Cells and Evolution

Table of Contents

1 Important Contributions

Epithet/Discovery Person
Father of Biology Aristotle
Father of Medicine Hippocrates
Father of Genetics Gregor Mendel
Blood circulation William Harvey
DNA Fingerprinting Alec Jeffreys
Pencillin Alexander Fleming
Vaccination (small pox) Edward Jenner

1.1 Charles Darwin

  • wrote On the Origin of Species
  • in which he proposed the theory of Natural Selection
  • which stemmed from his work carried out during his voyage aboard HMS Beagle.
  • His work was greatly influenced by his observations at Galapagos Islands (Pacific Ocean) off the coast of present day Ecuador.

2 Cell Biology

  • Cell theory proposed by Schleiden and Schwann.
Smallest cell Mycoplasma (bacteria)
Largest cell Ostrich egg
Longest cell Neuron

2.1 Types of organelles

2.1.1 Organelles with double membrane

  1. Mitochondria
  2. Nucleus
  3. Chloplasts/plastids (in plant cell only)

2.1.2 Organelles without any membrane

  1. Centriole - play a role in cell division
  2. Ribosomes - site of protein synthesis

2.1.3 Organelles bound by a single (unit) membrane

  1. Golgi bodies - secretion and intracellular transport
  2. Endoplasmic reticulum - transporting proteins
  3. Lysosomes - intracellular digestion, breaks down metabolic wastes into reusable material

2.2 Cell Wall

  • found only in plant cells, bacteria and fungi
  • provides shape and rigidity
Type of life material of cell wall
Plants cellulose, lignin
Fungi chitin
Bacteria peptido-glytin

2.3 Cell Membrane

  • selectively permeable membrane
  • made of phospholipids
  • regulates movement of molecules inside and outside the cell

2.4 Mitochondria - Respiration

  • site of cell respiration
  • aka powerhouse of the cell
  • the process of aerobic respiration is known as Krebs Cycle
  • Adenosine Triphosphate (ATP) is produced from ADP

Mitochondria has DNA, RNA and enzymes of its own. It functions like a cell within a cell and its division is carried out independently of the division of the larger cell.

2.5 Lysosome (suicidal sacs) - Digestion

  • cell digestion (contains hydrolytic enzymes)
  • disintegrate metablic wastes into reusable molecules

2.6 Ribosomes

  • synthesize polypeptides (proteins) from amino acids
  • structure and function studied by Venkatraman Ramakrishnan (Nobel Prize)

2.7 Plastids

  • occur in plant cells
  • of 3 types
    1. chloroplast - photosynthesis
    2. chromoplast - give colour to flowers, fruits
    3. leucoplasts - storage of starch

2.8 Golgi Bodies

  • also known as dictiosome
  • role in storage and processing of materials
  • more in number in plants cells

2.9 Vacuoles

  • larger size in plant cells
  • provide turgor pressure
  • store toxins and metabolic wastes

2.10 Cilia and Flagella

  • help in movement of the cell
  • cilia are more in number but smaller
  • flagella is longer but singular

2.11 RNA & DNA

single stranded double-stranded
contains uracil contains adenine, thumine, guanine, cyctosine bases but not uracil
present in nucleaus as well as in cytoplasm present only inside the nucleus

3 Evolution

3.1 Chronological evolution of molecules in nature

  1. Nitrogen
  2. Ammonia
  3. Methane
  4. Sugars
  5. Proteins
  6. Prokaryotes

3.2 Summary of origin of life

  1. Free atoms(C, H, O, N, P)
  2. Origin of molecules and simple inorganic compounds (water, ammonia, hydrogen)
  3. early organic compounds (methane, HCN)
  4. simple organic compounds (simple sugars, fatty acids, amino acids, nitrogen bases)
  5. complex organic compounds (carbohydrates, lipids, proteins, nucleic acids)
  6. co-acervates (aggregates of previous organic compounds)
  7. prokaryotes (bacteria)
  8. eukaryotes

3.3 Theories of evolution

Name of scientist Book Proposition
Lamarck Philosophie Zoologique Inheritence of acquired characteristics
Darwin On the Origin of Species Inheritance of useful variations by natural selection
Hugo de Vries   Mutation theory – sudden discontinuous variations

3.4 Classification of organs

Homologous organs Analogous organs Vestigal organs
same structure, different function different structure, same function organs present in reduced forms
forelimbs in frog, lizard, pigeon, whale wings of birds and insects vermiform appendix
mouth parts of insects sting of honeybee and scorpion wisdom tooth
  fins of fishes and whales nictitaping membrane
    caudal vertebrae

Author: likeaflower

Created: 2018-05-07 Mon 01:36

Emacs 24.5.1 (Org mode 8.2.10)