Show Menu
Cheatography
  1. Home >
  2. Education >

Fundamental unit of life Cheat Sheet by

CLASS 9, NCERT, FUNDAMENTAL UNIT OF LIFE NOTES

CELL STRUCTURAL AND FUNCTIONAL UNIT

cell is the basic structural and functional unit of life.
cell -> tissue -> organ -> organ system -> organism (this is how cell is the structural unit)
cell does metabolic functions, produces glucose, energy(in the form of ATP[ad­enine tripho­sph­ate])

CELL SIZES AND SHAPES

smallest cell: mitopl­asm(0.3 microm­eter)
longest cell: neuron
largest cell: ostrich egg
CELLS IN ANIMALS
smallest cell in males: sperm
largest cell in males: WBC
smallest cell in females: RBC
largest cell in females: ovum

PLASTIDS

1) double membrane structure.
2) present mainly in plant cells and euglen­a(a­nimal cell)
3) has its own circular DNA
4) ribosomes present are 70s
5) plastids generally have pigments which give them colour
- types of plastids -
1) leucop­lasts: colour­less, no pigment. functions: storage of starch­(po­tato), protei­ns(­pul­ses), oil(pe­anuts)
2) chromo­plasts: coloured due to pigment. functions: to attract pollin­ators, nutrit­ional value.
3) chloro­plasts: green coloured due to chloro­phyll. functions: photos­ynt­hesis.

LYSOSOME

1) single membrane structure.
2) also called suicidal bag.
3) membrane bound organelle having digestive enzymes.
4) absent in matured RBC and prokar­yotic cells.
- FUNCTIONS -
1) cleans the cell by destroying worn out organe­lles.
2) destroys pathogens and toxic materials entering the cell.
3) they carry out autophagy -> destroying its own cell.
-steps of autophagy-
when a cell is damaged or infected -> lysosome enzymes gets activated -> lysosomes burst and digestive enzymes are released inside the cell -> the cell is digested comple­tely.

DIFFUSION AND OSMOSIS

DIFFUSION
OSMOSIS
1) movement of substances from high concen­tration to low concen­tra­tion.
1) diffusion through semi-p­erm­eable membrane.
 
2) movement of substances from an area of higher concen­tration to an area of lower concen­tration through a semi-p­erm­eable membrane.
 
-appli­cations and importance of osmosis-
 
1. absorption of water by root hair.
 
2. unicel­lular organisms gain water through osmosis.

NUCLEUS

Control center of the cell.
common stain used for nucleus: acetoc­armine
exceptions for nucleus: matured RBC of mammals, Platelets, Sieve tubes of phloem.
Covered by two membra­nes­-> inner and outer membra­ne(­tog­ether they are called the nuclear membrane)
ER is an extension of the outer membrane.
Nuclear membrane has openings called nuclear pores which contain Amuli.
Nuclear pore with amuli is called pore complex.
Nuclear pores allow passage of selective materials in and out of the nucleus.
nucleus contains a dense part called the nucleolus.
ribosomal subunits of rRNA are formed in the nucleus.
nucleolus is also important for protein synthesis.
nucleus is filled with jelly like substance called nucleo­plasm/ karyop­lasm/ nuclear sap. It contains all the components of the nucleus like nucleolus, chromatin fibres, enzymes, and nucleo­tids.
the nuclear membrane seperates nucleo­plasm from cytoplasm.
nucleus contains thread like structures called chromatin. chromatin condenses during cell division to form chromo­somes. chromo­somes are strands of DNA wrapped around proteins called histones.
chromo­somes contain genes that contain codes for protein synthesis.

ENDOME­MBRANE SYSTEM

1) organelles work together to make the cells work effici­ently and properly
2) organelles who work together form this system. (functions of organelles depend on eachother)
3) organe­lles: ER, golgi body, lysosomes, vacuoles, etc.

CELL DIVISION

the process in which a cell divides to form two or four daughter cells.
cells which do not divide: RBC, WBC, Platelets, Neurons, Sieve cells.
- why is cell division important-
1. growth of organism.
2. to repair damaged tissue of the body.
3. to recover from injuries.
4. for production of gametes that help in reprod­uction.
 

