasma membrane is a living, selectively permeable membrane. It allows some selected materials to move in and out of the cell, and prevents the entry and exit of theother substances.
• The plasma membrane is made up of a bilayer of lipids and proteins. Small carbohydrates are attached at places to outer surface of lipids and proteins.
• The Fluid Mosaic Model proposed by Singer and Nicholson is widely accepted.

  According to this model:

  • The cell membrane is composed of lipid bilayer of phospholipid molecules into which variety of globular proteins are embedded.
  • Each phospholipid molecule has two ends- an outer head hydrophilic (water attracting) and the inner tail hydrophobic (water repelling)
• Biology Notes

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  Biology notes

  Table of Contents

  • Biology notes
  • BIOLOGICAL CLASSIFICATION/ CELL & ITS DIVISION
    • Classification of Organisms
      • • • Thing you must know
    • BINOMIAL SYSTEM OF CLASSIFICATION
  • Kingdom Plantae
    • • Kingdom Animalia
    • CELL : FUNDAMENTAL UNIT OF LIFE
      • CELL STRUCTURE
      • Cell Wall
      • Cell Membrane/Plasma Membrane
      • Function of cell membrane
      • CYTOPLASM
      • Endoplasmi Retculum
      • Functions of endoplasmic reticulum:
      • Golgi Bodies
    • Lysosomes
  • Golgi Bodies
    • • Mitochondria
      • Ribosomes
      • Cilia and Flagella
    • Biology : Cell Division
  BIOLOGICAL CLASSIFICATION/

  CELL & ITS DIVISION

  Biological classification is the scientific procedure of arranging organisms into groups and subgroups on the basis of their similarities and dissimilarities and placing the groups in a hierarchy of categories. The purpose of biological classification is to organize the vast number of known plants and animals into groups

  Why classifiation is needed?

  • help in the identification of organisms.
  • help in establishing relationship between different organisms and to know about their evolution.
  • study one or two organisms of one particular group and give the sufficient information of that group. It gives an idea of whole range of diversity found in organisms.
  • it gives an idea of the evolution of various groups of organisms.

  Systematics

  • . It is the study of the diversification of organisms and their relationship among
  • living things through time. It includes
  • Identification: It is a process of finding the correct name and place of an organism in a system of classification.
  • Classification: It is the arrangement of an organism in a particular group on the basis of their similarities and dissimilarities.
  • Nomenclature: It is a system of providing proper and distinct name to one particular organism which helps in recognizing that organism.
  • Taxonomy: It is a science dealing with the description, identification, naming and classification of organism.
  Classification of Organisms
  • It is the arrangement of grp according to their similarities and dissimilarties so that we can study them easily.below img (source: proreaders.in) give you nitty gritty of this topic
  Biology Notes - Classifiation of OrganismThing you must know
  • Carolus Linnaeus was a Swedish naturalist also known as the father of Taxonomy as he developed a way to name and organize species that we still use today. He wrote a
  • book named ‘Systema Naturae’ in which he describes the system of classification of nature.
  • Aristotle, also known as father of zoology classified animals on the basis of habitat into aquatic, terrestrial and aerial animals.
  • Theopharastus, also known as father of botany divided plants on the basis of form texture and habitat into four types as trees, shrubs, undershrubs and herbs. He wrotea book named ‘Historia Plantarum
  BINOMIAL SYSTEM OF CLASSIFICATIONBionomial System of Classifiation

