GEN BIOLOGY FIRST QUARTER FIRST LESSON

Cell

• is the smallest functional and structural unit of all living organism
  - an organism is any living thing that carriers out its own life processes
  - robert hooke was the first to describes cells he looked at the bark of a cerk tree under a microscope
  

Why are the most cell small?

• Cells are small becaue their size is limited by their outer surface are
  - if cells get too large,they cannot take in enought materials or get rid of enought wastes
  - the surface area to volume ratio of cell is the ratio at the outer surface to the cell volume

random cell facts

• the average human being is composed of around 100 trillion individual cells
  - it would take as many as 50 cells to cover the area of a dot ont the letter

what is cell theory

• all living organism are composed of cells
  - the cell serves as the fundamental unit of life
  - all cells orig from previously existing cells

modern cell theory

• the cell contains hereditary information ( dna ) which is passed on from cell to cell during cell division
  - all cells are basically the same in chemical composition and metabolic activities
  - all basic chemical composition and metabolic activities
  - all basic chemical physiological function are carried out inside the cells
  - cell activity depends on the activities of sub celliular structures within the cell ( organalles,nucleus,plasma membrane)

Biological Concept

Dna (deoxyribonucleic acid ) is the genetic material found in cells inherited traits and directed cells activies before a cell divides, its dna is replicated so that each new daughter celll receives a complete set of genetic information

why study scientific history

• enhances out understanding of how knowlegde-
  - demonstrates the significant of evidences and observation
  - unveiling collaboration among scientists

• utilizes secondary sources such as books,articles,and journals

robert hooke ( 1665 )

• he studied cork using a microscope in 1665
  - hooke notices box-like structures he called “cells”
  - he published his finding in microphia

anton van leeuwenhook ( 1670 )

• he improved miscroscope lens quality
  - the first to document living miscroorganisms or animalcules
  - he opened the field of microbiology

Matthias Schleiden ( 1838 )

• he studied plants under a microscope
  - he concluded that all plants consist of cells
  - he helped establish the cell as life fundamental unit

theodor schwan ( 1839 )

he studied plants and animal cells
- determine that all animals are made of cells
- published the 1st statement of the cell theory

rudolf virchow ( 1855 )

he said cells arise from pre - existing cell or “ omnis cellula e cellula”
he emphasize diseases start in cells, not organs or tissues
he strengthened modern cell theory

light microscope

also called an optical microscope functions by passing visible light throught or onto a specimen and using a system of lenses to magnify the image of observation

Eye piece ( ocular lens )

the lens closet to the that further magnifies the images produced by the objective lens

objective lenses

usually 3 -5 lenses on a rotating nosepiece,each with different magnification powers,responsible for forming the primary enlarged image of the specimen

condenser

focuses light from the illuminator onto the specimen to enchance clarity

diaphragm ( iris or aperture )

controls the amount and contrast of light passing through specimen

base

provides stability and support for the microscope

arm

connects the base to the head

stage

that platform where is the specimen

electron miscroscope

an electron miscroscope ( em ) is an instrument that uses a focused beam of electrons to illuminate a specimen producing highly magnified image for beyond the capbilities

Light Microscope

A microscope that uses visible light and glass lenses to magnify specimens.

Electron Microscope

A microscope that uses a beam of electrons and electromagnetic lenses to produce highly magnified images.

Source of Illumination (Light Microscope)

Uses visible light.

Source of Illumination (Electron Microscope)

Uses a beam of electrons.

Magnification (Light Microscope)

Up to 1,000–2,000×.

Magnification (Electron Microscope)

Up to 1,000,000× or more.

Resolution (Light Microscope)

About 200 nm.

Resolution (Electron Microscope)

About 0.1–0.2 nm.

Image Produced (Light Microscope)

Produces colored or natural-looking images.

Image Produced (Electron Microscope)

Produces black-and-white images that may be colorized digitally.

Specimen Condition (Light Microscope)

Can observe living or dead specimens.

Specimen Condition (Electron Microscope)

Can observe only dead specimens.

Specimen Preparation (Light Microscope)

Simple and quick preparation.

Specimen Preparation (Electron Microscope)

Complex and time-consuming preparation.

Lenses (Light Microscope)

Uses glass lenses.

Lenses (Electron Microscope)

Uses electromagnetic lenses.

Environment Required (Light Microscope)

Works under normal atmospheric conditions.

Environment Required (Electron Microscope)

Requires a vacuum chamber.

Cost (Light Microscope)

Less expensive.

Cost (Electron Microscope)

Very expensive.

Size of Instrument (Light Microscope)

Smaller and portable.

Size of Instrument (Electron Microscope)

Large and bulky.

Main Use of Light Microscope

Used to observe living cells, tissues, and microorganisms.

Main Use of Electron Microscope

Used to observe viruses, cell ultrastructure, and organelles.