BIO.A.4 Homeostasis and Transport
Topic Summary for Microscopy:
The invention of the microscope in the 1600s enabled researchers to see cells for the first time.
Robert Hooke named the empty chambers he observed in cork “cells.”
Anton van Leeuwenhoek was the first to observe living microorganisms.
Cells are the basic units of life.
Discoveries by German scientists Schleiden, Schwann, and Virchow led to the development of the cell theory, which states:
• All living things are made of cells.
• Cells are the basic units of structure and function in living things.
• New cells are produced from existing cells.
Scientists use light microscopes and electron microscopes to explore the structure of cells.
Compound light microscopes have lenses that focus light. They magnify objects by up to 1000 times. Chemical stains and fluorescent dyes make cell structures easier to see.
Electron microscopes use beams of electrons focused by magnetic fields. They offer much higher resolution than light microscopes. There are two main types of electron microscopes—transmission and scanning. Scientists use computers to add color to electron micrographs, which are photos of objects seen through a microscope.
Cells come in an amazing variety of shapes and sizes, but all cells contain DNA. Also, all cells are surrounded by a thin flexible barrier called a cell membrane. There are two basic categories of cells based on whether they contain a nucleus. The nucleus (plural: nuclei) is a large membrane-enclosed structure that contains DNA.
Eukaryotes are cells that enclose their DNA in nuclei.
Prokaryotes are cells that do not enclose their DNA in nuclei.
Topic Summary for Microscopy:
The invention of the microscope in the 1600s enabled researchers to see cells for the first time.
Robert Hooke named the empty chambers he observed in cork “cells.”
Anton van Leeuwenhoek was the first to observe living microorganisms.
Cells are the basic units of life.
Discoveries by German scientists Schleiden, Schwann, and Virchow led to the development of the cell theory, which states:
• All living things are made of cells.
• Cells are the basic units of structure and function in living things.
• New cells are produced from existing cells.
Scientists use light microscopes and electron microscopes to explore the structure of cells.
Compound light microscopes have lenses that focus light. They magnify objects by up to 1000 times. Chemical stains and fluorescent dyes make cell structures easier to see.
Electron microscopes use beams of electrons focused by magnetic fields. They offer much higher resolution than light microscopes. There are two main types of electron microscopes—transmission and scanning. Scientists use computers to add color to electron micrographs, which are photos of objects seen through a microscope.
Cells come in an amazing variety of shapes and sizes, but all cells contain DNA. Also, all cells are surrounded by a thin flexible barrier called a cell membrane. There are two basic categories of cells based on whether they contain a nucleus. The nucleus (plural: nuclei) is a large membrane-enclosed structure that contains DNA.
Eukaryotes are cells that enclose their DNA in nuclei.
Prokaryotes are cells that do not enclose their DNA in nuclei.