  FIVE KINGDOM CLASSIFICATION –Proposed by R.H. Whittaker

  Kingdom monera

  Kingdom protista

  Kingdom Fungi

  Kindom plantae

  kingdom animalia Kingdom Plantae

  • They are multicellular eukaryotes. All plants contain plastids.
  • Plastids are double membrane organelle that possesses photosynthetic pigments.
  • They are called chloroplast.
  • They are usually are usually autotrophic.
  • Chloroplast contains a green colour pigment called pigment called chlorophyll and prepares own food by the process of photosynthesis.
  • Cells have cell wall made up of cellulose. photosynthesis.Cells have cell wall made up of cellulose.
  • Kingdom plantae shows a lot of diversity, because of which, it has been divided into four divisions: Algae, Bryophyta, Pteridophyta, and Spermatophyta (Gymnosperms and Angiosperms)
  Kingdom Animalia
  • There are diverse group of animals in the whole world they lives in different habitats. All animals are multicellular except protozoa,
  • these are eukaryotic, lacks cell wall, heterotrophic, have power of locomotion and shows increased sensitivity through the nervous system.
  • On the basis of presence and absence of vertebrate column. Animal Kingdom are broadly divided into vertebrates and invertebrates.
  • Inverbrates consists 8-phylums named Porifera, Cnidaria, Platyhelmintus, Aschelminthus, Anellida, Arthropoda, Molluscs and Enchinodermata. Vertebrates or phylum chordata consists 3-subphylums, Urochordata, Cephalochordata and Vertebrata.
  CELL : FUNDAMENTAL UNIT OF LIFE
  • The smallest cell found is a mycoplasma cell, which is about 0.1 micron in diameter.
  • The longest cells are the nerve cells, measuring about a metre in length.
  • The largest cells are represented by eggs of Ostrich, which is about 170-135 mm.
  CELL STRUCTURE

  Cell Wall

  • Bacterial cell wall is made up of peptidoglycans.
  • The archean cell wall is made up glycoproteins and polysaccharides. The plant cell wall is mainly composed of cellulose hemi-cellulose
  • glycoproteins, pectins and lignin. Animal cell lacks cell wall.

  Plant Cell Wall

  • Plant cell walls are primarily made up of cellulose which is the most abundant micro molecule on the earth.
  • Plant cell wall consists of three layers, the primary cell wall, secondary cell wall wall and middle lamella
  Cell Membrane/Plasma Membrane
  • Plasma membrane is a living, selectively permeable membrane. It allows some selected materials to move in and out of the cell, and prevents the entry and exit of theother substances.
  • The plasma membrane is made up of a bilayer of lipids and proteins. Small carbohydrates are attached at places to outer surface of lipids and proteins.
  • The Fluid Mosaic Model proposed by Singer and Nicholson is widely accepted.

    According to this model:

    • The cell membrane is composed of lipid bilayer of phospholipid molecules into which variety of globular proteins are embedded.
    • Each phospholipid molecule has two ends- an outer head hydrophilic (water attracting) and the inner tail hydrophobic (water repelling)
  Differene bw plant cell and animal cellFunction of cell membrane
  • It provides definite shape to the cell and acts as a mechanical barrier between external and internal environment of the cells.
  • It regulates the movement of molecules in and out of cell.
  • The flexibility of membrane helps the cell to engulf food and other substances from its external environment by endocytosis.
  CYTOPLASM
  • It is living portion or protoplasm of cell that comprises gelly like Substance called cytosol and organells with nucleus. It is present in both plant and animal cell. It includes, ER, Golgi bodies, plastids, lysosomes, peroxisomes, ribosomes, Mitochondria, and Centrosomes.
  • in both plant and animal cell. It includes, ER, Golgi bodies, plastids, lysosomes, peroxisomes, ribosomes, Mitochondria, and Centrosomes.

CELL CYCLE

• Cell division is a biological process in all living organisms

in which mother cell divides into two daughter nuclei.

• Although cell growth (in terms of cytoplasmic increase)

is a continuous process, DNA synthesis occurs only

during one specific stage in the cell cycle. The replicated

chromosomes (DNA) are then distributed to daughter

nuclei by a complex series of events during cell division.

These events are themselves under genetic control.

• The sequence of events which occur during cell growth

and cell division are collectively called cell cycle.

It was introduced by Howard and pole in 1953.

Phases of Cell Cycle

The period required to complete one cell cycle (from beginning

of one cell division to the beginning of next) is called generation

time. It is 24 hours in human cells and 90 minutes in yeast. Cell

cycle is simpler in prokaryotes and more complex in eukaryotes.

The cell cycle is divided into two basic phases :

• Interphase
• M Phase (Mitosis phase)/Dividing phase

Interphase

• It is the period between the end of one cell division to the

beginning of next cell division.

• It is highly metabolically active phase, in which cell

prepares itself for next cell division.

Interphase is Completed into Three Successive

Stages

• G1 phase/Post mitotic/Pre-DNA synthetic phase/gap-I :

(ii) Synthesis of rRNA, mRNA ribosomes and proteins.

(iii) Metabolic rate is high.

(iv) Cell size increases.

(v) Synthesis of enzymes, amino acids, nucleotides etc. but

there is no change in DNA amount.

.

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