Topic 1 Flashcards
What are cells
• Cell: membrane enclosed unit filled with an aqueous solution of chemicals
• Cells create identical copies of themselves
- Through growth and division
- not all cells divide, neurons and blood cells don’t
• Cells are diverse
• Estimated 100 million species of life on Earth
• Ranges from single celled organisms to complex organisms consisting of many cells.
- Human bodies have 30 trillion cells
• Cells from organisms are diverse
• However, they are very similar in terms of how they work.
Cells vary in type
• Celltype: Prokaryotic and Eukaryotic
• Prokaryotes: include bacteria and archaea
• Eukaryotes: include animals, plants, fungi, protists
• Prokaryotes tend to be smaller and exist as single celled organisms
- no nucleus but have genome
• Eukaryotes (by definition) contain membrane enclosed organelles
- Organelles provide specialized functions within these cells
- nucleus with genome in it
- more complex
Cells vary in form (appearance)
Diversity of eukaryotic cells
• Difference in size
• Difference in form is related to function
- Neurons communicate by sending and receiving
information long distances
- Paramecia move using cilia that cover their membrane surface
Both have diff structures due to diff functions
How do researchers study cells?
Model organisms
• Information gained from the study of one organism can be used to understand a different kind of organism
Reasons for using model organisms
• Use mechanisms similar to humans
• Fast rate of reproduction
• Ease of genetic manipulation
• Large number of offspring produced (sample size)
• Cost and space of housing
• Ethical considerations
Examples
• Mice, zebrafish, frog, chick, worms, fruit flies, yeast, bacteria, Arabidopsis (plant)
• Computer modeling, cell culture
Cells are chemically similar
Cells are composed of the same kinds of molecules that are
• Structurally similar
• Have similar functions
• Involved in similar chemical reactions that drive cellular functioning
Biological (macro)molecules
• Carbon based small molecules are used for cellular energy and as building blocks for macromolecules
• Covalent linking of monomeric chemical subunits creates polymeric macromolecules
- Function of macromolecules is based on the specific sequences of the subunits
• Genetic information is stored as DNA in cells
- Prior to cell replication, DNA is copied (duplicated)
- DNA information is ‘decoded’ and used in cells through the processes of transcription and translation
• Researchers can manipulate these normal cellular processes to produce and modify proteins of interest or to inhibit the expression of specific proteins
Central Dogma: Flow of Genetic Information
• Replication
- DNA strands separate from each other and each is used as a template for new strand of DNA. G - C (3 bond), A - T (2 bond)
• Transcription
- DNA information is used as a template to make a complementary RNA copy
• Translation
- Process that converts nucleotide sequence of mRNA into a specific linear sequence of amino acids, creating a protein
• DNA→RNA→Protein
Central dogma is the basis of cell replication
• Positive feedback loop
- DNA information directs the synthesis of proteins
- Proteins are required to catalyze the replication of DNA and the transcription (synthesis) of RNA
Summary
• Life forms are diverse, but their cells are chemically and functionally similar
- Understanding how cells work is critical for our ability to treat diseases, increase food resources, etc.
• Information learned about cellular processes in one cell type can often be applied to another cell type
• In this course: we will discuss some of the approaches/techniques used to study the function of cells
