Functions What are cells? Cells are the basic units of living - - PowerPoint PPT Presentation

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Functions What are cells? Cells are the basic units of living - - PowerPoint PPT Presentation

Sep 13, 2023 104 likes •354 views

Cell Structures and Functions What are cells? Cells are the basic units of living organisms Microscopes Scientists use microscopes to view cells Scientists Who Contributed to Early Cell Research Robert Hooke Anton van

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Cell Structures and Functions

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What are cells?

  • Cells are the basic units of living organisms
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Microscopes

  • Scientists use microscopes to view cells
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Scientists Who Contributed to Early Cell Research

  • Robert Hooke
  • Anton van Leeuwenhoek
  • Mathias Schleiden
  • Theodor Schwann
  • Rudolf Virchow
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Robert Hooke

  • 1665
  • Observes cork under a microscope
  • Observes tiny chambers which he calls “cells”
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Anton van Leeuwenhoek

  • 1683
  • Observes microorganisms in pond water
  • Observes microscopic animal-like protozoans
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Matthias Schleiden

  • 1838
  • Botanist, proposed that all plants are

composed of cells, also researched fungi

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Theodor Schwann

  • 1839
  • Zoologist, studied histology (microscopic

structure of tissues)

  • Proposed that all animals are composed of

cells

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Rudolf Virchow

  • 1855
  • Observed dividing cells under a microscope
  • Proposed that all cells are produced from pre-

existing cells

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Cell Theory

  • Three components to the cell theory:

– All living organisms are composed of one or more cells – Cells are the basic unit of structure and function in all living organisms – Cells arise only from previously existing cells

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Unicellular Organisms

  • Composed of only one cell
  • Include all bacteria, some fungi and some

protists

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Multicellular Organisms

  • Composed of more than one cell
  • Includes all plants and animals, some fungi

and some protists

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Multicellular Levels of Organization

  • Multicellular organisms are composed of cells

which are then organized further into tissues,

  • rgans and organ systems
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Cell Diversity

  • There are many different cell types and each

cell type has a unique function in the organism

  • Structure of the cell type usually reflects

function

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Cell Diversity

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Prokaryotic and Eukaryotic Cells

  • Prokaryotic cells are bacteria (unicellular) with

no true nucleus or membrane-bound

  • rganelles
  • Eukaryotic cells are cells with a defined

nucleus and membrane-bound organelles

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Similarities Between All Cells

  • All cells (prokaryotic and eukaryotic) contain

DNA, cytoplasm, a plasma membrane and ribosomes

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Prokaryotic Cells

  • Prokaryotic cells are smaller, less complex in

structure, evolved before eukaryotic cells, and contain a single circular chromosome

  • Primitive cell type (~ 3.5 billion years ago)
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Eukaryotic Cells

  • Eukaryotic cells are larger, more complex in

structure, evolved after prokaryotic cells, and contain many linear chromosomes

  • Recent cell type (~ 2 billion years ago)
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Theory of Endosymbiosis

  • Proposes the origin of eukaryotic cells
  • The theory of endosymbiosis proposes that

eukaryotic cells formed from a symbiotic relationship among several different prokaryotic cells

  • Symbiosis = two different species benefit from

living and working together

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Theory of Endosymbiosis

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Internal Organization of Cells

  • Organelles are specialized structures within

living cells

  • Each organelle performs essential cell

function, such as protein synthesis and energy transformation