Cell Biology: Understanding Cells, Their Components and Functions, Slides of Cell Biology

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Cells

and Cell Components

Assoc. Prof. Bengi ÇINAR KUL

Robert Hooke (mid-1600s) Observed the cork Saw “row of empty boxes” Coined the term cell

Cell Size

Cell theory was put forward

in the early 19th century ....

Matthias Schleiden, Theodor Schwann, and Rudolf Virchow. Together, these scientists put forth the three basic rules:

• All living things are made up of cells.
• Cells are the basic units of structure and function in living things.
• Living cells come only from other living cells.

• Cells are alive Have independent metabolic activities can be replicated can produce and use energy Viruses?...

Viruses are non-cellular organisms that can only grow in a host cell.

• Genetic material is single or double-stranded DNA or RNA in a protein sheath.
• shapes and compositions show diversity
• They developed special mechanisms for infecting host cells. However;
• Viruses don't exist as cells and are not made up of cells (Cell theory, Rule 3).
• the viruses are alive, in that they have DNA and can infect other living things, but they have to use a hosts cells to replicate (Cell theory, Rule 1)

Cell Types

❑ Eukaryotic ❑^ Prokaryotic

Prokaryotic Cells

First cell type on earth Cell type of Bacteria and Archaea

• No membrane bound nucleus
• Nucleoid = region of DNA concentration
• Organelles not bound by membranes

Some bacteria cause inf. disease, but most are beneficial.

Genetic material in prokaryotic cells

• Single
• Circular
• Associated with a small number of proteins
• It does not include nuclear membrane
• There are many ribosomes in the cytoplasm.
• No introns in the DNA. Just exon !!!

Eukaryotic Cells

• Contain organelles surrounded by membranes
• Contain chromosomes
• Most living organisms, include fungi, protists, plant, and animal cells Plant (^) Animal http://library.thinkquest.org/C004535/eukaryotic_cells.html

Representative Animal Cell

Organelles

• Cellular machinery
• Two general kinds
  1. Derived from membranes
  2. Bacteria-like organelles (mitoch, chloropl)

• Genetic material is DNA
• The main difference between eukaryotic and prokaryotic cells is that eukaryotic cells have a nucleus
• Genomic DNA enclosed within the nucleus which is located in the cytoplasm
• Nucleus has a membrane and tiny pores, selectively permit certain macromolecules to enter and leave the nucleus
• DNA has exons and introns. .