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FUNDAMENTAL UNIT OF LIFE. CELLS. CELL THEORY . All living organisms are composed of one or more cells. The cell is the basic unit of structure, function, and organization in all organisms. All cells come from preexisting, living cells.

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cell theory
CELL THEORY
  • All living organisms are composed of one or more cells.
  • The cell is the basic unit of structure, function, and organization in all organisms.
  • All cells come from preexisting, living cells.
  • Usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientist like Rudolf Virchow contributed to the theory.
robert hooke
ROBERT HOOKE

CELLS WERE FIRST DISCOVERED BY HIM IN 1665

robert observed
ROBERT OBSERVED :
  • Slice of cork resembled the structure of the honeycomb consisting of small compartments. Robert called theselittle compartments as cells.

CORK COMES FROM THE BARK OF THE TREE

CORK SEEN UNDER THE MICROSCOPE OF HOOKE

structure of cell
STRUCTURE OF CELL
  • Cells come in all shapes and sizes. While most of the cells are spherical in shape, cells of various other shapes are also found. Most of the cells are microscopic in size, i.e. it is impossible to see them with naked eyes. Some cells are fairly large, e.g. a neuron in human body can be as long as 1 meter.
slide7

COMPARING CELLS

nerve cells can be 1m long

human egg cell is no bigger than the dot on this i

human red blood cells is 1/10 the size of a human egg cell

bacterium are even smaller-

8000 can fit inside a human egg cell

different cells
DIFFERENT CELLS

NERVE CELL

FAT CELL

BONE CELL

SPERM

OVUM

BLOOD CELL

cell types
CELL TYPES

PROKARYOTIC CELLS

no membrane bound structures

EUKARYOTIC CELLS

membrane-bound structures

slide10

UNICELLULAR ORGANISMS

  • ORGANISMS THAT HAVE A SINGLE
  • CELL-PROKARYOTIC CELLS.

AMOEBA

PARAMOECIUM

CHLAMYDOMONAS

slide11

MULTICELLULAR ORGANISMS

  • ORGANISMS HAVING MORE THAN ONE CELL TO PERFORM VARIOUS FUNCTIONS-EUKARYOTIC CELLS.

PLANTS

ANIMALS

FUNGI

slide12

CELL WALL

found in plants, algae, fungi, most bacteria

tough, rigid outer coverings that protect the cell and give it shape

plant cell walls are mainly made of cellulose

what makes the cell walls rigid? Pectin and lignin!

slide13

CELL MEMBRANE

Protective layer around all cells

If a cell has a cell wall, then the cell membrane is inside of it

what does it do? regulate interactions between the cell and the environment

food particles and some molecules enter and waste products leave through the cell membrane

water can move into and out of cell through the cell membrane

slide14

CYTOPLASM

Contains a framework called the cytoskeleton - this helps maintain or change the shape of the cell.

Gelatin like substance that fills cells which is constantly moving

Cytoskeleton

helps some cells

move

cytoskeleton is made up of thin, hollow tubes of protein and thin, solid protein fibers

slide15

ORGANELLES

contained within the cytoplasm

  • What do organelles do?
  • process energy
  • manufacture substances needed by the cell
  • move materials
  • act as storage sites
  • are surrounded by membranes
  • nucleus is usually the largest organelle
slide16

NUCLEUS

directs all cell activities

is surrounded by a membrane

a nucleolus is also within the nucleus

materials enter and leave through the membrane

contains instructions for everything in the cell, which are found on DNA

slide18

ENERGY-PROCESSING ORGANELLES

  • cells need energy to:
  • process food
  • make new substances
  • eliminate wastes
  • communicate with each other
slide19

PLANTS

  • food is made in green organelles called chloroplasts
  • contain green pigment chlorophyll
  • chlorophyll captures light energy that is used to make glucose
slide20

ANIMALS

  • energy in food is stored until it is released by the mitochondria
  • organelles where energy is released from the breakdown of food into carbon dioxide and water
  • muscle cells are more active, so they contain more mitochondria
slide21

GOLGI BODIES

proteins are made and sent to the Golgi bodies

Golgi bodies sort proteins and other cellular substances and package them into membrane-bound structures called vesicles

vesicles deliver cellular substances to areas inside the cell

Refrigerator - cells have membrane-bound spaces called vacuoles for temporary storage of materials (water, waste products, food, and other cellular materials)

slide22

RECYCLING ORGANELLES

lysosomescontain digestive chemicals that help break down food molecules, cell wastes, and worn-out parts

active cells break down and recycle substances

lysosome membrane keeps the chemicals from leaking into the cell

when a cell dies a lysosome’s membrane disintegrates, releasing digestive chemicals that quickly breakdown the cell’s contents

slide23

PRESENTED BY

  • LIPIKA BISWAS, TGT (SCIENCE), K.V. - BALLYGUNGE
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