Chapter 4: A Tour of the Cell Flashcards
Who were cells first seen by?
Robert Hooke, as he studied the bark of an oak tree
Who first saw living cells?
Antoni van Leeuwenhoek
What is a light microscope?
a microscope in which visible light is passed throguh the specimen and then through glass lenses that refracts the light and magnifies it
What is magnification?
the ration of an objects image size to its real size
How much can light microscopes magnify up to?
1000x
What is resolution?
the measure of the clarity of an image: the minimum distance that two points can be distinguished as seperate points
What is contrast?
the difference in brightness between the light and dark areas of an image. This is usually enhanced by straining
What does the electron microscope do?
focuses a beam of electrons through the specimen allowing scientists to study the membrane-enclosed structures called organelles inside the cells. These images are about 100x more powerful than the light microscope but unfourtunately it kills living cells
How is the scanning electron microscope especially useful?
for a detailed study of the topography of a specimen
How can the Transmission electron microscope be used for?
to look at the interior structure of a cell
What is cytology?
the study of cell structure
What is cell fractionation?
a very useful technique of studying cell structure and function which takes cells apart and spun down to seperate the organelles and other structrues
Explain the timeline of cell theory.
In 1838 Matthias Shielden and Theodore Schwann came up with the first two parts of cell theory, while Rudolf Virchow contributed the third in 1855
What is the first part of cell theory?
Cells are the basic unit of structure and function
What is the second part of cell theory?
All living things are made up of one or more cells
What is the third part of cell theory?
All cells come from pre-existing cells
What domains consist of prokaryotic cells
Bacteria and Archae
What domains consist of eukaryotic cells?
protists, fungi, animals, and plants
What are all cells bounded by?
a selective barrier, called the plasma membrane which surrounds a semifluid, jellylike substance called cytosol
What else do all cells contain?
chromosomes and ribosomes
What do chromosomes do?
carry genes in the form of DNA
What are ribosomes?
tiny complexes that make proteins according to the instructions from the genes
Where is DNA held in a Eukaryotic cell?
in an organelle called the nucleus which has a double membrane surrounding it
Where is DNA concentrated in a Prokaryotic cell?
in a region that is not membrane enclosed called the nucleoid
Which cell evolved first: Eukaryotic or Prokaryotic?
Prokaryotic cells
How long in diameter are typical bacteria?
1-5 micrometers
How long in diameter are typical eukaryotic cells?
10 - 100 micrometers
How does the plasma membrane function?
as a selective barrier that allows the passage of enough oxygen, nutrients and wastes to service the entire cell
What happens as a cell increases in size?
the surface area of a cell grows proportionately less than its volume
T/F: Larger organisms do not have larger cells than smaller organisms
False - they simply have MORE cells
What does the nuclues contain?
most of the genes in the eukaryotic cell.
if not in the nuclues, where are the other genes?
mitochondria and chloroplasts
What are mitochondria and chloroplasts surrounded by?
a nuclear envelope which seperates its contents from the surrounding cytoplasm.
How is DNA organized in the nucleus?
into discrete organisms called chromosomes