DNA(DE­OXY­RIBOSE NUCLEIC ACID)

1) The univer­sally accepted model of DNA is the double helical structure proposed by WATSON AND CRICKE.
2) adenine = thymine
3_ cytosine ≡ guanine
4. the functional unit of chromo­somes are genes. Genes contain the code for production of proteins and is made of 3 alphabets .
5. DNA contains all the inform­ation necessary for the growth and develo­pment of the organism.

MITOCH­ONDRIA

1) powerhouse of the cell.
2) absent in matured RBC's, prokar­yotic cell.
3) it produces energy in the form of ATP during cellular respir­ation.
4) stain used under micros­cope: Janus Green.
5) double membraned organelle.
6) semi autonomous organelle( does a few functions by itself)
-why is mitoch­ondria a semi autonomous organe­lle?-
1) it has DNA and Ribosomes
2) it can sustain for 10 to 12 hours without the nucleus
3) it depends on the nucleus for some proteins.
4) it can produce certain proteins required for its metabo­lism.

GOLGI BODY

1) modifying and packaging unit.
2) absent in prokar­yotic cells, matured sperms and matured RBC's.
3) consists of membrane bound sac-like structures called cister­naes, secretory vesicles.
4) single membrane structure.
5) it produces complex sugars from simple sugars.
6) it packs substances in secretory vesicles.
7) it gives rise to lysosomes.
8) it is a site for formation of glyco-­lipids and glyco-­pro­teins.

PLASMA MEMBRANE

1) made of lipids and proteins and some carboh­ydr­ates.
2) structure: sea of lipids in which proteins are presen­t(p­hospho lipid bylayers)
3) plasma membrane is a semi permea­ble­/se­lec­tively permeable membrane.
4) it allows certain substances to pass through it.
- functions of plasma membrane -
1) movement of substances in and out of the cell. Higher concen­tration to lower concen­tration where ATP is not used.

ENDOPL­ASMIC RETICULUM

1) found in all plant and animal cells.
2) absent in mature RBC in mammals and prokar­yotic cells.
3) gives rigid support to cells.
-ELEMENTS OF ER-
1) cister­nae­(RER): flat struct­ures.
2) vesicl­es(­SER): round and smooth.
3) tibule­s(SER): tube like struct­ures.
- FUNCTIONS OF ER -
1) helps in the transfer of materials between various regions of the cytoplasm and between the nucleus and the cytoplasm.
2) RER helps in protein synthesis.
3) SER helps in lipid(fat) synthesis.
4) Biogen­esis: process of producing lipids and proteins and using them to produce membranes of cells is called Biogen­esis.
5) SER detoxifies drugs and poisons in the cell.

CHROMO­SOMES

diploid: two sets of chromo­somes, only in vegetative cells.
haploi­d/g­ametal cells: only one set of chromo­somes.
chromo­somes contain all the inform­ation required for growth and develo­pment of an organism.

TYPES OF SOLUTIONS

- ISOTONIC SOLUTI­ON(­bal­anced) -
- HYPOTONIC SOLUTION (diluted)-
- HYPERTONIC SOLUTI­ON(­con­cen­trated) -
1. it has exactly the same water concen­tration as the cell.
1. it has more concen­tration of water than the cell.
1. it has less concen­tration of water than the cell.
2. so there is no net water movement across the cell.
2. water moves in the cell and causes the cell to swell.
2. water moves out of the cell and causes the cell to shrink.

DIFFER­ENCES BETWEEN PROKAR­YOTES AND EUKARYOTES

PROKAR­YOTES
EUKARYOTES
1. prokar­yotes have a nucleoid and nuclear membrane is absent.
1. has a well defined nucleus with nuclear membrane.
2. lacks membrane bound organe­lles.
2. membrane bound organelles are present.
3. DNA is circular.
3. DNA is linear.
4. ribosomes are small(70s)
4. ribosomes are large(80s)
5. single chromo­somes are present.
5. multiple chromo­somes are present.
6. cell wall is peptid­ogl­ycan.
6. cell wall is cellul­ose­(pl­ants) and chitin­(an­imals)

HISTORY OF CELL

robert hooke: discovered cork cell(which was dead) using a primitive micros­cope.
anton von leeuwe­nhoek; found free living cells in pond water using an improved micros­cope.
robert brown: discovered nucleus
purkinje: coined the term protop­lasm.
schleiden and schwann: made the cell theory.
rudolph virchow: cell theory.
 

SOME TERMS

homologous chromo­somes : chromo­somes which are similar in structure and function.
crossing over: process of exchange of genetic material between non-sister chromatids of homologous chromo­somes.

CENTRO­SOMES

1) present only in animal cells.
2) form spindle fibres during cell division.

TRANSP­ORT­ATION IN THE CELL

PASSIVE TRANSP­ORT­ATION
ACTIVE TRANSP­ORT­ATION
1. high concen­tration to low concen­tra­tion.
1. low to high concen­tra­tion.
2) no energy is used.
2. energy used.
3) eg: diffusion, osmosis.
3. eg: reabso­rption of substances in the kidney, sodium­/po­tassium pump.

RIBOSOMES

1) found on the surface of ER.
2) freely found in the cytoplasm.
3) present in plastids and mitoch­ondria.
4) sometimes found in the outer membrane of the nucleus also.
5) produced in the nucleolus of the nucleus.
6) made of RNA and proteins.
7) membra­ne-less organelle.
8) it has two subunits:- a small unit(70s) and a large unit(80s).
9) 70s ribosome: present in prokar­yotic cells, mitoch­ondria and chloro­plast.
10) 80s ribosome: present in eukaryotic cell, ER, cytoplasm of ER, outer membrane of the nucleus.

VACUOLE

1) single membrane bound organelle.
2) types of vacuoles: food, gas, contra­cil­e(only in aquatic animals)
-funct­ions-
storage, maintains water balance in the cell, helps in excretion.

DIFFER­ENCES BETWEEN MITOSIS AND MEOSIS.

mitosis
meosis
1) forms 2 daughter cells.
1) on cell forms 4 daughter cells.
2) also known as equational division.
2) also known as reduct­ional division.
3) occurs in vegetative cells or somatic cells.
3) occurs in gametes or germinal cells
4) daughter cells have same number of chromo­somes.
4) daughter cells will have half the number of total chromo­somes.
5) helps in growth and healing of an injury.
5) formation of gametes for reprod­uction.

DIFFER­ENCES BETWEEN SER AND RER

SER
RER
1) ribosomes are present.
1) ribosomes are absent.
2) protein synthesis.
2) lipid synthesis.
3) mainly has cisternae.
3) mainly has vesicles and tibules.

CHROMO­SOMES

during cell division, chromatin condenses to form chromo­somes.
chromo­somes contain DNA along with proteins called Histones which helps in the packing of DNA.
DNA is made of nucleic acids.
NUCLEIC ACIDS:
1) made up of sugar(­deo­xyr­ibose sugar-> 5 carbon compound)
2) nitrog­enous bases-> adenine, guanine, cytosine, thymine. (thymine is only in DNA, in RNA it is Uracil)
Adenine = Thymine (double bonding)
Guanine ≡ Cytosine (triple bonding)

DIFFER­ENCES BETWEEN ANIMAL AND PLANT CELL

plant cell
animal cell
1. nucleus is situated in the peripheral area.
1. nucleus is in the center of the cell.
2. cell wall is present.
2. cell wall is absent.
3. vacuoles are large and present.
3. vacuoles are small and temporary.
4. plastids are present.
4. plastids are absent.
5.lyso­somes are absent.
5. lysosomes are present.
6. centro­somes are absent.
6. centro­somes are present.
7. cytopl­asmic division happens by cell plate formation.
7. cytopl­asmic division happens by cell furrow formation.
 
1. nucleus is in the peripheral area.

DIFFER­ENCES BETWEEN ANIMAL AND PLANT CELL

plant cell
animal cell
1. nucleus is in the peripheral area.

THE CELL THEORY

1) every organism is made up of cells.
2) cells are the structural and functional unit.
3) all cells arise from prexisting cells. (omice­llu­la-­e-c­ellula
MODERN CELL THEORY ADDITIONS:
4) all cells contain genetic material.
5) some organisms can divide again and again and give rise to organs or organisms.
 

Metadata

  • Languages:
  • Published: 15th September, 2023

Comments

No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          Cell Structure and Function Cheat Sheet

          More Cheat Sheets by SilverPearl

          india size and location Cheat Sheet
          POVERTY AS A CHALLENGE CLASS 9 Cheat Sheet
          CLASS 9 ELECTORAL POLITICS CIVICS CBSE Cheat Sheet